Micro Midterm Test Questions – Flashcards
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| Which are the three domains in which prokaryotes as well as all living organisms are classified. |
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| 1.Bacteria- all pathogenic bacteria 2. Archea- type of bacteria but not associated with any disease. 3. Eukarya- Algae: protozoa. Fungi- Large parasites. Animalia, Plantae. |
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| Types of microscopes |
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| 1. Light Field- Resolution limited to wavelength of resolution. Visible light wavelength= 0.2 um. 2.Dark field- uses dark field condenser. used for visualizing small and slender organisms (spirochetes) Oblique source of light gives images against a dark field. 3. Fluorescent- source of light is ultraviolet. 4. Electron- transmission- sees internal details. Scanning- sees outer details. Scanning with flying spot of electrons. |
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| Gram Staining Procedure |
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| Bacteria on glass slide-> heat fixed or dip in 95% ethano/methanol- 5 min. air dry -> stain (crystal or methyl violet)-> flood with PKI (Grams Iodine) solution -> wash with DH2)-> decolorize 95% (ethyl alcohol) -> counter stain (saffranin for 20-30 secs) Then blot dry and examine. |
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| Gram Negative/Positive Stains |
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| Gram (+) Retains basic dye (violet) Gram (-) Does not retain violet- red-pink. Differences in G+ and G- are in cell wall. |
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| Shapes of Bacteria |
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| Rod- Bacillus Sphere- Coccus Spiral or curved- Spirochete (spirillium, vibrio) |
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| Size of Bacteria and examples |
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| Large: Spirochetes, Bacillus, Clostridium Medium: Enterobacteriacea, pseudomonas Small: Brucella, Pasteurella, Haemorphiles, Cocci. Pinpoint- Rickettsia, Chlamydia, Mycoplasma. |
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| Structure: Capsule |
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| Composed of polysaccharides and polypeptides. Virulence- relationship antiphagocytic activity adherence to cells for colonization *in starvation situations, can consume plasmid for nutrition. |
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| Structure: Cell Wall |
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| Composition- macetyl muranic acid, N-actylglucosamine. 20% weight in bacteria is cell wall. |
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| Function of Cell Wall |
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| 1. Rigid shape (peptidoglycans) 2. Prevents osmotic lysis 3. Responsible for virulence 4. Site of antibiotics action 5. G(+) thick peptidoglycan, G(-) Thin peptidoglycan. |
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| Structure: Flagella |
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| (H antigens) for motility. Locomotion or motility. Spirochetes- axial filaments for locomotion. Capsulated bacteria are non-motile. |
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| Structure: Axial Filament |
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| in spirochetes for mobility |
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| Structure: Fimbriae |
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| Colonizing factor or adherence |
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| Structure: Pili |
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| Conjugation: transfer of plasmids and genes in bacteria. Antibiotic resistance and toxic gene transfer. |
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| Structure: Endospores |
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| (clostridium and bacillus anthracis) Resistance- spore coat- resistant to UV rays. Boiling and autoclaving will destroy endospores. |
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| Structure: Plasmids and chromosomal DNA |
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| selective permeability and antigens and antibiotic actin site. |
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| Structure: Ribosomes |
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| Site of protein synthesis. Antibiotic action site. |
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| Major cell wall differences between gram positive and gram negative bacteria |
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| peptidoglycan, outer membrane |
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| Fungi |
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| Multicellular filamentous mold |
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| Yeast |
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| unicellular form |
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| Fungal Structures |
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| 1. Capsule- antiphagocytic 2. Cell wall- chitin, no peptidoglycans as seen in bacteria. 3. Cytoplasmic or plasma membrane. |
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| Target of Antifungal Drugs |
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| Zymasterol and Ergosterol- sterols in cell wall of fungi. |
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| Based on nutritional requirements, all microorganisms can be grouped as: |
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| a) photosynthetics - Cyanobacteria (blue-green algae) b) autotrophs c) heterotrophs – saprophytes. strict parasites. most pathogens |
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| Temprature based groups of bacteria |
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| a)Psycrotrophs (20-30C) * examples: L. monocytogenes b)mesophils (30-40C) * comprises all pathogens c) thermophils (50-90 C) |
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| Chemical and Physical requirements of growth |
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| Temperature, pH concnetration, CO2 Requirement, Oxygen requirement, Movement or Transport of Nutrients into the cell. |
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| Five groups based on O2 requirement- definitions |
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| a)obligate aerobe- can only grow in air. b)facultative anaerobe- all enterics c)microaerophil- ex. Campylobacter fetus. d)strict anaerobe- ex. Clostridium botulinum. e)aerotolerant aerobes- ex. Lactobacilli |
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| Oxygen toxicity |
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| enzyme to neutralize this. 1. superoxide dismutase. 2. catalase. 3. peroxidase. |
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| Transport of nutrients across plasma membrane of bacteria |
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| 1. Passive Transport- diffusion, osmosis. 2. Active transport- requires energy and carrier protein. *plasma membrane- selectively permeable. 3. Facilitated diffusion- requires carrier proteins. (group translocation (on found in bactera) Glucose outside the cell) |
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| Cellular metabolism |
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| production energy. Synthesis of bacterial components- proteins, lipids, DNA, RNA, carbohydrates. |
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| Catabolism |
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| (metabolism) degradation or decomposition or break down or hydrolysis of complex organic molecules. Produces energy- ATP. 1.Glycolysis 2. Krebs cycle |
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| Anabolism |
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| synthesis of bacterial components |
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| Enzymes |
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| Biological catalysts |
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| Protein |
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| Carry all synthetic and decomposition reactions. |
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| Most ATP is produced by which pathway: |
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| Electron transport chain |
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| Aerobic Respiration |
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| Oxygen as final electron acceptor. |
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| Anaerobic respiration |
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| Nitrate (NO3), Nitrite (NO2), CO3, SO4 are electron acceptors. Inorganic compounds as electron acceptors. |
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| Electron Carriers |
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| NAD+, NADP+, FAD+. Produce ATP Facultative anaerobes (enteric bacteria) |
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| Fermentation |
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| Anaerobic process. ) No O2 required b) inefficient energy production c) useful products, ex: wine, beer, vinegar, yogurt, etc |
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| Anabolism” and “catabolism” relationship to ATP? |
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| Catabolism: produces ATP Anabolism: ATP consumes |
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| What are the different types of media? |
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| Liquid Media- broth. Solid Media- Agar. Selective Media- promotes growth of certain bacteria, inhibits others. Enrichment Media- helps non-special bacteria gow. Differential media- differentiates between two types of bacteria on same culture plate. |
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| Bacterial Growth Curve |
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| Generation time. 1. lag phase. 2. log phase. 3. stationary phase. 3. death or decline phase. |
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| Parasitism |
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| Organisms live on or within another living organisms. Parasite benefits at the cost of the host. only small number cause disease. |
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| Commensialism |
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| Organsims- host- no disease. Organsim benefits, host does not. Potential pathogens- staphylococcus- mastitis. |
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| Opportunistic Pathogen |
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| generally commensal but under stress may cause disease. E-coli: urinary tract infection. |
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| Obligate Pathogen |
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| almost always cause disease. Ex. Brucella abortus. Mycobacterium paratuberculosis. |
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| Pathogenicity |
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| capacity of an organism to produce disease. |
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| Virulence |
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| Degree of pathogenicity |
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| Exotoxins |
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| excreted proteins. formalin treated- toxoids (inactivated). Protein in nautre. Vaccine effective. Highly toxic. Gram (+) Bacteria. |
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| Endotoxins |
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| Produced by Gram negative bacteria. Part of cell wall (not excreted) Lipopolysaccharide in nature (lipid A). Vaccine not effective. Poor antigens. Causes fever, shock and tissue inflammation. |
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| Carrier |
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| State of an animal |
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| Incidence |
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| New cases at a given point of time |
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| Prevalence |
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| all cases at given time taken into account. |
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| Latent or inapparent infections |
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| EX. Brucella |
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| Primary Agent of Disease |
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| Organism that initiates disease. EX brucella abortis. |
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| Secondary invader |
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| Follows primary agent. Could not have killed without primary agent. EX. Pasteurella mulocida-pneumonia. |
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| Entry by Preferred Route |
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| Respiratory Tract, GI tract, Urogenital Tract, Conjunctiva. |
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| Adherence |
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| Fimbriae/capsules |
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| Different types of Damage to Host |
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| Direct (Invasion) Localized abscess/ulcer. Production of enzymes (hemolysin, leukocidin, collagenase, streptokinase, etc) |
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| What are major portals of entry of different microorganisms? |
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| mucous membranes of: Respiratory tract, Digestive tract, Urogenital tract, Conjunctiva 2. broken skin 3.parenteral route by vector bites or by accidental puncture wounds |
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| Various structures and factors that enhance microbial pathogenicity |
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| a)capsule b)extracellular enzymes c)adherence colonization by fimbriae (adhesions), Pili, capsules |
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| Koch's Postulates |
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| 1. Organisms must be regularly isolated from disease. 2. Organisms must be isolated in a pure culture. 3. Such culture should produce typical disease in susceptible animals. 4. Same organisms must be isolated from these animals. |
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| Koch’s postulates: What does it establish? |
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| it proves conclusively that microorganisms causal role in disease. |
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| Defenses of Host: Non-Specific |
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| 1. Phagocytic cells (neutrophils, macrophages). 2. Complement system. 3. Interferon |
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| Defenses of Host: Specific |
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| 1. B-lymphocytes produce antibody. 2. T-lymphocytes: cytotoxic T-cells: 1. recognize hidden intracellular infected organism within cells. 2. Kills them and kills cancer cells. |
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| Streptococci Principle Characteristics |
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| Gram(+). Nonmotile. Nonsporing cocci. Occurs in pairs, single or chains. Facultative anaerobic, aerobic. CATALASE (NEGATIVE), OXIDASE (NEGATIVE). Lactose Fermenting. |
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| What is the basis of Lancefield classification of streptococci? |
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| Based on Component C (polysaccharide in cell wall) Done by ring Precipitation Test. 30 min- tube. |
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| Hemolysis type of on Blood Agar |
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| Beta- Complete lysis. Alpha- Greenish zone around colony. Gamma- Non hemolytic. |
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| What is the basis of Lancefield classification of streptococci? |
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| Based on Component C (polysaccharide in cell wall) Done by ring Precipitation Test. 30 min- tube. |
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| What are the 3 Genera of Streptococci |
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| 1. Streptococcus. 2. Enterococcus- Opportunistic Pathogen, bile salt resistant, grow on McConkey Agar. 3. Peptostreptococcus- anaerobe, |
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| Mode of Transportation for Streptococci |
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| 1. Endogenous 2. Exogenous- inhalation, ingestion, aerosol, direct contact, fomites. |
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| Streptococcus pyogenes |
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| sore throat – scarlet fever, flesh eating necrotizing fascitis in humans |
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| Streptococcus agalactae |
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| highly contagious mastitis |
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| Strep porcinus |
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| jowl abscess |
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| Streptococcus suis |
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| meningitis, arthritis |
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| Enterococcus faecalis |
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| urinary infections, endocarditis |
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| Streptococcus dysgalactiae, Streptococcus uberis |
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| mastitis |
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| Streptococcus equi |
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| strangles in horses |
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| Staphylococcus aureus |
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| – bovine (Botryomycosis) mastitis, food poisoning, toxic shock syndrome |
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| Staphylococcus hyicus |
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| greasy pig disease syndrome |
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| Strangles |
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| Highly Contagious, fever, abscess of cervical and submandibular lymph nodes, upper resp. infection. Lymph nodes may rupture, depression, anorexia. Transmission: inhalation, contact with discharge. Gutteral Pouch (carriers). |
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| Staphylococci Principal Characteristics |
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| Gram(+) cocci. Pairs, chains, clusters. Aerobic-f acultative anaerobe. Catalase (+) Oxidase (-). Non-motile, non spoirng, lactose fermenter. |
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| Habitat of Staph Aureus |
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| Commensal skin and mucous membrane of upper respiratory and GI tract. |
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| Staph. Aureus: Time, Signs, Foods |
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| 1-6 hours. Vomiting, nausea, diarrhea. Milk products, cream, ground meat. |
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| Salmonella: Time, Signs, Food |
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| 24-48 hours. Nausea, vomiting, diarrhea. Improperly cooked food/meat, water. |
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| Hemolysins of Staphlococci |
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| alpha hemolysin: rabbit erythrocytes: inner clear zone. Beta Hemolysin: sphingomyelinase C. |
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| Possible Factors synthesized and excreted from Staphlycocci |
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| 1. Coagulase (Plasma clotting- related with pathogenicity) 2. Enterotoxins 3. Hemolysins 4. Lipase 5. Staphylokinase (degrades fibrin) 6. Leukocidin 7. Exfoliative toxin 8. Hyleuronidase 9. Penicillinase (B-lactamase) 10. Protein A |
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| Pathogenesis of Staphylococci |
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| Pyogenic response, Capsule, Toxins, Generally immunocompromised host defense or stress, Abscess, Septicemia. |
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| Pathogenicity of Staphylococci |
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| Botryomycosis (chronic granulomatous lesion of udder of mare, cow, sow) Pyoderma of dogs, Bovine mastitis, Otitis, Arthritis, Urinary infections, Enterocolitis, Impedigo. |
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| Staph. Intermedius- Hemolysis, characteristics and types. |
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| B-hemolytic, Gray non-pigmented. Two types: Poly P- dog strains. Poly C- region strains. |
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| Staph. Hyicus |
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| Swine pathogen "Greasy pig disease" or exudative dermatitis. |
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| Micrococci |
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| Non-pathogenic, usually pigmented, Needs to be differentiated from S. aureus. |
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| Corynbacteria principal characteristics |
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| Gram(+), Small rods, Pleomorphic (Chinese letter arrangement), non-motile, non-sporing, facultative anaerobic, Catalase(+), Lactose fermentor. |
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| Species of Corynebacteria |
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| C. diphtheriae (human diphtheria), Corynebacterium renale (cystitis, urethritis, polynephritis in cows, kidney abscess in swine). C. pylosum and C. cistitidis. |
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| Habitat and Mode of transmission of Corynebacteria |
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| Male and female genital tract. Mode of transmission is venereal, contaminated urine. |
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| Mode of infection of Corynebacterium pseudotuberculosis |
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| Abraded skin or injury and inhalation |
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| Pathogenicity of Corynbacterium pseudotuberculosis |
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| Sheep and goat- caseous lymphadenitis- green pus. Cattle, horses and mules- Ulcerative lymphangitis. |
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| Identification of Corynebacterium pseudotuberculosis |
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| Nitrate reduction. Cattle and horses (positive). Sheep and goats (negative) |
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| Rhodococcus equi Principal Characteristics |
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| Gram(+), pleomorphic rods, non-lactose fermenter, catalase (+), Urease (+_, Colonies -pink pigment. Mucoid. |
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| Habitat and Mode of infection of Rhodococcus equi |
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| Habitat- horse feces and soil. Mode of infection (young foals common) inhalation or direct contact. Older horses: Carriers- transmit infections to foals. |
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| Pathogenicity and pathogenesis of Rhodococcus equi |
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| Supportive bronchopneumonia (foals) submandibular and cervical lymph node involvement. abortion in mares. |
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| Listeria Principal Characteristics |
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| Gram(+), small rods, motile at room temperature, catalase (+), oxidase(+). |
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| What is the Causative agent for Listeria |
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| Listeria monocytogenes- beta hemolytic, L. ivanovii (pathogenic) |
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| Habitat and Mode of infection of Listeria |
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| Silage (when pH rises above 5.5- bacteria multiplies in silage) Mode of infection- Neural form: mucous membranes of eyes, nose and throat. Visceral form: ingestion. |
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| What is that Pathogenicity and Pathogenesis of Listeria |
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| 1. Neural form (circling disease: cattle sheep and ruminants. Higher incidence in winter and early spring on feedlots. CNS involvement- unilateral ataxia, meningitis. 2. Visceral form: abortion in cow, mares, sows and humans, chicken and turkeys- septicemia. |
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| peScimen of Listeria |
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| 1. Neural form: brain- pons and medulla. 2. Visceral form: abortion- fetus and fetal membrane. |
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| Differential Diagnosis of L. monocytogenes and Erysipelothrix rhusiopathiae |
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| L. monocytogenes- Catalase (+) Motility (+) Culture bio (lethal) Erysipelothrix rhusiopathiae- catalase (-) motility (-) Culture bio (non) |
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| Erysipelothrix Principal Characteristics |
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| Gram (+), small rods, non-sporing, Catalase (-) |
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| Considerations for optimal bacterial growth |
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| a. appropriate conditions of moisture b. pH-optimal is neutral 7.2 c. Temperature- optimal is 37C or 98.6F d. Osmotic pressure e. Atmosphere f. Nutrients |
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| Bacteria increase in numbers througha process known as: |
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| Binary fission |
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| What is Generation time |
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| It is the amount of time that is required for 1 bacterium to yield 2 daughter cells. Genetics and nutrition influence this process. |
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| Bacterial Growth Graph |
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| Lag- aquire essential constituents prior to division. Exponential- binary fission is taking place. Stationary- essential nutrients start to deplete, replication slows. Decline- Death of bacteria |
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| What does "Aerobe" mean? |
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| Bacteria that requires oxygen. |
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| What does Microaerophilic mean |
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| Bacteria that requires reduced oxygen levels for growth |
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| What does Obligate Anaerobes mean? |
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| Bacteria that is unable to grow in oxygen |
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| What is facultative anaerobes |
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| Grow both in presence or lack of oxygen |
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| What is capnophils? |
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| bacteria that is aerobic, also requires carbon dioxide. |
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| What are the different FORMS of Media |
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| Liquid, Solid, Semi-solid |
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| Liquid media |
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| Broth is used for growing large amounts of bacteria. Liquid cultures are used in inoculating biochemical tests as well. |
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| Solid Media- reasons for concentration. |
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| Made from agar, which is used as a solidifying agent. Agar is an agent extracted from algae and usually added to broth at a concentration of 1.5% to make a solid agar plate. Two reasons for this concentration: 1. Wet enough to support bacterial growth. 2. Dry enough to keep colonies separate. |
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| Semi-solid media |
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| Type of liquid medium where agar is only added at a concentration of 0.5%-jello before it is refrigerated type consistency. Media used to test specific bacterias ability to utilize sugars. |
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| Types of Media |
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| Basic, Differential, Selective. |
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| Basic type of Agar |
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| Media will support aerobic growth of gram(-) and gram(+) bacteria. ex. Sheep blood agar |
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| Differential type of agar |
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| media which display a visible difference between colony types. Usually by color. Ex. Eosin methylene blue |
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| Selective type of Media |
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| Media in which specific inhibitors are added to prevent the growth of organisms you do not wish to grow. ex. Eosin methylene blue or phenylethanol agar. |
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| Methods to achieve selective media: |
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| pH adjustment (high or low can be inhibitory to bacterial growth) Addition of antibiotics (certain drugs will affect bacterial growth) Addition of growth inhibitors (Such as eosin dye, methylene blue and phenylethanol) |
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| Nutrition Agar |
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| Provides essential nutrients for growth of non-fastidious bacteria, not suitable for fastidious organisms. Suitable for demonstrating colonial morphology and pigmentation. Solid/Basic. |
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| Sheep Blood Agar |
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| Made from 5% defibrinated Sheep blood. Media which will support growth of both gram (-) and gram (+) organsims. Support and enhance growth of organsims, will determine patterns of hemolysis. |
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| Interpretation of Hemolysis looking at the Bottom of Agar |
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| Alpha- colonies surrounded bya zone of intact but greenish RBCs. Beta- colonies surrounded by a clear zone with no intact RBC's. Gamma- colonies do not change appearance of the RBCs (NO hemolysis) |
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| Chocolate Agar |
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| Heeat treated blood agar, red blood cells are lysed which releases 2 factors. X and V factors. Solid/ selective and Basic. Specific for haemofelis species. |
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| MacConkey Agar |
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| Contains bile and lactose which is useful in isolation of enterobacteria and other gram (-) organisms. Will differentiate between lactose fermentors and non-lactose fermenters. Solid/slective and differential. |
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| Interpretation of Colors on MacConkey Agar |
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| Colonies of lactose fermenters and surrounding medium are pink. Non-lactose fermenters impact a yellow color to the medium. |
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| Eosin Methylene Blue Agar |
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| Made with eosin dye and methylene blue. contains lactose and sucrose. will not grow gram (+) organsims. Isolation of gram (-) bacteria from contaminated sample. Differentiation of lactose fermenting from non-lactose ferming microorganisms. |
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| Interpretation of growth colors on EMB |
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| Blue/black colonies (strong lactose/sucrose fermentation)= STRONG LACTOSE FERMENTER SLF. Dark pink/dark center (lactose ferementer LF) Pink mucoid colonies (Weak lactose fermenter- WLF) Amber/colorless colonies- No fermentation of lactose/sucrose (Non-lactose fermenter- NLF) |
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| Colonial Description On EMB plate |
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| Color (Pink, purple, black, reen metallic sheen, translucent, amber, pink/purple) Carbohydrate fermentation (SLF, LF< WLF, NLF) Size, Texture, Border of the colony |
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| KOH test |
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| Reagent- Potassium hydroxide. Positive= stringy= Gram (-)....Negative=not stringy= Gram(+) |
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| Opportunistic Pathogen |
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| An infectious microorganism that is normally a commensal or does not harm its host but can cause disease when the host’s resistance is low. |
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| Lactose Fermenters are found on what plate |
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| EMB |
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| Streptococci- Gram Reaction. Group contains Shape Catalase |
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| Opportunistic pathogen Group contains: Streptococcus, Enterococcus (aerobic) Petptostreptococcus (anaerobic) Gram (+) Cocci Catalase - |
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| What are the types of differentiation tests that ID Streptococcus spp. from Enerococcus spp. |
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| 6.5% NaCl and PYR Test (pyrrolidonyl Arylamidase) |
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| 6.5% NaCl test- What does it do and what do the results mean? |
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| Will determine the salt tolerance of an organism. If salt can be tolerated the organism will grow and break down dextrose to produce an acidic pH. Positive= Growth of organism. Color= yellow. Enterococcus spp. Negative= No growth of organism. Color= Purple. Streptococcus spp. |
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| Positive 6.5% NaCl test |
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| Growth of organsim. Color= Yellow Enterococcus spp. |
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| Negative 6.5% NaCl test |
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| No growth of organism Color= purple Streptococcus spp. |
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| PYR test- what does it do and what do the results mean? |
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| The presence of amino peptidase enzyme results in a pink color with indicator. Positive= Cherry pink/red= Enterococcus spp. Negative= No color change= Streptococcus spp. |
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| Susceptibility test for Streptococcuswith Vancomycin 30mcg disk |
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| Vancomycin is an antimicrobial agent. Test is used to determine whether the specific bacteria that you are testing is Sensitive to this specific antibiotic. |
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| Interpretation of Susceptibility Test- Vancomycin 30 mcg disk |
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| Sensitive (s)= zone of inhibition around the organism. Enterococcus spp. and Streptococcus spp. will be sensitive to 30 mcg. Vancomycin disk. Resistant (r)= No zone of inhibition around the organism. |
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| What is the CAMP test? What is it used to identify? |
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| Determine the ability of an organism to produce an elaborate CAMP factor protein which acts synergistically with Staphylococcus aureus. Used to identify Streptococcus agalactiae |
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| Interpretation of CAMP test |
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| Positive= Production of an arrowhead zone of complete hemolysis located at the juncture of Staph and Strep. Identifies= streptococcus agalactiae. Negative= No arrowhead zone of hemolysis. NOT streptococus agalactiae. |
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| Catalase Test- What is it and what does it mean? |
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| An enzyme produced by anaerobes and facultative anaerobes, that causes the breakdown of hydrogen peroxide to oxygen and water. A positive oxidase test indicates the presence of cytochrome oxidase C in the bacterial cell. DO NO STAB AGAR TO COOL. Interpretation: Postive= bubbling Negative= No bubbling |
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| Example of Catalase test |
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| Streptococci spp= Negative Paseurella spp. = Positive. |
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| KOH test |
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| Potassium hydroxide. Used as a back-up to gram staining procedure. Gram(-) cell wall is destroyed when KOH is introduced and results in the liberation of viscid DNA. |
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| Oxidase Test- what it is and what is the interpretation |
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| Determines the presence of Cytochrome Oxidase enzymes. Watch for color change. Positive= A dark purple color will be produced within 10-30 seconds. Micrococcus spp. will yeild positive results. Negative: The organism will not turn purple before 30 seconds. Staphylococcus spp. will yield positive results. |
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| What are some factors that cause G(+) bacteria to appear G(-)? |
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| 1. Culture Age: As bacteria ages they lose their ability to retain Primary Stain. 2. Over-Decolorization: Crystal Violet may wash off with too much alcohol. 3. Over Rinsing: too much time spent rinsing with water can wash cells off the primary stain. |
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| Factors that cause G(-) bacteria to appear G(+) |
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| Over-crowding: Too much bacteria on microscope slide. |
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| Primary Stain |
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| Crystal Violet- Imparts blue color to all cells |
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| Grams Iodine |
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| Improves bonding between stain and specimen |
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| 95% Ethyl Alcohol |
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| Removes color from G(-) organisms, G(+) will remain blue |
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| Safranin |
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| G(-) bacteria turn pink, G(+) remain blue. |
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| Staphylococci Group Gram Stain Catalase |
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| Opportunistic- most cause skin issues Gropu contains the genera Staphylococcus spp. and Micrococcus spp. Gram (+) cocci Catalase (+) |
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| Differentiation tests for Staphylococci |
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| Susceptibility Test- Bacitracin and Furazolidone Oxidase Test Accu-Staph API-Staph |
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| Susceptibility Test for Staphylococci - Bacitracin 0.04 unites disk and Furazolidone 100 mcg disk |
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| Sensitive (S): Zone of inhibition around the organism. MICROCOCCUS SPP. sensitive to BACITRACIN STAPHYLOCOCCUS SPP. sensitive to FURAZOLIDONE. Resistant (R): No Zone of inhibition around the organism. MICROCOCCUS spp. resistant to Furazolidone STAPHYLOCOCCUS spp. resistant to BACITRACIN |
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| ACCU-STAPH |
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| Latex Slide Agglutination. Positive= Red clumps of agglutination- staphylococcus aureus. Negative= no agglutination- not staphylococcus aureus. |
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| Corynebacterium pseudotuberculosis |
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| Causes lymphadentitis, infection spreads via the lymph nodes. Colonies are more easily observed in 48 hours. Bacilli- Chinese letter arrangement- palisades. Small, dry, crumbly small zone of beta hemolysis. GRAM + CATALASE + |
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| Rhodococcus equi |
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| Formerly in the Corynebacterium genus. Causes pneumonia in foals.GRAM + CATALASE + Colonies are more easily observed in 48 hours Small rods, gamma hemolytic. |
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| Listeria monocytogenes |
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| Causes meningitis, encephalitis, uterine infections with abortions, still births, etc. GRAM + CATALASE + |
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| What is the Cold Enrichment Procedure for detection of Listeriosis? |
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| OLD METHOD- Organisms are intracellular. 1. Grind brain up in enrichment broth. 2. Store in fridge for 12 weeks. 3. Reculture each week for 12 weeks. |
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| Bacillus spp. |
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| Causes multiple issues including abortions, mastitis, food poisoning. Beta or Gamma hemolytic. GRAM + CATALASE + |
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| Bacillus anthracis-- how is it acquired? |
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| Very important pathogen. ANTHRAX. Death will result if not treated. Acquired by: 1. Inhalation 2. Ingestion 3. Wounds 4. Simple scratch. GRAM + CATALASE + |
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| Dermatophilus congolensis |
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| Gram + Bacilli, Catalase - Causes skin infections forming crusts. Direct Examination: 1. Scabs/hair are softened with DH20 in CO2 for 20 minutes. A scum will come to the surface of the water Plate the culture material. Remove the softened, scabs and mash between two slides and air dry Giemsa stain. Examine for morphology. "Train Track" Morphology- double row of coccoid spores called zoospores. |
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| What does TSI do? |
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| Triple Sugar Iron- will detect the fermentation and gas production from glucose, sucrose and lactose. Will also detect H2S production. Sucrose and Lactose in the slant. Glucose in the Butt. Na thiosulphate and Ferrous sulfate detects H2S production. Acid (A) yellow Alkaline (K) red |
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| Interpretation of TSI- Slant |
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| Red=K- no utilization of sucrose and lactose Yellow= A- Utilization of sucrose and lactose. |
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| TSI interpretation- Butt |
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| Red= K- No utilization of glucose Yellow= A- Utilization of glucose |
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| TSI interpretation- Gas |
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| Bubbles/ Splitting of Media= Gas production No Bubbles/ Splitting= No Gas Production |
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| TSI interpretation- H2S |
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| Black Precipitant= H2S production No Black Precipitant= No H2S production |
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| TSI Total Interpretation |
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| Slant/Butt/Gas/H2S EX. A/A/-/+ |
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| McFarland Standard |
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| 0.5=1.5 1=3 2=6 3=9 4=12 x 10^8/mL |
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| Indole Test |
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| Positive – a pink color 2. Negative – no pink color/ remains buff-yellow |
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| differential characteristics between B. anthracis and B. cereus. |
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| B. cereus- motility, capsule, penicillin susceptiblity, aerobic/facultative anaerobic. Clostridium- anaerobic, endospores (anthrax). |
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| Why is necropsy not recommended for an animal dying of anthrax? |
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| Because of inhalation mode of transmission. Spores can be released when opened. |
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| Components of anthrax toxin and their specific role in pathogenesis of disease. |
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| -Exotoxin -Capsule -All virulent straisn- capsulated an produce toxin. Peracute- Septicemia (bleeding from nose and mouth) Acute (cattle, sheep, horses) Chronic- cutaneous form Cuatneous- 90% humans Lethal if pulmonary. |
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| f) What is “string of pearl” test and what specific bacteriophage is used in typing of B. anthracis? |
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| Penicillin -Gamma phase lysis- positive -F.A> test. -Animal inoculation- guinea pig. PCR test. |
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| Environmental resistance of bacteria and its spores |
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| Endospores- highly resistant drying presence in soil, freezing- several years. boiling destroys bacteria in 10 minutes. 10-20% formaldehyde or 2% gluaraldehyde- 10 minutes. autoclaving- 15 lbs pressure for 15 minutes!!! |
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| How would you properly dispose an animal that dies of anthrax? |
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| Animal Carcasses- buried 6 feet in the ground with lime which will degrade animal and kill bacteria. |
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| Which vaccine is currently used for vaccination of cattle? |
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| Avirulent spore vaccine (stern's non-capsulated strain) |
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| What is the typical colony characteristic of most of corynebacterial colonies on blood agar plates? |
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| Blood agar- sticky colonies: Coryne ID. |
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| Difference on EMB agar of E. coli and Salmonella |
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| E. coli- lactose fermenter- metallic sheen greenish/blue colonies. Salmonella does not ferment lactose= clear colonies. |
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| Serotyping of Enterobacteria |
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| O= Antigen- cell wall H= Antigen- flagellar (E.coli) K= kapsular F= fimbrial P= Pili |
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| Escherichia coli |
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| Causes wide variety of infections in many animals. Some strains pathogentic Ferments lactose. EMB agar= metallic sheen McConkey agar= pink Serotyping- using O, K and H antigen which indicates virulence |
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| Fimbriae of E. Coli |
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| very important for attachment and colonization of pathogenic strains. |
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| Enterotoxigenic E.Coli strains |
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| diarrhea in young claves, pigs, lambs and post weaning diarrhea in pigs. Produce enterotxoins LT= heat Labile- enteritis ST= Reduce absorption Cary adhesions: F4 (K88) F5 (K99) F6 (987P) toxins. |
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| Enteropattogenic E. coli strain |
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| diarrhea pigs, lambs, pup. Produce intiminan adhesion. Attaching Effacing Destruction of microvilli: maldigestion/malabsorption. |
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| Verotoxigenic E. Coli |
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| Hemolytic urimic syndrome. SLT= shiga like toxin. |
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| Necrotoxigenic E. Coli |
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| Hemorrhagic colitis in cattle, enteritis in piglets and calves, diarrhea in rabbits, dysentery in horses. Bind Enterocytes- produce CNF1 and CNF2 CNF= Cytotoxic Necrotizing factore. |
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| Salmonella |
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| Gram - rods Nonlactose fermenter Most are motile More than 2400 serotypes Two species: 1. S. bongori 2. S. enterica All animal and human pathogens. |
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| Pathogenicity |
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| Invasive intracellular parasite Attach, resist phagocytosis and compliment mediated lysis Virulence factors include Endotoxins which also damage intestinal epithelial cells. |
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| Clinical infections of Salmonella |
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| Localize in mucosa of ileum, cecum and colon, mesenteric lymph nodes. |
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| ENteric Salmonellosis |
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| all ages, all species. |
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| Carrier state of salmonella |
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| Enteritis. Adults can be source of infection of young animals |
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| Public Health Significance of Salmonella |
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| Reservoir and sources of infection: Domestic animals, wild animals, humans all develop carrier state. Other sources: feces of humans and animals, eggs, egg products, milk and meat products. |
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| Transmission of Salmonella |
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| Ingestion (epidemics tracable to food products and contaminated water, carrier food handlers, equipment and utensils. |
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| 3 species of Yersinia |
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| 1. Y. pestis 2. Y. pseudotuberculosis 3. Y. enterocolitica |
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| Yersinia pestis |
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| Causes plague in rodents and humans. Humans are accidential hosts (flea transmits) found in man animal species. |
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| Escherichia: Immunity, Bacterins, Fimbriae |
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| Immunity: Antigenically heterogeneous Bacterins: limited usefulness Fimbriae: pilus vaccine useful because it prevents attachment and colonization. |
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| Salmonellosis: Immunity, Bacterins, S. typhimurium |
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| Immunity- cell mediated mainly Bacterins: limited value S. typhimurium: attenuated live vaccine used in cattle in england. |
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| Pathogenesis of Y. pestis |
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| Exotoxin found in all virulent strains. 2 forms: 1. bubonic form- lymph nodes leads to 2. pneumonia form- highly contagious and if not treated- fatal. |
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| Mechanism of transmission of sylvatic/or jungle plague to humans? |
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| Sylvatic plague-fleas-rodents-fleas-humans-sylvatic plague occurs in several states in sparsely populated rural areas. |
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| Two major differences between Y. pestis and Y. enterocolitica |
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| Y. enterocolitica does not affect animals and grows slow. |
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| Y. pseudotuberculosis |
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| lymphatinitis, causes orchitis in rams. involves mesenteric lymph node that spreads to liver and spleen. |
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| y. entercolitica |
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| does not affect animals but if they carry it on their meat will affect humans. Mesenteric adentitis and other infections. |
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| Cold enrichment in Y. enterocolitica. |
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| as in listeria monocytogenes. |
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| Cross reactions between Brucella and Y. enterocolitica serologic reaction during Brucellosis testing. |
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| Y. enterocolitica shares antigen with Brucella sp/ so may give FALSE BRUCELLA AGGLUTINaTION REACTION |
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| Chemotherapy- definition and requirement |
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| Definition: Treatment of infectious diseases by drugs which are lethal or inhibitory to infectious agents. Requirement- Should be selectively toxic to infectious agent but not to host or its cells. |
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| Antibiotics- definition and EXAMPLES |
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| Antimicrobial substance produced by living organisms. Ex: Fungus Penicillium notatum- penicillin Fungus Cephalosporium- Cephaolosporins Bacteria Streptomyces- Streptomycin Bacteria Bacillus polymyxa- polymyxin |
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| Bacterial drugs and examples |
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| rapid lethal action- drugs that will kill bacteria. Ex. Penicillin, streptomycin, cephalosporins, polymyxin. |
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| Bacteriostatic drugs |
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| inhibitory to the growth of organisms. EX. Tetracyclines, sulfonamides, chloramphenicol. MOST drugs generally have both kind of activity. |
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| Antimicrobial susceptibility test |
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| two types: disc susceptibility test (routinely done in vet diagnostic lab) 2. Tube susceptibility test (used at BVC) |
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| Disc Susceptibility Test |
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| Uniform inoculation of plate with bacteria on Media. Measure zone size. more than certain size- sensitive. Less than certain size- resistant. |
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| Tube susceptibility test |
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| determines the minimum inhibitory concentration (MIC). Those tubes without evidence of growth (turbidity) are plated out to determine the minimum bactericidial concentration (MBC) Inoculate same number of bacteria. |
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| Mechanisms of drug resistance (the four points listed with examples) |
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| a. Adoption to an alternate pathway EX. resistance to sulfonamides adoption of using folic acid from outside source. b. Production of an enzyme that destroys antibiotic. EX. Penicillinase (b-lactamase) by Staph aureus, pseudomonas c. Change in permeability of cell membrane. Ex: tetracycline to polymyxins. d. Altered target of drug: erythomycin resistant organsims ahve a modified protein on ribosomes. |
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| Adoption to an alternate pathway EXAMPLE |
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| resistance to sulfonamides adoption of using folic acid from outside source. |
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| Production of an enzyme that destroys antibiotic. EXAMPLE |
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| Penicillinase (b-lactamase) by Staph aureus, pseudomonas |
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| Change in permeability of cell membrane. EXAMPLE |
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| tetracycline to polymyxins. |
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| Altered target of drug EXAMPLE |
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| erythomycin resistant organisms have a modified protein on ribosomes. |
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| Superinfection |
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| by excessive antibiotic use of normal flora are killed, it may lead to super infection by fungi or yeast. ex.Canida, pseudomonas infection when normal bacteria are killed by antibiotic |
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| Infectious drug resistance EXAMPLE |
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| by transfer of multiple drug resistant plasmids from one strain to another closely related strain or bacteria (by conjugation mainly) Ex. E. coli to E. coli Salmonella to Salmonella E. Coli - Salmonella |
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| How could antibiotics in animal feed lead to selection of drug resistant bacteria? |
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| Use of sublethal or subinhibitory levels |
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| Synergistic |
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| penicillin and streptomycin= both bactericial |
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| antagonistic |
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| Penicillin(bactericial) + Tetracycline (bacteriostatic) |
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| How to limit Drug Resistance |
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| 1. No prophylactic use in feed. 2. Complete Course. 3. Prescription use only. |
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| Koch's Postulates |
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| 1. Organims must be regularly isolated from disease 2. Organisms must be isolated in a pure culture. 3. Such culture should produce typical disease in susceptible animals 4. Same organims much be isolated from these animals. |
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| Oxidative Phosphorylation |
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| Adenosine diphosphate (ADP) Adenosine triphosphate (ATP) P+ADP= ATP- source of energy |
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| Oxygen Toxicity |
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| enzyme to neuralize this: a. superoxide dismutase b. catalase c. peroxidase. |
