microbio test 1 – Flashcards
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| sterilization |
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| Kills everything |
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| disinfection |
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| does not kill endospores |
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| sanitation |
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| Cleansing technique that mechanically removes micro-organisms – not sterile but decreases number of microbes |
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| degermation |
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| reducing the number of microbes on human skin |
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| What is the difference between a microbicide and a microbistatic agent? |
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| A microbicide kills microbes, but a microstatic agent only temporarily prevents multiplication |
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| microbial death |
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| The permanent loss of reproductive capability even in optimal conditions |
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| What factors affect the death rate? |
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| Factors that influence action of antimicrobial agents: Number of microbes Nature of microbes in the population Temperature & pH of environment Concentration or dosage of agent Mode of action of the agent Presence of solvents, organic matter, or inhibitors |
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| Physical control of microbes is accomplished by which methods? |
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| heat and radiation, also cold temp. and dessication |
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| Which type of heat is the most effective and what method uses this type of heat? |
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| moist heat is most effective, an autoclave uses this type of heat |
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| What is the thermal death point? |
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| Lowest temperature required to kill ALL microbes in 10 minutes |
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| pasteurization |
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| Heat applied to liquids to kill potential agents of infection and spoilage |
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| cold sterilization |
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| Sterilizing using radiation instead of heat |
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| What is the difference between ionizing and non-ionizing radiation? |
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| Ionizing radiation penetrates much deeper, non-ionizing radiation is UV light and doesn’t penetrate past the surface |
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| What method is used to sterilize the air in hospital isolation rooms? |
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| filtration |
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| What are the four cellular targets of antimicrobials? |
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| Cell walls, cell membranes, DNA or RNA synthesis, protein function |
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| What types of microbes are the least resistant? Most resistant? |
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| Highest resistance=Bacterial endospores Moderate resistance=Pseudomonas sp., Mycobacterium tuberculosis, Staphylococcus aureus, Protozoan cysts Least resistance=Most bacterial vegetative cells, Fungal spore, Enveloped viruses, Yeast, Protozoan trophozoites |
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| Which chemical agents are the closest to ideal agents? |
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| Glutaraldehyde and hydrogen peroxide |
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| What class of chemical agents does chlorine and iodine belong to? |
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| Halogens |
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| What class of chemical agents does Lysol belong to? |
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| Phenolics |
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| What is the mechanism of action of alcohols? |
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| Dissolve membrane lipids, disrupt cell surface tension and denatures proteins |
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| chemiclave |
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| Automatic ethylene oxide sterilizer |
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| What is the mechanism of action of hydrogen peroxide? |
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| Germicidal effects are due to the direct and indirect actions of oxygen which forms free radicals that are highly toxic to microbes. |
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| Detergents are useful for which level of antimicrobial effects? |
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| Low level disinfection only |
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| What types of heavy metals have been used for microbial control? |
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| silver and mercury |
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| What class of chemical agents does Cidex belong to? What is it used for? |
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| Aldehydes – glutaraldehyde; sterilize equipment that cannot tolerate high heat. |
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| chemotherapy |
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| Any chemical used in the treatment, relief or prophylaxis |
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| prophylaxis |
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| Any chemical used to treat or prevent disease – meds used to prevent disease |
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| antibiotics |
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| Natural substances produced by micro-organisms that can inhibit or destroy other microbes. |
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| selective toxicity |
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| Kills microbial cells without damaging host cells |
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| What are narrow and broad spectrum? |
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| Narrow=limited range of microbes affected by the drug broad=large range of microbes affected by the drug |
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| What are some of the characteristics of the ideal antimicrobial drug? |
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| -selectively toxic to microbe but nontoxic to host cells -microbicidal rather than microbistatic -relatively soluble -not broken down or excreted prematurely -doesn't lead to development of antimicrob. resistance -complements or assists the activities of the host's defenses -remains active in tissues and body fluids -readily delivered to the site of infection -reasonably priced -does not disrupt the host's health by causing allergies or predisposing the host to other infection |
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| What are the mechanisms of action of antimicrobials? |
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| Inhibition of cell wall, DNA/RNA function, protein synthesis and interference with cell membrane structure or function. |
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| Which classes of drugs affect the bacterial cell wall? |
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| penicillins and cephalosporins |
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| Which classes of drugs affect DNA/RNA synthesis? |
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| Fluoroquinolones, Rifampin, antiviral drugs |
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| Which classes of drugs affect protein synthesis? |
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| tetracyclines, aminoglycosides, erythromycin |
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| Which classes of drugs affect cell membranes? |
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| Polymyxins, antifungals |
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| Antibiotics that affect the cell wall: |
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| Penicillins, Cephalosporins, beta-lactam antibiotics |
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| Antibiotics that damage the cell membrane: |
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| polymyxins |
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| Antibiotics that interfere with protein synthesis: |
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| Aminoglycosides, Tetracycline antibiotics, Chloramphenicol, Macrolides |
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| Antibiotics that block metabolic pathways: |
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| Sulfonamides |
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| What is unique about the structure of penicillins? How do microbes become resistant to penicillins? |
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| Beta lactam ring – develop enzymes to break the ring |
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| Penicillins are effective against what types of microbes? |
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| Gram positive cooci – streptococcus, staphylococcus, syphilis, some gram positive rods |
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| What is clavulanic acid? What drug is it found in? |
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| Chemical that inhibits beta-lactamase enzymes – augmentin |
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| What group of antibiotics account for the majority of all antibiotics administered? |
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| cephalosporins |
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| How many generations of cephalosporins are there and what is significant about these generations? |
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| There are 4 generations, first gen=gram pos organisms; second, third, & fourth gen=increasing effectiveness against gram negs |
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| What are 2 examples of aminoglycocides? |
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| Streptomycin and gentamicin |
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| What are the limiting factors of tetracyclines? |
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| GI disruption of normal flora and staining of teeth |
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| Which drugs are synthetic rather than natural antibiotics? |
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| Sulfonamides, fluoroquinolones, trimethoprim, dapsone |
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| Which drugs are used to treat fungal infections? |
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| Amphoteracin B, nystatins, and azoles |
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| Which drugs are classified as macrolides? |
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| Erythromycin, clindamycin, vancomycin, rifampin, clarithomycin, azithromycin |
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| Which drugs are used for protozoan infections? |
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| Quinines, metronidazole |
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| What is the mechanism of action of drugs used for helminth infections? |
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| Interfer with their metabolism so they are weakened and able to be excreted from the body |
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| What is the mechanism of action of antivirals? |
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| Inhibit viral penetration, multiplication or assembly |
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| How is drug resistance acquired? (4 ways) |
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| Drug inactivation decreased permeability/increased elimination change of metabolic pattern change in drug receptors |
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| What is natural selection and how does it effect drug resistance? |
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| The resistance microbes survive and replicate |
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| What are the 3 categories of adverse host-drug reactions? |
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| Direct toxicity to organs allergic responses changes to the normal flora/superinfection |
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| Most important considerations in selecting a medication? |
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| The nature of the microbe, the susceptibility of the microbe, overall medical condition of the patient, toxicity of the drug |
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| What is the MIC? |
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| Minimum inhibitory concentration – smallest effective dose of a drug against a specific microbe |
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| Therapeutic index |
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| The ratio of the toxic dose to the effective dose – the smaller the TI the more risk of toxicity to the patient. |
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| What is the difference between a true pathogen and an opportunistic pathogen? |
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| True pathogen (adequate infectious dose) will cause disease in an otherwise healthy person, opportunistic only causes disease when the immune system is compromised. |
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| What is normal flora and where does it occur? |
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| Beneficial bacteria that are present on the skin, in the GI tract, upper respiratory tract and GU tracts |
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| Where are staphylococcus spp found? |
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| Skin, mouth, upper resp tract, GU |
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| Where are coliforms found? |
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| GI tract mostly and small amt on urinary tract |
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| What are the primary events in the infectious process? |
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| Portal of entry invasion of tissue portal of exit |
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| What is an infectious dose? |
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| The amount of pathogen required to cause disease in the host |
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| What are the mechanisms of adhesion of pathogens? |
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| Fimbriae, capsules, spikes, hooks or flagella |
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| What are exoenzymes? |
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| Enzymes secreted by the pathogens that damage tissues and promote invasion |
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| What are endotoxins and exotoxins? |
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| Endotoxins are chemicals secreted when the pathogenic cells lyses/dies; exotoxins are secreted by active/live pathogens |
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| What is the difference between localized, systemic and focal infections? |
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| Localized=infection stays in portal of entry; systemic=infection spreads to several areas; focal=infection stays in portal of entry but releases toxins that effect other organs. |
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| What is the difference between and sign and a symptom? |
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| Signs=objective finding noted by the observer symptoms=subjective findings reported by the patient |
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| What does the acronym STORCH stand for? |
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| These are diseases that can infect the fetus from the mother: syphilis, Toxoplasmosis, Others (Hep B, HIV, chlamydia), Rubella. Cytomegalovirus, Herpes simplex virus |
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| What are some common portals of exit? Is the portal of exit the same as the portal of entry? |
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| The pathogen may leave the body by a different portal than used for the entry – respiratory and salivary, skin scales, fecal, urogenital tract, blood. |
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| What is latency? What are sequelae? |
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| The pathogen remains in the body in a dormant state – it may still be shed and the person is a chronic carrier. A Sequale is Long-term permanent damage from the pathogen |
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| What is prevalence? What is incidence? |
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| Prevalence= The number of existing cases in certain population. Incidence= The number of new cases compared to the general healthy population. |
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| What is the mortality rate? Morbidity rate? |
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| Mortality= Total number of deaths in a population due to a certain disease. Morbidity= Total number of cases afflicting members of the population. |
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| What is endemic? Epidemic? Pandemic? |
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| Endemic= The frequency of the disease is stable in a certain geographical area Epidemic= The frequency is increased in a certain area Pandemic= the disease has spread across continents |
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| What is disease carrier? What is a vector? What is a fomite? |
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| Disease carrier =An asymptomatic person who carries the pathogen and is able to transmit it. A vector is infected and transmits it between people (tick, mosquito). Fomite= Inanimate object that harbors and transmits pathogens. |
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| What is a nosocomial infection? What are the most common sites of a nosocomial infection? |
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| Disease acquired during a hospital stay – respiratory tract, urinary tract, surgical incisions |
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| What are the 3 lines of host defenses? |
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| First line – physical, chemical and genetic barriers Second line – inflammatory response, Interferons, Phagocytosis Third line – acquired/specific immunity |
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| Which lines of defense are inborn/innate? |
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| Only the first 2 lines of defense are inborn/innate – the third line is acquired |
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| What are some examples of physical barriers? |
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| Skin, rapid regeneration of mucous membranes, nasal hairs, ciliary defense in the respiratory tract, flushing by saliva, tears, sweat, vomiting, defecation, urination |
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| What are some examples of chemical barriers? |
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| Sebaceous secretions are antimicrobial, stomach acid, lysozyme in tears, lactic acid in sweat |
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| What are genetic defenses? |
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| Genetic defenses – some pathogens can only infect certain species – some genetic mutations make people immune to disease |
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| What 3 functions is the immune system responsible for ? |
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| Surveillance of the body Recognition of foreign material Destruction of foreign material |
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| What are markers and why are they important? |
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| Markers are proteins and/or carbohydrates that enable the immune system to identify a foreign particle. |
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| Which body compartments are involved in the immune function? |
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| Reticuloendothelial system extracellular fluid bloodstream lymphatic system |
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| What 2 systems are included in the circulatory system? |
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| Blood stream and lymphatic system |
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| Which type of blood cells are the most responsible for immune functions? |
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| Leukocytes – WBCs |
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| Which cells are agranulocytes? Granulocytes? |
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| Agranulocytes:Lymphocytes, monocytes Granulocytes: Neutrophils, Basophils, eosinophils |
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| Which cells are the largest phagocytes and what is their origin? |
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| Macrophages – differentiated from monocytes |
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| What types of cells do lymphocytes differentiate into? |
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| B-cells & T-cells |
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| What role does the eosinophil play in the immune system? |
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| Destroy eucaryotic pathogens especially helminth worms and fungi |
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| What role do lymphocytes play in the immune system? |
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| The third line of defense – specific/acquired immunity |
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| Which cells are involved in humoral immunity? |
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| B-cells |
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| what kind of cells are involved in cell mediated immunity? |
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| T-cells |
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| What functions are macrophages responsible for? |
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| Phagocytic and killing functions processing foreign material and presenting them to lymphocytes secreting substances that activate other cells of the immune system (cytokines, interleukins |
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| What is diapedesis? |
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| Ability to migrate out of the bloodstream into tissues |
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| What is chemotaxis? |
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| leukocytes migrate to the site of inflammation by following chemical stimuli |
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| What are the major functions of the lymphatic system? |
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| Provides an auxiliary route for return of extracellular fluid to the circulatory system Acts as a drain-off system for the inflammatory response Renders surveillance, recognition, and protection against foreign material through the use of lymphocytes, phagocytes and antibodies. |
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| Where does lymph come from? How is it circulated? |
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| From plasma; by skeletal muscle contraction |
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| Where in the body is lymphoid tissue? |
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| Lymph nodes, thymus, spleen, GI tract (GALT), tonsils etc |
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| What are the functions of the inflammatory response? |
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| Mobilize and attract immune components to the site of injury Set in motion mechanisms to repair tissue damage and localize and clear away harmful substances Destroy microbes and block their further invasion. |
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| What is the Inflammatory Response? |
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| The inflammatory response is a reaction to any traumatic event in the tissues. Classic signs and symptoms: Rubor – redness Calor – warmth Tumor – swelling Dolor – pain |
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| What substance initiates a fever? What are some examples of these? |
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| Pyrogens – exogenous (pathogens, blood, vaccines) endogenous (liberated by wbc’s during phagocytosis – interleukin 1 and tumor necrosis factor) |
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| What are some benefits of a fever? |
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| Inhibits multiplication of pathogens, impedes nutrition of bacteria, increases host’s metabolism and stimulates immune reactions |
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| Which cells are considered phagocytes? |
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| Neutrophils and macrophages (which have a larger role in the immune system than the neutrophils) |
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| What are histiocytes? |
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| Specialized macrophages that remain in certain tissues Examples: langerhans=skin kupffers=liver alveolar=lungs etc |
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| What are the functions of phagocytes? |
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| Survey tissues for microbes remove damaged tissue extract antigens from foreign material |
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| What is interferon? What are the different types? |
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| family of proteins produced by leukocytes and fibroblasts that inhibit the reproduction of viruses by degrading viral RNA or blocking the synthesis of viral proteinsThe different types of interferon’s are: Alpha Beta Gamma |
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| What is the complement system? How does it function? |
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| Complement is a complex defense system with multiple proteins involved that produces a cascade reaction |
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| What are the 3 stages of the complement cascade? |
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| Initiation amplification and cascade membrane attack |
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| What is the final result of the complement system? |
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| Formation of a membrane attack complex to make holes in the cell membrane of bacteria, cells and enveloped viruses. |
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| What is the difference between the 3 complement pathways? |
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| The major difference is the substance that initiated the cascade reaction. |
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| What is the third line of host defense? What are the two features that most characterize this defense? |
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| Acquired specific immunity; specificity to the antigen and memory |
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| What are the stages of acquired specific immunity? |
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| Development of the lymphocyte system Processing of Antigens and Clonal Selection Activation of lymphocytes and Clonal Expansion Antibody production Cell-Mediated Immunity |
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| What are receptors? What are their functions? |
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| Protein or carbohydrate markers on the surface of cells. Functions are to perceive & attach to foreign molecules, recognition of self molecules, to receive & transmit chemical messages, to aid in cellular development |
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| What is the clonal selection theory and what does it result in? |
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| It is preprogrammed lymphocyte specificity, existing in the genetic makeup before an antigen has ever entered the system Each genetically different type of lymphocyte expresses a single specificity - Undifferentiated lymphocytes undergo a continuous series of divisions and genetic changes that generate hundreds of millions of different cell types. |
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| What is immune tolerance? |
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| The elimination of any clones that may be specific for self cells. |
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| What is the specific B-cell receptor? |
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| Immunoglobulins – large glycoprotein molecules that serve as the specific receptors of B-cells and as antibodies. |
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| How are immunoglobulins synthesized? |
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| A heavy chain is bound with a light chain then the 2 heavy chains are bound together forming a Y structure. |
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| What are antigen binding sites? |
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| Highly variable in shape to fit very specific antigens – at the ends of the Y structure of the Ig. |
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| What are MHC receptors? What do the 3 groups of receptors react with? |
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| Receptors found on all cells except RBCs The 3 types of MHC receptors are: Class I – markers that display unique characteristics of self molecules & regulation of immune reactions. Required for T lymphocytes Class II – receptors that recognize & react with foreign antigens. Located primarily on macrophages & B cells. Involved in presenting antigen to T cells Class III – secreted complement components, C2 and C4 |
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| How are lymphocytes differentiated initially? |
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| Maturation occurs differently for B and T cells: B cells in the bone marrow T cells in the thymus |
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| What are the different classes of T-cell receptors called and why are they significant? |
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| CD receptors (cluster of differentiation) - Type of receptors dictates what is recognized by the T-cell |
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| What are the characteristics of an antigen? |
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| Provokes an immune reaction perceived as foreign by the immune system large enough to provoke an immune reaction |
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| What is an antigenic determinant? |
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| Small molecular group that is recognized by lymphocytes. It is the primary signal that the molecule is foreign. An antigen has many antigenic determinants |
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| What is a hapten? |
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| Are small molecules that are usually not antigenic unless attached to a larger carrier |
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| What is an allergan? |
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| Antigen that provokes allergic reactions |
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| Are most antigens t-cell dependant or do they react directly with b-cells? |
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| Most are t-cell dependant – only a few can interact with b-cells directly |
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| How is an antigen processed and presented? |
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| Must be processed by phagocytes (dendrites) called antigen presenting cells (APC). An APC/dendrite alters the antigen and attaches it to its MHC receptor where it can be presented to the b and t-cells |
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| What are interleukins? How are they involved in antigen processing & presentation? |
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| Interleukins are peptides that carry signals between leukocytes; Interleukin-1 is secreted by APC to activate TH cells; Interleukin-2 is produced by TH to activate B & other T-cells |
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| What happens to the b-cell once it is activated? |
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| They enter the cell cycle in preparation for mitosis and clonal expansion. Divisions give rise to plasma cells that secrete antibodies and memory cells that can react to the same antigen later. |
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| What 2 fragments make up the structure of the antibody? What do they attach to? |
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| Fab – antigen binding fragement binds the antigen and Fc - crystallizable fragment binds to various cells and molecules of the immune system. |
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| What are the functions of antibodies? |
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| To unite with, immobilize, call attention to, or neutralize the antigen; specifically opsonization, neutralization, agglutination and complement fixation |
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| What is opsonization? |
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| Antigens become coated with specific antibodies so that they will be more readily recognized by phagocytes to dispose of them |
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| neutralization |
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| antibodies fill the surface receptors on a microorganism to prevent it from functioning normally. |
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| What is agglutination? |
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| Cross-linking cells into larger clumps |
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| what is Complement fixation? |
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| The interaction of an antibody with complement can result in the specific rupturing of cells and some viruses. |
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| How many classes of immunoglobulins are there? Which class is the most prevalent? |
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| Five, IgG is the most prevalent |
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| Which class of Ig’s is the first responder with an initial antigen encounter? |
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| IgM |
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| Which class of Ig’s is in many secretions of the body and is present in breast milk? |
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| IgA |
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| Which class of Ig’s has the largest molecules? |
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| IgM |
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| Which class of Ig’s are produced by memory b-cells in a second exposure? |
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| IgG |
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| Which class of Ig’s are produced by memory b-cells in a second exposure? |
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| IgG |
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| Which class of Ig’s interact with mast cells and basophils and is involved with allergic responses? |
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| IgE |
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| What is cell mediated immunity? What cells are involved with CMI? |
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| Rather than making antibodies to control foreign antigens, the T-cells act directly against antigens and foreign cells. |
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| What are the 3 types of t-cells? How are they differentiated? |
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| Helper, suppressor, cytotoxic and delayed hypersensitivity T-cells. The functions of T-cells vary in their CD receptors and sensitivity to cytokines. |
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| Which receptor is common to all t-cells? Which t-cells have CD4? CD8? |
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| CD2 is common to all t-cells; t-helper cells have only CD4 receptors; t-cytotoxic cells have only CD8 receptors |
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| What is the most prevalent t-cell? What is significant about it? |
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| T-helper cells – the conductor of the immune response by assisting other T and B-cells. Reacts directly by receptor contact and indirectly by releasing cytokines such as interleukin-2. |
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| How does a patient with an HIV infection become immunosuppressed? |
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| HIV depresses and destroys the t-helper cells. |
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| What is the function of t-cytotoxic cells? |
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| Foreign receptors are presented to it and it mounts a direct attack against the target cell by secreting perforins that lyse cells by creating pores in the target cell membrane. |
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| What is the function of t-suppressor cells? |
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| Inhibit the actions of other T-cells and B-cells and regulate the immune response by producing protein inhibitors that prevent lymphocytes and macrophages from reacting with antigens. |
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| What is the function of t-delayed hypersensitivity cells? |
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| Responsible for allergies occurring several hours or days after contact such as the tuberculin reaction (TB test). |
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| What is natural immunity? |
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| Acquired as part of normal life experiences |
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| Artificial immunity |
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| acquired through a medical procedure such as a vaccine |
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| What is active immunity? |
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| Results when a person is challenged with Ag that stimulates production of Ab |
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| Passive immunity |
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| preformed Ab are donated to an individual. |
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| What type of immunity is the result of an infection and recovery? |
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| Natural active immunity |
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| What type of immunity is the result of pregnancy and lactation? |
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| Natural passive immunity |
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| What type of immunity is the result of a vaccination? |
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| Artificial active immunity |
