Flashcard Answers on MICRO – Microbiology
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| what bacteria is a genus of high G + C Gram positive bacteria? |
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| mycobacterium |
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| what has been historically classified as Gram negative bacteria but is genetically more simialr to low G+ C Grm positive bacteria? |
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| mycoplasmas |
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| what is one feature that differentiates Staphylococcus aureus from other species of staphylococci? |
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| it can produce coagulase |
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| Over 90% of Staphylococcus aureus bacteria can withstand the effect of PCN. Why? |
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| they produce B-lactamase |
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| a woman comes to the ED with a fever and vomitting. She soon developes a red rash all over her body, and her BP begins to drop. What is one possible diagnosis? |
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| Toxic shock Syndrome |
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| Bacteria collected from a severely inflamed wound are sent to the lab for analysis. The results come back as follows: Gram-positive cocci in irregular clusters, kinase and coagulase positive, and able to grow in the presence of most ABX except vancomycin. The bacteria in the wound are most likely? |
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| methicillin-resistant Staphylococcus aureus (MRSA) |
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| Streptococci are frequenlty classified by? |
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| the bacteria's Lancefield antigen |
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| How do group A streptococci camouflage themselves from WBC's? |
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| They have hyaluronic acid capsules |
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| Which of the following diseases is considered an autoimmune disease triggered by bacterial infections? |
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| rheumatic fever |
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| What is true about "flesh- eating" streptococci? |
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it is caused by group A streptococci, It is also known as necrotizing fasciitis b/c it travels along the fascia, it involves toxemia, it causes death in over 50% of cases |
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| Streptococcus agalactiae is associated with which of the following disease? |
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| neonatal bactermia, neonatal meningitis, and neonatal pneumonia |
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| What is True regarding Streptococcus pyogenes? |
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it is beta-hemolytic, it can be lysogenized by a temperate bacteriophage to produce erythrogenic toxins, it produces streptolysins, it has group A Lancefield antigens |
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| what differentiates virulent strains of Streptococcus pneumoniae from nonvirulent strains? |
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| the presence of a polysaccharide capsule that protects it from digestion after endocytosis |
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| untreated streptoccoccal pharyngitis may progress to? |
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| scarlet fever or rheumatic fever |
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| the Quellung reaction is uded to diagnose? |
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| Streptococcus pneumoniae |
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| Otitis media may lead to dangerous meningitis in children due to infections with? |
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| Streptococcus pneumoniae |
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Which of the following staphylococcal virulence factors produce the signs and symptoms of scalded skin syndrome? a) exfoliative toxin b) staphylokinase c) coagulase d) leukocidin e) hyaluronidase |
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a) exfoliative toxin
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| During a stay in the hispital, an accident victim develops symptoms of bactermia. a blood sample shows the presene of Gram- positive cocci in pairs. Lab tests determine that the bacteria are nonhemolytic and bile salt tolerant. The bacteremia is likely due to? |
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| enterococcus |
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| what streptococci is associated with dental caries? |
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| viridans streptococci |
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| Anthrax, which means "charcoal" in Greek, derives its name from? |
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| the black eschars it produces on human skin |
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| What is true about Bacillus anthracis? |
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| it can be lethal even after tx b/c antimicrobial drugs do not inactivate accumulated anthrax toxin, it normally dwells in the soil and can survivie in the environment for centures or longer, it has a capsule, it produces endospores. |
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| what is FALSE about Bacillus antrhacis? |
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| it is primarily a disease of humans--> FALSE! |
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| what bacteria produces one of the most deadly bacterial toxins known? |
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| Clostridium botulinum |
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| what bacteria can cause life-threatening pseudomembranous colitis? |
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| Clostridium difficile |
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| How does the toxin from Clostridiym tetani produce its action? |
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| The smaller polypeptide of its toxin can block the release of inhibitory neurotransmitters by inhibitory neurons in the central nervous system, causing simultaneous contractions of both muscles in the antagonistic pair. |
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| What is true concerning tetanus? |
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| its diagnostic feature is characteristic muscle contractions, which are often noted too late to save the pt, its toxin causes simultaneous contractions of both muscles in an antagonistic pair, it is a small, motile, obligate anaerobe, and it produces a terminal endospore that gives the cell a distinctive "lollipop" appearance |
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| what is FALSE about tetanus? |
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| its only source is from deep puncture wounds from a rusty nails----->>>> FALSE!!! |
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| Listeria's virulence is directly related to its ability to? |
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| live within cells and thus avoid exposure to the immune system of its host |
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| which of the following bacteria divide by "snapping division" in which daughter cells remain attached in characterisitic V-shapes? |
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| Corynebacterium |
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| What is TRUE about diphtheria? |
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| it produces a characteristic pseudomembrane that can adhere to the tonsils, uvula, palate, pharynx, and larynx; its toxin can be absorbed into the blood from cutaneous lesions and can lead to cardiac arrhythmia, coma, and death; its toxin destroys elongation factor, which is needed to synthesize polypeptides in eukaryotes; and although all species of Corynebacterium are pathogenic, the agent of diphtheria is the most widely known. |
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| what is FALSE about diphtheria? |
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| its growth on Loffler's medium is used for absolute diagnosis of the bacterium |
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| Mycoplasma pneumoniae is distinguished from other members of the genus? |
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| b/c it is strictly aerobic |
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| The pathogenicity of primary tuberculosis is due to the fact that the mycobacteria? |
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| prevent fusion of lysosomes with phagosomes |
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| a sample of fluid from the lungs contains microbes that grow in filaments, and the filaments tend to align with one another. The cells stain poorly in the Gram stain and are pink-red when acid-fast stained. The bacteria in the sample are? |
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| Mycobacterium species |
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| The pus from an abscess in a patient's jaw contains microbes that form yellowish grainy masses and appear filamentous under the microscope. Neither antifungal medication nor a normal course of antibiotics has been effective in treating the infection. The abscess is likely the result of infection with? |
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| antinomyces |
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| What is the most common disease caused by Propionibacterium? |
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| acne |
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| Mycetoma, which is a painless long-lasting infection characterized by swelling, pus production, and draining sores, is caused by? |
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| Nocardia |
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| Bacillus anthracis? |
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| Escar |
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| Norcardia asteroides ? |
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| Mycetoma |
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| Enterococcus ? |
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| Can grow in the presence of bile salts |
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| Streptococcus pyogenes ? |
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| Scarlatina |
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| Propionibacterium ? |
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| Acne |
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| Streptococcus pneumoniae ? |
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| Otiitis media |
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| Mycoplasma ? |
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| Gram- negative pleomorphic bacterium |
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| Mycobacterium leprae ? |
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| Intracellular parasite of nerve cells |
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| Clostridium ? |
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| Strict anaerobe |
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| Corynebacterium ? |
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| Pseudomembranes |
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| T/F Staphylococci divide by snapping division in which the daughter cells remain connected and form grapelike structures. |
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| FALSE |
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| T/F In contrast to other mycobacteria, Mycobacterium avium-intracellulare simultaneously affects almost every organ in the body. |
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| TRUE |
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| T/F Staphylococcus aureus can produce a toxin that dissolves the desmosomes that hold the adjoining cytoplasmic membranes of cells together and causes the pt's skin cells to separate from each other. |
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| TRUE |
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| T/F A person comes into the clinic with a wound that is severely inflamed, very painful, and turning black and "Bubbly". The diagnosis is leprosy? |
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| FALSE! |
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| T/F Group A streptococci are considered more virulent if their cytoplasmmic membrane contains M protein. |
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| TRUE |
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| T/F Most cases of pneumonia are caused by a virus. |
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| FALSE |
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| T/F The respiratory infection known as "walking pneumonia" is caused by Mycoplasma pneumoniae. |
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| TRUE |
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| Enterococci have the ability to secrete bacteriocins, which inhibit the growth of other bacteria. |
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| TRUE |
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| T/F Clostridium bacilli are high G + C Gram- positive, endospore- forming bacteria. |
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| FALSE |
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| T/F Streptococci are normal microbiota of the skin. |
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| FALSE |
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| A "summer cold" that lasts for weeks and is characterized by sore throat, mild fever, dry cough, and malaise may be? |
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| primary atypical pneumonia |
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| Nocardia contains ______, so cells are difficult to stain with the Gram stain, but they are acid-fast. |
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| Mycolic acid |
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| In its role in the development of acne, ____ typically grows in sebaceous glads of the skin. |
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| propionibacterium |
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| ______ media was developed especially to culture Corynebacterium diphtheriae. |
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| Lofflers |
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| in countries where tuberculosis is common, health care workers ar evaccinated with _____, which contains attenuated Mycobacterium bovis bacteria. |
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| BCG |
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| Palisade cell arrangemnts are characteristic of? |
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| Corynebacterium diptheriae |
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| Listeria's virulence is directly related to the production of a substance known as ____, which allows it to escape the phagosome into the host cell's cytosol, where it grows intracellularly. |
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| listeriolysin O |
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| _____ is resistant numerous antibicrobial agents; therefore vancomycin must be used for these infections. |
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| MRSA |
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| The neurotoxins Clostridium botulinum produce ____ paralysis by preventing muscle contraction. |
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| flaccid |
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| Bacterial food poisoning resulting from ____ contamination is characterized by watery diarrhea accompanied by interstinal cramping but not fever, and it resolves in about a day. |
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| clostridium perfrigens |
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| ____ grows at temps up to 45*C, at pH levels as high as 9.6, and in 6.5% NaCl, but they lack structural and chemical elements that make them virulent in the intestinal tract. |
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| enterococci |
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| the aerobic endospore-former ____ is a strict pathogen of humand and animals. |
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| bacillus anthracis |
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| the body limits the migration of ____ by binding it to the active sites of secretory IgA, which the bacteria overcome by secreting secretory IgA protease. |
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| streptococcus pneumoniae |
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| when streptococcal infections involve the skin and surrounding lymph nodes, triggering pain and inflammation, the condition is known as? |
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| erysipelas |
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| the ability to produce ____ enables Staphylococcus aureus to penetrate and stread through tissues. |
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| hyaluronidase |
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| A child with a long history of repeated cases of strep throat develops a heart murmur. What is the most likely diagnosis, and what has caused this condition to develop? |
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| The child is most likely suffering from rheumatic fever. This is a complication of untreated type A streptococcal pharyngitis-that is, strept throat. The condition is not caused directly by streptococcus, but is actually an autoimmune response. Antibodies against the streptococcal antigen cross- react with heart antigens, leading to damage of the heart valves. Damage may be so extensive that the valves must be replaced when the patient reaches middle age. |
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| A throat swab is taken from a patient with a respiratory infection. After 24 hours, 1- to 3-mm colonies develop, which are round, mucoid, nonpigmented, and dimpled in the middle. What is the most likely pathogen, and how could you confirm the diagnosis on the culture. |
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| The colonies described are characteristic of Streptococcus pneumoniae. Diagnosis of this pathogen is confirmed if they are alpha-hemolytic on blood agar when grown anaerobically. Pneummococcal colonies can be differentiated from other colonies of alpha-hemolytic strains by adding a drop of bile to a colony. The bile triggers chemicals in S. pneumoniae that lyse the cells. The colony dissolves in a few minutes, confirming that they are pneumococcal colonies. |
