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Sem 3 Mini 3 Micro

Ross University School of Medicine - Semester 3 - Microbiology - Mini 3

QuestionAnswer
What is the most common baceteria of STDs? Chlamydia Tracomatis. Second most common is Neisseria gonorrhaeae
Compare the presentation/effects of botulin toxin vs a tetanus toxin Botulin toxin --> flacid paralysis / Tetanus toxin --> spastic paralysis
What conditions are associated with Clostridium perfringens infxon? Gas gangrene (wound infxon, etc) and diarrhea/food poisening (from ingestion)GI infxon is normally self-limitting and will resolve in 12-24 hours
Describe the causative agent and features of TRACHOMA Trachoma is caused by Chlamydia trachomatis (serovars a-c). It is an occular disease most commonly seen in areas of poverty. THE WORLDS LEADING CAUSE OF PREVENTATIVE BLINDNESS. It is caused by the host immune response to the infxon
What is the rx for trichoma Azithromycin, doxycycline or ofloxacin
What is the cause of lymphogranuloma venerum? C. trichomatis infxon (L1 L2 or L3 serotype)commonly spread by anal intercourse or lymphatic spread
Wha is the presentation of lymphogranuloma venerum Marked inflammation and swelling of lymph nodes draining the inguinal region (most commonly) Fever, chills, anorrhexia, HA, proctitus, and myalgia.
What are the three major members of the chlamydiae family C. trachomatis --> STDC. Pneumoniae --> walking pneumoniaC. psittaci --> bird transmitted form
What disease is associated with Chlamydiae psitacci Psittacosis (aka ornithosis) - the bird transmittable form of chlamydia
What is psittacosis treated? Tetracycline or doxycycline (for bird: give bird chlortetracycline for 45 days)
What are the names and features of the 2 major toxins produced by C. diff? Toxin A - fluid production and damage to large bowel. Toxin B - causes rounding of tissue culture cells... working in conjunction with toxin A to cause symptoms
What is the tx for pt with tetanus ? Metronadozole. This is the DOC for anaerobic infxons. Pencillin G would also work but since it also inhibits GABA, it will also aggrevate the symptoms, so metronadazole is used.
List the major virulent strains of e.coli EHEC (shiga toxin producing, O157:H7), EPEC , ETEC (traveler's diarrhea), EAEC (seen freq in AIDS pt), DAEC, EIEC
Describe the method by whic each of the major types of Chlamydiae exit the cell following infxon.... C. Trichomatis and C. pneumoniae exist by reverse endocytosis while C. psittaci exists by lysing the cell.
What is the best lab technique for determining if a gene is present and actively expressed? Reverse transcriptase PCR
What is impetigo and what causes it? Impetigo is a small area that is similar in appearance to erythema that progresses to form a bullae. It is cause by S. aureua. It's chacteristic feature is the formation of a honey colored crust that forms as the lesions heal.
What is a bullae Blister like lesions filled with a cloudy fluid that forms as bullus impetigo progresses. (S. aureus causes this)
What are the 4 major infxons of Streptococcus pneumoniae Meningitis, Otitis media, Pneumonia, Sinusitis (M.O.P.S.)
Lecethinase is used by what bacteria? C. perfringens produces this toxin, it causes gas gangrine.
What is the result of exposing chlamydiae-infected cells to INF-gamma Induces an altered state in the reticular bodies known as PERSISTANCE.
What is persistence? What bacteria is this seen in? Persistence is a state in which the reticular bodies of a chlamydiae-infected cell are morpholgically enlarged and transcriptionally active, but have a slowed metabolic rate. These cells do not form the infectious elementary bodies.
What is the purpose of the state of persistence seen in chlamydiae To avoid immune response and linger in tissues. This is a possible mechanism of chronic disease with chlamydiae
What are major serotypes of chlamydiae and the features of each. A,B, and C: blindness. Commonly seen in africa.D-K: Urethritis/PID/ and reiter disease/ everything else.L1-L3: neonatal via birth canal and lymphogranuloma venerum.
What is the causative bacteria and toxin of gas gangrene? C. perfringens. Lecethinase.
What are the major encapsulated pathogens? Strept. pneumoniae, Klebsiella, Heomopholus influenza, Pseudomonas aeruginosa, Neisseria meningitidus, cryptococcus neoformans
What are the key features of Clostridium? Gram +, anaerobic, spore forming. These are the most clinically important anaerobes and include C. perfringens (gas gangrene), C. tetani, C. botulinum, and C. difficile.
What are the key features of mycobacterium? Obligate aerobes, slow growing, and acid fast (alpha alkyl B hydroxyl fatty acids in cell wall)
What is the differential test for species of staph. Coagulase test. S. aureus = Coag +, S. epidermis = Coag -
What is a radiologic finding of strep pneumoniae? Infiltrate / consolidation in the lungs.
What is the most common cause / source of S. aureus infxon. post-op nosocomial infxon.
In what type of bacterial infxon would tx with abx lead to exotoxin release? EHEC O157:H7 infxon (shiga like toxin)abx is c/i
What is a toxoid? a vaccination against a disease caused by exotoxin production. It is made by treating purified exotoxin with formalin, I, pepsin, etc
Compare the origin (site of encoding) of shigella dysenteria toxin (shiga toxin) vs E. coli shiga-life toxin. Shiga toxin is encoded on the bacterial chromosome, while shiga like toxin is encoded by bacteriophage.
What secretion system mediates the secretion of exotoxin through the INNER MEMBRANE of bacteria? SecYeg secretion system. Additional sytems are used in bacteria that have an outer membrane.
What bacteria is associated with Pott's disease? Mycobacterium tuberculosis. This disease is an osteomyelitis of the vertebrae.
What mediates the attachment of Staphylococci to mucoal surfaces and what structure does it actually attach to? Leipoteichoic acid mediates its attachment to Fibronectin on the mucosal surface.
What two bacteria possess the virulence factor IgA protease? Strep. pnemoniae and N. meningitidus
Describe the key feature of N. meningitidus... encapsulated, gram -, diplococcus.
What are the virulence factors of N. meningitidus? LPS, IgA protease, and polysaccharide capsule (resists phagocytosis)
Describe the effects of endotoxin on. 1) Kuppfer cells. 2) Neutrophils. 3) B-lymphs, and 4) compliment. Kupfer cells: causes the releas of TNF-alpha and IL-1 to mediate fever. Neutrophils: kinin release-> Vasodilation. B-lymphs: Activation to produce antibody. Compliment: inflammation
What are the key gram + pyogenic bacteria Gram + = ****staph aureus***(also epidermis and saprophyticus)Gram - = Neisseria, E.coli, P. aeruginosa, Bacteroides fragillis, and klebsiella pneumoniae. (mnemonic = "never expect professors to behavor kindly"
What the the general features of strep pneumoniae. (gram, motility, morphology, virulence factors, catalase test?) Gram positive/ENCAPSULATED, non-motile, diplococci, a-hemolytic/IgA protease, catalase negative. BILE SOLUBLE!
What virulence factor inhibits the phagocytosis of Strep pneumoniae? its capsule. The capsule also prevents C3b bining (preventing opsonization), activation of alternative pathway, as well as resistance to dessication (drying out)
What is optochin used for? It is used in disc assay as a differential test for Strep. veridens and Strep. pneumoniae. Veridens can grow in the presence of optochin while pneumoniae cannot.
What are some abx commonly associated with causing c.diff? cephalosporin, ampicillin and clindamycin.
How is s. pneumoniae diff'd from s. veridens Opthican test. growth in the presence of opthican = veridans.
What is myenecrosis? Gas gangrene. Cause by C. perfringens / lecithinase toxin
How does s. pneumoniae kill cilliated cells? By the release of pneumolysin (triggered by host autolysin release). Pneumolysin perforates the cell membrane causing the formation of pores.
What is pneumolysin? A cytotoxin who's release is stimulated by host mediated release of autolysin. It perforates the host cell membrane by binding to cholesterol... forming pores and causing lysis.
Pneumolysin is found in what bacetria. S. pneumoniae.
What cell wall component facilitates invasion into alveolar cells? What is the mechanism? Choline. It binds to the platelet activating factor (PAF) receptors and enters the cell via endocytic vacules. This also activates teh compliment pathway to induce IL-1 and TNF-A.
What are the two major alpha-hemolytic bacteria? Strep. veridans and Strep. pneumoniae
Tx of EHEC? Rehydrdation. NO ANTIBIOTICS!
Bundle forming pili are a feature of what type of E. coli? EPEC. This protein causes actin filament condendation
How is EHEC differentiated from other types of E. coli? EHEC cannot ferment sorbitol.... the other types can.
What is the mechanism of EHEC Production of shiga toxin which is injected into the cell while the bacteria remains extra cellular. This is accomplished by attachment via intimin. Adhesion and Effacement leion and RBC b/d with enterohemolysin leads to bloody diarrhea and edema.
Renal failure due to binding at glomerular GBS receptor is a feature of what toxin/bacteria combo Shiga-like toxin in EHEC O157:H7
EHEC vs EPEC with regard to pt presentation/clinical features. EHEC does not produce a fever, EPEC does. Also, EPEC does not produce a toxin... instead it used bundle forming pili to adhere to cell and cause A/E lesions.
What is the only type of invasive E. coli... what symptoms does it's infxon yield? EIEC. Watery diarrhea with a + fecal WBC test
What is a common cause of persistant baceterial diarrhea in AIDS pts and infants. EAEC (enteraggregative E. coli)
Common cause of neonatal meningitis? E.coli infxon from mother.
What media is selective for gram negative bacteria and differential for lactose fermenters? MCconkey agar.
What are the 3 antigens of e.coli? O-antigen: capsular. K-antigen: fimbriae, H-antigen: flagella (motile bacteria only)
What is a ghon complex? A TB granuloma with lobal/perihilar node involvement. It reflect a primary infxon or exposure to TB
What is the most common site in the lungs where reactivation of TB occurs? In the apices.
What is the most common site of primary TB infexion? Middle lobe of lungs
What is the primary cause of tissue damage in TB? Host immune response
What is the biggest consequence of lymphohematogenous dissemination of TB? Seeding the lung apices. Primary or secondary lung disease can occur.
What is the mos important case of reactivation of TB leading to 2ary TB? HIV coninfxon
What is the major complication of a hypersensitivity to TB Pulmonmary TB/ tissue damage in apical cavities. This is the most common manifestation of adult TB.
What 2 cytokines contribute most to TB symptoms? TNF-alpha and IL-1?
What stain is used for mycobacterium? Fuschin or flurochrome
A strong CMI with weak humoral immununity is characteristic of what type of leprosy? Tuberculoid leprosy
Weak CMI with strong humoral immunity is characteristic of what type of leprosy? Lepromatous leprosy
Bone resorption is a feature of _________ leprosy. Lepromatous.
What is the gold standard for dx of TB. Sputum culture.
What is the tx for TB Isoniazid, rifampin, pyrazinamide, ethambutol.
What is the role of antibodies in TB? None. TB requires a cellular immune respone, which doesn't occur until several weeks following exposure.
How do mycobacteria increase their chances of survival once inside of a macrophage. They inhibit the acidification of the phagolysosome.
Disseminated/milliary TB is most common in what individuals? Immunocompromised. The absence of cell mediated immunity allows for dissemination and manifesation into a systemic disease. Muiltiorgan failure.
What hepatitis virus is enveloped? Hep B
What hepatitis virus is naked? Hep A
What is the difference between a positive and a negative virus? A positive virus can be directly translated into a amino acid, while a negative virus must first be copied to it's codon form
What feature is characteristic for all (-)RNA viruses except for retroviruses? They are all enveoped and carry their own RNA dependent RNA pol.
What is the viral cause of hepatocellular carcinoma? Chronic hepatitis infxon
Hep B is counteracted by what immune response type? Cell mediated.
Who are at highest risk for Hep B infxon alcoholics and neonates.
What is a faruncle and what is a carbuncle? A carbuncle a collection of faruncles. A faruncle is a large pus contrailing lesion in the dermis that exudes perulent material f/ a single opening. Faruncle = boil.
Osteomyelitis is commonly caused by what type of bacteria? S. aureus.
What is the function of coagulase? Formation of a fibrin capsule in S. aureus.
Coagulase is a virulence factor of what bacteria S. aureus
What is the most common cause of meningitis? Strep. pneumoniae
What is the function of protein A in staph. aureus. binds to the H chain of antibody and inhibits Ab mediated opsonization and phagocytosis
By what mechanism does S. aureus avoid getting phagocytosed. By the release of protein A, which prevents opsonization by Ab, and also by coagulase, which form a fibrin capsule around the bacteria.
What toxins are produced by S. aureus. Hemolysin, Leukocidin, entertoxin, exfolliative toxin, TSST-1, and protein A + Coagulase
Exfolliative toxin is a virulence factor of what bacteria? S. aureus.
TSS is caused by what bacteria? S. Aureus (via TSS toxin)
Diffeentiate the CSF findings if a funal mengingitis vs a bacterial meningitis? Fungal = Increase in lymphocytes, bacterial = increase in PMNs
Asplencic individuals are most likely at risk for what type of infxon? Encapsulated bacterial infxon. (ie; S. pneumoniae in an older sickle cell patient)
What virulence factor mediates the formation of a fibrin capsule around the infectious loci of s. aureus? Coagulase
Describe the structure of exotoxin and the key role of each component? A domain: delivered into host cell. Posseses enzymatic activity to induce the toxin. B domain: binds hos cell membrane to deliver the A domain.
How are exotoxins activated? By cleaving the disulphide bond between the A and B domain.
How do exotoxins enter the host cell? The A domain is transported across the membrane by the B domain.
Botulinum toxin and tetanus toxin are both what kind of toxins? Zinc proteases / neurotoxins
Hemiagglutination inhibition involed IgG or IgM? IgG - late phase infxon / 2ry immune response
What type of microscopy requires staining? What kind does not ? Bright field microscopy requires staining. Phase contrast does not.
What kind of microscopy is used for parasites? Phase contrast
Where is a francisella tularensis infxon commonly aquired? Working in a lab setting. This bacteria can penetrated intact skin (no wound required) because of its small size.
Early phase antibody response is mediated by: IgM
Late phase antibody response is mediated by: IgG
Hemiagglutination inhibition test with a positive result means? A positive result means that antiboduy against the antigen in question is present and patient has been exposed to the agent (hemoagglutination is inhibited).
In the presence of O2, a methlyene blue strip is what color? Blue
Describe the basic flow of lab diagnosis? 1)Microscopy is performed on specimen. 2) the sample is cultured 3) cultivated organisms are analyzed and ID'd / tested for susceptability
In order for a microbial susceptabiity test o be
What stain is used for mycobacterium? Fuschin or flurochrome
A strong CMI with weak humoral immununity is characteristic of what type of leprosy? Tuberculoid leprosy
Weak CMI with strong humoral immunity is characteristic of what type of leprosy? Lepromatous leprosy
Bone resorption is a feature of _________ leprosy. Lepromatous.
What is the gold standard for dx of TB. Sputum culture.
What is the tx for TB Isoniazid, rifampin, pyrazinamide, ethambutol.
What is the role of antibodies in TB? None. TB requires a cellular immune respone, which doesn't occur until several weeks following exposure.
How do mycobacteria increase their chances of survival once inside of a macrophage. They inhibit the acidification of the phagolysosome.
Disseminated/milliary TB is most common in what individuals? Immunocompromised. The absence of cell mediated immunity allows for dissemination and manifesation into a systemic disease. Muiltiorgan failure.
What hepatitis virus is enveloped? Hep B
What hepatitis virus is naked? Hep A
What is the difference between a positive and a negative virus? A positive virus can be directly translated into a amino acid, while a negative virus must first be copied to it's codon form
What feature is characteristic for all (-)RNA viruses except for retroviruses? They are all enveoped and carry their own RNA dependent RNA pol.
What is the viral cause of hepatocellular carcinoma? Chronic hepatitis infxon
Hep B is counteracted by what immune response type? Cell mediated.
Who are at highest risk for Hep B infxon alcoholics and neonates.
What is a faruncle and what is a carbuncle? A carbuncle a collection of faruncles. A faruncle is a large pus contrailing lesion in the dermis that exudes perulent material f/ a single opening. Faruncle = boil.
Osteomyelitis is commonly caused by what type of bacteria? S. aureus.
What is the function of coagulase? Formation of a fibrin capsule in S. aureus.
Coagulase is a virulence factor of what bacteria S. aureus
What is the most common cause of meningitis? Strep. pneumoniae
What is the function of protein A in staph. aureus. binds to the H chain of antibody and inhibits Ab mediated opsonization and phagocytosis
By what mechanism does S. aureus avoid getting phagocytosed. By the release of protein A, which prevents opsonization by Ab, and also by coagulase, which form a fibrin capsule around the bacteria.
What toxins are produced by S. aureus. Hemolysin, Leukocidin, entertoxin, exfolliative toxin, TSST-1, and protein A + Coagulase
Exfolliative toxin is a virulence factor of what bacteria? S. aureus.
TSS is caused by what bacteria? S. Aureus (via TSS toxin)
Diffeentiate the CSF findings if a funal mengingitis vs a bacterial meningitis? Fungal = Increase in lymphocytes, bacterial = increase in PMNs
Asplencic individuals are most likely at risk for what type of infxon? Encapsulated bacterial infxon. (ie; S. pneumoniae in an older sickle cell patient)
What virulence factor mediates the formation of a fibrin capsule around the infectious loci of s. aureus? Coagulase
Describe the structure of exotoxin and the key role of each component? A domain: delivered into host cell. Posseses enzymatic activity to induce the toxin. B domain: binds hos cell membrane to deliver the A domain.
How are exotoxins activated? By cleaving the disulphide bond between the A and B domain.
How do exotoxins enter the host cell? The A domain is transported across the membrane by the B domain.
Botulinum toxin and tetanus toxin are both what kind of toxins? Zinc proteases / neurotoxins
Hemiagglutination inhibition involed IgG or IgM? IgG - late phase infxon / 2ry immune response
What type of microscopy requires staining? What kind does not ? Bright field microscopy requires staining. Phase contrast does not.
What kind of microscopy is used for parasites? Phase contrast
Where is a francisella tularensis infxon commonly aquired? Working in a lab setting. This bacteria can penetrated intact skin (no wound required) because of its small size.
Early phase antibody response is mediated by: IgM
Late phase antibody response is mediated by: IgG
Hemiagglutination inhibition test with a positive result means? A positive result means that antiboduy against the antigen in question is present and patient has been exposed to the agent (hemoagglutination is inhibited).
In the presence of O2, a methlyene blue strip is what color? Blue
Describe the basic flow of lab diagnosis? 1)Microscopy is performed on specimen. 2) the sample is cultured 3) cultivated organisms are analyzed and ID'd / tested for susceptability
In order for a microbial susceptabiity test to be run, what MUST be true. The organism in question must be know to be th causative agent of the condition.
During endotoxin induced innate immune system activation, what is the cell type and effector that is responsible for fever? Cytokine C5a from mononuc. phagocytes lead to TNF-a and IL-1 release
How does endotoxin act as an immunological adjuvent? By causing B-cell proliferation via the induction if IL-1 release
How does endotoxin induce B-cell proliferation. Via its induction of IL-1
What two bacteria release endotoxin by "blebbing" N. Meningitidus and N. gonorrhea
What acts as a notification to the immune system that a gram negative bacteria is present? Endotoxin.
Lipooligsaccharide (LOS) is a feature what bacteria? Endotoxin found in membrane of N. meningitidus.
What bacteria has LOS as a virulence factor? N. meningitidus!
Productive cough with rust colored sputum may be indicative of what bacteria? Strep. pneumoniae (typical pneumonia)
Most bacterial cause of pneumonia? Strep pnemoniae. Most commoly by direct extension (ie otitis media-->pneumoniae)
What are the virulence factors of S. aureus. Capsule, coagulase, protein A, leukocidin (kills leukocytes)
Coagulase negative staph infxon is associated with what risk factors? indwelling medical devices
What bacteria is very common in pastries, cream, etc? S. aureus
Lipoteichoic acid is associated with gram ___ bacteria gram +
what is the most important virulence factor of S. pneumoniae Its polysaccharide capsule which prevents opsonization by C3b and inhibits activation of alternative pathway.
How do endotoxins differ from exotoxins? Endotoxins are normal components of the cell membrane of the bacterium while exotoxins are secreted or attached to cell exterior. Endotoxins are only made in Gram neg bacteria.
Why is there no immnune response to the endotoxins of the natural flora of our GI tract? Because we do not possess the toll-like receptors (TLRs) to response to those endotoxins. Diseases such as Chron's and IBS involve the recruitment of extra-GI macrophages, which are sensitive to these toxins.
What is the gram + equivalent to endotoxin? Lipoteichoic acid.
Following the injection of endotoxin, what is the order of cytokines release? TNF-a----> IL-1 (IL-6 slowly rises and is released at same time as IL-1)
What is the most toxic portion of LPS Lipid A
What is LPS Lipopolysaccharide - Endotoxin
Created by: rkirchoff
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