USMLE-Microbiology-basic bacteriology IV

lehakiko's version from 2016-01-12 16:39

Section 1

Question Answer
What is an obligate aerobes?Use an O2-dependant system to generate ATP
What is the name of the obligate aerobe who has a predilection for the apices of the lung, which have the highest PO2?reactivation of M.tuberculosis
What is the mnemonic for examples of obligate aerobes?"Nagging Pests Must Breathe''= Nocardia, Pseudomonas aeruginosa, Mycobacterium tuberculosis and Bacillus
When do we see P. aeruginosa?seen in burn wounds, complication of diabetes, nosocomial pneumonia, and pneumonia in cystic fibrosis patients
What are the characteristics of obligate anaerobe?they lack catalase and/or superoxide dismutase and are thus susceptible to oxidative damage. Generally foul smelling, are difficult to culture and produce gas in tissue
What are the gases produced by obligate anaerobes?CO2 and H2
What is the mnemonic for examples of obligate anaerobes?anaerobes Frankly Can't Breathe Air= Clostridium, Bacteroides and Actinomyces
Where do anaerobes are normal flora?in the GI tract and pathogenic elsewhere
What antibiotics is ineffective against anaerobes?aminO2glycosides are ineffective against anaerobes because these antibiotic require O2 to enter into bacterial cell

Section 2

Question Answer
What is the mnemonic for the names of obligate intracellular bugs?stay inside (cells) when it's Really Cold =Rickettsia, Clamydia. can't make own ATP
What is the mnemonic for the names facultative intracellular bugs?Some Nasty Bugs May Live FacultativeLY= Salmonella, Neisseria, Brucella, Mycobacterium, Listeria, Francisella, Legionella, Yersinia pestis
What is a positive quellung reaction?if encapsulated bug is present, capsule swells when specific anticapsular antisera are added (mnemonic: Quellung=capsular "swellung")
What is the mnemonic for examples of encapsulated bacteria?SHiNE SKiS= Streptococcus pneumoniae, Haemophilus influenza type B, Neisseria meningitidis, E.coli, Salmonella, Klebsiella pneumonia and group b strep
What is the function of the capsule of an encapsulated bacteria?their capsules serve as an antiphagocytic virulence factor. Capsule + protein conjugate serve as an antigen in vaccines
How encapsulated bacteria are cleared by spleen?by opsonization
Asplenics people have decreased opsonizing ability and are at risk for severe infection. Against what agents do we give vaccine?S pneumoniae, H. Influenza, N.menigitidis

Section 3

Question Answer
What is a catalase?it's an enzyme that degrade H2O2 before it can be converted to microbicidal products by the enzyme myeloperoxidase
What kind of people have recurrent infections with catalase positive organisms because they degrade the limited H2O2?People with chronic granulomatous disease (NADPH oxidase deficiency)
What is the mnemonic for examples of catalase positive organisms?you need PLACESS for your CATs (where cat stand for catalase) =Pseudomonas, Listeria, Aspergillus, Candida, E.coli, S.aureus, Serratia

Section 4

Question Answer
What is the physiology of a polysaccharide vaccine with no conjugated protein as pneumovax?a polysaccharide antigen alone cannot be presented to T cells; therefore, only IgM antibodies would be produced.
What is the physiology of a conjugated vaccine as H.influenza type B and meningococcal vaccines?for vaccines containing polysaccharide capsule antigens, a protein is conjugated to the polysaccharide antigen to promote T-cell activation and subsequent class switching
What is the mnemonic for the names of urease-positive bugs?CHuck norris hates PUNKSS= Cryptococcus, H.pylori, Proteus, Ureaplasma, Nocardia, Klebsiella, S.epidemidis, S. saprophyticus
What bacterias produce yellow pigments?Actinomyces ISRAELii (mnemonic=ISRAEL has yellow sand) and S.aureus (aureus in latin means gold)
What is the name of the bacteria producing red pigment?serratia MARCESCENS (think RED MARACHINO cherries)
What is the name of the bacteria producing green pigment?pseudomonas AERUGinosa (mnemonic: AERUGula is green) (aerugula= de la roquette)
What are the 3 bacterial virulence factors?1)protein A 2)IgA protease 3) M protein
What is the action of protein A of bacteria?Binds Fc region of Ig. Prevents opsonization and phagocytosis. Expressed by S.aureus
What is the action of IgA protease of bacteria?Enzyme that cleaves IgA. Secreted by S.pneumonia, H.iinfluenza type b and Neisseria (mnemonic SHiN) in order to colonize respiratory mucosa
What is the action of M protein of bacteria?Helps prevent phagocytosis. Expressed by group A streptococci