Microbiology Bugs exam questions and answers Rated A+

Microbiology Bugs




Staph aureus - answerGram +, Cocci, Cat (+), Coag (=)
-Protein A (virulence factor) binds Fc-IgG, inhibiting complement
1.Inflamm Disease: skin infx (impetigo), organ abscess, pneumonia
2.Toxim-mediated: TSST
3.MRSA

Causes acute bacterial endocarditis, osteomyelitis

Staph Epidermidis - answerGram +, Cocci, Cat (+), Coag (-), Novobiocin Sens
-Prosthetic devices and catheters with biofilm

Strep Pneumo - answerCocci, Cat (-), a-hemolytic, Opthochin sens, Lancet shaped,
Capsule, "rusty" sputum
-Most common cause of:
Meningitis
Otitis Media
Pneumonia
Sinusitis

Viridians Strep - answerGram +, Cocci, Cat (-), a-hemolytic, opthochin resistant
1. Strep mutans: normal floral, cause dental carries
2. Strep sanguis: subacute bacterial endocarditis

Strep Pyogenes (Group A Strep) - answerGram +, Cocci, Cat (-), B-hemolytic,
Bacitracin sens
-M protein (prevent phagocytosis)
-ASO titer detects infx
1.Pyogenic: pharyngitis, cellulitis, impetigo
2.Toxigenic: scarlet fever, TS-like syndrome
3.Immunologic: rheumatic fever, acute glomerulonephritis

Strep agalactiae (Group B Strep) - answerGram +, Cocci, Cat (-), B-hemolytic,
Bacitracin resistant

,-B is for Babies!
-colonizes vagina: causes pneumo, mening, sepsis in babies
-Screen pregnant women and give prophylaxis penicillin

Enterococci (Group D Strep) - answerGram +, Cocci, Cat (-), gamma-hemolytic
-Normal floral and are penicillin G resistant
-UTI and endocarditis
VRE: important cause of nosocomial infection

Streptococcus bovis (Group d Strep) - answerGram +, Colonizes gut, causes
bacteremia and subacute endocarditis in colon cancer patient

Corynebacterium diptheriae - answerGram +, Rod (bacilli)
-Exotoxin encoded by B-phage: inhibits protein synthesis via ADP ribisulation of EF-2
-Clinical picture: pseudomembranous pharyngitis (grayish white) with lymphadenopathy

Toxoid Vaccine: Diptheria, Pertussis, Tetanus
-produces IgG against circulating proeins

Spore Formers - answerGram +, Bacillis anthracis, Clostridium perfringens, Clostridium
tetani, B. cereus, C. botulinum, Coxiella burnetti

Clostridia tetani - answerGram +, Rod (bacilli), anaerobe
Exotoxin causing tetanic paralysis by blocking glycine and GABA release (no inhibition)

Clostridia botulinum - answerGram +, Rod (bacilli), anaerobe
Preformed, heat-labile toxin inhibits ACh release at NM Jx leading to flaccid paralysis
-Found in bottles of food and honey

Clostrida prefringens - answerGram +, Rod (bacilli), anaerobe
Produces a-toxin causing myonecrosis and hemolysis in open wounds

Clostridia difficile - answerGram +, Rod (bacilli), anearobe
1.Toxin A: binds to brush boarder of gut
2.Toxin B: destroys cytoskeleton of enterocyte causing pseudomembranous colitis
-Often secondary to antibiotic use
Treatment: oral vancomycin or metronidazole

Bacillus anthracis - answerGram +, Rod (bacilli), aerobe
-The only bacterium with polypeptide capsule (contains D-glutamate)
1.Cutaneous: contact->black eschar->caused by edema and lethal factors->death
2. Pulmonary: flu-like symptoms (think Woolsorter's disease)

Listeria Monocytogenes - answerGram +, Rod (bacilli), intracellular microbe
-Form "actin rockets" to get from cell to cell (tumbling motility)
-Ingestion of unpasturized milk/cheese

, -Vaginal transmission during birth--- lots of birthing problems
Tx: usually self limited, ampicillin in infants

Actinomyces israelii - answerGram +, branching filament, anaerobe, forms yellow "sulfur
granules" in sinus tracts
-oral/facial abcess
Tx: penicillin

Nocardia asteroides - answerGram +, branching filament, aerobe
-pulmonary infx in immunocompromised
Tx: sulfa

Primary tuberculosis - answerHilar nodules and Ghon complex

Secondary tuberculosis - answerFibrocaseous cavitary lesion

Mycobactera tuberculosis - answerGram +, Rod (bacilli), acid fast, aerobe
TB- often resistant to many drugs
Symptoms: fever, night sweats, weight loss, hemoptysis

Mycobacteria avium - answerGram +, Rod (bacilli), acid fast
Disseminated disease in AIDS
Prophylactically treat with azithromycin

Mycobacteria leprae - answerGram +, Rod (bacilli), acid fast
-Cool temps, infects skin and superficial nerves
1. Lepromatous: communicable, humoral Th2 response, lethal
2. Tuberculois: high cell-mediated immunity with Th1 response

Tx: long term dapsone (tox: hemolysis and methemoglobinemia) OR rifampin,
clofazimine/dapsone

Obligate Aerobes - answer"Nagging Pests Must Breathe"
Nocardia +
Psueodomonas aeruginosa -
Mycobacterium TB +
Bacillus -

Obligate Anaerobes - answer"Can't Breathe Air"
Clostridium +
Bacteroides -
Actinomyces +

Intracellular Bugs - answerRickettsia, Chlamydia
Factultative: Salmonella, Neisseria, Brucella, Mycobacterium, Listeria, Francisella,
Legionella, Yersinia pestis