Microbiology--Clinical Bacteria Flashcards Preview

USMLE Step 1 > Microbiology--Clinical Bacteria > Flashcards

Flashcards in Microbiology--Clinical Bacteria Deck (73):
1

Staphylococci identification: novobiocin sensitivities

on "staph" retreat, there was NO StRES: saprophyticus--resistant; epidermidis--sensitive

2

Strep identification: optochin and bacitracin

OVRPS: optochin--viridans is resistant; pneumoniae is sensitive

B-BRAS: bacitration--group B is resistant; group A is sensitive

3

green ring around colonies on blood agar

alpha hemolytic, Strep pneumoniae or viridans

4

clear area of hemolysis on blood agar

B-hemolytic bacteria: staph aureus, strep pyogenes, strep agalactiae, listeria monocytogenes

5

how does MRSA gain resistance to methicillin and nafcillin

altered penicillin binding protein

6

infects prosthetic devices and IV catheters by biofilm

staph epidermidis

7

second most common cause of uncomplicated UTI in women

staph saprophyticus

8

"rusty sputum" sepsis in sickle cell anemia and splenectomy

Strep pneumoniae: MOPS are Most OPtochin Sensitive: most common cause of meningitis, otitis media (in kids), pneumonia, sinusitis; gram + diplococci, IgA protease

9

strep species that is associated with dental caries and bacterial endocarditis on damaged valves

Strep viridans: mutans-cavities; sanguinis--bacterial endocarditis; optochin resistant, bile does not lyse, catalase -

10

pharyngitis, scarlet fever, rheumatic fever, glomerulonephritis

Strep pyogenes (group A strep); M protein, ASO titer

11

bacitracin resistant, B hemolytic, colonizes vagina--affects babies

Strep agalactiae (group B strep); colonies at 35-37 weeks in pregnant women, if positive, give prophylactic penicillin; hippurate test +

12

gram+, catalase -, gamma/alpha hemolytic, growth in bile and hypertonic salt

Enterococcus (group D strep) E faecalis, faecium

13

bacteria that colonizes the gut, can cause subacute endocarditis in colon cancer patients

Strep bovis

14

gram positive rods with metachromatic blue/red granules

Corynebacterium diphtheriae; black colonies on cystine tellurite agar, beta prophage (with diptheria toxin), Elek test for toxin; toxoid vaccine available

15

Spore forming gram + bacteria found in soil:

bacillus anthracis, clostridium perfringens, C tetani
other spore formers: B cereus, C botulinum, Coxiella burnetii

16

gram positive, spore forming, obligate anaerobic bacteria

clostridium spp

17

bad bottles of food and honey

Clostridium botulinum (preformed heat labile botulinum toxin)

18

boil-like lesion--ulcer with black eschar that is painless and necrotic

cutaneous bacillus anthracis (gram positive spore forming rod); only bacteria with polypeptide D glutamate capsule

19

flu like symptoms that progress rapidly to fever, pulmonary hemorrhage, mediastinitis, and shock

pulmonary anthrax

20

reheated rice/pasta

bacillus cereus--spore forming gram+ that causes nausea and vomiting within 5 hrs of ingestion via preformed toxin cereulide; watery nonbloody diarrhea and GI Pain within 8-18 hrs

21

ingestion of unpasteurized dairy products/deli meats

Listeria monocytogenes: facultative intracellular microbe; rocket tails via actin that allow for cell penetration; only G+ organism to produce LPS

22

oral facial abscesses that drain through sinus tracts, form yellow sulfur granules

actinomyces (gram +, anaerobic, not acid fast)

23

pulmonary infection in immunocompromised, cutaneous infection after trauma in competent

Nocardia (gram+, aerobic, weakly acid fast)

24

How does mycobacterium avoid immune clearance?

cord factor in virulent strains inhibits macrophage maturation and induces release of TNF-alpha; sulfatides (surface glycolipids) inhibit phagolysosomal fusion

25

"glove and stocking" loss of sensation and cannot be grown in vitro. armadillo reservoir in US

Mycobacterium leprae: lepromatous form--low cell mediated immunity with a humoral Th2 response; tuberculoid form--high cell mediated immunity with largely Th1-type mediated response

26

strong and weak lactose fermenting enteric bacteria

Lactose is KEE; Test with macConKEE'S agar; klebsiella/e coli/enterobacter are fast fermenters; citrobacter/serratia are weak fermenters

27

neisseria gonorrhea vs meningitidis?

both are gram negative diplococci; both ferment glucose and produce IgA protease; MeninGococci ferment maltose and glucose; Gonococcal ferment glucose only; gonorrhea often intracellular within neutrophils

28

epiglottitis, meningitis, otitis media, pneumonia in children

HiB, culture on chocolate agar requires V (NAD+) and X (hematin); gram- coccobacillary rod; vaccine has type B polysaccharide conjugated to protein

29

severe pneumonia,fever, GI and CNS symptoms

Legionnaires disease; legionella; gram negative rod; detect with urine antigen; use silver stain, grow on charcoal yeast extract with iron and cysteine; labs show HYPOnatremia

30

associated with wound and burn infections

pseudomonas aeruginosa: gram negative rode, non lactose fermenting, oxidase +; pyocyanin (blue/green pigment); grape like odor; endotoxin and exotoxin (inactivates EF2)

31

What are e coli virulence factors?

fimbriae: cystitis/pyelonephritis; K capsule: pneumonia, neonatal meningitis; LPS endotoxin: septic shock

32

microbe invades intestinal mucosa causing necrosis and inflammation. dysentery.

EIEC

33

produces heat labile and heat stabile enterotoxins. No inflammation or invasion

ETEC

34

adheres to apical surface, flattens villu, prevents absorption

EPEC--diarrhea in children

35

HUS e coli

EHEC--does not ferment sorbitol (distinguishes from other E coli)

36

Salmonella vs Shigella: flagella

only Salmonella have flagella

37

Salmonella vs Shigella: dissemination

Salmonella: hematogenously; Shigella: cell to cell, no hematogenous

38

Salmonella vs Shigella: reservoirs

Salmonella: many; Shigella: only humans and primates

39

Salmonella vs Shigella: hydrogen sulfide

only salmonella

40

Salmonella vs Shigella: antibiotics

Salmonella: prolong course; Shigella: shorten course

41

Salmonella vs Shigella: immune response

Salmonella: invades mucosa, monocytic response; Shigella: invades mucosa, neutrophil response

42

Salmonella vs Shigella: diarrhea bloody/nonbloody

Salmonella: sometimes bloody; Shigella: bloody

43

Rose spots on abdomen, fever, headache, diarrhea

Salmonella typhi--typhoid fever, can remain in gallbladder and cause carrier state

44

major cause of bloody diarrhea esp in children

Campylobacter jejuni; fecal oral transmission through foods; grows at 42 C; common antecedent to GBS and reactive arthritis

45

rice water diarrhea via enterotoxin

vibrio cholerae--toxin permanently activates Gs; grows in alkaline media; oral rehydration

46

transmitted from pet feces; contaminated milk or pork--mimics Crohns or appendicitis

Yersinia enterocolitica--causes mesenteric adenitis

47

curved gram - rode that is catalase, oxidase, and urease +

helicobacter pylori

48

flu like symptoms, jaundice, photophobia with conjunctival erythema w/out exudate

Leptospira interrogans--spirochete; prevalent among surfers and in tropics; water contaminated w/ animal urine

49

natural reservoir is the mouse

Lyme disease--big spirochete, facial nerve palsy, arthritis, cardiac AV block, erythema migrans

50

congenital syphilis

saber shins, saddle nose, CN 8 deafness, hutchinson teeth, mulberry molars; to prevent treat mother early in pregnancy--transmission occurs after 1st trimester

51

false positives of VDRL test

VDRL: viruses (mono, hepatitis); drugs; rheumatic fever; lupus and leprosy

52

Ixodes ticks (deer and mice)

anaplasmosis: infection in RBS by rickettsia spp; increased HR, hematuria, use Giemsa stain; lyme disease

53

Cat scratch

bartonella spp: bacillary angiomatosis. lymphadenopathy

54

Louse

borrelia recurrentis: recurrent fever; variable surface antigens; rickettsia proweseki (endemic typhoid)

55

unpasteurized dairy

brucella spp: brucellosis; undulant fever

56

puppies, livestock (fecal oral, ingestion of undercooked meat)

Campylobacter: bloody diarrh

57

Parrots, birds

chlamydophila psittaci: psittacosis-severe pneumonia, typhoid mimic

58

aerosols of cattle/sheep amniotic fever

coxiella burnetii: q fever--mild flu like illness--chronically can cause endocarditis/hepatitis

59

lone star ticks

ehrlichiosis: obligate intracellular bacteria that infect/kill WBCs; supress TNF-alpha

60

ticks, rabbits, deer fly

tularemia

61

animal urine

leptospirosis

62

animal bite, cats, dogs

pasteurella multocida

63

dermacentor ticks

rickettsia rickettsii: RMSF

64

Fleas

rickettsia typhi--endemic typhus

65

Fleas (rats/prairie dogs are reservoirs)

yersinia pestis--plague

66

rash starting at wrists/ankles and spreadin to trunk/palms/soles

RMSF

67

differential for palm and sole rash:

CARS: Cocksackievirus A, RMSF, 2 syphilis

68

rash starting centrally and spreads out, sparing palms and wrists

Typhus

69

monocytes with morulae (berry like inclusions) in cytoplasm

ehrlichiosis--tick vector

70

granulocytes with morulae in cytoplasm

anaplasmosis

71

2 forms of chlamydia

Elementary body (small/dense) that is Enfections/Enters cell via Endocytosis and transforms into Reticulate body that Replicates by fission and reorganizes into Elementary body

72

what is unusual about chlamydia cell walls?

lack muramic acid

73

high titer of cold agglutinins IgM

Mycoplasma pneumoniae: IgM can aggregate or lyse RBCs, no cell wall, membrane has sterols for stabilityq