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Flashcards in Microbio Deck (63):
1

peptidoglycan function and structure

- protects against osmotic pressure
- sugar backbone with peptide side chains cross-linked by transpeptidase

2

periplasm is the location for what?

hydrolytic enzymes, including b-lactamases

3

Unique to gram (-) or gram (+)

gram (+): lipoteichoic acid
gram (-): porins, endotoxin/LPS (outer membrane), periplasmic space

4

Special cultures (H. flu, N. gonorrhoeae, Legionella)

H flu - chocolate agar (requires factors X hematin and V NAD+)
N gonorrhoeae - Thayer-Martin ( Very Typically Cultures Neisseria - vanc + trimethoprim + colistin + nystatin)
Legionella - charcoal yeast

5

Aerobes - Nagging Pests Must Breathe

Require O2 to generate ATP

Nocardia, Pseudomonas, MycoBacterium tb

6

Anaerobes - Frankly Can't Breathe Air

normal in GI tract, can't use aminoglycosides (which require O2 to enter cell)

Fusobacterium, Clostridium, Bacteroides, Actinomyces

7

Encapsulated bacteria (SHiNE SKiS)

Strep pneumo, H. flu, N. meningitidis, E. coli, Salmonella, Klebsiella, group b Strep

8

Bacterial virulence proteins - Protein A, IgA protease, Protein M

Protein A - binds Fc region of IgG, Staph aureus
IgA protease - cleaves IgA, SHiN (S. pneumo, H. flu, N.m)
Protein M - prevent phagocytosis by decreased activation of alternate complement pathway, group A strep

9

ENDOTOXIN

Edema
Nitric Oxide
DIC/Death
Outer membrane
TNF-a
O-antigen
eXtremely heat stable
IL-1
Neutrophil chemotaxis

10

Gram-positive algorithm

bacilli vs. cocci
catalase + (clusters) --> coagulase
catalase - (chains) --> hemolysis
then sensitivities (coag -: novobiocin, cat -/a-hemolytic: optochin, cat-/B-hemolytic: bacitracin)

11

Strep bovis (bovis in the blood = ?)

Group D strep

Bovis in the blood = cancer in the colon

12

Diphtheria ABCDEFG

ADP-ribosylation
B-prophage
Corynebacterium
Diphtheriae
Elongation Factor-2
Granules (intracellular, polyphosphate)

Gram positive rod

13

Clostridia toxins (Gram positive rod)

tetani - cleave SNARE proteins, block release of NTs (spastic paralysis)
botulinum - block Ach release (floppy baby)
perfringens - alpha toxin = lecithinase - phospholipid breakdown (also, myonecrosis by collagen breakdown)
dificile - toxin A: enterotoxin. Toxin B: cytotoxin (depolymerizes actin filaments) (pseudomembranous colitis)

14

Listeria bacteria features

facultative intracellular Gram positive rod
rocket tails - actin polymerization, rapid movement
neonatal meningitis!
grows at 4 degrees (contaminates refrigerated food, food = most common transmission)

15

Leprosy (mycobacterium)

- cool temperature distribution (glove and stocking)
- tx: dapsone and rifampin
- lepromatous: low immunity (Th2)
- tuberculoid: high immunity (Th1)

16

Gram-negative algorithm

diplocoi vs. coccoid rods vs. cocci
- maltose fermentation vs. not
- lactose fermentation or not
- oxidase + (pseudomonas) vs. not

17

Lactose fermenters (Klebsiella and E. coli)

MacConkey's agar
Lactose is key with MacConKEY's agar

18

Neisseria gono vs. mening

GoNO - no polysaccharide capsule, no maltose fermentation, no vaccine, FHC syndrome
Mening - maltose fermentation, W-F syndrome

19

H. flu leads to what?
hEMOPhilus

haEMOPhilus causes:
Epiglottitis
Meningitis
Otitis media
Pneumonia

20

Legionella

use silver stain on charcoal culture with iron and cysteine (silver helmet over campfire with iron dagger - not a sissy!)

aerosol transmission

21

Pseudomonas is associated with what?

PSEUDDO
Pneumonia
Sepsis
otitis Externa
UTIs
Drugs/Diabetes
Osteomyelitis

think pseudomonas in burn victims!
exotoxin A -

22

E. coli subtypes (I, T, P, H)

EIEC: invasive
ETEC: enteroToxins, Traveler's (watery, heat-stable vs. heat-labile)
EPEC: Pediatrics
EHEC: O157:H7, Shiga-toxin, HUS (anemia, thrombocytopenia, renal failure due to damaged endothelium)

23

Klebsiella (4A's)

Aspiration pneumonia
Abscesses (lung/liver)
Alcoholics
diAbetics

24

Campylobacter

Bloody diarrhea
Gullain-Barre
reactive arthritis (arthritis, conjunctivitis, urethritis)
Undercooked meat!

25

Cholera mechanism

Enterotoxin that permanently activates Gs, causing increased cAMP activity

26

Leptospirosis (surfers, tropics)

flu-like symptoms
myalgias (calves!)
jaundice
photophobia

27

Lyme symptom progression (FACE)

early - flu-like, classic rash, facial nerve palsy (bilateral)
later - arthritis, AV nodal block, neurologic
Lyme pie to the FACE: Facial nerve palsy, Arthritis, Cardiac block, Erythema migrans

28

False positives on VDRL

Viruses
Drugs
Rheumatic fever
Lupus/leprosy

29

Animal transmission

cat scratch - Bartonella
armadillo - leprosy
dog tick - rickettsia (RMSF)
sheep amniotic fluid - Coxiella (Q fever)

30

Gardnerella

bacterial vaginosis
clue cells
KOH whiff test

31

Palms and soles rash

CARS
Coxsackie A
RMSF
Syphillis

32

E's and R's of chlamydia

Elementary body is enfectious, enters cell through Endocytosis

Reticulate body Replicates in cell by fission, Reorganizes into elementary bodies for spread to other cells

Reactive arthritis - uveitis/conjunctivitis, arthritis, urethritis

33

Chlam subtypes

ABC - Africa, blindness, chronic infection
D-K - everything else!

34

High titer of cold agglutinins (IgM)

Mycoplasma pneumoniae
X-ray is worse than patient
antigenic similarity with RBCs, so immune response destroys RBCs!
no cell wall

35

Systemic Mycoses (HBCP)

Histo - hides within macrophages
Blasto bus broadly
Coccidio crowds (spherule filled with spores)
Paracoccidio parasails with captain's wheel to Latin America

36

Tinea versicolor mechanism

degradation of lipids produces acids that damage melanocytes and cause hypopigmentation

37

Opportunistic fungal infections (6 total)

Candida - superficial or systemic (no pulm involvement)
Aspergillus - invasive; ABPA (asthma and CF, look for eosinophilia); aspergilloma (post-TB infection). A for Acute Angles in Aspegillus.
Cryptococcus - heavily encapsulated, latex agglutination (polysaccharide capsular antigen test)
Mucor/Rhizopus - rhinocerebral, frontal lobe abscess, CST
Pneumocystis - diffuse ground-glass opacities, disc-shaped yeast
Sporothrix - ascending lymphangitis (rose in the pot)

38

GI protozoa

Giardia - foul-smelling, fatty
Entamoeba - liver abscess (anchovy paste), RBCs in cytoplasm, cysts with 4 nuclei
Cryptosporidium - severe diarrhea in AIDS

39

CNS protozoa

Toxo - congenital (chorioretiniti, calcifications, hydrocephalus), AIDS (brain abscess)
Naegleria - rapidly fatal, freshwater lakes
Trypanosoma brucei (African sleeping) - lymph nodes, recurring fever, somnolence. "Sure is nice to sleep with Melatonin" tx = suramin, melarsoprol

40

Heme protozoa

Malaria (Plasmodium) - fevers are 48 hrs apart in vivax/ovale, look for spots in RBCs, quinidine = watch for G6PDH def.!
Babesia - same tick as Lyme, hemolytic anemia, Maltese cross in RBC, predilection for asplenia!

41

Other protozoa

Chagas dz (trypanosoma cruzi) - dilated cardiomyopathy + achlasia/megacolon + unilateral periorbital swelling, kissing bug feces
Leishmaniasis - sandfly, fevers/HSM/pancytopenia

42

Trichomonas (what does cervix look like?)

strawberry cervix, foul-smelling, treat pt and partner!

43

roundworm treatment (pinworms, hookworms, etc.)

Bendazoles are bendy for intestinal infection

44

Biliary tract dz -cholangiocarcinoma (parasite)

Clonorchis sinensis (undercooked fish), pigmented gallstones

45

Brain cysts/seizures (parasite)

Taenia solium (cysticercosis) when eggs are ingested

46

Hematuria, bladder SCC (parasite), less likely =

Schistosoma haematobium, lives in snails!

47

Liver hydatid cysts (parasite)

Echinococcus (dog feces, sheep, kill daughter cysts before removal with ethanol)

48

Microcytic anemia (parasite)

Ancylostoma (blood sucker!)

49

Myalgias (parasite)

Trichinella (undercooked meat)

50

Perianal pruritis (parasite)

Enterobius (pinworm)

51

Portal hypertension (parasite)

Schistosoma mansoni, schistosoma japonicum

52

Vitamin B12 deficiency (parasite)

Diphyllobothrium latum (raw freshwater fish)

53

Match the food to the bug
Rice
Canned food/honey
Undercooked meat
Poultry/meat/eggs
Meats/mayonnaise
Seafood

Rice - bacillus cereus
Canned food/honey - C. botulinum
Undercooked meat - E. coli
Poultry/meat/eggs - Salmonella, Campylobacter
Meats/mayonnaise - Staph aureus
Seafood - Vibrio

54

HIV + diseases

<100: Aspergillus (pleuritic pain), Crypto (meningitis), Candida (esophagitis), CMV (retinitis, colitis, enceph), EBV (oral hairy leukoplakia, B-cell lymphoma), Histo (const. sx), MAC (non-specific sx)

55

Three prion diseases

CJD: rapidly progressive dementia
Bovine spongiform encephalopathy: mad cow disease
Kuru: human cannibalism

56

Diarrhea etiologies

Bloody: Campy, Enteamoeba, EHEC, EIEC, E. coli, Salmonella, Shigella, Yersinia
Watery: Clostridium (diff/perf), ETEC, Giardia/Crypto, Vibrio, Rota/Noro/Adeno

57

Special pneumonia groups (alcoholics, atypical, CF)

Alcoholics: Klebsiella
Atypical: Mycoplasma, Legionella, Chlam
CF: Pseudomonas, S. aureus

58

Brain abscess

Viridans strep
Staph aureus
Toxo reactivation

59

Osteomyelitis special risk factors (generally S. aureus, except...)

Sickle cell - Salmonella, S. aureus
Vertebral involvement - M. tuberculosis
Cat/dog bites - Pasteurella

60

UTI bugs

E. coli - green metallic sheen on EMB agar
Staph sapro
Klebsiella - + urease test

61

Congenital infections (ToRCHeS)

Toxo - chorioretinitis, hydrocephalus, intracranial calcs
Rubella - PDA, cataracts, deafness
CMV - hearing loss, seizures, petechial rash
HSV-2 - encephalitis
Syphilis - facial abnormalities

62

Red rashes of childhood

Coxsackie Type A - HFM dz
HHV-6 (roseola) - fever followed by rash
Measles (rubeola) - 3 C's, descending rash
Rubella - post-auricular adenopathy, descending rash
Strep pyogenes - scarlet fever, sandpaper-like rash
VZV - lesions of different ages

63

Random bug hints
asplenia, branching rods, chronic granulomatous dz, currant jelly sputum, dog/cat bite, health care provider, neutropenia, organ transplant, PAS +, palms/soles rash, surgical wound, traumatic open wound

SHiN - strep pneumo, H. flu, Neisseria
Actinomyces (oral infections)
catalase + (S. aureus, Burkholderia)
Klebsiella
Pasteurella
HBV
Candida, Aspergillus
CMV
Tryponema Whipplei
CARS: coxsackie A, Rickettsia, Syphillis
Staph aureus
Pseudomonas