One Word_Microbiology Flashcards Preview

USMLE > One Word_Microbiology > Flashcards

Flashcards in One Word_Microbiology Deck (40):
1

ADP ribosylating A-B toxins - Bordetella pertussis

Increases cAMP by inhibiting Gαi; causes whooping cough; inhibits chemokine receptor, causing lymphocytosis

2

ADP ribosylating A-B toxins - Corynebacterium diphtheriae

Inactivates elongation factor (EF-2) (similar to Pseudomonas exotoxin A); causes pharyngitis and "pseugomembrane" in throat

3

ADP ribosylating A-B toxins - E. coli

Heat-labile toxin stimulates adenylate cyclase. Heat-stable toxin stimulates guanylate cyclase. Both cause watery diarrhea.

4

ADP ribosylating A-B toxins - Vibrio cholerae

ADP ribosylation of G protein stimulates adenylyl cyclase; ↑ pumping of Cl- into gut and ↓ Na+ absorption. H2O moves into gut lumen; causes voluminous rice-water diarrhea

5

Bacterial structures - Capsule

Function - Protects against phagocytosis Chemical composition - Polysaccharide (except Bacillus anthracis, which contains D-glutamate)

6

Bacterial structures - Cell wall/cell membrane (gram positives)

Function - Major surface antigen Chemical composition - Peptidoglycan for support. Teichoic acid induces TNF and IL-1

7

Bacterial structures - Flagellum

Function - Motility Chemical composition - Protein

8

Bacterial structures - Glycocalyx

Function - Mediates adherence to surfaces, especially foreign surfaces (e.g., indwelling catheters) Chemical composition - Polysaccharide

9

Bacterial structures - Outer membrane (gram negatives)

Function - Site of endotoxin (lipopolysaccharide); major surface antigen Chemical composition - Lipid A induces TNF and IL-1; polysaccharide is the antigen

10

Bacterial structures - Peptidoglycan

Function - Gives rigid support, protects against osmotic pressure Chemical composition - Sugar backbone with cross-linked peptide side chains

11

Bacterial structures - Periplasm

Function - Space between the cytoplasmic membrane and peptidoglycan wall in gram-negative bacteria Chemical composition - Contains many hydrolytic enzymes, including β-lactamases

12

Bacterial structures - Pilus/fimbria

Function - Mediate adherence of bacteria to cell surface; sex pilus forms attachment between 2 bacteria during conjugation Chemical composition - Glycoprotein

13

Bacterial structures - Plasma membrane

Function - Site of oxidative and transport enzymes Chemical composition - Lipoprotein bilayer

14

Bacterial structures - Plasmid

Function - Contains a variety of genes for antibiotic resistance, enzymes, and toxins Chemical composition - DNA

15

Bacterial structures - Ribosome

Function - Protein synthesis Chemical composition - 50S and 30S subunits

16

Bacterial structures - Spore

Function - Provides resistance to dehydration, heat, and chemicals Chemical composition - Keratin-like coat, dipicolinic acid.

17

Bacterial virulence factors - IgA protease

Enzyme that cleaves IgA. Secreted by S. pneumoniae, H. Influenzae type B, and Neisseria (SHiN) in order to colonize respiratory mucosa

18

Bacterial virulence factors - M protein (group A streptococcus)

Helps prevent phagocytosis

19

Bacterial virulence factors - Protein A (S. aureus)

Binds Fc region of Ig. Prevents opsonization and phagocytosis.

20

Lysogeny, specialized transduction

①Shiga-like toxin ②Botulinum toxin ③Cholera toxin ④Diphtheria toxin ⑤Erythrogenic toxin of Streptococcus pyogenes

21

Other toxins - Bacillus anthracis

Edema factor, part of the toxin complex, is an adenylate cyclase

22

Other toxins - C. botulinum

Blocks the release of acetylcholine; causes anticholinergic symptoms, CNS paralysis, especially cranial nerves; spores found in canned food, honey (causes floppy baby)

23

Other toxins - C. tetani

Blocks the release of inhibitory neurotransmitters GABA and glycine; causes "lockjaw"

24

Other toxins - Clostridium perfringens

α toxin, a lecithinase that acts as a phospholipase to cleave cell membranes and causes gas gangrene; get double zone of hemolysis on blood agar

25

Other toxins - S. pyogenes

Streptolysin O is a hemolysin; antigen for ASO antibody, which is used in the diagnosis of rheumatic fever

26

Other toxins - Shigella

Shiga toxin (also produced by E. coli O157:H7) cleaves host cell rRNA (inactivates 60S ribosome); also enhances cytokine release, causing HUS

27

Parasite hints - B12 deficiency

Diphyllobothrium latum

28

Parasite hints - Biliary tract disease, cholangiocarcinoma

Clonorchis sinensis

29

Parasite hints - Brain cysts, seizures

Taenia solium (cysticercosis)

30

Parasite hints - Hematuria, bladder cancer

Schistosoma haematobium

31

Parasite hints - Hemoptysis

Paragonimus westermani

32

Parasite hints - Liver cysts

Echinococcus granulosus

33

Parasite hints - Microcytic anemia

Ancylostoma, Necator

34

Parasite hints - Perianal pruritus

Enterobius

35

Parasite hints - Portal hypertension

Schistosoma mansoni

36

Superantigens - S. aureus

TSST-1 superantigen causes toxic shock syndrome (fever, rash, shock). Other S. aureus toxins include enterotoxins that cause food poisoning as well as exfoliatin, which causes staphylococcal scalded skin syndrome.

37

Superantigens - S. pyogenes

Scarlet fever-erythrogenic toxin causes toxic shock-like syndrome

38

Unusual cell membranes/walls - Chlamydiae

Cell wall lacks muramic acid

39

Unusual cell membranes/walls - Mycobacteria

Contain mycolic acid. High lipid content

40

Unusual cell membranes/walls - Mycoplasma

Contain sterols and have no cell wall