Microbiology

Question 1

Gonococcal Arthritis symptoms

Answer 1

TRIAD: dermatitis, tenosynovitis, polyarthralgia/arthritis

Lesions on skin- macules, papules

Question 2

Viral Arthritis species

Answer 2

Rubella, Parvo B19, HCV, HBV

Question 3

Vertebral Osteomyelitis Spp.

Answer 3

S. Aureus, MTB, Brucellosis

Question 4

Osteomyelitis in someone who stepped on a nail

Answer 4

P. Aeruginosa

Question 5

Osteomyelitis in Neonates

Answer 5

GBS, E. Coli

Question 6

Osteomyelitis in Sickle Cell - Sp. and Pathogenesis

Answer 6

Salmonella - sickling may infarct the gut and allow salmonella invasion, then reduced clearance due to spleen issues

Question 7

Osteomyelitis in IVDU Spp

Answer 7

S. Aureus, P. Aeruginosa, Candida

Eikenella corrodens - (“needle licker osteomyelitis”)

Question 8

Osteomyelitis in IVDU clinical manifestation

Answer 8

Unusual sites of infection are common: sternoclavicular, sternochondral joint, pubic symphysis

Question 9

Myositis Pathogenesis

Answer 9

Clostridium Perfringens
Alpha toxin: damages cell membrane including erythrocytes, causing hemolysis and creiptus

Gram + Rods

Question 10

Staph Areus Microbiology

Answer 10

Catalase +
Coagulase +
B-Hemloytic
+ Mannitol Fermentation

Question 11

Staph Aureus Pathogenesis

Answer 11

“Produce B-Lactamse
MRSA: mec-A genes encode altered PBPs on cassettes cause
VRSA: D-lactate for D-ala
D Test: evaluates for inducible Clindamycin resistance
VISA: Thickened cell wall”

Question 12

Staphyloxanthin (Carotenoid)

Answer 12

enhances pathogenecity by inactivating microbicidal effect of superoxides from neutrophils

Question 13

Protein A

Answer 13

protein in cell wall that prevents complement activation, no C3b produced so phagocytosis is greatly reduced

Question 14

Alpha Toxin/Hemolysin

Answer 14

hemolytic toxin that causes necrosis of skin and hemolysis

Question 15

Scalded Skin Syndrome Toxin

Answer 15

Exfloiative toxins A and B, act as proteases to cleave desmosomes

Question 16

Staph Aureus Food Poisoning

Answer 16

Enterotoxin A causes vomiting and watery, non-bloody diarrhea
Stimulates IL-1 and IL-2

Question 17

Bullous Impetigo

Answer 17

Exfoliative toxin
Forms bullae with clear/ yellow fluid
Ruptured Bullae leave thin brown crust
Trunk more frequently affected

Question 18

Toxic Shock Syndrome STAPH

Answer 18

Tampons, nasal packing, post-op, septic joints
Stimulates IL-1, IL-2, and TNF
Blood cultures are commonly negative and isolation of bacteria is not required for diagnosis

Clindamycin suppresses protein synthesis so is used in treatment to stop toxin production

DIC is a complication

Question 19

Staph. Epidermidis Microbiology

Answer 19

"Catalase +
Coagulase -
Non-Hemolytic
Urease +
- Mannitol Fermentation
Novobiocin sensitive"

Question 20

Staph. Epidermidis Pathogenesis

Answer 20

"Biofilms:
Most infections occur in foregin devices
Surface adhesins interact with host proteins
Produces polysaccharide matrix
MRSE"

Question 21

Staph. Saprophyticus Microbiology

Answer 21

"Catalase +
Coagulase -
Non-Hemolytic
- Mannitol Fermentation
Novobiocin resistant"

Question 22

Hyaluronidase

Answer 22

degrades hyaluronic acid, known as spreading factor, facilitates cellulitis and other skin infections

Question 23

Streptolysin O

Answer 23

enhanced virulence, oxygen labile, antigenic, casues hemolysis

Question 24

GAS Necrotizing Fasciitis

Answer 24

Progressive destruction of fascia and underlying fat due to poor blood supply
Pain out of proportion to exam
M Proteins
Lack of neutrophils at infection due to destruction of IL-8
Can become septic, Surgical Emergency

Question 25

Streptococcal TSS

Answer 25

Does not require Nec Fas. But it occurs in 75% of cases Septic symptoms DIC, AKI, ARDS Isolation of GAS from a normally sterile site is required for diagnosis (different from STAPH)

Question 26

Scarlet Fever

Answer 26

Effects children ages 3-15 Erythrogenic toxin-mediated Sore throat with development of edema and rash (pharyngitis) Rash feels sand-papery and desquamates after several days Strawberry tongue

Question 27

Post-Strep Glomerulonephritis

Answer 27

Antigen-Antibody complexes on the glomerular basement mebrane HTN, edema, dark urine Unclear if early treatment can prevent PSGN (unlike Rheumatic Fever)

Question 28

Acute Rheumatic Fever

Answer 28

2 weeks after untreated GAS pharyngitis JONES citeria for diagnosis ASO titers aid in diagnosis

Question 29

Strep Agalactiae Microbiology

Answer 29

(- )Hydrolysis of bile esculin agar (+) Hydrolysis of hippurite Bacitracin Resistant CAMP Test

Question 30

"PROM in women Causes neonatal sepsis, meningitis, PNA "

Answer 30

Strep Agalactiae

Question 31

Enterococcus Faecalis Microbiology

Answer 31

(+) Hydrolysis of esculin agar with presence of bile | Grows in hypertonic saline

Question 32

Streptococcus Bovis Microbiology

Answer 32

Hydrolysis of esculin agar with presence of bile | Does not grow in hypertonic saline

Question 33

Endocarditis in patient with Colon Cancer

Answer 33

Streptococcus Bovis

Question 34

Strep Viridans Microbiology and disease

Answer 34

"Alpha-Hemolytic Resistant to lysis by bile Optochin Resistant Most common cause of subacute endocarditis