NMSK A1

Question 0

MRSA

Answer 0

-methicillin resistant Staph. aureus
-leading case of healthcare associated infection
Virulence
-SCCmec=beta-lactam resistance
-PVL=forms pores in neut membranes=PUS

Question 1

Staphylococcus aureus

Answer 1

Gr+ cocci (clusters)
-fac. anaerobe
-nares, skin, MM, throat, perineum, vagina
-loose slime layer, capsule, nonmotile, nonendospore
-coagualse-, catalse+
-forms pus
Labs
-High salt mannitol salt agar (ferments mannitol)
-Beta hemolysis (true hemolysis)
Virulence
-Protein A=binds to Fc of IgG, antiphagocytic effect
-cytolytic exotoxins- PVL
-enzymes=lipase, nuclease, protease, coagulase
-fibronectin-binding protein=promotes binding to mucosal cells and tissue matrices
-superantigens
Pathology
-cause septic arthritis, most common for NJI for all age groups (nongonococcal), and early PJI (first 3 months after surgery)
-SOFTPAINS
skin and soft tissue infection
osteomyelitis
food poisoning
toxic shock syndrome
pneumonia
acute endocarditis
infective arthritis (septic)
nec fasc
sepsis

Question 2

Streptococcus pyogenes

Answer 2

-Gr+ coccus, chains
- oropharynx, skin (transient)
-capsule (mucoid colony)
-cataslase-
Lab
-blood agar+CO2=beta-hemolysis
Virulence
-capsule
-hyaluronic acid
-SpyCEP
-cleaves IL-8
-against C5a peptidase
-adhesins (M protein)
-cytotoxins (streptolysin S, O, antigenic)
-xtracellular spreading factors (streptokinase, hyaluronidase, DNases A-D)
-superantigens (pyrogenic exotoxins, SpeB=exotoxin B)
Path
-nec fasc
-myositis
-impetigo
-pharyngitis
-pneumonia
-lymphangitis
-eryspelas and cellulitis
-scarlet fever/streptococcal
-TSS
P

Question 3

Pseudomonas aeruginosa

Answer 3

-Gr- rod
-soil, water, plants, normal microbiota
-capsule, motile
Lab
-oxidase+=has cytochrome c oxidase
-nonfermenter
-wide temp range, salt tolerant, simple growth requirments (in DI water)
-odor of grapes or tortilla chips
-produces green/blue colors
Virulance
-slime, alginate capsule
-spreading factors
-exotoxin A (A-B toxin)
-intrinsic and acquired antibiotic resistance
Path
-HAIs

Question 4

Nocardia spp.

Answer 4

• Gr+ filamentous bacillus
• *soil
• strict aerobe, fac. intracellular
• *weakly acid fast
• beaded/speckled appearance on staining

Question 5

Actinomyces israelii

Answer 5

• Gr+ filamentous bacillus
• nasopharynx, intestines, GU
• *non-acid fast
• fastidious and slow, canophilic (loves co2)
• “molar tooth colonies”

Question 6

Clostridium perfingens

Answer 6

-Gr+ rectangular shaped rod
-soil, h2o, GI, GU
-capsule, nonmotile
-grows rapidly in culture
Virulence
-endospore forming
-*alpha+8 toxin=double zone hemolysis
-spreading factors
Path
-cellulitis, gas gangrene, pyomyositis, food poisoning

Question 7

Brucella spp.

Answer 7

-Gr- coccobacillus
-zoonoses (goats)
-granulomatous response
Path
-*undulant fever

Question 8

Pasturella multocida

Answer 8

-Gr- coccobacillus
-*zoonoses (dogs&cats)
-capsule
Path
-most common from infected dog/cat bite/scratch
-localized cellulitis, lymphadenitis, osteomyelitis, septic arthritis

Question 9

Bartonella henselae

Answer 9

-Gr- rod
-*zoonoses (cat)
Path
-“cat scratch disease”