Summaries and buzzwords

Question 1

Staphylococcus aureus
- Classification
- capsule
- exotoxins
- transmission and flora
- diseases
- treatment

Answer 1

Classification:
G+ cocci, Catalase+, Coagulase +

Virulence:
Protein A, capsule

Exotoxins:
TSST-1, Epidermolytic toxins, enterotoxins, α toxin

Transmission:
droplets and contact, colonise 30% anterior nares

Diseases:
i) HAP
ii) Acute endocarditis in healthy native valves in IV drug abusers
iii) SSTI, SSSS, Ritter’s disease
iv) TSS
v) GIT
vi) Deep infections

Treatment:
MSSA: penicillinase → Cloxacillin, Erythromycin, co-amoxiclav
MRSA: PBP2a (mecA gene) → IV Vanco, 5th gen Cephalosporins, Linezolid

Question 2

What specific medium can be used to culture/determine Staph aureus?

Answer 2

Mannitol Salt agar

Question 3

Staphylococcus epidermidis
- classification
- location
- diseases

Answer 3

Classification:
G+ cocci, catalase+, coagulase-

Location:
- #1 skin flora

Diseases:
- subacute endocarditis w prosthetic valves
- prosthetic joint infections

Question 4

Staphylococcus saprophyticus
- classification
- location
- disease

Answer 4

Classification:
G+ cocci, catalase+, coagulase-

Location:
- normal skin flora

Disease
- UTI in young, sexually active women

Question 5

Streptococcus pneumoniae
- classification
- virulence factors
- vaccines
- transmission
- diseases
- treatment

Answer 5

Classification:
G+ diplococci, Catalase-, Optochin S

Virulence factors:
Antiphagocytotic capsule, pneumolysin

Vaccines:
PPSV23 (polysaccharide, 23 serotypes, T independent response)
PCV13 (conjugate, 13 serotypes + conjugate protein, btr for children, elicits immune memory)

Transmission: Respi droplets

Diseases
i) #1 cause of CAP (lobar, rust coloured sputum)
ii) URTI
iii) Otitis media
iv) Sinusitis
v) severe meningitis
vi) Empyema, abscesses

Treatment:
- Penicillin, amoxicillin
- IV Vanco

Question 6

What microbe grows as draughtsman colonies?

Answer 6

Streptococcus pneumoniae on blood agar