Session 4- cellulitis, UTI, pneumonia

Question 1

Two microbes likely to cause cellulitis?
How to tell which one?
Treatment?

Answer 1

Staphylococcus Aureus
Streptococcus Pyogenes

Aureus = clusters
Pyogenes = chains

Flucloxacillin

Question 2

What does DD transpeptidase do?

Answer 2

Enzyme which catalyses cross linking in peptidoglycan layer of the bacterial cell wall

Question 3

The urinary dipstick test of a patient with a UTI would show..?

Answer 3

• Nitrites (due to reduction of nitrates to nitrites by gram negative bacterial like E.Coli)
• Leukocyte esterase (enzyme released by neutrophils and macrophages; indicates pyuria- excess WBC’s in urine)

Question 4

Pyuria

Answer 4

Literally; pus in urine

Excess of WBC’s indicatibg infection

Question 5

Does a dipstick test positive for nitrites always mean infection?

Answer 5

No, need leukocyte esterase to test positive too

• May have higher nitrites due to vegetarian diet
• May have lower nitrites without enough time for reduction to occur (bladder incubation time of urine)
• May have none despite infection bc certain gram positive enterococci do not produce the reductase enzyme (enterococci)

Question 6

Innate barriers of urinary tract

Answer 6

Epithelial lining
Mucus
Flushing of urine