Streptococcus Pyogenes

Question 0

Transmission (2)

Answer 0

Respiratory droplets

Direct contact

Question 1

Character (4)

Answer 1

Catalase -ve
Beta haemolytic
NOT normal flora
Carriage in pharynx

Question 2

Virulence factors (4)

Answer 2

Streptolysin O and S
M protein (resists phagocytosis)
Streptococcal pyrogenic exotoxins A-C (All: fever, A+C: scarlet fever, A: streptococcal toxic shock syndrome)
Hyaluronidase (breaks down intracellular cement)

Question 3

Clinical presentation (5)

Answer 3

Pharyngitis/tonsillitis (1/3 of all cases)
Scarlet fever (circumoral pallor, generalized rash)
SSTI (erysipelas, cellulitis, impetigo, wound infections)
Necrotising fasciitis
Streptococcal TSS

Question 4

Non-suppurative complications (2)

Answer 4

ARF: relaxing cause of childhood heart disease, M types 5, 14, 18, 24, may result in RHD
(Revised Jones Criteria - 2 maj or 1 maj w 2 min w evidence of strep infection - Maj: carditis, polyarthritis, chorea, erythema marginatum, subQ nodules; Min: fever, arthralgia, raised acute phase reactants, longer P-R interval)

AGN: results in acute renal failure, ASO diagnosis unreliable

Question 5

Diagnosis (2)

Answer 5

Anti-streptolysin O titre

Antibodies to hyaluronidase or DNAse B

Question 6

Treatment (2 general + 2 conditions)

Answer 6

Pen G
Erythromycin
Clindamycin (for nec fas)
IVIG for TSS