A Streptococcus pyogenes outbreak caused by an unusual serotype of low virulence: the value of typing techniques in outbreak investigations.
OBJECTIVE
To investigate and stop the spread of an outbreak of Streptococcus pyogenes infection in a district general hospital, involving 19 patients and two nurses over a 20-day period.


METHODS
All suspected persons were investigated using conventional bacteriological techniques, followed by M, T and exotoxin gene-typing of the isolates in a national reference laboratory.


RESULTS
11 patients and both nurses were associated with the acute surgical ward on one floor of the hospital. They were infected with serotype M 9/T B3264, a strain with apparently low virulence, which has not been previously associated with outbreaks. Two other patients on the same floor each had different types and there were two clusters of another S. pyogenes serotype on other floors, each involving two patients. Two (unrelated) patients yielded other types of S. pyogenes. The patients were not seriously ill but had some delay in wound healing.


CONCLUSIONS
The value of typing the isolates of S. pyogenes in this outbreak was in defining which patients were involved. No added value could be ascribed to the exotoxin gene-typing results.
Davies
B I
BI
Department of Medical Microbiology, Atrium Medical Centre, Heerlen, The Netherlands.
Hirsch
J
J
Werink
T J
TJ
Toenbreker
H
H
Bainczijk
F
F
van Leeuwen
W J
WJ
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004196:Disease Outbreaks; D006769:Hospitals, General; D006801:Humans; D008875:Middle Aged; D009426:Netherlands / Q000453:epidemiology; D016133:Polymerase Chain Reaction; D012703:Serotyping; D013290:Streptococcal Infections / Q000453:epidemiology* / Q000382:microbiology; D013297:Streptococcus pyogenes / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification / Q000472:pathogenicity; D013530:Surgical Wound Infection / Q000382:microbiology