Surveillance for invasive group A streptococcal infection
» Background
Population based surveillance for invasive group A streptococcal
disease has been ongoing in Ontario (including Metropolitan Toronto/Peel
region) since 1992. In 2002, 354 cases of invasive group A streptococcal
disease was reported in Ontario, 185 (52%) of which were in the
Metro Toronto/Peel region population area. This surveillance program
has been responsible for monitoring changes in rates of invasive
disease (most notably necrotizing fasciitis and streptococcal
toxic shock), assessing the impact of new therapies on outcomes
(eg. Use of IVIG for STSS), and defining various spectrums of
disease and their risk factors (eg. Streptococcal pneumonia, streptococcal
soft tissue infections, and nosocomial group A strep disease).
The Toronto Invasive Bacterial Diseases Network will continue
to perform population-based surveillance in metropolitan Toronto
and Peel Region for disease associated with an isolate of group
A strep from a normally sterile site.
» Methods
The microbiology laboratories serving hospitals in Toronto, Peel,
Durham, Simcoe, Hamilton, and York Regions and the three largest
private laboratories will continue to report invasive group A
streptococcal isolates to the study office and forward the bacterial
isolate to the study laboratory. The postal code of residence
of the patient will be screened to determine eligibility: Cases
will be eligible if the postal code of their home address is within
the defined population areas. Homeless persons who visit hospitals
in the area are also considered residents. Annual audits of cultures
from all laboratories will be performed to evaluate reporting
accuracy.
Initial demographic data (date of birth and postal code of residence)
are available from the reporting laboratory. When a microbiology
laboratory telephones the central study office and the case is
identified as eligible, a "tracking record" is initiated
on which is recorded the date, reporting lab, patient initials,
study code number, hospital, physician name and telephone number.
A patient chart review will be conducted to determine specific
demographic, medical and treatment outcome information (data forms
previously approved). All isolates from surveillance are shipped
to the central study lab. Isolates are confirmed as group A strep
using standard methodology. Serotyping is performed by the National
Centre for the Streptococcus.
