A comparison of Streptococcus pyogenes (group A streptococcal) bacteremia at an urban and a suburban hospital. The importance of intravenous drug use.

BACKGROUND

There has been a recent resurgence of severe infections with Streptococcus pyogenes, including bacteremias and a toxic shock-like syndrome. The purpose of this study was to examine the influence of intravenous drug use on the incidence, clinical epidemiology, and severity of S pyogenes bacteremia.

METHODS

We conducted a retrospective survey of medical records at a 500-bed tertiary care urban hospital and at a nearby 500-bed suburban university-affiliated hospital. All patients from each hospital with documented S pyogenes bacteremia from January 1, 1979, to December 31, 1989, were included. We examined demographic and clinical data from cases at the two institutions, serologic findings from a subset of isolates from the urban hospital, and factors associated with mortality from S pyogenes bacteremia by stepwise logistic regression analysis.

RESULTS

Ninety-five cases of S pyogenes bacteremia were identified, with 65% (62 cases) occurring at the urban center. Intravenous drug use occurred more frequently at the urban center (P < .005); the injecting drug users were significantly younger than the non-drug-using population (P = .001). Infection with the human immunodeficiency virus occurred in a subset of the injecting drug users at the urban center. Cellulitis and cutaneous abscesses were the most common sources of bacteremia at both centers. During the study period, the numbers of S pyogenes bacteremias increased at the urban center (P = .007), accompanied by a significant increase in the proportion of infections associated with parenteral drug use (P = .003). There was no change in the prevalence of any T type throughout the study period and no clustering of T types among injecting drug users. The overall mortality was 23% (20/89). By logistic regression analysis, age older than 65 years (relative risk [RR], 14; 95% confidence interval [CI], 3.2 to 68) and the presence of the toxic shock-like syndrome (RR, 36; 95% CI, 2.2 to 600) were significantly associated with mortality due to S pyogenes bacteremia.

CONCLUSIONS

Intravenous drug use accounted for an increase in cases of S pyogenes bacteremia at an inner-city hospital. However, advanced age and the toxic shock-like syndrome were the most important predictors of mortality.