Streptococcus pneumoniae: bacteremia in an era of penicillin resistance

The proportion of penicillin-resistant Streptococcus pneumoniae isolates and associated risk factors varies by geographic area in the United States. We conducted a retrospective study to determine the extent of penicillin-nonsusceptible S pneumoniae bacteremia and associated risk factors in a tertiary care medical center in San Diego.

Patients with S pneumoniae bacteremia at the University of California, San Diego Medical Center from September 15, 1991, through July 31, 1998, were identified by hospital-based computerized microbiology records. Hospital records included demographic information, patient data, and antibiotic prescription records for patients with bacteremia as a result of S pneumoniae. Univariate and multivariate analyses were used to determine risk factors for penicillin-nonsusceptible S pneumoniae bacteremia.

Of 281 isolates of S pneumoniae identified, 192 (68%) were from hospitalized patients. After controlling for other factors, patients from 1 to 5 years of age (P = .01; odds ratio [OR] = 3.96; 95% CI, 1.50 to 10.44), 6 to 18 years of age (P =.04; OR = 6.42; 95% CI, 1.13 to 36.51), and HIV seropositive patients (P =.002; OR = 5.12; 95% CI, 1.83 to 14.32) were more likely to have penicillin-nonsusceptible S pneumoniae bacteremia. There was a significant increasing trend of penicillin-nonsusceptible S pneumoniae bacteremia from 14% in 1991 to 42% in 1998 (P = .001; OR = 1.42; 95% CI, 1.16 to 1.73); this included only 2 isolates that were highly resistant to penicillin. There was no increase in mortality in patients who had penicillin-nonsusceptible S pneumoniae bacteremia.

With the increase in S pneumoniae resistance to penicillin, it is important to continue surveillance of infections caused by S pneumoniae. Hospital-based studies are useful for tracking epidemiologically important pathogens.