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Penicillin-nonsusceptible Streptococcus pneumoniae at San Francisco General Hospital
L G Winston1, J L Perlman, D A Rose
1Center for Epidemiology & Prevention Interventions, Department of Medicine, University of California, San Francisco 94143-0654, USA.
Abstract:
Positive pneumococcal cultures of specimens from adult inpatients at San Francisco General Hospital (SFGH) during the period of 11 August 1994 through 31 December 1996 were identified retrospectively. Of the isolates recovered, 15.5% were not penicillin-susceptible (MIC, > or =.1 microg/mL). A case-control study was performed to evaluate risk factors for colonization or infection with penicillin-nonsusceptible Streptococcus pneumoniae (PNSP) and outcomes. Cases (n = 65) were adult inpatients with a positive culture for PNSP, and controls (n = 411) were adult inpatients with a positive culture for penicillin-susceptible pneumococci (PSSP) and no evidence of PNSP. Cases were less likely to have pneumococcal bacteremia (15.4% versus 39.4%; P<.001) and less likely to have pneumonia (50.8% versus 68.9%; P = .006). In a multiple logistic regression model, recent hospital admission and absence of bacteremia were independent predictors of penicillin-nonsusceptibility. Human immunodeficiency virus infection, mortality, and length of hospitalization were not significantly different among cases and controls. These data suggest that PNSP may be less virulent (cause less pulmonary infection) and/or less invasive (cause fewer bloodstream infections) than PSSP at SFGH.
Insights
Penicillin-nonsusceptible Streptococcus pneumoniae (PNSP) infections were less likely to cause bacteremia or pneumonia compared to penicillin-susceptible strains. This suggests PNSP may be less virulent and invasive in adult inpatients.
Area of Science:
- Infectious Diseases
- Microbiology
- Clinical Medicine
Background:
- Penicillin-nonsusceptible Streptococcus pneumoniae (PNSP) emerged as a significant public health concern.
- Understanding the epidemiology and clinical impact of PNSP is crucial for patient management.
Purpose of the Study:
- To investigate the prevalence of PNSP among adult inpatients at San Francisco General Hospital (SFGH).
- To identify risk factors associated with PNSP colonization or infection.
- To compare clinical outcomes between PNSP and penicillin-susceptible S. pneumoniae (PSSP) infections.
Main Methods:
- Retrospective identification of pneumococcal isolates from adult inpatients between August 1994 and December 1996.
- A case-control study comparing patients with PNSP (cases) to those with PSSP (controls).
- Analysis of clinical data including bacteremia, pneumonia, HIV status, mortality, and length of hospitalization.
Main Results:
- 15.5% of pneumococcal isolates were not penicillin-susceptible.
- PNSP cases were significantly less likely to have pneumococcal bacteremia (15.4% vs. 39.4%) and pneumonia (50.8% vs. 68.9%) compared to PSSP controls.
- Recent hospital admission and absence of bacteremia were independent predictors of penicillin-nonsusceptibility.
Conclusions:
- PNSP infections at SFGH were associated with lower rates of bacteremia and pneumonia compared to PSSP.
- These findings suggest that PNSP may exhibit reduced virulence and invasiveness relative to PSSP.
- Further research is warranted to elucidate the clinical implications of PNSP in different healthcare settings.