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Increasing frequency of penicillin-resistant pneumococci: epidemiological aspects and case-control study
Insights
The frequency of penicillin-resistant pneumococci increased significantly in children from 1979-82. Increased beta-lactam antibiotic use in general practice may contribute to the emergence of these resistant strains.
Area of Science:
- Microbiology
- Infectious Diseases
- Public Health
Background:
- The prevalence of penicillin-resistant pneumococci (RPRP) has been a growing concern.
- An increase in RPRP isolates was observed at Hadassah University Hospital between 1979 and 1982.
Purpose of the Study:
- To investigate the rise in RPRP isolates.
- To identify risk factors associated with RPRP, particularly antibiotic usage patterns.
Main Methods:
- Retrospective analysis of RPRP isolate frequency from 1979-1982.
- Disk sensitivity and minimal inhibitory concentration (MIC) testing for penicillin resistance.
- Case-control study examining antibiotic usage in the 60 days prior to pneumococcal isolation.
Main Results:
- RPRP isolate frequency rose from 0.9% to 10.8%, with a notable impact on infants and children (<14 years).
- MIC values confirmed penicillin G resistance in RPRP isolates (0.25-0.50 µg/ml).
- Case-control study revealed significantly higher beta-lactam antibiotic usage (13.3 days) in RPRP patients compared to controls (4.2 days).
Conclusions:
- General antibiotic prescribing practices, especially beta-lactam use, may drive the emergence of RPRP strains.
- Pediatric populations are particularly vulnerable to the increasing prevalence of RPRP.
- Prudent antibiotic stewardship is crucial to mitigate the spread of antibiotic resistance.
Abstract:
At the Hadassah University Hospital, Mt. Scopus, Jerusalem, the frequency of patients with relatively penicillin-resistant pneumococci (RPRP) isolates has increased from 0.9 to 10.8% during the years 1979-82. Infants and children were particularly involved. Significantly more RPRP isolates were found in those less than 14 years old than in those who were older (P less than 0.005). The determination of susceptibility or relative resistance to penicillin was based on the disk sensitivity method, which remained unchanged throughout the study period. The minimal inhibitory concentration (MIC) to penicillin G was also determined for 20 RPRP isolates and was found to be in the range of relative resistance to penicillin (0.25 to 0.50 micrograms/ml) in all 20 isolates. A case-control study of 16 index patients examined antibiotic usage during the 60 days preceding pneumococcal isolation. Total antibiotic usage was high in both groups (18.8 vs. 8.8 days, P = 0.2); beta-lactam antibiotic usage was significantly higher in the RPRP group than in the control group (13.3 vs. 4.2 days, 0.01 less than P less than 0.02). General prescribing practices, even in nonisolated areas where there is no need for public health programs to dispense prophylactic antibiotics, may produce sufficiently high antibiotic exposures to aid the emergence of RPRP strains.