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[Hospital and district differences in susceptibilities to antibiotics of main clinical isolates]
J Igari1, M Shitara, M Shitara
1Department of Clinical Pathology, School of Health Science Faculty of Medicine, University of the Ryukyus.
Abstract:
A nationwide survey of susceptibilities of Staphylococcus aureus, Escherichia coli, Klebsiella sp. and Proteus mirabilis initiated in 1980 was continued in 1986. This report documents differences in susceptibilities of clinical isolates of the above microorganisms to ampicillin (ABPC), cefazolin (CEZ), cefmetazole (CMZ) and gentamicin (GM) among general hospitals throughout Japan. Clinical isolates of each species of microorganisms which were collected in 24 hospitals made up each study group and were collected at the Kosei General Hospital, Tokyo, from April 1980 to March 1986. We compared the variability in the resistant rates (MIC greater than or equal to 25 micrograms/ml) and MICs of each antibiotic for 50% and 80% of the isolates among the hospitals. MICs were determined by the serial 2 fold agar plate dilution method, standardized by the Japan Society of Chemotherapy, with an inoculum of approximately 10(6) CFU/ml or 10(8) CFU/ml. Susceptibility patterns of S. aureus to ABPC, CEZ and GM, of E. coli to ABPC, of Klebsiella sp. to CEZ and GM and of P. mirabilis to ABPC, CEZ and GM varied from hospital to hospital. On the other hand, the differences in the susceptibility patterns among the 6 districts of Japan were not obvious, because the differences were affected by different susceptibility patterns of each hospital located in each district.
Insights
Antibiotic resistance in Staphylococcus aureus, E. coli, Klebsiella, and Proteus mirabilis varied significantly between Japanese hospitals. Hospital-specific susceptibility patterns, not geographic regions, drove these differences in antibiotic resistance.
Area of Science:
- Clinical Microbiology
- Infectious Diseases
- Pharmacology
Background:
- Antibiotic resistance is a growing global health concern.
- Monitoring antimicrobial susceptibility is crucial for effective treatment strategies.
- Previous studies have indicated regional variations in bacterial resistance patterns.
Purpose of the Study:
- To investigate and document inter-hospital variations in antibiotic susceptibility of common bacterial pathogens in Japan.
- To compare the susceptibility of clinical isolates of Staphylococcus aureus, Escherichia coli, Klebsiella sp., and Proteus mirabilis to key antibiotics.
- To identify factors contributing to observed differences in antimicrobial resistance rates.
Main Methods:
- A nationwide survey conducted from April 1980 to March 1986, involving 24 general hospitals across Japan.
- Clinical isolates of S. aureus, E. coli, Klebsiella sp., and P. mirabilis were collected and tested.
- Antimicrobial susceptibility testing using the agar plate dilution method for ampicillin, cefazolin, cefmetazole, and gentamicin.
Main Results:
- Significant hospital-to-hospital variability was observed in the susceptibility patterns of S. aureus, E. coli, Klebsiella sp., and P. mirabilis to ampicillin, cefazolin, and gentamicin.
- Resistance rates (MIC ≥ 25 µg/ml) and MIC50/MIC80 values demonstrated considerable differences among participating hospitals.
- Geographic location (6 districts in Japan) did not show significant differences in susceptibility patterns, likely due to the overriding influence of individual hospital variations.
Conclusions:
- Hospital-specific factors play a more significant role in shaping antimicrobial susceptibility patterns than broad geographic regions in Japan.
- The findings highlight the need for localized antimicrobial stewardship programs and continuous surveillance of resistance.
- Understanding hospital-level resistance trends is essential for optimizing empirical antibiotic therapy.