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The prevalence of high-level methicillin resistance in multiply resistant hospital staphylococci
Abstract:
This study was prompted by observing in the summer of 1975, five lethal septicemias caused by methicillin resistant staphylococci. Among the 17 initial S. aureus strains, only 36% were killed at 250 micrograms per ml of methicillin. One phage type of S. aureus predominated (85, group III). Methicillin resistance was found in 17 of 102 S. aureus and in 28 off 102 S. epidermidis septicemias; the mortality among methicillin resistant S. aureus cases was 52.9%, corresponding to 39.3% for S. epidermidis sepsis. Antibiograms revealed methicillin resistance in 59/400 S. aureus and 94/400 S. epidermidis isolates. Cross-resistance to other drugs was common. It is concluded that the emergence of methicillin and gentamicin-tobramycin resistance among hospital staphylococci represents a serious, persistent problem. Certain microbiologic characteristics of these resistant strains differ from results heretofore reported by others.
Insights
Methicillin-resistant staphylococci caused five lethal septicemias in 1975. Resistance in Staphylococcus aureus and Staphylococcus epidermidis poses a significant, ongoing challenge in hospitals.
Area of Science:
- Medical Microbiology
- Infectious Diseases
- Antimicrobial Resistance
Background:
- Observed five lethal septicemias caused by methicillin-resistant staphylococci in the summer of 1975.
- Initial S. aureus strains showed limited susceptibility to methicillin (36% killed at 250 µg/ml).
Purpose of the Study:
- To investigate the prevalence and characteristics of methicillin-resistant staphylococci.
- To assess the clinical significance and mortality associated with these resistant strains.
Main Methods:
- Analysis of S. aureus and S. epidermidis isolates from septicemia cases.
- Antibiogram testing to determine methicillin resistance and cross-resistance patterns.
- Phage typing to identify predominant strains.
Main Results:
- Methicillin resistance detected in 17/102 S. aureus and 28/102 S. epidermidis septicemias.
- Mortality rates were 52.9% for methicillin-resistant S. aureus and 39.3% for S. epidermidis sepsis.
- Prevalence of methicillin resistance was 59/400 S. aureus and 94/400 S. epidermidis isolates, with common cross-resistance.
Conclusions:
- The emergence of methicillin and gentamicin-tobramycin resistance in hospital staphylococci is a serious and persistent problem.
- Resistant strains exhibit distinct microbiologic characteristics compared to previously reported findings.
- Urgent strategies are needed to address the growing threat of antimicrobial resistance in staphylococcal infections.