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Characteristics of some co-trimoxazole-resistant Enterobacteriaceae from infected patients
Abstract:
Two isolates of Proteus mirabilis and four of Esch. coli which would not grow on commonly used commercial sensitivity test media are reported. These organisms appear to be resistant to co-trimoxazole, are exacting towards thymidine, and five of six were isolated from patients who had been treated with co-trimoxazole. A method for the detection of these strains is given and their significance in the laboratory and clinical practice discussed.
Insights
Certain Proteus mirabilis and Escherichia coli strains resist standard antibiotic sensitivity testing. These thymidine-exacting bacteria, often resistant to co-trimoxazole, require specific detection methods for accurate laboratory and clinical management.
Area of Science:
- Clinical microbiology
- Bacteriology
- Antimicrobial resistance
Background:
- Standard antibiotic sensitivity testing media may fail to support the growth of certain bacterial strains.
- Specific bacterial isolates, including Proteus mirabilis and Escherichia coli, present challenges in routine laboratory diagnostics.
Purpose of the Study:
- To report on unusual isolates of Proteus mirabilis and Escherichia coli that do not grow on common sensitivity test media.
- To investigate the characteristics and clinical relevance of these difficult-to-grow bacterial strains.
Main Methods:
- Evaluation of bacterial growth on various commercial sensitivity test media.
- Assessment of antimicrobial susceptibility, focusing on co-trimoxazole resistance.
- Investigation of thymidine requirements for bacterial growth.
- Development and description of a detection method for these specific strains.
Main Results:
- Two Proteus mirabilis and four Escherichia coli isolates failed to grow on standard sensitivity test media.
- These isolates exhibited resistance to co-trimoxazole and had specific thymidine requirements.
- Five of the six isolates were recovered from patients previously treated with co-trimoxazole.
Conclusions:
- The study highlights the existence of bacterial strains that necessitate specialized media or methods for accurate sensitivity testing.
- Understanding the characteristics of these strains is crucial for effective laboratory diagnostics and appropriate clinical treatment strategies.
- The findings underscore the importance of considering bacterial nutrient requirements and prior antibiotic exposure in antimicrobial susceptibility testing.