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Infection caused by thymidine-requiring, trimethoprim-resistant bacteria
Journal of Clinical Microbiology
|July 1, 1983
Summary
Thymidine-requiring gram-negative bacilli are emerging pathogens. These bacteria pose diagnostic challenges and are often resistant to common antibiotics like trimethoprim-sulfamethoxazole.
Area of Science:
- Clinical Microbiology
- Infectious Diseases
- Antimicrobial Resistance
Background:
- Thymidine-requiring gram-negative bacilli have recently appeared in clinical settings.
- These organisms present challenges in standard laboratory identification methods.
Purpose of the Study:
- To describe the characteristics and clinical significance of thymidine-requiring gram-negative bacilli.
- To highlight diagnostic and susceptibility testing difficulties associated with these strains.
Main Methods:
- Clinical specimen analysis.
- Evaluation of bacterial growth on various media (Mueller-Hinton, MacConkey agar).
- Assessment of identification using API 20E and Vitek Enterobacteriaceae-Plus Cards.
Main Results:
- Ten patients were identified with colonization or infection by these bacilli.
- Variable growth observed on MacConkey agar; inadequate growth for identification in automated systems.
- Organisms demonstrated routine resistance to sulfonamides and trimethoprim, often linked to prior therapy.
Conclusions:
- Thymidine-requiring gram-negative bacilli can act as pathogens.
- These bacteria present significant challenges in laboratory diagnosis, identification, and antimicrobial susceptibility testing.
- Association with prior sulfamethoxazole-trimethoprim therapy suggests a potential mechanism for emergence.