Susceptibility testing performed in general practice by urinary tract infections

Area of Science:

• Clinical microbiology
• General practice diagnostics
• Antimicrobial stewardship

Background:

• Dip-slides are a proven method for diagnosing significant bacteriuria in general practice.
• Susceptibility testing from urine specimens using dip-slides or agar plates appears straightforward but carries potential errors.
• Commercial methods adapted for general practice may introduce inaccuracies compared to standard techniques.

Purpose of the Study:

• To evaluate the predictive values of results from two commercial susceptibility testing methods used in general practice.
• To identify and quantify errors in susceptibility testing performed in a general practice setting.
• To assess the clinical implications of inaccurate susceptibility testing on antibiotic prescribing.

Main Methods:

• A multi-practice study was conducted involving general practitioners.
• Two commercial methods for urine specimen susceptibility testing were assessed.
• Predictive values of the test results were calculated based on quantitative urine cultures.

Main Results:

• A significant number of errors were detected in the susceptibility testing results.
• The primary error involved classifying susceptible bacteria as resistant.
• This misclassification can lead to unnecessary limitations in antibiotic treatment options.

Conclusions:

• Commercial susceptibility testing methods, when simplified for general practice, are prone to significant errors.
• Inaccurate susceptibility results can compromise effective patient treatment and limit clinicians' therapeutic choices.
• Further refinement or validation of these methods is crucial for reliable antimicrobial therapy in primary care.