Laboratory diagnosis of urinary tract infection in ambulatory women

Area of Science:

• Clinical Microbiology
• Infectious Diseases
• Urology

Background:

• Accurate identification of urinary tract infections (UTIs) is essential for effective patient treatment.
• Traditional methods relying solely on high bacterial colony counts may miss infections with lower counts.

Purpose of the Study:

• To evaluate the accuracy and workload of six different methods for identifying UTIs in a clinical microbiology setting.
• To determine the most efficient approach for diagnosing UTIs in ambulatory women.

Main Methods:

• Analysis of 387 midstream urine (MSU) specimens from ambulatory women.
• Dual-plating technique to detect both low (10^2-10^4 CFU/mL) and high (≥10^5 CFU/mL) bacterial colony counts.
• Examination for pyuria and correlation with culture results and patient symptoms.

Main Results:

• Seventy-four UTIs were identified, with 24 (32%) characterized by low colony counts missed by a ≥10^5 CFU/mL criterion.
• The presence of pyuria, when used to guide microbiological processing, proved to be the most accurate and efficient diagnostic method.
• Rapid screening methods for pyuria could further enhance efficiency.

Conclusions:

• Pyuria-based strategies are superior for identifying UTIs in voided urine specimens from ambulatory women.
• Relying solely on high colony counts can lead to underdiagnosis of UTIs.
• Integrating pyuria screening into laboratory workflows improves UTI detection accuracy and efficiency.