Polymicrobic bacteriuria: significant association with bacteremia

Area of Science:

• Clinical Microbiology
• Infectious Diseases
• Urology

Background:

• Current practice often discards urine cultures with three or more isolates, assuming contamination.
• The clinical significance of polymicrobic bacteriuria (multiple bacterial species in urine) is not fully understood.

Purpose of the Study:

• To evaluate the validity of discarding urine cultures with multiple isolates.
• To determine the association between polymicrobic bacteriuria and bacteremia originating from the urinary tract.

Main Methods:

• Retrospective review of patients with positive blood cultures and urinary tract infections.
• Analysis of bacterial isolates and antibiograms from blood and urine cultures.
• Prospective reculturing of patients with polymicrobic bacteriuria to confirm findings.

Main Results:

• Of 18 patients with bacteremia and urinary tract infections, 11 (61%) had polymicrobic bacteriuria.
• Patients with polymicrobic bacteriuria often had prolonged indwelling bladder catheter use.
• Prospective cultures confirmed polymicrobic bacteriuria in 78% of cases, suggesting it is not always due to contamination.

Conclusions:

• Polymicrobic bacteriuria is clinically significant and frequently associated with urinary tract infection-related bacteremia.
• Current practice of discarding such specimens may lead to missed diagnoses.
• Further investigation into the management of polymicrobic bacteriuria is warranted.