Comparison of different urine culture methods in urinary tract infection

Midstream urine specimen cultures play an important role in assisting clinicians to choose antibiotics to remove urinary tract pathogens. At present, there are many culture methods for obtaining midstream urine specimens. In this article, different urine culture methods were compared to improve the detection rate of pathogenic bacteria in patients with urinary tract infections (UTIs).

Urina sanguinis specimens were collected from 90 outpatients and inpatients who had UTI symptoms, had been clinically diagnosed with UTI between February and March 2021, and had been tested within 2 h using the conventional 1-µL culture method, the modified 100-µL culture method, and the centrifugal urine sediment culture method. After incubation at 35 °C with 5% carbon dioxide (CO₂) for 48 h, the detection rates of pathogenic bacteria in UTIs were compared among the three methods.

A total of 75 strains of pathogenic bacteria were detected in the 90 specimens. The positive detection rates of pathogenic microorganisms were 23.33%, 73.33%, and 75.56% for the conventional 1-µL culture method, the modified 100-µL culture method, and the centrifugal urine sediment culture method, respectively. Among the patients who used antibiotics before the collection of the urine specimens, the positive detection rates of pathogenic microorganism were 16.00%, 66.00% and 66.00% for the conventional 1-µL culture method, the modified 100-µL culture method, and the centrifugal urine sediment culture method, respectively. In the specimens grown aseptically using the conventional 1-µL culture method, a similar average number of colonies was found using the modified 100-µL culture method and the centrifugal urine sediment culture method. Among the specimens with bacterial growth in the conventional 1-µL culture method, the average colony numbers of the three methods were similar.

The modified 100-µL culture method and the centrifugal urine sediment culture method greatly improved the positive detection rates of pathogenic bacteria in patients with UTIs.