Is it meaningful to apply midstream urine culture to urine specimens with negative Gram stain results?

• Published in: Journal of infection and chemotherapy : official journal of the Japan Society of Chemotherapy 2023-08, Vol.29 (8), p.764-768
• Main Authors: Saeki, Masachika, Ichihara, Koji, Yasuda, Mitsuru, Nirasawa, Shinya, Takahashi, Satoshi
• Format: Article
• Language: English
• Subjects: Bacteria; Female; Gram stain; Humans; Male; Midstream urine; Retrospective Studies; Staining and Labeling; Urinalysis - methods; Urinary tract infection; Urinary Tract Infections - drug therapy; Urine - microbiology; Urine culture
• ISSN: 1341-321X; 1437-7780
• DOI: 10.1016/j.jiac.2023.04.012

Gram staining is a convenient method for bacterial estimation. Urine culture is typically used to diagnose urinary tract infections. Therefore, urine culture is also performed on Gram stain-negative urine specimens. However, the frequency of uropathogen identification in these samples remains unclear. From 2016 to 2019, we retrospectively compared the results of Gram staining and urine culture tests on midstream urine specimens submitted for the diagnosis of urinary tract infections to confirm the significance of urine culture on Gram stain-negative specimens. Analysis was performed according to the patients’ sex and age, and the frequency of uropathogen identification in the culture was examined. A total of 1763 urine specimens (women, 931; men, 832) were collected. Of these, 448 (25.4%) were not positive on Gram staining but were positive on culture. In specimens without bacteria on Gram staining, the frequencies of specimens with uropathogens detected on culture were 20.8% (22/106) in women aged