Point-of-care urine Gram staining linked to narrower antibiotic prescribing in febrile urinary tract infections

A new observational study from Japan suggests that a simple bedside technique, point-of-care Gram staining of urine, may help clinicians choose narrower, more targeted antibiotics without waiting for the microbiology laboratory.

The study, published in BMC Infectious Diseases, was conducted at a single center between May 2015 and October 2024. It included patients aged 15 years or older who were admitted with suspected febrile urinary tract infections. The researchers compared two approaches to initial antibiotic selection: one in which the first prescription was guided by urine point-of-care Gram staining results, and one in which antibiotics were chosen empirically without Gram staining.

Point-of-care Gram staining is not a new technique in principle. Gram staining is widely used in clinical laboratories, but operational constraints often restrict it to regular working hours. Some facilities have implemented the method at the point of care so that results and treatment decisions can be made even outside those hours, including at night and on weekends. What has remained unclear, according to the study authors, is whether this practice actually reduces the use of broad-spectrum antibiotics.

Among the 251 patients analyzed, 184 had initial therapy guided by point-of-care Gram staining and 67 were treated empirically. The Gram staining group received Access antibiotics, the category of the World Health Organization’s AWaRe classification considered to have the narrowest spectrum and lowest resistance concern, in 15.2 percent of cases, compared with 4.5 percent in the empiric group. That difference was statistically significant, with a risk difference of 0.11 and a 95 percent confidence interval of 0.035 to 0.18.

The contrast was even more pronounced for narrow-spectrum agents overall. These were prescribed in 28.8 percent of the Gram staining group versus 4.5 percent of the empiric group, a risk difference of 0.24 with a confidence interval of 0.16 to 0.32. In a multivariable analysis of Access antibiotic selection that included five covariates, point-of-care Gram staining was associated with an adjusted odds ratio of 3.93, though the researchers noted that the wide confidence interval, spanning 1.12 to 13.7, indicated an imprecise result.

Importantly, narrowing the spectrum did not appear to come at the cost of picking the wrong drug. The initial agent showed in vitro activity against the cultured pathogen in 94.5 percent of the Gram staining group and 89.5 percent of the empiric group, a difference that was not statistically significant. The authors emphasized that clinical effectiveness was not evaluated in this study, so the findings speak to laboratory-measured appropriateness rather than patient outcomes.

Cost and speed also featured in the analysis. The median pharmaceutical cost of the first intravenous dose was lower in the Gram staining group, at 486 Japanese yen versus 844 yen, a difference that was statistically significant. However, the time from initial evaluation to the antibiotic decision did not differ between the groups, with medians of 111 minutes in the Gram staining group and 123 minutes in the empiric group, a nonsignificant difference.

The study’s conclusions are measured. Using urine point-of-care Gram staining to estimate pathogens was associated with more narrow-spectrum prescribing and lower first-dose pharmaceutical costs, with no statistically significant difference detected in in vitro activity or time to antibiotic order. As a single-center observational study, it cannot establish causation, and the wide confidence interval around the adjusted odds ratio reflects the modest number of Access antibiotic prescriptions overall. The authors also note that clinical effectiveness was outside the scope of the analysis.

Subject of Research: The effect of urine point-of-care Gram staining on antibiotic selection in febrile urinary tract infections

Article Title: Effect of urine point-of-care Gram staining on broad-spectrum antibiotic use in febrile urinary tract infections

Article References: Taniguchi, T., Fujii, Y., Miyoshi, S., & Sugino, M. (2026). Effect of urine point-of-care Gram staining on broad-spectrum antibiotic use in febrile urinary tract infections. BMC Infectious Diseases. https://doi.org/10.1186/s12879-026-14732-2

Image Credits: AI Generated

DOI: 10.1186/s12879-026-14732-2

Keywords: urinary tract infection, Gram staining, point-of-care testing, antibiotic stewardship, broad-spectrum antibiotics, AWaRe classification, narrow-spectrum antibiotics, observational study, antimicrobial resistance, emergency care, Effect, urine