POC Susceptibility Testing No Aid for Antibiotic Prescribing with UTI

Adding point-of-care (POC) susceptibility testing to POC culture does not improve appropriateness of antibiotic prescribing for patients with suspected, uncomplicated urinary tract infection (UTI) in general practice, according to a study published online Oct. 16 in BMJ Open. The authors say POC susceptibility testing should be reserved for patients at high risk of resistance and complications.

UTI is commonly treated in general practice and is one of the leading causes for antibiotic prescriptions. But given the increasing concern about antibiotic resistance there is increased interest in POC testing that can improve antibiotic stewardship in primary care.

Twenty general practices in Denmark recruited women with suspected uncomplicated UTI, including elderly patients, patients with recurrent UTI, and patients with diabetes, as is reflective of a general practice. Participants were randomly assigned to either culture and susceptibility testing (n=191 patients) or culture only (n=172 patients) using the Flexicult SSI-Urinary Kit (SSI DIagnostica, Denmark) and ID Flexicult, respectively. Both tests were incubated at 35°C overnight, although negative culture can only be determined after 24 hours. Appropriate antibiotic prescribing was defined as either prescribing a first-line antibiotic to which the infecting pathogen was susceptible or a second line if a first line could not be used for patients with UTI on the day after consultation, while no antibiotic prescription was defined as appropriate for patients without UTI.

The researchers found that overall, 63 percent of patients had a UTI and 12 percent of these infections were resistant to the most commonly used antibiotic, pivmecillinam. Significantly more patients were treated appropriately in the culture only group (75 percent in the culture-only group versus 67 percent in the culture and susceptibility-testing group). There was no significant difference between the groups with respect to clinical recovery or microbiological cure on day 5.

“The significant overall difference in appropriate prescribing between the groups was driven by three factors (none of them individually significant): first, undertreatment; second, treatment with an antibiotic to which the infecting pathogen was resistant and third, inappropriate choice of a second-line antibiotic,” write the authors led by Anne Holm, from the University of Copenhagen in Denmark. Holm adds that if all patients had been treated with first-line antibiotics based on clinical history and positive dipstick finding, then roughly 45 percent of patients would have been inappropriately treated, versus the 29 percent in this study.

“Based on these results, performing POC culture prior to treatment for patients with uncomplicated UTI seems rational, but adding POC susceptibility testing should be reserved for those patients at high risk of a resistant infection or complications or for geographical areas with high levels of resistance,” the authors conclude.

Takeaway: While possibly defying expectations, adding POC susceptibility testing to POC culture does not improve appropriateness of antibiotic prescribing for patients with suspected, uncomplicated UTI.