Women may be receiving unnecessary antibiotics for overdiagnosed urinary tract infections while their sexually transmitted infections go undetected, according to a recent study in an urban academic emergency department.

“Our study is a reflection of what happens in current clinical practice in an ED setting including adult women 18-65 years of age for whom UTI diagnoses and empiric therapy for UTI are often given even in the absence of any UTI-related symptoms and without a urine culture,” Dr. Michelle T. Hecker of MetroHealth Medical Center, Cleveland, and her colleagues wrote in the Journal of Clinical Microbiology (J. Clin. Microbiol. 2015 [doi:10.1128/JCM.00670-15]).

Overdiagnosis of UTI was not only a common cause of unnecessary antibiotic use, it also contributed to underdiagnosis of STI since 64% of the patients with a missed STI were diagnosed as having a UTI instead, they reported.

The researchers compared urinalysis, culture, and nucleic acid amplification testing for gonorrhea, chlamydia, and trichomoniasis among 264 women, aged 18-65 years, who presented to an urban academic emergency department over a 2-month period. Although providers diagnosed 66% of these women with UTIs, less than half these women (48%) had a positive urine culture and more than half (57%) received treatment without a urine culture.

Among the 23% of women overall who had at least one positive STI test, 37% (22 of 60 women) did not receive treatment for their STI within 7 days of their visit, and 14 of those 22 women (64%) received a UTI diagnosis instead of an STI diagnosis.

Urinalysis was abnormal for 92% of all the women in the study and did not predict positive urine cultures. The researchers determined the positive predictive value of abnormal urinalysis to be 41% and the negative predictive value to be 76%.

“Based on our data and others, we believe that alternative test and treat strategies for managing women with [genitourinary] and nonspecific abdominal pain in the ED should be evaluated,” Dr. Hecker and her associates wrote.

They specifically recommended decreasing urinalysis testing and increasing urine culture and STI testing.

The research was supported by a grant from the Centers for Disease Control and Prevention. One of the researchers reported that he is an R&D scientist employed by Hologic.