Prevalence of UTI and STD in Women with UTI Symptoms

Abstract & Commentary

Source: Shapiro T, et al. The prevalence of urinary tract infections and sexually transmitted disease in women with symptoms of a simple urinary tract infection stratified by low colony count criteria. Acad Emerg Med 2005;12:38-44.

There is considerable overlap between the presentation of lower urinary tract infection (UTI) and sexually transmitted disease (STD) in women, making the evaluation somewhat complicated. Are symptoms indicative of UTI, STD, or both? Research in this area has been hampered by a retrospective approach in some studies, as well as the inclusion of voided (and thus, potentially contaminated) specimens for UTI evaluation in others. Shapiro and colleagues sought to address those issues in their prospective study looking at the prevalence of UTI and STD in patients presenting to the ED with symptoms suggestive of the former.

Nonpregnant, female patients ages 18-55 years presenting to an urban ED were eligible if their complaint was consistent with a simple UTI—dysuria, frequency, urgency, or suprapubic pain/pressure without significant vaginal discharge. Exclusion criteria included UTI or antibiotic use within the past two weeks; vaginal or pelvic infection with chlamydia, gonorrhea, trichomonas, or yeast within the past four weeks; significant vaginal discharge; febrile presentation (T>100.4°F), or prior hysterectomy. Emergency medicine residents, medical students, and attending physicians were trained regarding study protocol and data collection, which included collection of urine specimens (by bladder catheterization with the Female Speci-Cath Kit), STD cultures (via endocervical swab sent for polymerase chain reaction for gonorrhea and chlamydia), as well as performance of microscopic analysis of the vaginal wet mount (for trichomonas or bacterial vaginosis, as well as yeast). Treatment was at the discretion of the treating physicians, and was based upon the history and physical examination, the urinalysis, and the examination of the wet mount. Presence or absence of UTI was determined by laboratory culture of the catheterization specimens using two threshold criteria: the traditional 105 colony-forming units (CFU)/mL of bacteria as well as a perhaps more sensitive 102 CFU/mL. The authors offered literature support from the infectious disease/ internal medicine literature of the 1990s for this approach, and presented a cogent argument in the discussion section regarding this issue.

Of 528 patients ultimately diagnosed with UTI during the study period, 290 (55%) were study eligible; 94 patients were approached and ultimately 92 (32%) were enrolled, examined, and treated. Due to an unforeseen laboratory mishap, 17 of those 92 did not have UTI culture performed, leaving 75 patients for data analysis.

The presence of UTI in these 75 women with UTI symptoms and urine cultures performed was 57% (102 CFU/mL) or 43% (105 CFU/mL), depending upon the criterion threshold. Escherichia coli was the predominant organism (54%), although nine others had only gram-negative rods (i.e., no organism) reported.

The prevalence of STD in these 75 patients with UTI symptoms and urine cultures performed was 17%; the STD rate in the 91 (one missing value from the original 92) women who were enrolled, examined, and treated was not much different—14%—and no significant difference was found in rate of STD between urine culture positive and negative groups, regardless of CFU/mL criterion. Using logistic regression analysis on the 91 patients, number of sex partners during the past year was the only variable found to significantly predict who had an STD. Fifty percent of those patients ultimately found to have an STD were not diagnosed and treated as such at the end of their ED visit. The authors conclude that women with classic UTI symptomatology often do not have UTI, and that diagnosis of either entity—UTI or STD—based solely on clinical evaluation (history, physical examination, urinalysis, and vaginal wet prep) is problematic.

Commentary by Richard Harrigan, MD, FAAEM

This topic reminds me of the approach to the patient with pharyngitis: It is a common problem we see every day, yet the right way to diagnose and treat is not abundantly clear. Why does such a simple problem have such complex issues? Like most complex things, the reasons are multiple. First, doing a definitive study of such an issue requires that most, if not all, eligible patients be captured. The authors admit that their study is limited by low enrollment numbers: 198 potential study patients were not approached in this case, partly because those physicians not involved intimately in the study were less likely to enroll patients. This is a chronic frustration at academic medical centers; without a SWAT team of research associates to hound faculty and assist them with patient enrollment, busy EDs are tough places to take the time to enroll patients in a study when the caregivers are also the research data gatherers. Thus, the specter of selection bias enters this study. Another problem is defining the gold standard of disease: a colony count that defines UTI, diagnosis of trichomoniasis, or adequacy of vaginal swab for detection of gonorrhea and chlamydia. (In this study, where seven people had trichomoniasis, the diagnosis rested upon real-time identification on the ED microscope; reality in my ED, but not truly a gold standard. Assumably, we are not as good as polymerase chain reaction at detecting this disease.) Like the throat swab for streptococcal pharyngitis, the STD will go undetected if the specimen is inadequate. The authors are to be congratulated on controlling many variables that have been omitted in prior research in this area, such as in their design (prospective rather than retrospective) and their use of straight catheterization of the bladder.

So what can we take away from this study? The UTI/STD dilemma in women with symptoms of UTI remains a dilemma. Remember, women with simple UTI complaints make up the denominator here; any change in usual vaginal discharge by history or finding of significant vaginal discharge on physical examination led to exclusion. And the STD rate in this group (in this environment) was high (17%). Moreover, only 54% of those women with UTI complaints had a UTI—even using a liberal gold standard of low bacteria counts.

Thus, it is probably prudent to evaluate patients completely for both STD and UTI, despite symptomatology that favors the former diagnosis.

Dr. Harrigan, Associate Professor of Emergency Medicine, Temple University Hospital and School of Medicine, Philadelphia, PA, is Editor of Emergency Medicine Alert.