Do Urine Cultures for Urinary Tract Infections Decrease Follow-up Visits?

Jeremy Daniel Johnson, MD, MPH; Heather M. O'Mara, DO; Hyrum F. Durtschi, DO; Branko Kopjar, MD PhD, MS

Disclosures

J Am Board Fam Med. 2011;24(6):647-655. 

In This Article

Results

We reviewed the records of 1199 patients. We excluded 420 and were left with 779 patients (Figure 1). Of the 779 patients studied, 332 (43%) had no urine culture ordered during the management of their UTI (cohort 1), and 447 (57%) did have a urine culture ordered during the management of their UTI (cohort 2). Table 1 lists demographic characteristics for cohorts 1 and 2. Table 2 lists clinical characteristics for cohorts 1 and 2.

Figure 1.

Patient exclusions. *Improperly coded diagnoses included asymptomatic bacteruria, history of urinary tract infection (UTI), abdominal pain, vaginal complaint, pyelonephritis, and upper respiratory infection. **Complicated UTIs included patients with Wilms tumor, hydronephrosis and chronic renal failure, solitary kidney, lymphoma, renal stent, small kidney, and unspecified genetic disorder causing UTIs.

Primary and Secondary Outcome Measures

When evaluating our primary hypothesis, we found the follow-up rate for cohort 1 (no urine culture) was 28 of 332 patients (8.4%), whereas the follow-up rate for cohort 2 (urine culture obtained) was 39 of 447 patients (8.7%). The χ2 test showed no statistically significant difference between the groups (χ2 = 0.02; P = .89; Table 3). Similarly, there was no statistically significant difference between the cohorts when looking at either a second antibiotic being prescribed within 2 weeks of the initial visit or a telephone consult for continued UTI symptoms within 2 weeks of the initial visit, though the study was not powered for these outcomes (Table 3).

Urine Culture Results

Of the 447 urine cultures ordered, 243 (54%) grew ≥1,000 colony-forming units per milliliter of a specific bacteria, whereas 101 (23%) had no growth and 94 (21%) grew mixed contaminants only (see Appendix 1 for isolates and resistance rates). The Escherichia coli resistance to TMP-SMX in our sample was 13% (similar to 15% for our hospital).

Of all 447 urine cultures ordered, only 21 (5%) grew bacteria that were resistant to the antibiotic prescribed (17 TMP-SMX, one fluoroquinolone, two amoxicillin, one nitrofurantoin), and one culture (0.2%) showed intermediate resistance to the medication prescribed (nitrofurantoin). Nine of these 21 patients did not follow-up for continued symptoms because they were either contacted by their provider to change their medication (n = 6) or they presumably self resolved (n = 3). The other patients (n = 12) followed up for continued UTI symptoms and had their antibiotic changed, but most (n = 7) did not have urine culture results by the time they followed up. One patient in the urine culture group was initially sent home after her outpatient visit, but returned to the emergency department later the same day with inability to tolerate liquids. She was then admitted to the hospital with a diagnosis of pyelonephritis.

Bivariate and Multivariate Testing

Because ordering a urine culture did not seem to have any significant relationship with obtaining a follow-up visit (see Table 3), we tested all variables in our model with bivariate methods to determine if any had a significant relationship to a patient obtaining a follow-up visit for continued UTI symptoms. Of all variables tested, only having a urine culture that grew an organism that was resistant to the antibiotic prescribed showed a significant relationship to obtaining a follow-up visit for continued UTI symptoms (Table 4). On multivariate analysis using the enter method, ordering a urine culture did not decrease the odds of a follow-up visit (adjusted odds ratio, 1.11; 95% CI, 0.65–1.90). The variable for urine culture growing a resistant organism was not added to the multivariate logistic regression because it would have excluded patients who had no urine culture performed (see Table 5).

Comments

3090D553-9492-4563-8681-AD288FA52ACE
Comments on Medscape are moderated and should be professional in tone and on topic. You must declare any conflicts of interest related to your comments and responses. Please see our Commenting Guide for further information. We reserve the right to remove posts at our sole discretion.
Post as:

processing....