BACKGROUND-New evidence has indicated geographic clusters of antimicrobial resistance (AR) in adult urinary tract infections. We aimed to evaluate the impact of a pediatric patient’s place of residence on AR in a subsequent positive urine culture. We hypothesized that AR levels surrounding a patient’s place of residence will positively influence their likelihood of AR in a urine culture.
METHODS-This retrospective cohort study used Intermountain Healthcare’s (IH’s) data repository which includes information from all clinical encounters across all 201 IH hospitals and clinics. Inclusion criteria were: age 2 months to 18 years; an outpatient urine culture obtained between 2016 and 2023 that tested positive with >100,000CFU/mL of a single bacteria; and, a known Utah home address at time of culture. Exclusion criteria were: an inpatient urine culture; pyelonephritis (ICD-10: N10,N11); underlying congenital urologic anomalies (ICD-10: N12-N15,Q54,Q62); and, any hospitalization within the last 30 days.
Each patient/culture was assigned a "community" (i.e., a 36km2 hexagon) based on home address at time of culture. A patient's community-level resistance was defined at the hexagon level as the fraction of AR positive urine cultures in the prior 2 years, excluding the patient's own culture(s) (Figure 1).
The primary outcome was AR in a positive urine culture. The primary exposure was community-level resistance. Multivariable logistic regression models were fit to assess the likelihood of AR based on community-level resistance, controlling for prior (within 2 years) personal urine culture AR, gender, age, and urban/rural status.
RESULTS-The three most common isolates from 27,629 positive urine cultures meeting inclusion criteria were: Escherichia coli (23,813(86%)), Enterococcus faecalis (1,188(4%)), and Klebsiella pneumonia (612(2%)). 2,648(10.3%) cultures occurred in patients with a prior personal resistant culture. The vast majority of AR occurred in E. coli isolates (n:7,011(98.8%)). The analysis reported here represents the combination of E. coli and K. pneumonia cultures, though sensitivity analyses showed almost all of the signal being influenced by AR in E. coli cultures.
Figure 1 demonstrates that community-level resistance is not uniform but variable and is dependent on a patient’s place of residence. Figure 2 and Table 1 indicate a clinically significant 1% increase in AR in a urine culture for every 1% increase in community-level resistance. Nevertheless, the strongest predictor for AR was a personal history of previous AR (OR 1.94; 95%CI:1.78-2.11;p<0.001).
CONCLUSIONS-These results support our hypothesis that a patient’s place of residence does influence their likelihood of AR in a positive urine culture. The next step and focus of current work is determining how this information improves empiric antimicrobial selection for children with suspected UTIs.
| Table 1: Adjusted odds of antimicrobial resistance in Escherichia coli or Klebsiella pneumonia positive urine culture based on community-level resistance and other factors | |||
| Variable | Odds Ratio | 95% confidence interval | p-value |
| Community-level resistance (for each 1% increase) | 1.008 | 1.006-1.011 | <0.001 |
| History of culture with antimicrobial resistance (Ref=none) | 1.94 | 1.78-2.11 | <0.001 |
| Female Sex (Ref=male) | 0.85 | 0.73-0.99 | 0.03 |
| Age (for each 1-year increase) | 0.97 | 0.96-0.98 | <0.001 |
| Small urban area (Ref=large urban area) | 0.94 | 0.84-1.06 | 0.3 |
| Rural area (Ref=large urban area) | 1.07 | 0.92-1.22 | 0.4 |
