Resistant organisms more likely in children with urinary tract infection who have had recent antimicrobial treatment

Article Outline

• Question
• Design
• Setting
• Participants
• Intervention
• Outcomes
• Main Results
• Conclusions
• Commentary
• Reference
• Copyright

Paschke AA, Zaoutis T, Conway PH, Xie D, Keren R. Previous antimicrobial exposure is associated with drug-resistant urinary tract infections in children. Pediatrics 2010;125:664-72.

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Question 

Among children who have a first urinary tract infection (UTI), does previous antimicrobial exposure affect the development of antimicrobial resistance?

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Design 

Retrospective cohort study.

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Setting 

27 outpatient pediatric practices in the Children's Hospital of Philadelphia network. Patients were seen between July 1, 2001, and May 31, 2006.

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Participants 

533 children aged 6 months to 6 years who received their first diagnosis of UTI.

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Intervention 

A review of the electronic and paper medical records was performed for every included child, collecting data on antimicrobial exposure, antimicrobial susceptibilities, child care attendance, and siblings.

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Outcomes 

The primary outcome of interest was the development of a UTI with an antimicrobial-resistant organism. The relationship between antimicrobial resistance in UTI isolates and exposure to specific antimicrobial agents (amoxicillin, amoxicillin-clavulanate, cefdinir, trimethoprim-sulfamethoxazole, and azithromycin) in the previous 120 days was adjusted for potential confounders such as age, number of siblings, recent hospitalizations, and child care exposure.

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Main Results 

Of the 533 subjects, 8%, 14%, and 21% were exposed to antimicrobial agents within 30, 60, and 120 days before the UTI, respectively. Amoxicillin exposure within 30 days (odds ratio [OR]: 3.6 [95% confidence interval (CI), 1.6 to 8.2]) and 31 to 60 days (OR: 2.8 [95% CI, 1.0 to 7.5]) before UTI both were associated with ampicillin resistance. Exposure to amoxicillin >60 days before the UTI was not associated with ampicillin resistance. Amoxicillin exposure within 30 days of UTI was also associated with amoxicillin-clavulanate resistance (OR: 3.9 [95% CI, 1.8 to 8.7]). No association between exposure to other antimicrobial agents and resistance to any of the antimicrobial agents was seen.

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Conclusions 

Recent antimicrobial exposure is associated with antimicrobial-resistant UTIs among pediatric outpatients, and the magnitude of this association decreases with time since exposure. Judicious antimicrobial prescribers should consider this association when selecting empiric antimicrobial agents for a new UTI and should use strategies to reduce unnecessary antimicrobial use to avoid development of resistant bacteria.

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Commentary 

It has been well-documented that antimicrobial resistance is increasing in outpatient settings and that this possibility must be considered by clinicians as they select appropriate antibiotic treatment. In this well-done, large retrospective study, the investigators carefully reviewed the electronic medical record (EMR) of the 533 children with a first UTI. They identified a clear association between recent antibiotic prescription and UTIs with resistant organisms. For example, children exposed to amoxicillin within 30 days of their first UTI had a 3.6 (CI, 1.6 to 8.2) higher odds of having a UTI with an organism resistant to ampicillin than children not exposed to amoxicillin. Because the EMR also included data on age, sex, race, number of siblings, and recent hospitalizations, the investigators were able to adjust for these potential confounders in their analysis. The main limitation of these data was that day care attendance, which is related to both the exposure (antimicrobial prescription) and outcome (antimicrobial resistance), was not consistently recorded in the EMR. Despite this, this study demonstrates that antibiotic used for respiratory tract infections not only promotes resistance among nasopharyneal pathogens,¹ but also for urinary tract pathogens. Clinicians ought to keep this in mind when treating children who present with their first urinary tract infection.

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Reference 

1. Greenberg D, Givon-Lavi N, Sharf AZ, Vardy D, Dagan R. The association between antibiotic use in the community and nasopharyngeal carriage of antibiotic-resistant Streptococcus pneumoniae in Bedouin children. Pediatr Infect Dis J. 2008;27:776–782
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