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Is Cefalexin better than trimethoprim for treating UTI in children?

Three Part Question

In [paediatric patients presenting to the emergency department] is [cefalexin better than trimethoprim] at [treating the infection]?

Clinical Scenario

You're in clinic sifting through the pathology file. While drinking coffee and moaning that no-one else seems to do the file (it's a particularly huge one!) you notice three children in a row whose urine culture has grown E.coli, resistant to the usual trimethoprim but sensitive to cefalexin. You wonder if there is any evidence for a change in antibiotic policy.

Search Strategy

Ovid Medline 1950-present, EMBASE 1980-present, British Nursing Index 1994-present. The EBM reviews available (Cochrane DSR, ACP Journal Club, DARE, CCTR, CMR, HTA, and NHSEED) were also searched.
{ or exp trimethoprim/} AND { OR exp cefalexin/} AND { urinary tract OR exp urinary tract infection/ OR} LIMIT to humans and English Language

Search Outcome

The search returned 304 results. Of these 6 were identified for relevance to the three part question. On retrieving the papers three did not answer the three part question. Only one was a direct RCT; however this was in adults. In the remaining two, although there is no direct comparison, data can be extrapolated that answer the three part question. One other paper was identified from perusal of the references of the other papers. This too is included.

Relevant Paper(s)

Author, date and country Patient group Study type (level of evidence) Outcomes Key results Study Weaknesses
SS Mehr, CVE Powell and N Curtis
100 paediatric patients aged 6 or under presenting to an emergency department with culture proven UTI.Retrospective cohort study.Bacterial resistance14% resistance to trimethoprim, 24% to cefalexinSmall numbers. Tested for cefalothin. Not direct comparison. Did not investigate treatment success.
Lu K.-C., Chen P.-Y., Huang F.-L., Yu H.-W., Kao C.-H., Fu L.-S., Chi C.-S., Lau Y.-J., Lin J.-F
338 paediatric patients presenting with a first episode of UTI to a general hospital.Retrospective studyE coli susceptibilitycefazolin (C) 86.5% cotrimoxazole (T) 48.6%Compares cefazolin (a first generation cephalosporin), not cefalexin and trimethoprim-sulfamethoxazole. Again, uses bacterial susceptibility rather than treatment. Data extracted from table, purpose of study was to compare combination antibiotic therapy with cephalosporins alone.
P mirabilis suceptibilityC 85.7% T 35.7%
K pneumoniaeC 68.7% T 62.5%
304 consecutive paediatric patients presenting to the emergency department.Prospective cohort study.Antibiotic sensitivity % (CI)Cefalexin 95.5 (93.2–97.8) Trimethoprim 86.0 (82.2–89.8)Again compares antibiotic sensitivity rather than treatment.
S Ladhani, W Gransden
2 groups of children presenting with UTI, one from general practice, the other being patients of the tertiary renal service at Guy's Hospital, London. There were 2815 in the community groupFive year retrospective.Antibiotic resistanceCompares cefadroxil (also first generation cephalosporin). Again lists antibiotic resistance rather than cure. Largest study here.
E coliCefadroxil (C) 1.5% Trimethoprim (T) 27.6%
Proteus spp.C 1.3% T 22.0%
Klebsiella spp.C 2.1% T 25.5%


UTI is a common problem in paediatric patients and presentation at the emergency department. The most common pathogens are E coli and proteus. It is important to be aware of changes in antibiotic resistance in order to provide appropriate antibiotic therapy. The recent NICE guideline (CG54) provides no advice on therapy although none of the studies provides a direct comparison of cefalexin and trimethoprim, the extrapolated evidence (from antibiotic resistance) points towards cefalexin as a more appropriate first line antibiotic.

Clinical Bottom Line

Cefalexin appears to be a more appropriate empirical first choice antibiotic for UTI in a paediatric patient. A prospective RCT would help to clarify this. Clinicians should be aware of local antibiotic resistance patterns to help guide prescribing.


  1. SS Mehr, CVE Powell and N Curtis Cephalosporin resistant urinary tract infections in young children J. Paediatr. Child Health 2004 (40) , 48–52
  2. Lu K.-C., Chen P.-Y., Huang F.-L., Yu H.-W., Kao C.-H., Fu L.-S., Chi C.-S., Lau Y.-J., Lin J.-F Is combination antimicrobial therapy required for urinary tract infection in children? Journal of Microbiology, Immunology and Infection March 2003, pp 56-60
  3. JC CRAIG,LM IRWIG, JF KNIGHT P SURESHKUMAR and LP ROY Symptomatic urinary tract infection in preschool Australian children Journal of Paediatrics and Child Health 1998 (34) 154-159
  4. S Ladhani, W Gransden Increasing antibiotic resistance among urinary tract isolates Arch Dis Child 2003;88:444–445