Recurrent urinary tract infections in infancy: relapses or reinfections?
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Published on: December 4, 2020
M E Jantunen1, H Saxén, E Salo
1Hospital for Children and Adolescents, University of Helsinki, Finland. maria.jantunen@ktl.fi
Insights
Recurrent urinary tract infections (UTIs) in infants are typically caused by the same Escherichia coli strain relapsing from the initial infection, not new bacterial strains. This suggests endogenous relapses are more common than reinfections.
Area of Science:
- Pediatrics
- Infectious Diseases
- Microbiology
Background:
- Recurrent urinary tract infections (UTIs) are common in infants.
- Escherichia coli is a primary pathogen causing infant UTIs, including pyelonephritis.
- Understanding the source of recurrent UTIs is crucial for effective management.
Purpose of the Study:
- To investigate the microbial etiology of recurrent UTIs in infants following an initial pyelonephritis episode.
- To differentiate between endogenous relapses and exogenous reinfections as causes of recurrent UTIs.
- To analyze the genetic characteristics of Escherichia coli strains involved in recurrent UTIs.
Main Methods:
- Multiplex polymerase chain reaction (PCR) was used to detect papG gene alleles (classes I-III) in E. coli strains.
- Pulsed-field gel electrophoresis (PFGE) was employed for genomic fingerprinting of E. coli isolates.
- Infants with an index pyelonephritis episode were monitored for 18 months for recurrent UTIs.
Main Results:
- All 17 infants experienced at least one recurrent UTI caused by the same pathogen.
- The papG gene was present in 71% of index E. coli strains and 70% of recurrent isolates.
- PFGE analysis indicated that 65% of recurrent isolates were indistinguishable or highly similar to previously encountered strains within the same infant.
Conclusions:
- Most recurrent UTIs in infants are endogenous relapses of the initial Escherichia coli infection.
- The papG gene, particularly class II alleles, is prevalent in E. coli strains causing recurrent UTIs in this age group.
- Genetic analysis supports the hypothesis that infant recurrent UTIs predominantly stem from persistent or reactivated infections rather than new acquisitions.
Abstract:
Seventeen infants with an index episode of pyelonephritis caused by Escherichia coli were monitored for 18 months for recurrent urinary tract infections (UTIs). All the infants had at least 1 recurrent UTI caused by the same pathogen. Twenty-six recurrent UTI episodes were recorded. The 40 E. coli strains available were analyzed by multiplex polymerase chain reaction for 3 alleles (classes I-III) of the papG gene and by pulsed-field gel electrophoresis (PFGE) after genomial digestion by XbaI. Of the 17 index strains, 12 (71%) carried the papG gene; 67% of these strains had class II alleles. In recurrent UTI isolates, the papG-positive E. coli appeared in 16 (70%) of 23 isolates. The proportion of all recurrent isolates available that represented a strain previously encountered (indistinguishable or highly similar in PFGE) in the same infant was 65%. Our results suggest that most recurrent UTIs in infants are endogenous relapses rather than reinfections caused by new organisms.
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