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Journal of Clinical Microbiology, January 2009, p. 99-105, Vol. 47, No. 1
0095-1137/09/$08.00+0     doi:10.1128/JCM.01419-08
Copyright © 2009, American Society for Microbiology. All Rights Reserved.

Persistence of Escherichia coli Clones and Phenotypic and Genotypic Antibiotic Resistance in Recurrent Urinary Tract Infections in Childhood

Siiri Kõljalg,^1* Kai Truusalu,¹ Inga Vainumäe,² Jelena Stsepetova,¹ Epp Sepp,¹ and Marika Mikelsaar¹

Institute of Microbiology, University of Tartu, Ravila 19, 50411,¹ Department of Paediatrics, University of Tartu, Lunini 6, 51014, Tartu, Estonia²

Received 24 July 2008/ Returned for modification 14 September 2008/ Accepted 23 October 2008

We assessed the clonality of consecutive Escherichia coli isolates during the course of recurrent urinary tract infections (RUTI) in childhood in order to compare clonality with phenotypic antibiotic resistance patterns, the presence of integrons, and the presence of the sul1, sul2, and sul3 genes. Altogether, 78 urinary E. coli isolates from 27 children, who experienced recurrences during a 1-year follow-up after the first attack of acute pyelonephritis, were investigated. The MICs of sulfamethoxazole, trimethoprim-sulfamethoxazole (SXT), ampicillin, cefuroxime, cefotaxime, and gentamicin and the presence or absence of the intI gene for class 1 integrons and the sulfamethoxazole resistance-encoding genes sul1, sul2, and sul3 were determined. All E. coli strains were genotyped by pulsed-field gel electrophoresis. There were no significant differences in the prevalences of resistance to beta-lactams and SXT between initial and consecutive E. coli isolates (41 versus 45% and 41 versus 29%, respectively). However, the E. coli strains obtained after SXT administration more frequently carried two or more sul genes than the nonexposed strains (9/21 [43%] versus 11/57 [19%], respectively; P = 0.044). In 78% of the patients, the recurrence of unique clonal E. coli strains alone or combined with individual strains was detected. Phenotypic resistance and the occurrence of sul genes were more stable in clonal strains than in individual strains (odds ratios, 8.7 [95% confidence interval {95% CI}, 1.8 to 40.8] and 4.4 [95% CI, 1.1 to 17.7], respectively). Thus, in children with RUTIs, the majority of E. coli strains from consecutive episodes are unique persisting clones, with rare increases in the initially high antimicrobial resistance, the presence of sul genes, and the presence of integrons.

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* Corresponding author. Mailing address: Institute of Microbiology, University of Tartu, Ravila 19, 50411, Tartu, Estonia. Phone: 372 7 374170. Fax: 372 7 374172. E-mail: Siiri.Koljalg{at}kliinikum.ee

Published ahead of print on 29 October 2008.

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Journal of Clinical Microbiology, January 2009, p. 99-105, Vol. 47, No. 1
0095-1137/09/$08.00+0     doi:10.1128/JCM.01419-08
Copyright © 2009, American Society for Microbiology. All Rights Reserved.

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