Comparative study of antimicrobial resistance of Escherichia coli strains isolated from urinary tract infection in patients from Caracas and Lima

Alfonso J. Rodrígueza,*, Renald A. Niño Cotrinac, Carlos Neyra Pérezc, Cruz N. Rodríguezb, Rosa Barbellaa, Mónica Lakatosa, Nilda Molinab, Ada Garcíab, Carmen Duqueb and Pilar Meijomilb

a Vargas Medical School, Faculty of Medicine, Central University of Venezuela; b Laboratory of Microbiology, José Gregorio Hernández West General Hospital, C. R. Los Angeles T-2 10-2 La Boyera 1083, Caracas, Venezuela; c San Fernando Faculty of Medicine, UNMSM, and 2 de Mayo National Hospital, Lima, Peru

Sir,

Members of the Enterobacteriaceae are the cause of the majority of urinary tract infections (UTI).1 In developing countries such as Venezuela and Peru, where socioeconomic conditions do not allow many individuals access to a clean water supply or adequate sewage disposal, UTI and gastroenteritis are very common infections. These are often caused by multiply resistant organisms.

For these reasons studies concerned with the surveillance of antibiotic resistance are needed. We report on such a study of the antimicrobial resistance of Escherichia coli strains isolated from urine from patients with suspected UTI in two hospitals in Latin America, one in Caracas (Venezuela) and the other in Lima (Peru), during the year September 1999–2000. Thirteen antimicrobial agents were tested against 885 strains of E. coli. Susceptibilities of the isolates were assessed by an agar disc diffusion method as described by the National Committee for Clinical Laboratory Standards (NCCLS).2 Differences were statistically assessed by Student's t-tests (95% confidence).

A total of 525 strains was isolated in Lima and 360 strains in Caracas. Of the 885 strains of E. coli 361 (40.8%) were resistant to ampicillin; 278 (31.4%) to ampicillin/ sulbactam; 307 (34.7%) to cephalothin; 136 (15.3%) to gentamicin; 217 (24.5%) to ciprofloxacin; and 498 (56.3%) to trimethoprim–sulphamethoxazole.

There were differences in resistance patterns between isolates from the two cities (TableGo). In Caracas, of the 360 strains, 220 (615) were resistant to ampicillin, whilst in Lima, of 525 strains, only 142 (27%) were resistant to ampicillin. For ampicillin/sulbactam there were also significant differences (46% resistant strains in Lima compared with 10% in Caracas). Similarly, for cephalothin there were differences of 40% compared with 27% resistance, and for gentamicin 19% compared with 10% between Lima and Caracas.


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Table.  Differences in antimicrobial resistance of 885 strains of E. coli isolated from UTI in Caracas and Lima (1999–2000)
 
The level of quinolone resistance was an interesting finding in this study. In Caracas 0–15% of strains were resistant to various quinolone antibiotics, whilst in Lima this figure was 31–38%. One explanation of this difference may be the extensive use of these antibiotics in the treatment of gastroenteritis, especially cholera (endemic) in Peru.3 Use of trimethoprim–sulphamethoxazole and resistance amongst E. coli in Lima can again be explained in part by its use in gastroenteritis, including cholera. In Caracas this drug is used mainly in the treatment of UTI. As regards differences in ampicillin and ampicillin/sulbactam susceptibility, it is known that strains of E. coli from Peru produce TRI ß-lactamase, which confers resistance to ß-lactam inhibitors.4

This brief study has clearly demonstrated the differences in in vitro susceptibility of E. coli strains isolated from cases of UTI between two cities in South America (Lima and Caracas). The results reinforce the need for continuous local surveillance to show trends in antibiotic resistance, which can be used as an aid to the rational prescribing of antimicrobial agents in clinical settings.

Notes

J Antimicrob Chemother 2001; 47: 903–904

* Corresponding author. Tel: +58-14-267-1032; Fax: +58-2-265-4040; E-mail: bacteroides79{at}hotmail.com Back

References

1 .  Eisenstein, B. I. & Zaleznik, D. F. (2000). Enterobacteriaceae. In Principles and Practice of Infectious Diseases, 5th edn, (Mandell, G. L., Ed.), pp. 2294–309. Churchill Livingstone, New York.

2 .  National Committee for Clinical Laboratory Standards. (1998). Performance Standards for Antimicrobial Susceptibility Testing—Eighth Information Supplement; Approved Standards M2-A6 and M7-A4. NCCLS, Villanova, PA.

3 .  Blake, P. A. (1993). Epidemiology of cholera in the Americas. Gastroenterology Clinics of North America 22, 639–60.[ISI][Medline]

4 .  Vedel, G., Belaaouaj, A., Gilly, L., Labia, R., Philippon, A., Nevot, P. et al. (1992). Clinical isolates of Escherichia coli producing TRI ß-lactmases: novel TEM-enzymes conferring resistance to ß-lactamase inhibitors. Journal of Antimicrobial Chemotherapy 30, 449–62.[Abstract]





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