title: Comparative analysis of antimicrobial resistance in enterotoxigenic Escherichia coli isolates from two paediatric cohort studies in Lima, Peru.
abstract: BACKGROUND
  Antibiotic resistance is increasing worldwide, being of special concern in low- and middle-income countries. The aim of this study was to determine the antimicrobial susceptibility and mechanisms of resistance in 205 enterotoxigenic Escherichia coli (ETEC) isolates from two cohort studies in children <24 months in Lima, Peru.
  
  
  METHODS
  ETEC were identified by an in-house multiplex real-time PCR. Susceptibility to 13 antimicrobial agents was tested by disk diffusion; mechanisms of resistance were evaluated by PCR.
  
  
  RESULTS
  ETEC isolates were resistant to ampicillin (64%), cotrimoxazole (52%), tetracycline (37%); 39% of the isolates were multidrug-resistant. Heat-stable toxin producing (ETEC-st) (48%) and heat-labile toxin producing ETEC (ETEC-lt) (40%) had higher rates of multidrug resistance than isolates producing both toxins (ETEC-lt-st) (21%), p<0.05. Only 10% of isolates were resistant to nalidixic acid and none to ciprofloxacin or cefotaxime. Ampicillin and sulfamethoxazole resistance were most often associated with blaTEM (69%) and sul2 genes (68%), respectively. Tetracycline resistance was associated with tet(A) (49%) and tet(B) (39%) genes. Azithromycin inhibitory diameters were ≤15 mm in 36% of isolates, with 5% of those presenting the mph(A) gene.
  
  
  CONCLUSIONS
  ETEC from Peruvian children are often resistant to older, inexpensive antibiotics, while remaining susceptible to ciprofloxacin, cephalosporins and furazolidone. Fluoroquinolones and azithromycin remain the drugs of choice for ETEC infections in Peru. However, further development of resistance should be closely monitored.
authors.affiliation: Instituto de Medicina Tropical Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru.
authors.forename: Anicia M
authors.initials: AM
authors.lastname: Medina
authors.affiliation: Instituto de Medicina Tropical Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru.
authors.forename: Fulton P
authors.initials: FP
authors.lastname: Rivera
authors.affiliation: ISGlobal, Barcelona Ctr. Int. Health Res. (CRESIB), Hospital Clínic - Universitat de Barcelona, Barcelona, Spain Universidad Peruana de Ciencias Aplicadas Lima, Peru.
authors.forename: Maria J
authors.initials: MJ
authors.lastname: Pons
authors.affiliation: Instituto de Medicina Tropical Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru.
authors.forename: Maribel
authors.initials: M
authors.lastname: Riveros
authors.affiliation: ISGlobal, Barcelona Ctr. Int. Health Res. (CRESIB), Hospital Clínic - Universitat de Barcelona, Barcelona, Spain.
authors.forename: Cláudia
authors.initials: C
authors.lastname: Gomes
authors.affiliation: Department of Bacteriology, U.S. Naval Medical Research Unit No. 6, Callao, Peru.
authors.forename: María
authors.initials: M
authors.lastname: Bernal
authors.affiliation: Department of Bacteriology, U.S. Naval Medical Research Unit No. 6, Callao, Peru.
authors.forename: Rina
authors.initials: R
authors.lastname: Meza
authors.affiliation: Department of Bacteriology, U.S. Naval Medical Research Unit No. 6, Callao, Peru Division of Infectious Diseases, Naval Medical Center San Diego, San Diego, California, USA.
authors.forename: Ryan C
authors.initials: RC
authors.lastname: Maves
authors.affiliation: Universidad Peruana Cayetano Heredia, Lima, Peru Universidad Nacional Mayor de San Marcos, Lima, Peru Instituto Nacional de Salud del Niño, Lima, Peru Instituto de Investigación Nutricional, Lima, Peru.
authors.forename: Luis
authors.initials: L
authors.lastname: Huicho
authors.affiliation: Universidad Peruana Cayetano Heredia, Lima, Peru.
authors.forename: Elsa
authors.initials: E
authors.lastname: Chea-Woo
authors.affiliation: Instituto de Investigación Nutricional, Lima, Peru.
authors.forename: Claudio F
authors.initials: CF
authors.lastname: Lanata
authors.affiliation: Instituto de Investigación Nutricional, Lima, Peru.
authors.forename: Ana I
authors.initials: AI
authors.lastname: Gil
authors.affiliation: Instituto de Medicina Tropical Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru Universidad Peruana Cayetano Heredia, Lima, Peru Center for Infectious Diseases, University of Texas School of Public Health, Houston, Texas, USA joruiz@clinic.ub.es quim.ruiz@cresib.cat.
authors.forename: Theresa J
authors.initials: TJ
authors.lastname: Ochoa
authors.affiliation: ISGlobal, Barcelona Ctr. Int. Health Res. (CRESIB), Hospital Clínic - Universitat de Barcelona, Barcelona, Spain joruiz@clinic.ub.es quim.ruiz@cresib.cat.
authors.forename: Joaquim
authors.initials: J
authors.lastname: Ruiz
mesh_terms: D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D017963:Azithromycin / Q000627:therapeutic use*; D002675:Child, Preschool; D015331:Cohort Studies; D003967:Diarrhea / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology*; D004311:Double-Blind Method; D054307:Enterotoxigenic Escherichia coli / Q000187:drug effects* / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000150:complications / Q000188:drug therapy / Q000382:microbiology*; D005260:Female; D024841:Fluoroquinolones / Q000627:therapeutic use*; D006801:Humans; D007223:Infant; D008297:Male; D008826:Microbial Sensitivity Tests; D010568:Peru / Q000453:epidemiology; D060888:Real-Time Polymerase Chain Reaction
chemical_list: D000900:Anti-Bacterial Agents; D024841:Fluoroquinolones; D017963:Azithromycin
keywords: Antibiotic resistance; Children; Diarrhoea; Enterotoxigenic Escherichia coli; Peru