Laboratorio de Referencia de E.coli (LREC) 
Departamento de Microbiología y Parasitología 
FACULTAD DE VETERINARIA 
Universidad de Santiago de Compostela, Campus de Lugo27002, Lugo, España  
TEL-FAX  34-982-285936  
E-mail ecoli@lugo.usc.es

PREVALENCE OF BACTERIAL RESISTANCE TO QUINOLONES AND OTHER ANTIMICROBIALS AMONG AVIAN ESCHERICHIA COLI STRAINS ISOLATED FROM SEPTICEMIC AND HEALTHY CHICKENS IN SPAIN

JESUS E. BLANCO, MIGUEL BLANCO, AZUCENA MORA, JORGE BLANCO*
Reference Laboratory of E. coli, Department of Microbiology and Parasitology,
Faculty of Veterinary, University of Santiago de Compostela, 27002 Lugo, Spain

JOURNAL OF CLINICAL MICROBIOLOGY (1997) 35:2184-2185

INTRODUCTION. Escherichia coli is a major pathogen of worldwide importance in commercially produced poultry, contributing significantly to economic losses in both chickens and turkeys. Colibacillosis begins, in general, with an infection of the upper respiratory tract, followed by septicemia. E. coli is commonly found in the intestinal tract of animals, but in general only certain pathogenic serotypes that show virulence factors (adhesive ability, aerobactin production, serum resistance, and presence of the Col V plasmid) cause disease conditions. Antimicrobial therapy is an important tool in reducing both the incidence and mortality associated with avian colibacillosis. However, resistance to existing antimicrobials is widespread and of concern to poultry veterinarians. The fluoroquinolones are a new class of antimicrobials that exhibit excellent activity against gram-negative bacilli. Althought, the use of this group of antimicrobials in poultry may be inappropriate because of cross-resistance with fluoroquinolones used for treatment of important human enteric infections. The aim of this study was to evaluate the frequency of resistance to quinolones and other groups of antimicrobial agents in avian E. coli strains.

ABSTRACT. Antimicrobial therapy is an important tool in reducing the enormous losses in the poultry industry caused by Escherichia coli infections (colibacillosis). However, resistance to existing antimicrobials is widespread and of concern to poultry veterinarians. The antibiograms perform to 468 avian E. coli strains isolated in Spain showed very high levels of resistance to trimethoprim+sulfamethoxazole (67%) and the new fluoroquinolones (13% to 24%). As of use of these antimicrobial agents may cause cross-resistance with human enteric pathogens, prudent use in veterinary medicine is highly recommended.