Prevalence and Diversity of <i>Salmonella</i> Serotypes in Ecuadorian Broilers at Slaughter Age

<div><p><i>Salmonella</i> is frequently found in poultry and represent an important source for human gastrointestinal infections worldwide. The aim of this study was to investigate the prevalence, genotypes and antimicrobial resistance of <i>Salmonella</i> serotypes in broilers from Ecuador. Caeca content from 388 at random selected broiler batches were collected in 6 slaughterhouses during 1 year and analyzed by the ISO 6579/Amd1 protocol for the isolation for <i>Salmonella</i>. Isolates were serotyped and genotypic variation was acceded by pulsed field gel electrophoresis. MIC values for sulfamethoxazole, gentamicin, ciprofloxacin, ampicillin, cefotaxime, ceftazidime, tetracycline, streptomycin, trimethropim, chloramphenicol, colistin, florfenicol, kanamycin and nalidixic acid were obtained. Presence of <i>bla</i>_CTX-M, <i>bla</i>_TEM, <i>bla</i>_SHV and <i>bla</i>_CMY; and <i>mcr-1</i> plasmid genes was investigated in resistant strains to cefotaxime and colistin respectively. Prevalence at batch level was 16.0%. The most common serotype was <i>S</i>. Infantis (83.9%) followed by <i>S</i>. Enteritidis (14.5%) and <i>S</i>. Corvallis (1.6%). The pulsed field gel electrophoresis analysis showed that <i>S</i>. Corvallis, <i>S</i>. Enteritidis and <i>S</i>. Infantis isolates belonged to 1, 2 and 12 genotypes respectively. <i>S</i>. Infantis isolates showed high resistance rates to 12 antibiotics ranging from 57.7% (kanamycin) up to 98.1% (nalidixic acid and sulfamethoxazole). All <i>S</i>. Enteritidis isolates showed resistance to colistin. High multiresistant patterns were found for all the serotypes. The <i>bla</i>_CTX-M gene was present in 33 <i>S</i>. Infantis isolates while <i>mcr-1</i> was negative in 10 colistin resistant isolates. This study provides the first set of scientific data on prevalence and multidrug-resistant <i>Salmonella</i> coming from commercial poultry in Ecuador.</p>