Journal Article

Trends in antimicrobial resistance, phage types and integrons among <i>Salmonella</i> serotypes from pigs, 1997–2000

Wondwossen A. Gebreyes, Siddhartha Thakur, Peter R. Davies, Julie A. Funk and Craig Altier

in Journal of Antimicrobial Chemotherapy

Published on behalf of British Society for Antimicrobial Chemotherapy

Volume 53, issue 6, pages 997-1003
Published in print June 2004 | ISSN: 0305-7453
Published online June 2004 | e-ISSN: 1460-2091 | DOI:
Trends in antimicrobial resistance, phage types and integrons among Salmonella serotypes from pigs, 1997–2000

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Objectives: The objectives of this study were to determine antimicrobial resistance and to identify phage types and class 1 integrons among non-typhoidal Salmonella isolates from 24 pig farms in North Carolina collected between 1997 and 2000.

Methods: A total of 1314 isolates of 30 serotypes from pig faecal samples were collected and analysed over a 3 year period. The isolates were characterized using antimicrobial susceptibility testing, phage typing, PCR and DNA sequencing for class 1 integrons.

Results: A high frequency of resistance to antimicrobial agents including tetracycline (85%), ampicillin (47%), co-amoxiclav (23%) and chloramphenicol (21%) was detected. Two multidrug resistance patterns were common in Typhimurium (including variant Copenhagen): isolates with co-amoxiclav, ampicillin, chloramphenicol, streptomycin, sulfamethoxazole and tetracycline (R-type AxACSSuT) [36%] and isolates with ampicillin, kanamycin, streptomycin, sulfamethoxazole and tetracycline (R-type AKSSuT) [45%] resistance patterns. Definitive Type 104 (DT104) was the most common (34%) among eight phage types identified. AKSSuT was found among non-DT104 phage types, particularly DT21 and DT193. Class 1 integrons were detected among various serotypes including Typhimurium, Derby, Muenchen, Worthington, Bere and Muenster. aadA was the most common resistance gene insert, and the oxa30 β-lactamase resistance gene was also identified among serovar Muenchen.

Conclusions: In this study, two most important multidrug resistance patterns (AxACSSuT and AKSSuT) and phage types of public health significance (DT104 and DT193) constituted two-thirds of the serotype Typhimurium isolates. The findings imply that pigs raised in the commercial production system may pose a risk in serving as reservoirs of resistant Salmonella.

Keywords: Keywords: swine, food safety, antibiotic resistance, salmonellae

Journal Article.  4743 words.  Illustrated.

Subjects: Medical Oncology ; Critical Care

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