Session:

Epidemiology & Public Health

Abstract No.:

53.010

Title:

Molecular characterization of antibiotic resistant bacteria isolated from chicken meats sold at supermarkets in Bangkok, Thailand

Author(s):

C. Chaisatit¹, C. Tribuddharat¹, S. Dejsirilert², C. Pulsrikarn²; ¹Mahidol University, Department of Microbiology, Faculty of Medicine Siriraj Hospital, Bangkok/TH, ²National Institute of Health, Department of Medical Sciences, Nonthaburi/TH

Abstract:

Background: Antibiotic resistant bacteria contaminated in foods pose a major health risk and possibly a large economy loss. In Thailand, even prevalence data are available, little is known about molecular characteristics of these bacteria. Our objective is to determine the prevalence and molecular characteristics of antibiotic resistant Salmonella spp. and Escherichia coli from fresh chicken meats sold at supermarkets in Bangkok.
Methods: Two hundred sealed packages of chicken meats were collected and processed aseptically according to standard methods. An antimicrobial susceptibility testing (AST) by disk diffusion method and most probable number (MPN) were performed. For Salmonella, serogrouping, and serotyping were also determined. Class 1 integron was identified by PCR and dot blot hybridization, and was confirmed by DNA sequencing. Genetic relatedness of Salmonella isolates was determined by: plasmid profile study, randomly amplified polymorphic DNA (RAPD-PCR), and multilocus sequence typing (MLST).
Results: The prevalence of Salmonella spp. and E. coli were 18.67% (14/75), and 53% (106/200), respectively. MPN analysis revealed that 56.66% of the samples (34/60) violated the limit of allowable coliform bacteria in raw chicken meat, with the highest value of 46,000. Multi-drug resistant phenotype was found in both Salmonella spp. and E. coli. Class 1 integron was detected by PCR amplification with primers specific to intI1 and found in 42.86% (6/14), and 37.74% (40/106) in Salmonella spp. and E. coli, respectively. Resistance genes identified in this study were aadA2, aadA4, aadA12, aadA22, and aadA23 (for aminoglycoside resistance); dfrA5 (for trimethoprim resistance); and lnuF (for lincosamide resistance). The spread of resistant bacteria among supermarkets was evidenced from typing data incorporated with demographic data. Four of Salmonella isolates were subjected to MLST analysis. MLST results were ST 50, ST 96, ST 1543, and ST 1549, which matched well with strains from Vietnam, Denmark, Chile, USA, Tunisia, and Australia reflecting worldwide spread.
Conclusion: This study demonstrated that antibiotic resistant bacteria and integron elements now have been spread among food producing animals, and can be spread to human through consumption of undercooked food. Antibiotic use in human and animals should be tighter monitored in order to limit the emergence of antibiotic resistant bacteria.