Characterization of Antimicrobial Resistance of Listeria monocytogenes Strains Isolated from a Pork Processing Plant and Its Respective Meat Markets in Southern China

TY - JOUR

T1 - Characterization of Antimicrobial Resistance of Listeria monocytogenes Strains Isolated from a Pork Processing Plant and Its Respective Meat Markets in Southern China

AU - Li, Lili

AU - Olsen, Rikke Heidemann

AU - Ye, Lei

AU - Wang, Wenyan

AU - Shi, Lei

AU - Yan, He

AU - Meng, Hecheng

PY - 2016/5

Y1 - 2016/5

N2 - A total of 78 Listeria monocytogenes isolates from a pork processing plant and the respective meat markets in southern China were examined. This number includes 60 isolates from pork at markets, 5 from cooked pork products at markets, 10 from pork at a processing plant, and 3 from food-contact surfaces at the processing plant. All isolates were subjected to serotyping, antimicrobial susceptibility testing, pulsed-field gel electrophoresis (PFGE), and molecular basis of antibiotic resistance. Four serogroups were identified among the 78 tested isolates, with serogroup I (serotypes: 1/2a and 3a) being predominant (42.3%, 33/78). Antimicrobial resistance was most frequently observed for tetracycline (20.5%, 16/78), streptomycin (9.0%, 7/78), cefotaxime (7.7%, 6/78), and gentamicin (6.4%, 5/78). Multiple resistances occurred among 10.2% (8/78) isolates. All strains were sensitive to ampicillin, ampicillin/sulbactam, imipenem, ciprofloxacin, levofloxacin, trimethoprim/sulfamethoxazole, and vancomycin. Two isolates were resistant to five antimicrobials. Twelve strains carried tet(M) and located on Tn916. PFGE analysis revealed genetic heterogeneity among individual serotypes. Two predominant PFGE types were found persistent from the processing plant to markets indicating that these two types of isolates were able to survive under environmental adverse conditions from the processing plant to markets, which need to be monitored. Compared to samples from the pork processing plant, the prevalence of L. monocytogenes in meat market samples tended to be higher, serovar was more variable, and the antibiotic resistance range was wider, probably due to secondary contamination. Therefore, stringent hygiene measures and bacteriological controls should be observed to reduce the risk of transmission of L. monocytogenes from food to humans.

AB - A total of 78 Listeria monocytogenes isolates from a pork processing plant and the respective meat markets in southern China were examined. This number includes 60 isolates from pork at markets, 5 from cooked pork products at markets, 10 from pork at a processing plant, and 3 from food-contact surfaces at the processing plant. All isolates were subjected to serotyping, antimicrobial susceptibility testing, pulsed-field gel electrophoresis (PFGE), and molecular basis of antibiotic resistance. Four serogroups were identified among the 78 tested isolates, with serogroup I (serotypes: 1/2a and 3a) being predominant (42.3%, 33/78). Antimicrobial resistance was most frequently observed for tetracycline (20.5%, 16/78), streptomycin (9.0%, 7/78), cefotaxime (7.7%, 6/78), and gentamicin (6.4%, 5/78). Multiple resistances occurred among 10.2% (8/78) isolates. All strains were sensitive to ampicillin, ampicillin/sulbactam, imipenem, ciprofloxacin, levofloxacin, trimethoprim/sulfamethoxazole, and vancomycin. Two isolates were resistant to five antimicrobials. Twelve strains carried tet(M) and located on Tn916. PFGE analysis revealed genetic heterogeneity among individual serotypes. Two predominant PFGE types were found persistent from the processing plant to markets indicating that these two types of isolates were able to survive under environmental adverse conditions from the processing plant to markets, which need to be monitored. Compared to samples from the pork processing plant, the prevalence of L. monocytogenes in meat market samples tended to be higher, serovar was more variable, and the antibiotic resistance range was wider, probably due to secondary contamination. Therefore, stringent hygiene measures and bacteriological controls should be observed to reduce the risk of transmission of L. monocytogenes from food to humans.

U2 - 10.1089/fpd.2015.2087

DO - 10.1089/fpd.2015.2087

M3 - Journal article

C2 - 27058266

SN - 1535-3141

VL - 13

SP - 262

EP - 668

JO - Foodborne Pathogens and Disease

JF - Foodborne Pathogens and Disease

IS - 5

ER -