Antimicrobial Susceptibility of Listeria in Colombian Swine Processing Plants12 April 2013
Susceptibility was in the range of 84 to 100 per cent for most antimicrobials tested but Colombia-based researchers concluded from a recent study that antimicrobial susceptibility related to the circulating strains of L.monocytogenes has been stable over the past five years in the areas studied.
In the latest issue of Journal of Swine Health and Production, Andrea Gamboa-Marín of Pontificia Universidad Javeriana in Bogotá and co-authors there and at the University of Tolima and Rochem Biocare Group report on their analysis of the distribution of Listeria monocytogenes serotypes and antimicrobial susceptibility of Listeria isolates from a domestic swine processing facility.
Presumptive Listeria isolates (314) were molecularly identified to discriminate between L. monocytogenes, L. ivanovii and Listeria species. L. monocytogenes serotypes were identified by polymerase chain reaction (PCR) and PCR-restriction enzyme analysis (PCR-REA) and tested for antimicrobial susceptibility.
Isolates were identified as L.monocytogenes (259; 82.5 per cent), L.ivanovii (2; 0.6 per cent) and Listeria species (53; 16.9 per cent).
Distribution of L.monocytogenes serotypes: 4a/4c (0.4 per cent), 4b (11.2 per cent), 4d/4e (14 per cent), 4b/4d/4e (9.3 per cent), 1/2a (26.3 per cent), 3a (7.7 per cent), 1/2a/3a (6.2 per cent), 1/2b/3b (1.2 per cent), 1/2c (5 per cent), 3c (1.2 per cent) and 1/2c/3c (5.4 per cent). Thirty-two L.monocytogenes isolates (12.4 per cent) were not typeable by PCR-REA, suggesting the possibility of serotypes 4ab/7.
Susceptibility was 84.2 per cent to 100 per cent for most antimicrobials. Major resistance (R) and intermediate (I) susceptibility were found for clindamycin (R=36.7 per cent, I=39.8 per cent for L.monocytogenes; R=100 per cent for L.ivanovii and R=14 per cent, I=86 per cent for Listeria species).
Drugs of choice for treatment of human listeriosis (penicillin, ampicillin and trimethoprim-sulfamethoxazole) remained effective; 1.2 per cent of L.monocytogenes were Β-lactam resistant. Multi-drug resistance was found only in L.monocytogenes (26.6 per cent) and Listeria species (26.4 per cent), with (clindamycinI or R - erythromycinR - azithromycinR) and (ciprofloxacinI - clindamycinI) the most frequent phenotypes.
Resistance to clindamycin and ciprofloxacin are shared between L.monocytogenes and untyped Listeria, concluded Gamboa-Marín and co-authors. They added that, although erythromycin is a drug of choice for prophylaxis in Colombian pigs, resistance is low. The Colombian group found no specific relationships between serotypes, sources and antimicrobial susceptibility.
Gamboa-Marín A., D.C. Mejía-Wagner, P.A. Moreno-Ocampo, S.M. Buitrago, K.I. Pérez-Pérez; Z. Ruiz-Bolivar, R.A. Poutou-Piñales, A.K. Carrascal-Camacho, A. Velasco-Briceño and M.L. Ocampo-Guerrero. 2013. Antimicrobial susceptibility of Listeria monocytogenes, Listeria ivanovii, and Listeria species isolated from swine processing facilities in Colombia. J Swine Health Prod. 21(1):10–21.
You can view the full report by clicking here.