Distribution of Listeria monocytogenes serotypes isolated from foods, Colombia, 2000-2009

Abstract

Introduction. Listeria monocytogenes is an intracellular, opportunistic pathogen which can causesevere infections such as meningitis, encephalitis and bacteremia. It can also cause abortions inhuman beings. Foods are the vehicle for infection of the host. Serotypification has discriminated 13serotypes: 1/2a,1/2b, 1/2c, 3a, 3b, 3c, 4a, 4ab, 4b, 4c, 4d, 4e, 7. 4b is the cause of the majority of casesof listeriosis in the world.

Objective. The frequency of serotypes of L. monocytogenes was determined in bacteria isolated fromfoods in Colombia.

Materials and methods. The study is descriptive and retrospective. Over a 10-year period, 2000-2009, 1,599 isolates were examined. All were confirmed as Listeria monocytogenes and other strainsof Listeria, using biochemical tests recommended by the Food and Drug Administration (USA) and APIListeria and serotyped using the Seeliger and Höhne method.

Results. Of the 1,599 isolates, 1,424 were confirmed as L. monocytogenes. Serotypes identified were:1/2a, 135 (9.5%); 1/2b, 154 (10.8%); 1/2c, 68 (4.8%); 3a, 4 (0.3%); 3b, 29 (2.0%); 3c, 2 (0.1%); 4a, 44(3.1%); 4b, 820 (57.6%); 4c, 6 (0.4%); 4d- 4e, 140 (9.8%); 4e, 17 (1.2%); 7, 2 (0.1%); not susceptibleof serotypification, three cases, (0.2%). Isolates came mainly from the Capital District of Bogotá, 1,035(73%); from Antioquia 199 (14%), from Nariño, 109 (8%); from Valle del Cauca 50 (3,5%) and fromother provinces 33 (2.3%).

Conclusion. Of the analyzed isolates, 1,424 (89%) belonged to L. monocytogenes, showing a goodquality in isolation and identification. Most of these isolates belonged to serotype 4b, 820 (57.6%), ahighly virulent serotype. Obligatory surveillance of this microorganism is recommended.

doi: http://dx.doi.org/10.7705/biomedica.v32i3.709