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Introduction: Listeria monocytogenes is a pathogen acquired through the consumption of contaminated foods.Thirteen serotypes have been reported, of which 1/2a, 1/2b, and 4b are responsible for 98% of human listeriosis cases. This study examines the association between serotypes and virulent clones, offering greater information and providingtools to prevent and control diseases caused by L. monocytogenes serotype 4b. Objective: To identify the serotypes from L. monocytogene strains isolated from different samples by performingthe molecular subtyping technique; to determine the 85M fragment that codifies for epidemic clone I.Methods : 108 strains of L. monocytogenes were used, isolated from samples of animals, body fluids, foods, and food processing plant equipment and spaces. The samples were identified by following the Bacteriological AnalyticalManual protocol described by the Food and Drug Administration (FDA). The strains were identified by PolymeraseChain Reaction (PCR) using primers and a standardized protocol from a previous research project. Serotypeidentification was performed by multiplex PCR. The determination of the 85M fragment of the SSCS cassette was done by following the protocol by Yildrim et al. Results : Of the 108 L. monocytogenes strains analyzed, 60.2% (65 strains) belonged to the 4b-4d-4e serotype, 17.6%(19 strains) were identified as 1/2a-3a serotype, 14.8% (16 strains) were 4a-4c serotype, 3.7% (4 strains) belonged to the 1/2c-3c serotype, and (3.7%) corresponded to the 1/2b-3b-7 serotype. It was determined that the L. monocytogenes strains serotype 4b-4d-4e and 1/2a-3b have the 85M fragment of the SSCS cassette.Conclusion : This study reports the predominant existence of L. monocytogenes strains serotype 4b-4d-4e in food, environmental, and clinical samples. The presence of an epidemic clone I region was also found in L. monocytogenes strains.

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The prevalence of diarrheagenic Escherichia coli in childhood diarrhea and the role of contaminated food products in disease transmission in Colombia are largely unknown. The aim of this study is to identify E. coli pathotypes, including E. coli O157:H7, from 108 stool samples from children with acute diarrhea, 38 meat samples and 38 vegetable samples. Multiplex PCR and Bax Dupont systems were used for E. coli pathotype detection. Eighteen (9.8%) E. coli diarrheagenic pathotypes were detected among all clinical and food product samples tested. Four different pathotypes were identified from clinical samples, including enteroaggregative E. coli, enterotoxigenic E. coli, shiga-toxin producing E. coli, and enteropathogenic E. coli. Food product samples were positive for enteroaggregative and shiga-toxin producing E. coli, suggesting that meat and vegetables may be involved in transmission of these E. coli pathotypes in the community. Most E. coli strains identified belong to the phylogenetic groups A and B1, known to be associated with intestinal rather than extraintestinal E. coli clones. Our data is the first molecular E. coli report that confirms the presence of E. coli pathotypes circulating in Colombia among children with diarrhea and food products for human consumption. Implementation of multiplex PCR technology in Latin America and other countries with limited resources may provide an important epidemiological tool for the surveillance of E. coli pathotypes from clinical isolates as well as from water and food product samples.

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Introducción. Enterobacter sakazakii es un patógeno oportunista emergente de alto riesgo, responsable de meningitis grave y enterocolitis necrosante. El principal vehículo de transmisión de esta bacteria son los productos infantiles deshidratados, debido a su contaminación después del tratamiento térmico. Objetivo. Identificar cepas de E. sakazakii en muestras de lactarios recolectadas en la ciudad de Bogotá, D.C. Materiales y métodos. Se analizaron 222 muestras de 9 lactarios, de superficies estériles y no estériles, utensilios empleados para la preparación de biberones y operarios. Se realizó recuento de coliformes totales y detección de E. sakazakii utilizando el protocolo propuesto por la Food and Drug Administration y por el Sistema Automático Bax® Dupont Qualicon. Resultados. De las 222 muestras recolectadas en las clínicas de Bogotá, se reportó que 27,4% (61) de las muestras analizadas presentaban coliformes totales; se detectó la presencia de E. sakazakii en 3,6% por el método automatizado de PCR BAX Dupont a partir de muestras de biberones y superficies. Conclusiones. Se demostró la presencia de E. sakazakii en lactarios en Colombia. Debido a que este microorganismo es un patógeno oportunista de alto riesgo para neonatos y que está asociado a las prácticas higiénicas en los lactarios, la información de este estudio puede ser útil para la toma de medidas profilácticas que reduzcan el riesgo de contaminación con este patógeno para la población infantil y, también, aporta información importante para la salud pública.

Introduction: Enterobacter sakazakii is an emergent opportunistic pathogen of high risk responsible of severe meningitis and necrotizing enterocolitis in neonates and infants with underlying medical conditions. One of the principal transmission vehicles for the transmission of these bacteria, is the infant dehydrated formula after exposing them to the heating treatment. Objective: To identify strains of E. sakazakii in milk feeders’ samples from Bogotá. Materials and methods: 222 samples from 9 milk feeders including sterile and non sterile surfaces, utensils used for the formula preparation and food handlers were analyzed. Total coliforms counts and identification of E. sakazakii was done using the FDA protocol and the automatic system Bax ® Dupont Qualicon. Results: From de 222 samples collected from hospitals in Bogotá, it was reported that 27.4% (61) had total coliforms, and the presence of E. sakazakii was detected in 3.6% (8) from one feeding bottle and surfaces. Conclusion: The presence of E. sakazakii strains was reported in Colombian milk feeders. Because this microorganism is a high risk opportunistic pathogen for newborn infants, usually associated with hygiene practices in milk feeders, the information of this research could be useful to develop preventive measurements to reduce the risk of contamination in the infant population and provides important public health information.

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The aim of this study was to characterize Shiga toxigenic Escherichia coli (STEC) by PCR using strains isolated from ham, beef, and cattle in Colombia. A total of 189 E. coli strains were tested for the presence of the uidA, stx1, and stx2 genes, and identification was confirmed by the automated PCR BAX system for E. coli O157:H7. Genes encoding Shiga-like toxins (stx) were found in eight (6.06%) of 132 strains previously isolated from minced beef; four (50%) of these strains yielded amplification products for both toxin genes (stx1 and stx2), and four (50%) yielded products only for the stx2 toxin. None of the strains analyzed were positive by PCR for the presence of the single base-pair mutation in the uidA gene from E. coli O157:H7; these results were confirmed by the BAX system analysis. A multiplex PCR assay was standardized for the three genes. Results from this study confirmed previous data about the low prevalence of E. coli O157:H7 and Shiga-like toxins in Colombia and is the first known report of the prevalence of non-O157 enterohemorrhagic E. coli in this country.

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Resumen Objetivo. Utilizar la técnica de amplificación aleatoria de ADN polimórfico ( random amplification of polymorphic DNA, RAPD para caracterizar molecularmente cepas de Staphylococci productoras de toxinas, aisladas de operarios de plantas de producción de alimentos. Materiales y métodos. Se utilizaron 31 aislamientos enterotoxigénicos de Staphylococci para la extracción y cuantificación de ADN. Posteriormente, se realizó un ciclo general de amplificación utilizando los oligonucleótidos HLWL-74 y arbitrario, seguido por la visualización de los productos de RAPD por electroforesis en gel de agarosa. Resultados. Para los dos oligonucleótidos utilizados, se observaron de 1 a 15 bandas, dos linajes, divididos en tres conglomerados (A, B y C). El oligonucleótido arbitrario generó 10 bandas polimórficas (66,66%) y el oligonucleótido HLWL-74 arrojó 13 bandas altamente polimórficas (86,66%). Cada oligonucleótido mostró un agrupamiento diferente de cada una de las cepas, lo cual muestra una alta diversidad de aislamientos de Staphylococci presentes en humanos. Conclusiones. Se presentó una alta diversidad molecular en cuanto a aislamientos de garganta, nariz y manos de un mismo individuo, así como en todos los aislamientos analizados, lo cual demuestra que las cepas enterotoxigénicas de Staphylococci encontradas en los operarios analizados tienen una alta diversidad molecular.

Objective. To use Randomly Amplified Polymorphic DNA (RAPD) to compare molecularly enterotoxigenic Staphylococci strains isolated from people working in food processing plants. Materials and methods. 31 Staphylococci enterotoxigenic isolates were used for extraction and quantification of DNA, followed by a general amplification cycle with the HLWL-74 and arbitrary oligonucleotides with visualization of the RAPD products by agarose gel electrophoresis. Results. The two oligonucleotides used generated 1 to 15 bands, two mayor lineages divided in three clusters (A, B, and C). The arbitrary oligonucleotide generated 10 polymorphic bands (66.66%), the HLWL-74 oligonucleotide generated 13 polymorphic bands (86.66%). Each oligonucleotide generated a different type of grouping with respect to each of the strains analyzed. This shows a high diversity between the human isolates of Staphylococci. Conclusion. A high molecular diversity was present amongst throat, nose and hands isolates from the same person, and among the analyzed isolates; this demonstrates a high molecular diversity in Staphylococci enterotoxigenic isolates.

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