Caracterización higiénico-sanitaria de la leche bovina del departamento de Nariño

RESUMEN Objetivo. Evaluar la calidad higiénico-sanitaria de la leche bovina de Nariño mediante los recuentos de mesófilos aerobios y de células somáticas y determinar presencia de microorganismos ambientales importantes en salud pública como Salmonella spp., Escherichia coli O157, Listeria monocytogenes, Staphylococcus aureus y Yersinia enterocolítica y evaluar las variaciones de los parámetros de calidad en dos periodos lluviosos diferentes. Materiales y métodos. Se tomaron muestras de leche en 180 predios de cuatro subregiones naturales, en épocas de diferente precipitación. A cada muestra se le realizó recuento de aerobios mesófilos, y el recuento de células somáticas por citometría de flujo, y el de Coliformes totales mediante lectura en placa. La detección de Salmonella spp., Escherichia coli O157:H7 y Listeria monocytogenes por el sistema de detección molecular MDS 3M, Staphylococcus aureus y Yersinia enterocolitica por microbiología convencional. Resultados. Los recuentos de células somáticas fueron superiores en la época de altas precipitaciones. La mediana de los recuentos de mesófilos y coliformes totales fue de 20.085 UFC/ml, 265 UFC/ml respectivamente sin diferencias significativas en los dos periodos. No se detectó Salmonella spp. ni E. coli O157/H7. No se observaron diferencias significativas en la frecuencia de presentación de Listeria sp., L. monocytogenes, Y. enterocolítica, Staphylococcus aureus y Staphylococcus coagulasa negativa entre los dos periodos de lluvia evaluados". Conclusiones. Se observó que el 80% de las muestras de leche analizadas en este estudio cumplen con los estándares de calidad higiénico-sanitaria y no se observó influencia de la época de muestreo sobre la calidad higiénica de la leche.

ABSTRACT Objective. The aim of this study is to evaluate the hygienic and sanitary quality of bovine milk from dairy farms of Nariño, Colombia by determining the presence of environmental microorganisms of public health importance such as Salmonella spp., Escherichia coli O157, Listeria monocytogenes, Staphylococcus aureus and Yersinia enterocolitica and to evaluate the impact that the rainy seasons have on milk quality Materials and methods. Milk samples were taken in 180 farms located in four natural subregions, both in the high rainfall season and in the low rainfall season. Mesophilic aerobic count, a somatic cell count by automated methods, and a total coliform count in 3M Petrifilm® plates were done to each milk sample. Detection of Salmonella spp., Escherichia coli O157:H7 and Listeria monocytogenes was done by the 3M MDS system, Staphylococcus aureus and Yersinia enterocolitica were isolated by conventional microbiology techniques. Results. The highest somatic cell counts were found during the high rain season. The median of the mesophilic, total coliform and somatic cell counts were 20,085 CFU/ml, 265 CFU/ml and 219,170 cells/ml, respectively, with no significant differences in the two rainy periods. Neither Salmonella spp. nor E. coli O157/H7 were detected. There was no significant difference among the presence of Listeria sp., L. monocytogenes, Y. enterocolitica, Staphylococcus aureus and coagulase negative Staphylococcus between the two rainy seasons. Conclusions. 80% of the milk samples met the hygienic and sanitary quality standards and no influence of the sampling period on the hygienic quality of the milk was observed.

[Profile of antimicrobial resistance in isolates of Staphylococcus spp. obtained from bovine milk in Colombia]. / Perfil de resistencia antimicrobiana en aislamientos de Staphylococcus spp. obtenidos de leche bovina en Colombia.

Staphylococcus spp. is one of the pathogens that cause bovine mastitis and may present multiple resistance to different antimicrobial groups. The aim of this study was to phenotypically identify Staphylococcus spp. isolates obtained from bovine milk and to characterize their antimicrobial resistance profile. The 101 strains were classified by phenotypic tests, their resistance to oxacillin, cefoxitin, penicillin, ampicillin, tetracycline, kanamycin, sulfamethoxazole / trimethoprim, clindamycin and erythromycin was determined by the Kirby-Bauer technique and the presence of resistance genes by PCR. A total of 65 strains was S. aureus and 36 strains were coagulase-negative staphylococci (CoNS). We found different patterns of resistance to antibiotics evaluated in strains of S. aureus and CoNS, only the resistance to ampicillin was found associated with the species (p<0.005). In the 101 strains, the mecA gene was detected in 27%, aph(3')-IIIa in 75.2%, aac(6')/aph(2")-3 in 47.4%, ant(4')-Ia in 32.7%, tetM in 63% and tetK in 43.6%; however, no association was found with the resistance to penicillin, ampicillin, cefoxitin, kanamycin and tetracycline, respectively (p>0.05). On the other hand, the blaZ gene was found in 59.4% of the 101 strains and the ermCgene in 62.3%, which was associated with resistance to ß-lactams and macrolides, respectively (p<0.001). In this study, antimicrobial multiresistance was found in S. aureus and CoNS strains. This finding impacts on the dairy industry, representing a risk to public health.

Identification of Brucella abortus biovar 4 of bovine origin in Colombia / Identificación de Brucella abortus biovar 4 de origen bovino en Colombia

The objective of this study was to identify twelve Brucella abortus isolates of bovine origin from the department of Nariño in Colombia up to the biovar level. These isolates are included in the collection of the Germplasm Bank of Microorganisms of Animal Health Interest -Bacteria and Virus (BGSA-BV). The identification was carried out through conventional methods such as macro and microscopic morphological descriptions, enzymatic activity, biochemical profile, substrate use and sensitivity to dyes. Complementary genotypic characterization was carried out using multiplex PCR for B. abortus, Brucella melitensis, Brucella ovis, and Brucella suis-Erytritol (AMOS-ERY-PCR), RFLP-IS711, by southern blot hybridization, as well as by the multiple locus variable number of tandem repeat analysis (MLVA) using the ery gene and the insertion sequence IS711 and variable number of tandem repeats (VNTR) as molecular markers. The results of the phenotypic and molecular characterization allowed to identify twelve isolates as B. abortus biovar 4 as well as to differentiate field from vaccine strains. This is the first study on the phenotypic and molecular identification of B. abortus isolates in Colombia. It was concluded that the phenotypic and molecular identification of twelve isolates as B. abortus biovar 4 could be achieved using conventional and molecular techniques with enough resolution power. The identification of these isolates to the biovar level in taxonomic and epidemiological terms will allow the use of this genetic resource as reference strains in future research. This finding constitutes the basis for identifying biotypes not previously reported in the country that might be useful to support brucellosis survey programs in Colombia.

El objetivo de este estudio fue identificar 12 aislamientos de Brucella abortus de origen bovino procedentes del departamento de Narino, Colombia, hasta la descripción de biovar. Estos aislamientos conforman la colección del Banco de Germoplasma de Microorganismos de Interés en Salud Animal, Bacterias y Virus. La identificación se hizo mediante métodos convencionales, como la descripción morfológica macro y microscópica de actividad enzimática, de perfiles bioquímicos, de utilización de sustratos y de sensibilidad a colorantes. Se hizo una caracterización genotipica complementaria mediante PCR múltiple para Brucella abortus, Brucella melitensis, Brucella ovisy Brucella suis-eritritol (AMOS-ERY-PCR); RFLP-/S7II; hibridación Southern blot y análisis multi-locus de repeticiones en tándem de número variable (MLVA), empleando como marcadores moleculares el gen ery, la secuencia de inserción /S711 y el número variable de repeticiones en tándem (VNTR). Los resultados de la caracterización fenotípica y molecular permitieron identificar 12 aislamientos de campo como B. abortus biovar 4 y diferenciar cepas de campo de cepas vacunales. Este es el primer estudio de identificación fenotípica y molecular de aislamientos de B. abortus en Colombia. Por su importancia taxonómica y epidemiológica, la identificación de estos aislamientos hasta el nivel de biovar permitirá disponer de recursos genéticos que se pueden emplear como cepas de referencia en futuras investigaciones. Estos resultados pueden considerarse como una base para la identificación de biotipos no reportados en el país y podrán ser utilizados en programas de monitoreo y vigilancia de la brucelosis bovina en Colombia.

Identification of Brucella abortus biovar 4 of bovine origin in Colombia.

The objective of this study was to identify twelve Brucella abortus isolates of bovine origin from the department of Nariño in Colombia up to the biovar level. These isolates are included in the collection of the Germplasm Bank of Microorganisms of Animal Health Interest - Bacteria and Virus (BGSA-BV). The identification was carried out through conventional methods such as macro and microscopic morphological descriptions, enzymatic activity, biochemical profile, substrate use and sensitivity to dyes. Complementary genotypic characterization was carried out using multiplex PCR for B. abortus, Brucella melitensis, Brucella ovis, and Brucella suis-Erytritol (AMOS-ERY-PCR), RFLP-IS711, by southern blot hybridization, as well as by the multiple locus variable number of tandem repeat analysis (MLVA) using the ery gene and the insertion sequence IS711 and variable number of tandem repeats (VNTR) as molecular markers. The results of the phenotypic and molecular characterization allowed to identify twelve isolates as B. abortus biovar 4 as well as to differentiate field from vaccine strains. This is the first study on the phenotypic and molecular identification of B. abortus isolates in Colombia. It was concluded that the phenotypic and molecular identification of twelve isolates as B. abortus biovar 4 could be achieved using conventional and molecular techniques with enough resolution power. The identification of these isolates to the biovar level in taxonomic and epidemiological terms will allow the use of this genetic resource as reference strains in future research. This finding constitutes the basis for identifying biotypes not previously reported in the country that might be useful to support brucellosis survey programs in Colombia.