Evaluación de capacidad de adherencia de cepas de Staphylococcus aureus en materiales de uso frecuente en equipoas de ordeño en lecherías
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Date
2024
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Universidad de Concepción
Abstract
Staphylococcus aureus (S. aureus) es un microorganismo patógeno de gran relevancia causante de infecciones intramamarias (IMI) en rebaños lecheros. Las IMI generan un detrimento en la calidad microbiológica y organoléptica de leche. La leche puede contaminarse con S. aureus al tener contacto con superficies que tengan presencia de adherencias bacterianas facilitadas por la formación de biopelículas en las superficies en contacto con la leche durante los procesos de ordeño, enfriamiento, y transporte. Las biopelículas pueden proveer bacterias viables en el equipo de ordeño, generando reservorios dentro de las granjas lecheras. Estos reservorios facilitan la permanencia de S. aureus y la potencial contaminación de la leche con toxinas estafilocócicas, causales de intoxicaciones alimentarias. El objetivo de esta investigación es comparar la capacidad de adherencia de 3 cepas de S. aureus obtenidas desde biopelículas en equipos de ordeño en granjas lecheras ubicadas en la Región de Ñuble. Se crearon biopelículas in vitro en superficies de cupones de PVC, goma EPDM, acero 316 con electro pulido, vidrio borosilicato, silicona, acero 304, policarbonato y goma Buna-N en un reactor CDC con flujo continuo por 96 horas. Se observó la formación de biopelículas por las cepas de S. aureus en la superficie de los 8 materiales estudiados en imágenes de microscopía electrónica (SEM). Adicionalmente se realizaron recuentos microbianos para evaluar la densidad
bacteriana adherida. La evaluación de las diferencias en UFC/mL entre cepas y entre materiales mediante ANOVA presentaron una mayor capacidad de formación de biopelículas en los materiales de tipo goma. Las cepas de alta (L11171), media (L1-030) y baja (L1-256) capacidad de adherencia exhibieron un comportamiento similar en la goma Buna-N. Sin embargo, para la goma EPDM la cepa L1-1171 (altamente adherente) tuvo una formación de biopelícula significativamente mayor (p<0,0001). La presente investigación señala que cepas de S. aureus presentes en adherencias macroscópicas en las superficies de equipo de ordeño podrían suponer un riesgo a la calidad microbiológica de la leche. Destacando la importancia del recambio correspondiente de piezas del equipo de ordeño, como estrategia de control de este patógeno intramamario y potencial patógeno humano.
Staphylococcus aureus (S. aureus) is one of the main pathogenic microorganisms causing intramammary infections (IMI) in dairy herds. IMI cause a detriment to the microbiological and organoleptic quality of milk. Milk can become contaminated with S. aureus when it comes in contact with surfaces that have bacterial adhesions facilitated by the formation of biofilms on surfaces in contact with milk during milking, cooling and transport processes. Biofilms can provide viable bacteria on milking equipment, generating reservoirs within dairy farms. These reservoirs facilitate the residence of S. aureus and the possible contamination of milk with staphylococcal toxins, causing food poisoning. The objective of this research is to compare the adherence capacity of 3 strains of S. aureus obtained from biofilms on milking equipment in dairy farms located in the Ñuble Region of Chile. Biofilms were generated in vitro on surfaces of PVC coupons, EPDM rubber, electro-polished 316 steel, borosilicate glass, silicone, 304 steel, polycarbonate and Buna-N rubber in a CDC reactor with continuous flow for 96 hours. Biofilm formation by S. aureus strains on the surface of the 8 materials studied was observed in electron microscopy (SEM) images. Additionally, microbial counts were performed to evaluate the adhered bacterial density. The evaluation of the differences in CFU/mL between strains and between materials by ANOVA showed a greater capacity for biofilm formation in the rubber-type materials. Strains with high (L1-1171), medium (L1-030) and low (L1-256) adherence capacity exhibited similar behavior on Buna-N rubber. However, for EPDM rubber strain L1-1171 (highly adherent) had significantly higher biofilm formation (p<0.0001). This study indicates that S. aureus strains present in macroscopic adhesions on milking equipment surfaces could pose a risk to the microbiological quality of milk. Emphasizing the importance of the corresponding replacement of milking equipment parts as a control strategy for this intramammary pathogen and potential human pathogen.
Staphylococcus aureus (S. aureus) is one of the main pathogenic microorganisms causing intramammary infections (IMI) in dairy herds. IMI cause a detriment to the microbiological and organoleptic quality of milk. Milk can become contaminated with S. aureus when it comes in contact with surfaces that have bacterial adhesions facilitated by the formation of biofilms on surfaces in contact with milk during milking, cooling and transport processes. Biofilms can provide viable bacteria on milking equipment, generating reservoirs within dairy farms. These reservoirs facilitate the residence of S. aureus and the possible contamination of milk with staphylococcal toxins, causing food poisoning. The objective of this research is to compare the adherence capacity of 3 strains of S. aureus obtained from biofilms on milking equipment in dairy farms located in the Ñuble Region of Chile. Biofilms were generated in vitro on surfaces of PVC coupons, EPDM rubber, electro-polished 316 steel, borosilicate glass, silicone, 304 steel, polycarbonate and Buna-N rubber in a CDC reactor with continuous flow for 96 hours. Biofilm formation by S. aureus strains on the surface of the 8 materials studied was observed in electron microscopy (SEM) images. Additionally, microbial counts were performed to evaluate the adhered bacterial density. The evaluation of the differences in CFU/mL between strains and between materials by ANOVA showed a greater capacity for biofilm formation in the rubber-type materials. Strains with high (L1-1171), medium (L1-030) and low (L1-256) adherence capacity exhibited similar behavior on Buna-N rubber. However, for EPDM rubber strain L1-1171 (highly adherent) had significantly higher biofilm formation (p<0.0001). This study indicates that S. aureus strains present in macroscopic adhesions on milking equipment surfaces could pose a risk to the microbiological quality of milk. Emphasizing the importance of the corresponding replacement of milking equipment parts as a control strategy for this intramammary pathogen and potential human pathogen.
Description
Tesis presentada para optar al grado de Magíster en Ciencias Veterinarias
Keywords
Estafilococos, Leche - Calidad, Lecherías