Consuelo Borie

Bacteriophage cocktail reduces Salmonella enterica serovar Enteritidis counts in raw and smoked salmon tissues

The use of bacteriophages for the biocontrol of food-borne pathogens is increasingly gaining acceptance. In this study, the effectiveness of bacteriophages to reduce Salmonella Enteritidis counts was evaluated in raw and smoked salmon tissues. Groups of 25 samples each were contaminated with S. Enteritidis, treated with a phage mix and then incubated for ten days at 18 °C and 4 °C. A significant bacterial reduction was obtained on days 3, 6 and 10 in raw salmon samples incubated at 18 °C (from 0.75 to 3.19 log10 CFU/g) and at 4 °C (from 2.82 to 3.12 log10 CFU/g), whereas in smoked salmon lower reductions were achieved (from 1.02 to 1.96 log10 CFU/g at 18 °C and from 0.50 to 1.16 log10 CFU/g at 4 °C). These results show the potential effectiveness of this bacteriophage cocktail as a biocontrol agent against S. Enteritidis in raw and smoked salmon tissues.

Genomic variants of bacteriophages against Salmonella enterica serovar Enteritidis with potential application in the poultry industry

Salmonella enterica serovar Enteritidis (SE) is a prevalent gastrointestinal pathogen worldwide, threatening both animal and human health. In the latter, disease is associated to the consumption of SE-contaminated products from the poultry industry. The control of SE infection is largely based on the use of antibiotics and vaccines, but the use of lytic bacteriophages is re-emerging as an additional strategy for SE control. In fact, a number of recent reports point to the adequacy of bacteriophage as an efficient prophylactic or therapeutic countermeasure to SE infections. However, less attention has been focused on the basic biology of these bacteriophages. Here we report on three bacteriophages (f18, IF1 and EST2) that share a common viral particle morphology but are genomic variants as judged by their EcoRI DNA restriction patterns. Furthermore, they differ in their lytic capability towards SE, being EST2 the most efficient. They show a very narrow host range, efficiently infecting only SE strains. In terms of stability in various suspension media, including distilled water, all three bacteriophages remained viable, without noticeable decay in titer for at least 15 days at 25oC. These results suggest the suitability of the tested bacteriophages as SE-controlling agents in the poultry industry.

Application of a virulent bacteriophage cocktail leads to reduction of Salmonella enterica serovar Enteritidis counts in processed meat products

ABSTRACT Salmonella enterica serotype Enteritidis (SE) is a major cause of food-borne disease outbreaks worldwide. We evaluated the effectiveness of five lytic bacteriophages applied as a cocktail to reduce the counts of SE in two types of processed meat products: cooked (turkey ham (TB) and chicken sausage (CS)) and cured sausage (Italian salami (IS) and barbecue sausage (BS)). Groups of 25 samples each were contaminated with SE, treated with a phage cocktail using a multiplicity of infection of 105 and then incubated for ten days at 18°C and 4°C. A significant reduction in bacteria was obtained on days 3, 6 and 10 in all matrices incubated at 18°C (from 0.48 to 2.12 log Colony Forming Units (CFU) g−1) and at 4°C (from 0.23 to 2.06 log CFU g−1), with the exception of BS at day 3 at 4°C, and IS at both incubation temperatures throughout the trial. The viral titre remained stable in all matrices analysed except in BS. These results show the effectiveness of this bacteriophage cocktail against S. enterica serovar Enteritidis in some processed meat products such as CS, BS and TB.

The use of a bacteriophage cocktail as a biocontrol measure to reduce Salmonella enterica serovar Enteritidis contamination in ground meat and goat cheese

We evaluated the effectiveness of phages on meats and goat cheese contaminated with Salmonella Enteritidis (SE). In meats, reductions of SE were observed during the whole experiment, while in goat cheese a reduction was only observed at day 3. We discuss the relevance of phages as a biocontrol in food.

El desafío de controlar las enfermedades transmitidas por alimentos: bacteriófagos como una nueva herramienta biotecnológica

Foodborne diseases are an increasing public health issue, in which bacterial pathogens have a transcendental role. To face this situation, the food industry has implemented several control strategies, using in the last decade some biotechnological tools, such as direct application of bacteriophages on food, to effectively control bacterial pathogens. Their bactericidal and safe properties to humans and animals have been widely described in the literature, being nowadays some bacteriophage-based products commercially available. Despite this, there are so many factors that can interfere in their biocontrol effectiveness on food, therefore is essential to consider these factors before their application. Thus, the optimal bacterial reduction will be achieved, which would produce a safer food. This review discusses some factors to consider in the use of bacteriophages as biocontrol agents of foodborne pathogens, including historical background, taxonomy and biological description of bacteriophages, and also advantages, disadvantages, and considerations of food applications.

Variability in the response of canine and human dendritic cells stimulated with Brucella canis

Brucella canis is a small intracellular Gram-negative bacterium whose primary host is the dog, but it also can cause mild human brucellosis. One of the main causes of an inefficient immune response against other species of Brucella is their interaction with dendritic cells (DCs), which affects antigen presentation and impairs the development of an effective Th1 immune response. This study analysed the cytokine pattern production, by RT-qPCR and ELISA, in human and canine DCs against whole B. canis or its purified LPS. Human and canine DCs produced different patterns of cytokines after stimulation with B. canis. In particular, while human DCs produced a Th1-pattern of cytokines (IL-1β, IL-12, and TNF-α), canine cells produced both Th1 and Th17-related cytokines (IL-6, IL-12, IL-17, and IFN-γ). Thus, differences in susceptibility and pathogenicity between these two hosts could be explained, at least partly, by the distinct cytokine patterns observed in this study, where we propose that human DCs induce an effective Th1 immune response to control the infection, while canine DCs lead to a less effective immune response, with the activation of Th17-related response ineffective to control the B. canis infection.

Primer reporte de aislamiento de Staphylococcus schleiferi subespecie coagulans en perros con pioderma y otitis externa en Chile

Staphylococcus schleiferi subesp. coagulans fue identificado y descrito por primera vez por Igimi y col (1990) en perros con otitis. El objetivo de este reporte fue determinar la frecuencia de aislamiento de S. schleiferi subesp. coagulans en muestras de perros con pioderma y/u otitis externa en Chile y establecer los perfiles de resistencia frente a antimicrobianos de uso habitual y caracterizar molecularmente la resistencia a quinolonas. Se obtuvieron muestras de 237 caninos adultos diagnosticados con pioderma y/u otitis externa, en el Hospital Veterinario de la Universidad de Chile. La identificacion de Staphylococcus schleiferi subesp. coagulans se realizo con BBL™ Crystal GP. La concentracion minima inhibitoria se determino mediante el metodo de dilucion en agar. El panel de antimicrobianos utilizado fue oxacilina, amoxicilina, cefradina, mupirocina, clindamicina, enrofloxacino, doxiciclina, tetraciclina, kanamicina y sulfametoxazol / trimetoprim. De 237 muestras analizadas, 135 fueron aisladas de pioderma y 102 de otitis. Staphylococcus spp. se identifico en 117 y 52 de las muestras respectivamente. S. schleiferi subesp. coagulans se identifico en 8 cepas aisladas desde pioderma (6,8%) y en 11 cepas de otitis (21,2%). Todas las cepas de S. schleiferi subesp. coagulans de pioderma y el 54,5% de otitis resultaron sensibles a todos los antimicrobianos. La susceptibilidad fue de un 90,9% mupirocina, enrofloxacino y sulfametoxazol/trimetoprim; 81,8% a amoxicilina y kanamicina y el 72,7% a clindamicina. Solo una cepa aislada de otitis presento multirresistencia. La cepa de Staphylococcus schleiferi subesp. coagulans que evidencio resistencia fenotipica a quinolonas presento mutacion en los genes gyrA y grlA.