Detecção de genes toxigênicos em amostras de Staphylococcus spp. isoladas de queijos de coalho

Objetivou-se com este trabalho isolar quantificar e investigar em amostras de Staphylococcus spp. isoladas de queijos de coalho, a presença dos genes toxigênicos sea-see, seg-sej, tst, eta e etb através da Reação em Cadeia da Polimerase (PCR). Foram verificadas contagens de Staphylococcus coagulase positiva (SCP) variando de 10² a 10(6) UFC.g-1. Os genes toxigênicos tst, sec, sed, seg, seh, sei e sej foram identificados em 18 dos 20 isolados de Staphylococcus spp. com os seguintes percentuais 5, 11, 9, 20, 16, 25 e 14% respectivamente. A presença de elevado percentual de isolados contendo diferentes genes toxigênicos é preocupante para a saúde do consumidor pela possibilidade de produzirem toxinas responsáveis por intoxicações alimentares. A ocorrência de vários genes toxigênicos em amostras de Staphylococcus coagulase negativa é outro fato importante, pois no Brasil não existe legislação com determinação de limites para Staphylococcus coagulase negativa em alimentos.

Formação de biofilme em aço inoxidável por Aeromonas hydrophila e Staphylococcus aureus usando leite e diferentes condições de cultivo

O objetivo desta pesquisa consistiu em avaliar a formação de biofilme em aço inoxidável por Aeromonas hydrophila e Staphylococcus aureus usando leite e diferentes condições de cultivo. As variáveis em estudo consistem no cultivo monoespécie e combinado, dos referidos microrganismos e nas temperaturas de 4, 7 e 18 °C. Recipientes contendo 1000 mL de leite, densidade populacional de 10(5) UFC.mL-1 de cada microrganismo e 10 cupons de aço inoxidável (10 × 20 mm) foram lacrados e armazenados, sob agitação de 60 rpm, por um período de 10 dias. As análises ocorreram a cada 48 horas. Células sésseis de A.hydrophila e S. aureus foram enumeradas através do plaqueamento seletivo em ágar m-Aeromonas selective e Baird-Parker, respectivamente. Estudos sobre o tempo de geração, enumeração de células planctônicas e observação dos cupons através da microscopia eletrônica de varredura foram conduzidos. S. aureus, em monocultivo, formou biofilme a 18 °C e a 7 °C. Para 4 °C, foi observado um processo de adesão. A presença de A. hydrophila reduziu o desempenho de S. aureus. Nesta condição de cultivo multiespécie houve formação de biofilme a 18 °C. A. hydrophila, tanto em monocultivo quanto em presença de S. aureus, formou biofilme em todas as condições pesquisadas.

Effectiveness of cleaning and sanitizing procedures in controlling the adherence of Pseudomonas fluorescens, Salmonella Enteritidis, and Staphylococcus aureus to domestic kitchen surfaces

The effectiveness of cleaning and sanitizing procedures in controlling Staphylococcus aureus, Salmonella Enteritidis, and Pseudomonasfluorescens adhered to granite and stainless steel was evaluated. There was no significant difference (p > 0.05) in the adherence of pure cultures of these microorganisms to stainless steel. The numbers of P. fluorescens and S. Enteritidis adhered to granite were greater (p < 0.05) than the numbers of S. aureus. Additionally, the adherence of P. fluorescens was similar to the adherence of S. Enteritidis on granite surface. In a mixed culture with P. fluorescens, S aureus adhered less (p < 0.05) to stainless steel surfaces (1.31 log CFU.cm-2) than when in a pure culture (6.10 log CFU.cm-2). These results suggest that P. fluorescens inhibited the adherence of S. aureus. However, this inhibition was not observed in the adherence process for granite. There was a significant difference (p < 0.05) between the number of adhered cells before and after pre-washing for S. aureus on stainless steel and granite surfaces, and after washing with detergent for all microorganisms and surfaces. The efficiency of the cleaning plus sanitizing procedures was not significantly different (p > 0.05) between the surfaces. However, a significant difference was observed (p < 0.05) between the sanitizer solutions. Sodium hypochlorite and peracetic acid were more bactericidal (p < 0.05) than a quaternary ammonium compound. With regard to microorganisms, S. aureus was the least resistant to the sanitizers. These results show the importance of good cleaning and sanitization procedures to prevent bacterial adherence and biofilm formation.

Standardization of a multiplex PCR for the identification of coagulase-positive Staphylococcus

The enterotoxigenic species Staphylococcus aureus, S. hyicus and S. intermedius show very similar characteristics, making their identification through conventional microbiological methods difficult. This study aimed at the development of a Multiplex PCR (mPCR) for the identification of S. aureus, S. intermedius and S. hyicus using the nuc gene as the target sequence. The results obtained suggest that the set of primers used was specific for the three species of Staphylococcus evaluate with a detection limit of 10² CFU.mL-1.

Enterotoxigenic potential of Staphylococcus aureus isolated from Artisan Minas cheese from the Serra da Canastra - MG, Brazil

This study aimed to evaluate the presence of enterotoxigenic S. aureus in the endogenous starter and in Artisan Minas cheeses from the Serra da Canastra. Sixteen samples of endogenous starters and cheese were collected during the rainy and dry seasons. The isolation and enumeration of S. aureus were performed using the PetrifilmTM-Rapid S. aureus Plate Count method. The presence of enterotoxin in the cheese samples was analyzed by the Optimal Sensitivity Plate (OSP) method and the ELFA-VIDAS®-Staph enterotoxin-II assay. S. aureus strains were tested for their ability to produce enterotoxins using the Optimal Sensitivity Plate (OSP) method and the polymerase chain reaction (PCR) assay for the classical enterotoxin genes. The Optimal Sensitivity Plate (OSP) method data showed that staphylococcal enterotoxin A (SEA) was detected in 75% of the cheese samples, but no toxin was detected with the ELFA-VIDAS method. It was found that 12.5% of the isolated strains produced staphylococcal enterotoxin A (SEA) and staphylococcal enterotoxin C (SEC). When using the the polymerase chain reaction (PCR) assay, only one isolate was found to harbor an enterotoxin gene, contrary our expectations. However, discrepancies between the immunological and molecular assays are not uncommon. Despite the fact that most isolates did not produce classical enterotoxins, high S. aureus counts in the cheese samples causes concern since there is a risk of the presence of non-classical enterotoxins.

Detection of exopolysaccharide production and biofilm-related genes in Staphylococcus spp. isolated from a poultry processing plant

Staphylococcus spp. can survive in biofilms for long periods of time, and they can be transferred from one point to another and cause environmental contamination in food processing. The aim of this study was to detect Staphylococcus strains isolated from a poultry processing plant by the presence of adhesion genes and the phenotypic production of exopolysaccharide. In the present study, the production of exopolysaccharide and the presence of adhesion genes in 65 strains of Staphylococcus spp. were evaluated. All strains of Staphylococcus spp. produced exopolysaccharide, as confirmed by formation of black and opaque colonies in Congo Red Agar. The variation of sucrose content was critical for the production of exopolysaccharide in Congo Red Agar since at low sucrose concentrations all strains presented a characteristic result, i.e., there was no exopolysaccharide production. The atl gene was found in all strains, and the icaA and icaD genes were found in 97% of them. The data obtained suggest that Staphylococcus spp. isolated from the poultry processing plant evaluated has a potential for biofilm formation. An efficient control of this microorganism in food processing environment is necessary as they may represent a potential risk to consumers.

Inactivation of Staphylococcus aureus in raw salmon with supercritical CO2 using experimental design

Abstract Considering the microbial safety of consumption of raw foods (Asian food), this study aimed to explore the inactivation S. aureus in raw salmon by supercritical CO2 treatment (SC-CO2). For this purpose, experimental design methodology was employed as a tool to evaluate the effects of pressure (120-220 bar), the depressurization rate (10 to 100 bar.min–1) and the salmon:CO2 mass relation (1:0.2 to 1:1.0). It was observed that the pressure and the depressurization rate was statistically significant, i.e. the higher the system pressure and depressurization rate, the greater the microbial inactivation. The salmon: CO2 mass relation did not influence the S. aureus inactivation in raw salmon. There was a total reduction in S. aureus with 225 bar, a depressurizing rate of 100 bar.min–1, a salmon: CO2 mass relation of 1:0.6, for 2 hours at 33 °C.

Estudio molecular del gen de la prolactina en el gato doméstico (Felis catus)

Tesis (Maestría en Ciencias con Especialidad en Biología Molecular e Ingeniería Genética) UANL

Estado actual de la rabia, cobertura y porcentaje de vacunación antirrábica en perros Canis familiaris (L.) 1758 y gatos felis catus (L.)1758, durante 1997 y 1998, en el área limítrofe de la zona metropolitana de Monterrey, Nuevo León, México

Tesis (Maestría en Ciencias con Especialidad en Manejo de Vida Silvestre) UANL

Estudio de los genes relacionados a prolactina en el gato doméstico(Felis catus)

Tesis (Maestría en Ciencias con Especialidad en Biología Molecular e Ingeniería Genética) UANL

Elección de las condiciones más adecuadas para la obtención de extractos de plantas superiores con actividad sobre una cepa de Staphylococcus aureus resistente

Tesis (Maestría en Ciencias con Orientación Terminal en Química Biomédica) UANL

Obtención de enterotoxinas B y C de Staphylococcus aureus e implentación de técnicas inmunoenzimáticas para su detección en productos lácteos

Tesis (Maestría en Ciencias con Especialidad en Microbiología Médica) U.A.N.L.

Estudio sobre el efecto de diferentes concentraciones de alcoholes primarios sobre la viabilidad de Staphylococcus aureus y escherichia coli y la integridad de sus respectivos esferoplastos

Tesis de María Alicia Suárez Semour (Maestro en Ciencias con especialidad en Microbiología Médica) U.A.N.L.

Caracterización del casete cromosómico estafilocócico mec de staphylococcus hominis.

Tesis (Maestría en Ciencias con Especialidad en Microbiología Médica) UANL, 2012.

Activación del macrófago por Escherichia coli y Staphylococcus aureus bajo la influencia del zinc

Tesis (Doctorado en Ciencias con Especialidad en Inmunología) UANL