Biofilm formation capacity of Salmonella serotypes at different temperature conditions / Capacidade de produção de biofilme por cepas de diferentes sorovares de Salmonella em quatro temperaturas de incubação

Salmonella spp. are one of the most important agents of foodborne disease in several countries, including Brazil. Poultry-derived products are the most common food products, including meat and eggs, involved in outbreaks of human salmonellosis. Salmonella has the capacity to form biofilms on both biotic and abiotic surfaces. The biofilm formation process depends on an interaction among bacterial cells, the attachment surface and environmental conditions. These structures favor bacterial survival in hostile environments, such as slaughterhouses and food processing plants. Biofilms are also a major problem for public health because breakage of these structures can cause the release of pathogenic microorganisms and, consequently, product contamination. The aim of this study was to determine the biofilm production capacity of Salmonella serotypes at four different temperatures of incubation. Salmonella strains belonging to 11 different serotypes, isolated from poultry or from food involved in salmonellosis outbreaks, were selected for this study. Biofilm formation was investigated under different temperature conditions (37°, 28°, 12° and 3°C) using a microtiter plate assay. The tested temperatures are important for the Salmonella life cycle and to the poultry-products process. A total of 92.2% of the analyzed strains were able to produce biofilm on at least one of the tested temperatures. In the testing, 71.6% of the strains produced biofilm at 37°C, 63% at 28°C, 52.3% at 12°C and 39.5% at 3°C, regardless of the serotype. The results indicate that there is a strong influence of temperature on biofilm production, especially for some serotypes, such as S. Enteritidis, S. Hadar and S. Heidelberg. The production of these structures is partially associated with serotype. There were also significant differences within strains of the same serotype, indicating that biofilm production capacity may be strain-dependent.(AU)

Salmonella spp. são um dos mais importantes agentes causadores de doenças transmitidas por alimentos em vários países, inclusive no Brasil. Produtos avícolas e ovos são os principais alimentos envolvidos na transmissão dos sorovares de Salmonella que são responsáveis por surtos de salmonelose em humanos. Salmonella possui a capacidade de formar biofilmes em diversas superfícies. O processo de formação de biofilme depende da interação entre as células bacterianas, a superfície de adesão e as condições do ambiente onde a bactéria se encontra. Estas estruturas favorecem a sobrevivência bacteriana em ambientes hostis, como em matadouros-frigoríficos e em indústrias processadoras de alimentos. Biofilmes são um grande problema em saúde pública, pois a ruptura destas estruturas pode provocar a liberação de microrganismos patogênicos e, consequentemente, a contaminação dos produtos. O objetivo deste estudo foi avaliar a capacidade de produção de biofilme por diferentes sorovares de Salmonella submetidos a quatro temperaturas de incubação. Cepas de Salmonella de 11 sorovares foram selecionadas. A produção de biofilme foi avaliada através do método de incubação em microplacas de poliestireno incubadas a 37°, 28°, 12° e 3°C. Estas temperaturas são importantes durante o ciclo de vida de Salmonella e para o processamento de produtos avícolas. Do total de cepas avaliadas, 92,2% foram capazes de produzir biofilme em pelo menos uma das quatro temperaturas testadas. Neste estudo, 71,6% das cepas produziram biofilme a 37°C, 63% a 28°C, 52,3% a 12°C e 39,5% a 3°C, independentemente do sorovar. Os resultados indicam uma forte influência da temperatura na produção de biofilme, especialmente para os sorovares S. Enteritidis, S. Hadar e S. Heidelberg. A produção de biofilme está parcialmente associada com o sorovar da cepa. Também foi observado que existe variação quanto à produção destas estruturas dentro de um mesmo sorovar, indicando que possivelmente a produção de biofilme é cepa-dependente.(AU)

Serotype distribution characteristics and molecular typing of Salmonella in Yunnan Province from 2015 to 2017 / 中华微生物学和免疫学杂志

Objective To study the serotype distribution characteristics and genotypes of Salmo-nella strains isolated in Yunnan Province from 2015 to 2017. Methods Automatic microbiological identifi-cation system and mass spectrometer were used to identify Salmonella strains. Their serotypes were detected using the White-Kauffmann-Le Minor (WKL) scheme based on serological detection. Genotyping was car-ried out by referring to the molecular typing method of Salmonella serotype pulse field gel electrophoresis (PFGE) in PulsenetChina. Cluster analysis was performed with Bionumerics (7.6). Results A total of 408 strains of Salmonella were detected in food and patients in Yunnan Province form 2015 to 2017,belong-ing to 70 serotypes. Thirty-four Salmonella derby strains were detected in food,accounting for 19.10% of all Salmonella strains detected in food. Among the Salmonella strains detected in patients,71 were Salmonella enteritis and 67 were Salmonella typhimurium,accounting for 30.34% and 27.63%, respectively. Results of PFGE revealed that Salmonella derby and Salmonella typhimurium were polymorphic,and Salmonella en-teritis had obvious advantages PFGE band patterns. No obvious time or geographical aggregation was found in the PFGE bands of the three Salmonella species. Conclusion Seventy Salmonella serotypes had been iden-tified in Yunnan Province by 2017. Salmonella derby was the predominant serotype detected in food, while Salmonella enteritidis and Salmonella typhimurium were the predominant serotypes in patients. These three Salmonella species caused sporadic infections in Yunnan Province.