Search

A quantitative microbial risk assessment was conducted to assess the health risks associated with the exposure of agricultural workers to tertiary treated wastewater in irrigated fields through soil ingestion in Cyprus. Three pathogenic microorganisms were chosen, particularly E. coli (bacteria), rotavirus (viruses) and Cryptosporidium. Two extreme exposure scenarios were investigated. Monte Carlo simulations were performed using input data from literature, and the model outputs were compared to the health standards of the World Health Organization (WHO). The results suggested that additional treatment is required for all pathogens to satisfy the health standards. Sensitivity analysis identified the source concentration and pathogen reduction due to soil aquifer passage as the most influential factors in the model outputs. Additional computations were performed to evaluate the minimum pathogen reduction due to soil aquifer passage so that the health targets are achieved for the 95 % of the output values. Rotavirus and Cryptosporidium were found to require more treatment than E. coli. The inclusion of these reference pathogens to the monitoring network of the local authorities is recommended, and the role of soil aquifer passage is emphasized on reducing the concentration of the contaminants. [ABSTRACT FROM AUTHOR]

The type III secretion injectisome is a complex nanomachine that allows bacteria to deliver protein effectors across eukaryotic cellular membranes. In recent years, significant progress has been made in our understanding of its structure, assembly and mode of operation. The principal structural components of the injectisome, from the base located in the bacterial cytosol to the tip of the needle protruding from the cell surface, have been investigated in detail. The structures of several constituent proteins were solved at the atomic level and important insights into the assembly process have been gained. However, despite the ongoing concerted efforts of molecular and structural biologists, the role of many of the constituent components of this nanomachine remain unknown. [ABSTRACT FROM AUTHOR]

RpoS, the alternative sigma factor σs, is important for bacterial survival under extreme conditions. Many enterobacteria are opportunistic human pathogens and their ability to survive in a changing environment could be an essential step for their virulence. To determine the presence of this gene in enteric bacteria, an Escherichia coli rpoS probe was constructed and used to detect the presence of this gene in different species. A gene homologous to rpoS was found in Citrobacter amalonaticus, Enterobacter cloacae, Klebsiella planticola, Kluyvera cryocrescens, Serratia rubidaea, Shigella sonnei, and Yersinia ruckeri. Providencia stuartii and Proteus vulgaris were the only tested enterobacteria that did not show any signal with the E. coli rpoS probe or that did not lead to amplification of an rpoS fragment using specific primers. The rpoS gene from E. cloacae and from K. cryocrescens was cloned and sequenced and a mutant allele was constructed in E. cloacae. Survival rates under different harsh conditions were followed in order to determine the effect of rpoS inactivation in exponential- and stationary-phase cells of both strains. E. cloacae rpoS mutants were more sensitive to extreme pH, high osmolarity, and high temperature than the wild-type. [ABSTRACT FROM AUTHOR]

Several bacterial pathogens make use of a specialized protein secretion system to inject effector proteins into host cells. This system, commonly referred to as type III secretion, is always associated with phenotypes related to intimate interactions between the pathogen and its respective host cells. The enteric pathogen Salmonella typhimurium utilizes a type III secretion system to invade nonphagocytic intestinal epithelial cells. Whereas the invasion-associated type III system of S. typhimurium has evolved to perform a specific function, many of the components of this system are conserved among the type III systems of other bacterial pathogens. This review will discuss the common and unique features of the S. typhimurium system in relation to the type III systems of other human pathogens. Topics discussed include the phenotypes associated with various type III systems, the genetic loci encoding these systems, the components of the type III secretion apparatus, the effector proteins and the mechanisms by which they enter host cells as well as the mechanisms used to regulate the expression of type III systems. [ABSTRACT FROM AUTHOR]

For communities in developing countries, the majority of drinking water-related issues are due to pathogens from poor sanitation, resulting in infection and diarrhea. One cause of this is that these communities often do not have access to centralized water treatment facilities. Point-of-use (POU) systems are key solutions for treating water in developing communities; they are typically user-friendly, low cost, low maintenance, and grid-independent. Importantly, they treat and reduce the number of pathogens in water supplies, and many POU systems have been deployed and used by these communities, improving their livelihood. This review focuses on POU systems that cater to households or communities, with the aim to examine and evaluate technologies that have been implemented in POU systems in the past decade. [ABSTRACT FROM AUTHOR]

This article focuses on molecular virulence attributes and occurrence of pYV-bearing strains among human clinical isolates of Yersinia enterocolitica in Poland. Yersinia enterocolitica includes both pathogenic and nonpathogenic strains. Strains implicated in human disease harbor the virulence-associated plasmid 70-75 kbp known as pYV and exhibit a distinctive phenotype that is characterized by dependence on calcium ions for growth at 37 degree centigrade and an affinity for Congo red dye. Studies suggest that assays detecting the pYV-associated phenotype may be considered a useful tool for virulence screening in the clinical laboratory.