Legionellosis: Why should I test and report?

Amyloid hybrid membranes for bacterial & genetic material removal from water and their anti-biofouling properties

Water scarcity and contamination by biological pollutants are global challenges that significantly affect public health. Reverse osmosis, nanofiltration and ultrafiltration technologies are very effective for the elimination of pathogens and most contaminants but associated with considerable capital and operating costs, high energy consumption and the use of chlorinated chemicals to suppress membrane fouling. Additionally, the pressure needed by these techniques may disrupt the pathogenic microbial cell membranes, causing the release of genetic material (fragments of DNA, RNA and plasmids) into the water. Here, we introduce the simultaneous removal of both bacteria and associated genetic material using amyloid hybrid membranes, via a combined adsorption and size exclusion mechanism. Amyloid hybrid membranes can remove upto and beyond 99% of the genetic material by adsorption, where amyloid fibrils act as the primary adsorbing material. When the same membranes are surface-modified using chitosan, the anti-biofouling performance of the membranes improved significantly, with a bacterial removal efficiency exceeding 6 log.

Genomic characterization of a large outbreak of Legionella pneumophila serogroup 1 strains in Quebec City, 2012

During the summer of 2012, a major Legionella pneumophila serogroup 1 outbreak occurred in Quebec City, Canada, which caused 182 declared cases of Legionnaire's disease and included 13 fatalities. Legionella pneumophila serogroup 1 isolates from 23 patients as well as from 32 cooling towers located in the vicinity of the outbreak were recovered for analysis. In addition, 6 isolates from the 1996 Quebec City outbreak and 4 isolates from patients unrelated to both outbreaks were added to allow comparison. We characterized the isolates using pulsed-field gel electrophoresis, sequence-based typing, and whole genome sequencing. The comparison of patients-isolated strains to cooling tower isolates allowed the identification of the tower that was the source of the outbreak. Legionella pneumophila strain Quebec 2012 was identified as a ST-62 by sequence-based typing methodology. Two new Legionellaceae plasmids were found only in the epidemic strain. The LVH type IV secretion system was found in the 2012 outbreak isolates but not in the ones from the 1996 outbreak and only in half of the contemporary human isolates. The epidemic strains replicated more efficiently and were more cytotoxic to human macrophages than the environmental strains tested. At least four Icm/Dot effectors in the epidemic strains were absent in the environmental strains suggesting that some effectors could impact the intracellular replication in human macrophages. Sequence-based typing and pulsed-field gel electrophoresis combined with whole genome sequencing allowed the identification and the analysis of the causative strain including its likely environmental source.