Salmonella enterica Serotype Typhi with Nonclassical Quinolone Resistance Phenotype

We report Salmonella enterica serotype Typhi strains with a nonclassical quinolone resistance phenotype (i.e., decreased susceptibility to ciprofloxacin but with susceptibility to nalidixic acid) associated with a nonsynonymous mutation at codon 464 of the gyrB gene. These strains, not detected by the nalidixic acid disk screening test, can result in fluoroquinolone treatment failure

CRISPR Typing and Subtyping for Improved Laboratory Surveillance of Salmonella Infections

Laboratory surveillance systems for salmonellosis should ideally be based on the rapid serotyping and subtyping of isolates. However, current typing methods are limited in both speed and precision. Using 783 strains and isolates belonging to 130 serotypes, we show here that a new family of DNA repeats named CRISPR (clustered regularly interspaced short palindromic repeats) is highly polymorphic in Salmonella. We found that CRISPR polymorphism was strongly correlated with both serotype and multilocus sequence type. Furthermore, spacer microevolution discriminated between subtypes within prevalent serotypes, making it possible to carry out typing and subtyping in a single step. We developed a high-throughput subtyping assay for the most prevalent serotype, Typhimurium. An open web-accessible database was set up, providing a serotype/spacer dictionary and an international tool for strain tracking based on this innovative, powerful typing and subtyping tool

Foodborne Outbreak and Nonmotile Salmonella enterica Variant, France

We report a food-related outbreak of salmonellosis in humans caused by a nonmotile variant of Salmonella enterica serotype Typhimurium in France in 2009. This nonmotile variant had been circulating in laying hens but was not considered as Typhimurium and consequently escaped European poultry flock regulations

Primers used for the spacer content inventory.

1<p>Degenerate positions: R = G or A; Y = T or C; M = A or C; K = G or T; D = G or A or T; B = G or T or C.</p>2<p>AE006468, serotype Typhimurium LT2 strain; AE014613, serotype Typhi Ty2 strain.</p>3<p>The primer pairs used for CRISPR1 amplification for each of the 744 strains are indicated in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0036995#pone.0036995.s004" target="_blank">Table S2</a>.</p

CRISPR1 spacer content in various O:9 and O:2 serotypes.

1<p>ST (sequence type) 11 group consists of ST11 and its single-locus variants (SLV).</p>2<p>Includes the 5 ST136 “Danysz”» strains used as rodenticides.</p>3<p>Ent20−//−Ent35, 15 unique spacers are located between Ent20 and Ent35 (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0036995#pone.0036995.s004" target="_blank">Table S2</a>).</p>4<p>Serotype Gallinarum biovar Duisburg is different from serotype Duisburg.</p

CRISPR sizing by PCR for the rapid comparison of <i>Salmonella</i> spp isolates.

<p>Results of PCR amplification for 8 <i>S. enterica</i> serotype Typhimurium isolates collected from the same city during a single week (cluster E in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0036995#pone.0036995.s009" target="_blank">Table S7</a>). Three cases were from the same food poisoning cluster (the food isolate was also tested), whereas the other cases were unrelated.</p