Correction to: Genome analysis of Salmonella enterica subsp. diarizonae isolates from invasive human infections reveals enrichment of virulence-related functions in lineage ST1256

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Genome analysis of Salmonella enterica subsp. diarizonae isolates from invasive human infections reveals enrichment of virulence-related functions in lineage ST1256

Abstract Background Salmonella enterica subsp. diarizonae (IIIb) is frequently isolated from the environment, cold-blooded reptiles, sheep and humans; however only a few studies describe the isolation of this subspecies from invasive human infections. The factors contributing to this unusual behavior are currently unknown. Results We report here the genome features of two diarizonae strains, SBO13 and SBO27, isolated from endocervical tissue collected post-abortion and from cerebrospinal fluid of a newborn child, respectively, in the city of Santa Cruz, Bolivia. Although isolated six years apart, SBO27 in 2008 and SBO13 in 2014, both strains belong to the same sequence type 1256 (ST1256) and show a high degree of genome conservation sharing more than 99% of their genes, including the conservation of a ~ 10 kb plasmid. A prominent feature of the two genomes is the presence of 24 genomic islands (GIs), in addition to 10 complete Salmonella pathogenicity islands (SPI) and fragments of SPI-7, a pathogenicity island first reported in the human-adapted serovar Typhi. Some of the GIs identified in SBO13 and SBO27 harbor genes putatively encoding auto-transporters involved in adhesion, lipopolysaccharide modifying enzymes, putative toxins, pili-related proteins, efflux pumps, and several putative membrane cation transport related-genes, among others. These two Bolivian isolates also share genes encoding the type-III secretion system effector proteins SseK2, SseK3 and SlrP with other diarizonae sequence types (ST) mainly-associated with infections in humans. The sseK2, sseK3 and slrP genes were either absent or showing frameshift mutations in a significant proportion of genomes from environmental diarizonae isolates. Conclusions The comparative genomic study of two diarizonae strains isolated in Bolivia from human patients uncovered the presence of many genes putatively related to virulence. The statistically-significant acquisition of a unique combination of these functions by diarizonae strains isolated from humans may have impacted the ability of these isolates to successfully infect the human host

Additional file 2: of Genome analysis of Salmonella enterica subsp. diarizonae isolates from invasive human infections reveals enrichment of virulence-related functions in lineage ST1256

Table S2. Genes related to antibiotic resistance found in S. enterica subsp. diarizonae strains SBO13 and SBO27. (PDF 1179 kb

PCR typing of representative blood isolates from Lima hospitals using different gene markers.

<p>A) The <i>gyrA-</i>IS200-<i>rcsC</i> amplification distinguishes serovar Typhi from other serovars. B) and C) The <i>spvC</i> and <i>spvRA</i> markers detect the virulence plasmid (pSV). D) <i>traC</i> is a marker for the megaplasmid of Infantis (pESI). E) Plasmid profiles of the same strains. The asterisks below the bands in the plasmid profiles indicate the plasmid suspected to be the pSV. Tm, Typhimurium; E, Enteritidis; Ch, Choleraesuis; Ty, Typhi; PA, Paratyphi A; PB, Paratyphi B; and I, Infantis.</p

Characterization of <i>Salmonella enterica</i> isolates causing bacteremia in Lima, Peru.

<p>Characterization of <i>Salmonella enterica</i> isolates causing bacteremia in Lima, Peru.</p

Characterization of <i>Salmonella enterica</i> isolates causing bacteremia in Lima, Peru, using multiple typing methods

<div><p>In this study, different molecular typing tools were applied to characterize 95 <i>Salmonella enterica</i> blood isolates collected between 2008 and 2013 from patients at nine public hospitals in Lima, Peru. Combined results of multiplex PCR serotyping, two- and seven-loci multilocus sequence typing (MLST) schemes, serotyping, IS200 amplification and RAPD fingerprints, showed that these infections were caused by eight different serovars: Enteritidis, Typhimurium, Typhi, Choleraesuis, Dublin, Paratyphi A, Paratyphi B and Infantis. Among these, Enteritidis, Typhimurium and Typhi were the most prevalent, representing 45, 36 and 11% of the isolates, respectively. Most isolates (74%) were not resistant to ten primarily used antimicrobial drugs; however, 37% of the strains showed intermediate susceptibility to ciprofloxacin (ISC). Antimicrobial resistance integrons were carried by one Dublin (<i>dfra1</i> and <i>aadA1</i>) and two Infantis (<i>aadA1</i>) isolates. The two Infantis isolates were multidrug resistant and harbored a large megaplasmid. Amplification of <i>spvC</i> and <i>spvRA</i> regions showed that all Enteritidis (n = 42), Typhimurium (n = 34), Choleraesuis (n = 3) and Dublin (n = 1) isolates carried the <i>Salmonella</i> virulence plasmid (pSV). We conclude that the classic serotyping method can be substituted by the multiplex PCR and, when necessary, sequencing of only one or two loci of the MLST scheme is a valuable tool to confirm the results. The effectiveness and feasibility of different typing tools is discussed.</p></div

Multilocus sequence typing of 18 selected <i>Salmonella</i> isolates from Lima, Peru^*.

<p>Multilocus sequence typing of 18 selected <i>Salmonella</i> isolates from Lima, Peru^{<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0189946#t002fn001" target="_blank">*</a>}.</p