Genetic makeup of Shiga toxin-producing Escherichia coli in relation to clinical symptoms and duration of shedding: a microarray analysis of isolates from Swedish children.

Shiga toxin (Stx)-producing Escherichia coli (STECs) cause non-bloody diarrhea, hemorrhagic colitis, and hemolytic uremic syndrome, and are the primary cause of acute renal failure in children worldwide. This study investigated the correlation of genetic makeup of STEC strains as revealed by DNA microarray to clinical symptoms and the duration of STEC shedding. All STEC isolated (n = 96) from patients <10 years of age in Jönköping County, Sweden from 2003 to 2015 were included. Isolates were characterized by DNA microarray, including almost 280 genes. Clinical data were collected through a questionnaire and by reviewing medical records. Of the 96 virulence genes (including stx) in the microarray, 62 genes were present in at least one isolate. Statistically significant differences in prevalence were observed for 21 genes when comparing patients with bloody diarrhea (BD) and with non-bloody stool (18 of 21 associated with BD). Most genes encode toxins (e.g., stx2 alleles, astA, toxB), adhesion factors (i.e. espB_O157, tir, eae), or secretion factors (e.g., espA, espF, espJ, etpD, nleA, nleB, nleC, tccP). Seven genes were associated with prolonged stx shedding; the presence of three genes (lpfA, senB, and stx1) and the absence of four genes (espB_O157, espF, astA, and intI1). We found STEC genes that might predict severe disease outcome already at diagnosis. This can be used to develop diagnostic tools for risk assessment of disease outcome. Furthermore, genes associated with the duration of stx shedding were detected, enabling a possible better prediction of length of STEC carriage after infection.

Outbreak of Salmonella Enteritidis phage type 13a infection in Sweden linked to imported dried-vegetable spice mixes, December 2014 to July 2015.

From 24 December to 24 July 2015, 174 cases were reported in a nationwide salmonellosis outbreak in Sweden: 108 cases were connected to a single restaurant. A spice mix, containing dried vegetables from the restaurant tested positive for the outbreak strain. Additional spice mixes with similar content from different suppliers also tested positive. The outbreak investigation suggests there could be a risk of contaminated products being also on the market in other countries.

Molecular typing of Escherichia coli O157:H7 isolates from Swedish cattle and human cases: population dynamics and virulence.

While all verotoxin-producing Escherichia coli O157:H7 bacteria are considered potential pathogens, their genetic subtypes appear to differ in their levels of virulence. The aim of this study was to compare the distribution of subtypes of E. coli O157:H7 in the cattle reservoir and in human cases with and without severe complications in order to gain clues about the relationship between subtype and relative virulence. A lineage-specific polymorphism assay (LSPA-6), multilocus variable-number tandem-repeat analysis (MLVA), and a novel real-time PCR assay to identify clade 8 were applied to a large and representative set of isolates from cattle from 1996 to 2009 (n = 381) and human cases from 2008 to 2011 (n = 197) in Sweden. Draft genome sequences were produced for four selected isolates. The E. coli O157:H7 isolates in Swedish cattle generally belonged to four groups with the LSPA-6 profiles 211111 (clade 8/non-clade 8), 213111, and 223323. The subtype composition of the cattle isolates changed dramatically during the study period with the introduction and rapid spread of the low-virulence 223323 subtype. The human cases presumed to have been infected within the country predominantly carried isolates with the profiles 211111 (clade 8) and 213111. Cases progressing to hemolytic-uremic syndrome (HUS) were mostly caused by clade 8, with MLVA profiles consistent with Swedish cattle as the source. In contrast, infections contracted abroad were caused by diverse subtypes, some of which were associated with a particular region. The work presented here confirms the high risk posed by the clade 8 variant of E. coli O157:H7. It also highlights the dynamic nature of the E. coli O157:H7 subtype composition in animal reservoirs and the importance of this composition for the human burden of disease.

Legionellosis acquired through a dental unit: a case study.

In 2012, an elderly immunocompromised man died from legionellosis at a hospital in Uppsala, Sweden. The patient had visited a dental ward at the hospital during the incubation period. Legionella spp. at a concentration of 2000 colony-forming units/L were isolated from the cupfiller outlet providing water for oral rinsing. Isolates from the patient and the dental unit were Legionella pneumophila serogroup 1, subgroup Knoxville and ST9. Pulsed-field gel electrophoresis and whole-genome sequencing strongly suggested that the isolates were of common origin. This report presents one of few documented cases of legionellosis acquired through a dental unit.

Characterization of plasmid-mediated AmpC-producing E. coli from Swedish broilers and association with human clinical isolates.

A selection of plasmid-mediated AmpC-producing Escherichia coli isolates carrying blaCMY-2 from Swedish broilers were characterized to establish their relatedness to and a possible overlap with human clinical E. coli isolates. The results showed diversity among the E. coli isolated from broilers, indicating that the spread in the population was not due to one strain. However, only one type of plasmid belonging to replicon type incK was identified. Furthermore, there were no indications of spread of blaCMY-2 E. coli isolates from broilers to human clinical settings, although Swedish broilers may be a source of blaCMY-2 and/or the plasmid carrying blaCMY-2 .

Use of green fluorescent protein and luciferase biomarkers to monitor survival and activity of Arthrobacter chlorophenolicus A6 cells during degradation of 4-chlorophenol in soil.

The recently isolated novel species Arthrobacter chlorophenolicus A6 is capable of growth on and degradation of high concentrations of 4-chlorophenol (up to 350 microg ml(-1)) as the sole carbon and energy source. This strain shows promise for bioremediation of environmental sites contaminated with high levels of chlorophenols. In this study, green fluorescent protein (gfp) or luciferase (luc) genes were used as biomarkers for monitoring cell number and activity, respectively, during degradation of 4-chlorophenol by A. chlorophenolicus cells. The individual marked strains, Arthrobacter chlorophenolicus A6L (luc-tagged) and Arthrobacter chlorophenolicus A6G (gfp-tagged), were monitored during degradation of 250 microg ml(-1) 4-chlorophenol in pure culture and 175 microg g(-1) 4-chlorophenol in soil microcosms. Both gene-tagged strains were capable of cleaning up the contaminated soil during 9 d incubation. During the bioremediation experiments, the luc-tagged cells were monitored using luminometry and the gfp-tagged cells using flow cytometry, in addition to selective plate counting for both strains. The cells remained at high population levels in the soil (evidenced by GFP-fluorescent cell counts) and the A. chlorophenolicus A6L population was metabolically active (evidenced by luciferase activity measurements). These results demonstrate that the Arthrobacter chlorophenolicus A6 inoculum is effective for cleaning-up soil containing high concentrations of 4-chlorophenol.