ABSTRACT
During a large outbreak of Shiga toxin-producing Escherichia coli illness associated with an agricultural show in Australia, we used whole-genome sequencing to detect an IS1203v insertion in the Shiga toxin 2c subunit A gene of Shiga toxin-producing E. coli. Our study showed that clinical illness was mild, and hemolytic uremic syndrome was not detected.
Subject(s)
Diarrhea/epidemiology , Disease Outbreaks , Escherichia coli Infections/epidemiology , Escherichia coli O157/genetics , Genome, Bacterial , Shiga Toxin 1/genetics , Adolescent , Adult , Aged , Animals , Australia/epidemiology , Child , Child, Preschool , Contact Tracing , Diarrhea/diagnosis , Diarrhea/microbiology , Escherichia coli Infections/diagnosis , Escherichia coli Infections/microbiology , Escherichia coli O157/classification , Escherichia coli O157/isolation & purification , Escherichia coli O157/pathogenicity , Feces/microbiology , Female , Goats/microbiology , Humans , Infant , Male , Middle Aged , Serotyping , Severity of Illness Index , Sheep/microbiology , Shiga Toxin 1/classification , Shiga Toxin 1/isolation & purification , Whole Genome SequencingABSTRACT
By conducting a molecular characterization of Corynebacterium diphtheriae strains in Australia, we identified novel sequences, nonfunctional toxin genes, and 5 recent cases of toxigenic cutaneous diphtheria. These findings highlight the importance of extrapharyngeal infections for toxin gene-bearing (functional or not) and non-toxin gene-bearing C. diphtheriae strains. Continued surveillance is recommended.
Subject(s)
Corynebacterium diphtheriae/pathogenicity , Diphtheria Toxin/genetics , Diphtheria/epidemiology , Genes, Bacterial , Australia/epidemiology , Corynebacterium diphtheriae/genetics , Diphtheria/immunology , Diphtheria/microbiology , Diphtheria/prevention & control , Diphtheria Toxin/biosynthesis , Diphtheria Toxoid/administration & dosage , Epidemiological Monitoring , Humans , Lower Extremity/microbiology , Lower Extremity/pathology , Mass Vaccination , Mutation , Pharynx/microbiology , Pharynx/pathology , Skin/microbiology , Skin/pathologyABSTRACT
Escherichia coli O157 is a food-borne pathogen whose major reservoir has been identified as cattle. Recent genetic information has indicated that populations of E. coli O157 from cattle and humans can differ genetically and that this variation may have an impact on their ability to cause severe human disease. In addition, there is emerging evidence that E. coli O157 strains from different geographical regions may also be genetically divergent. To investigate the extent of this variation, we used Shiga toxin bacteriophage insertion sites (SBI), lineage-specific polymorphisms (LSPA-6), multilocus variable-number tandem-repeat analysis (MLVA), and a tir 255T>A polymorphism to examine 606 isolates representing both Australian and U.S. cattle and human populations. Both uni- and multivariate analyses of these data show a strong association between the country of origin and multilocus genotypes (P < 0.0001). In addition, our results identify factors that may play a role in virulence that also differed in isolates from each country, including the carriage of stx1 in the argW locus uniquely observed in Australian isolates and the much higher frequency of stx2-positive (also referred to as stx2a) strains in the U.S. isolates (4% of Australian isolates versus 72% of U.S. isolates). LSPA-6 lineages differed between the two continents, with the majority of Australian isolates belonging to lineage I/II (LI/II) (LI, 2%; LI/II, 85%; LII, 13%) and the majority of U.S. isolates belonging to LI (LI, 60%; LI/II, 16%; LII, 25%). The results of this study provide strong evidence of phylogeographic structuring of E. coli O157 populations, suggesting divergent evolution of enterohemorrhagic E. coli O157 in Australia and the United States.
Subject(s)
Escherichia coli O157/genetics , Genome, Bacterial , Polymorphism, Genetic , Polymorphism, Single Nucleotide , Tandem Repeat Sequences , Animals , Australia , Bacteriophages/genetics , Cattle , Cattle Diseases/epidemiology , Cattle Diseases/microbiology , DNA Transposable Elements , Escherichia coli Infections/epidemiology , Escherichia coli Infections/microbiology , Escherichia coli Infections/veterinary , Escherichia coli O157/virology , Humans , Multilocus Sequence Typing/veterinary , Phylogeography , Prevalence , Shiga Toxins/genetics , Shiga Toxins/metabolism , United StatesABSTRACT
Novel real-time TaqMan primers and probes were developed to detect the serogroup specific genes of Neisseria meningitidis serogroups B, C, W-135 and Y. These assays were rapid, sensitive, and specific when extensively validated.
Subject(s)
Bacterial Proteins/genetics , Neisseria meningitidis/isolation & purification , Real-Time Polymerase Chain Reaction/methods , Serotyping/methods , DNA Primers/genetics , Humans , Meningitis, Meningococcal/microbiology , Neisseria meningitidis/classification , Neisseria meningitidis/genetics , Sensitivity and Specificity , Species SpecificityABSTRACT
Enteropathogenic Escherichia coli (EPEC) are an important cause of diarrhoea worldwide, particularly in children. Sixty-one EPEC strains isolated from stool specimens of symptomatic persons from 2008 to 2011 were characterised for the prevalence of diarrhoea-associated putative virulence genes. Phylogenetic typing, serotyping, multilocus variable-number repeat analysis (MLVA), and multilocus sequence typing (MLST) were also performed. The EPEC isolates were highly heterogeneous, representing all 4 phylogenetic groups and comprising 59 MLVA types, 49 MLST types, and 43 serotypes. This diversity is indicative of the complexity of the human enteric EPEC population, which may be either commensal or pathogenic.
