In 2013, during a routine laboratory analysis performed on food samples, one finished product from a European factory was tested positive for Salmonella Hadar. At the same period, one environmental isolate in the same laboratory was serotyped Salmonella Hadar. Prior to this event, the laboratory performed a proficiency testing involving a sample spiked with NCTC 9877 Salmonella Hadar. The concomitance of Salmonella Hadar detection led to the suspicion of a laboratory cross-contamination between the Salmonella Hadar isolate used in the laboratory proficiency testing and the Salmonella Hadar isolate found on the finished product by the same laboratory. Since the classical…
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Klebsiella pneumoniae sequence type (ST) 307 is an emerging global antimicrobial drug-resistant clone. We used whole-genome sequencing and PCR to characterize K. pneumoniae ST307 with oxacillinase (OXA) 181 carbapenemase across several private hospitals in South Africa during 2014-2016. The South Africa ST307 belonged to a different clade (clade VI) with unique genomic characteristics when compared with global ST307 (clades I-V). Bayesian evolution analysis showed that clade VI emerged around March 2013 in Gauteng Province, South Africa, and then evolved during 2014 into 2 distinct lineages. K. pneumoniae ST307 clade VI with OXA-181 disseminated over a 15-month period within 42 hospitals…
Persistence of bacterial pathogens in the airways has profound consequences on the course and pathogenesis of chronic obstructive pulmonary disease (COPD). Patients with COPD continuously acquire and clear strains of Moraxella catarrhalis, a major pathogen in COPD. Some strains are cleared quickly and some persist for months to years. The mechanism of the variability in duration of persistence is unknown. Guided by genome sequences of selected strains, we studied the expression of Hag/MID, hag/mid gene sequences, adherence to human cells, and autoaggregation in longitudinally collected strains of M. catarrhalis from adults with COPD. Twenty-eight of 30 cleared strains of M.…
Multidrug-resistant enterococcal strains emerged in the early 1980s and are now among the leading causes of drug-resistant bacterial infection worldwide. We used functional genomics to study an early bacterial outbreak in patients in a Wisconsin hospital between 1984 and 1988 that was caused by multidrug-resistant Enterococcus faecalis The goal was to determine how a clonal lineage of E. faecalis became adapted to growth and survival in the human bloodstream. Genome sequence analysis revealed a progression of increasingly fixed mutations and repeated independent occurrences of mutations in a relatively small set of genes. Repeated independent mutations suggested selection within the host…
Predominant community-associated methicillin-resistant Staphylococcus aureus strain USA300 is believed to have originated from an ancestral methicillin-susceptible strain, although the details of that evolution remain unknown. To help understand the emergence of this highly successful strain, we sequenced the genomes of two methicillin-susceptible Staphylococcus aureus clinical strains that are very closely related to USA300. Copyright © 2019 McClure and Zhang.
Salmonella enterica subsp. enterica serovar Dublin (S. Dublin) is a zoonotic pathogen that often leads to invasive bloodstream infections in humans that are multidrug resistant. Described here are the results of Canadian national surveillance of S. Dublin from 2003 - 2015 in humans and bovines, principally collected through the Canadian Integrated Program for Antibiotic Resistance Surveillance (CIPARS). An increase in human infections due to multidrug resistant (MDR) S Dublin was observed in 2010, many of which were bloodstream infections. Phylogenomic analysis of human and bovine isolates revealed a closely-related network that differed by only 0-17 single nucleotide variants (SNVs) suggesting…
Enterococcus faecalis and Enterococcus faecium are human and animal gut commensals. Vancomycin-resistant enterococci (VRE) are important opportunistic pathogens with limited treatment options. Historically, the glycopeptide antibiotics vancomycin and avoparcin selected for the emergence of vancomycin resistance in human and animal isolates respectively, resulting in global cessation of avoparcin use between 1997 and 2000. To better understand human and animal-associated VRE strains in the post-avoparcin era, we sequenced the genomes of 231 VRE isolates from New Zealand (NZ) (75 human clinical, 156 poultry) cultured between 1998 and 2009. E. faecium lineages and their antibiotic resistance carriage patterns strictly delineated between agricultural…
When choosing antibiotics to treat bacterial infections, it is assumed that the susceptibility of the target bacteria to an antibiotic is reflected by laboratory estimates of the minimum inhibitory concentration (MIC) needed to prevent bacterial growth. A caveat of using MIC data for this purpose is heteroresistance, the presence of a resistant subpopulation in a main population of susceptible cells. We investigated the prevalence and mechanisms of heteroresistance in 41 clinical isolates of the pathogens Escherichia coli, Salmonella enterica, Klebsiella pneumoniae and Acinetobacter baumannii against 28 different antibiotics. For the 766 bacteria-antibiotic combinations tested, as much as 27.4% of the…
In November 2015, plasmid-mediated transferable colistin resistance encoded by the mcr-1 gene in Escherichia coli and Klebsiella pneumonia isolates was reported in China with a high rate of in vitro horizontal transfer (10-1–10-3 cells per recipient cell by conjugation).1 At that time, the mcr-1 gene had already been identified in >30 countries across five continents, with novel mcr-2, mcr-3, mcr-4 and mcr-5 genes being reported subsequently.2–5 Recently, a surveillance study was performed on mainland China to investigate the prevalence of the mcr-1 gene in foodborne Salmonella isolates isolated from various food matrices and others collected...
Escherichia coli O157:H7 (O157) has been linked to numerous foodborne disease outbreaks. The ability to rapidly sequence and analyze genomes is important for understanding epidemiology, virulence, survival, and evolution of outbreak strains. In the current study, we performed comparative genomics to determine structural and functional features of the genome of a foodborne O157 isolate NADC 6564 and infer its evolutionary relationship to other O157 strains.The chromosome of NADC 6564 contained 5466?kb compared to reference strains Sakai (5498?kb) and EDL933 (5547?kb) and shared 41 of its 43 Linear Conserved Blocks (LCB) with the reference strains. However, 18 of 41 LCB had…
Recent adva1nces in whole genome sequencing (WGS) based technologies have facilitated multi-step applications for predicting antimicrobial resistance (AMR) and investigating the molecular epidemiology of Neisseria gonorrhoeae. However, generating full scaffolds of N. gonorrhoeae genomes from short reads, and the assignment of molecular epidemiological information (NG-MLST, NG-MAST, and NG-STAR) to multiple assembled samples, is challenging due to required manual tasks such as annotating antimicrobial resistance determinants with standard nomenclature for a large number of genomes.We present Gen2Epi, a pipeline that assembles short reads into full scaffolds and automatically assigns molecular epidemiological and AMR information to the assembled genomes. Gen2Epi is a…
Several emerging pathogens have arisen as a result of selection pressures exerted by modern healthcare. Klebsiella quasipneumoniae was recently defined as a new species, yet its prevalence, niche, and propensity to acquire antimicrobial resistance genes are not fully described. We have been tracking inter- and intra-species transmission of the Klebsiella pneumoniae carbapenemase (KPC) gene, blaKPC, between bacteria isolated from a single institution. We applied a combination of Illumina and PacBio whole-genome sequencing to identify and compare K. quasipneumoniae from patients and the hospital environment over 10 and five-year periods respectively. There were 32 blaKPC-positive K. quasipneumoniae isolates, all of which…
The genome sequence of Exophiala lecanii-corni, a melanized dimorphic fungus with the capability of degrading several volatile organic compounds, was sequenced using PacBio single-molecule real-time (SMRT) sequencing to assist with understanding the molecular basis of its uncommon morphological and metabolic characteristics. The assembled draft genome is presented here.
A diverse, antibiotic-naive microbiota prevents highly antibiotic-resistant microbes, including carbapenem-resistant Klebsiella pneumoniae (CR-Kp), from achieving dense colonization of the intestinal lumen. Antibiotic-mediated destruction of the microbiota leads to expansion of CR-Kp in the gut, markedly increasing the risk of bacteremia in vulnerable patients. While preventing dense colonization represents a rational approach to reduce intra- and interpatient dissemination of CR-Kp, little is known about pathogen-associated factors that enable dense growth and persistence in the intestinal lumen. To identify genetic factors essential for dense colonization of the gut by CR-Kp, we constructed a highly saturated transposon mutant library with >150,000 unique mutations…