Horizontal transfer of plasmids encoding antimicrobial-resistance and virulence determinants has been instrumental in Staphylococcus aureus evolution, including the emergence of community-associated methicillin-resistant S. aureus (CA-MRSA). In the early 1990s the first CA-MRSA isolated in Western Australia (WA), WA-5, encoded cadmium, tetracycline and penicillin-resistance genes on plasmid pWBG753 (~30 kb). WA-5 and pWBG753 appeared only briefly in WA, however, fusidic-acid-resistance plasmids related to pWBG753 were also present in the first European CA-MRSA at the time. Here we characterized a 72-kb conjugative plasmid pWBG731 present in multiresistant WA-5-like clones from the same period. pWBG731 was a cointegrant formed from pWBG753 and a…
The antimicrobial resistance (AMR) crisis represents a serious threat to public health and has resulted in concentrated efforts to accelerate development of rapid molecular diagnostics for AMR. In combination with publicly-available web-based AMR databases, whole genome sequencing (WGS) offers the capacity for rapid detection of antibiotic resistance genes. Here we studied the concordance between WGS-based resistance prediction and phenotypic susceptibility testing results for methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin resistant Enterococcus (VRE) clinical isolates using publicly-available tools and databases.Clinical isolates prospectively collected at the University of Pittsburgh Medical Center between December 2016 and December 2017 underwent WGS. Antibiotic resistance gene…
The evolution and global transmission of antimicrobial resistance has been well documented in Gram-negative bacteria and healthcare-associated epidemic pathogens, often emerging from regions with heavy antimicrobial use. However, the degree to which similar processes occur with Gram-positive bacteria in the community setting is less well understood. Here, we trace the recent origins and global spread of a multidrug resistant, community-associated Staphylococcus aureus lineage from the Indian subcontinent, the Bengal Bay clone (ST772). We generated whole genome sequence data of 340 isolates from 14 countries, including the first isolates from Bangladesh and India, to reconstruct the evolutionary history and genomic epidemiology…
The hospital-acquired methicillin-resistant Staphylococcus aureus (HA-MRSA) strain WCUH29 has been intensively and widely used as a model system for identification and evaluation of novel antibacterial targets and pathogenicity. In this announcement, we report the complete genome sequence of HA-MRSA WCUH29 (NCIMB 40771).Copyright © 2019 Lei et al.
USA300 is a predominant community-associated methicillin-resistant Staphylococcus aureus strain causing significant morbidity and mortality in North America. We present the full annotated genome sequences of two methicillin-resistant Staphylococcus aureus isolates related to the USA300 pulsotype with the goal of studying the evolutionary relationships of this highly successful strain type.Copyright © 2019 McClure and Zhang.
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.
Staphylococcus aureus is a significant human pathogen whose evolution and adaptation have been shaped in part by mobile genetic elements (MGEs), facilitating the global spread of extensive antimicrobial resistance. However, our understanding of the evolutionary dynamics surrounding MGEs, in particular, how changes in the structure of multidrug resistance (MDR) plasmids may influence important staphylococcal phenotypes, is incomplete. Here, we undertook a population and functional genomics study of 212 methicillin-resistant S. aureus (MRSA) sequence type 239 (ST239) isolates collected over 32?years to explore the evolution of the pSK1 family of MDR plasmids, illustrating how these plasmids have coevolved with and contributed…
Bacteriophages, viruses that only kill specific bacteria, are receiving substantial attention as nontraditional antibacterial agents that may help alleviate the growing antibiotic resistance problem in medicine. We describe the design and preclinical development of AB-SA01, a fixed-composition bacteriophage product intended to treat Staphylococcus aureus infections. AB-SA01 contains three naturally occurring, obligately lytic myoviruses related to Staphylococcus phage K. AB-SA01 component phages have been sequenced and contain no identifiable bacterial virulence or antibiotic resistance genes. In vitro, AB-SA01 killed 94.5% of 401 clinical Staphylococcus aureus isolates, including methicillin-resistant and vancomycin-intermediate ones for a total of 95% of the 205 known multidrug-resistant…
Severe community-acquired pneumonia (CAP) caused by methicillin-resistant Staphylococcus aureus (MRSA) is relatively rare and is usually associated with rapid progression to death. Here, we report the complete genome sequence of the MRSA strain JMUB3031, which was isolated from a patient with fatal CAP.
Bacteria harboring conjugative plasmids have the potential for spreading antibiotic resistance through horizontal gene transfer. It is described that the selection and dissemination of antibiotic resistance is enhanced by stressors, like metals or antibiotics, which can occur as environmental contaminants. This study aimed at unveiling the composition of the conjugative plasmidome of a hospital effluent multidrug resistant Escherichia coli strain (H1FC54) under different mating conditions. To meet this objective, plasmid pulsed field gel electrophoresis, optical mapping analyses and DNA sequencing were used in combination with phenotype analysis. Strain H1FC54 was observed to harbor five plasmids, three of which were conjugative…
The past two decades have witnessed an alarming expansion of staphylococcal disease caused by community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA). The factors underlying the epidemic expansion of CA-MRSA lineages such as USA300, the predominant CA-MRSA clone in the United States, are largely unknown. Previously described virulence and antimicrobial resistance genes that promote the dissemination of CA-MRSA are carried by mobile genetic elements, including phages and plasmids. Here, we used high-resolution genomics and experimental infections to characterize the evolution of a USA300 variant plaguing a patient population at increased risk of infection to understand the mechanisms underlying the emergence of genetic elements…
Acidovorax citrulli is the causal agent of bacterial fruit blotch (BFB), a serious threat to cucurbit crop production worldwide. Based on genetic and phenotypic properties, A. citrulli strains are divided into two major groups: group I strains have been generally isolated from melon and other non-watermelon cucurbits, while group II strains are closely associated with watermelon. In a previous study, we reported the genome of the group I model strain, M6. At that time, the M6 genome was sequenced by MiSeq Illumina technology, with reads assembled into 139 contigs. Here, we report the assembly of the M6 genome following sequencing…
The aim of this work was to assess a novel pseudo-staphylococcal cassette chromosome mec (?SCCmec) element in methicillin-resistant Staphylococcus aureus (MRSA) blood isolates. Community-associated MRSA E16SA093 and healthcare-associated MRSA F17SA003 isolates were recovered from the blood specimens of patients with S. aureus bacteremia in 2016 and in 2017, respectively. Antimicrobial susceptibility was determined via the disk diffusion method, and SCCmec typing was conducted by multiplex polymerase chain reaction. Whole genome sequencing was carried out by single molecule real-time long-read sequencing. Both isolates belonged to sequence type 72 and agr-type I, and they were negative for Panton-Valentine leukocidin and toxic shock…
Methicillin-resistant Staphylococcus aureus (MRSA) may cause potentially lethal infections. Increasing evidence suggests that the gut microbiota is associated with human health. Yet, whether patients with MRSA infections carry specific signatures in their fecal microbiota composition has not been determined. Thus, this study aimed to compare the fecal microbiota profile of MRSA-positive patients (n=15) with individuals without MRSA infection (n=15) by using the PacBio single molecule, real-time (SMRT) DNA sequencing system and real-time quantitative polymerase chain reaction (qPCR). Mann-Whitney tests and unweighted UniFrac principal coordinate analysis (PCoA) showed that the profile of fecal microbiota was apparently different between the two populations.…
Acquisition of genes through horizontal gene transfer (HGT) allows microbes to rapidly gain new capabilities and adapt to new or changing environments. Identifying widespread HGT regions within multispecies microbiomes can pinpoint the molecular mechanisms that play key roles in microbiome assembly. We sought to identify horizontally transferred genes within a model microbiome, the cheese rind. Comparing 31 newly sequenced and 134 previously sequenced bacterial isolates from cheese rinds, we identified over 200 putative horizontally transferred genomic regions containing 4733 protein coding genes. The largest of these regions are enriched for genes involved in siderophore acquisition, and are widely distributed in…