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July 7, 2019

Acetylcholinesterase 1 in populations of organophosphate-resistant North American strains of the cattle tick, Rhipicephalus microplus (Acari: Ixodidae).

Rhipicephalus microplus, the cattle fever tick, is a global economic problem to the cattle industry due to direct infestation of cattle and pathogens transmitted during feeding. Cattle fever tick outbreaks continue to occur along the Mexico-US border even though the tick has been eradicated from the USA. The organophosphate (OP) coumaphos targets acetylcholinesterase (AChE) and is the approved acaricide for eradicating cattle fever tick outbreaks. There is evidence for coumaphos resistance developing in cattle ticks in Mexico, and OP-resistant R. microplus ticks were discovered in outbreak populations of Texas in 2005. The molecular basis of coumaphos resistance is not known, and our study was established to gather further information on whether AChE1 is involved in the resistance mechanism. We also sought information on allele diversity in tick populations with different levels of coumaphos resistance. The overarching project goal was to define OP resistance-associated gene mutations such that a DNA-based diagnostic assay could be developed to assist the management of resistance. Three different AChE transcripts have been reported in R. microplus, and supporting genomic and transcriptomic data are available at CattleTickBase. Here, we report the complete R. microplus AChE1 gene ascertained by sequencing a bacterial artificial chromosome clone containing the entire coding region and the flanking 5′ and 3′ regions. We also report AChE1 sequences of larval ticks from R. microplus strains having different sensitivities to OP. To accomplish this, we sequenced a 669-bp region of the AChE1 gene corresponding to a 223 amino acid region of exon 2 to assess alleles in seven strains of R. microplus with varying OP resistance phenotypes. We identified 72 AChE1 sequence variants, 2 of which are strongly associated with OP-resistant phenotypes. Esterase-like sequences from the R. microplus transcriptome RmiTr Version 1.0 were compared to the available sequence databases to identify other transcripts with similarity to AChE1.


July 7, 2019

Sequencing of plasmids pAMBL1 and pAMBL2 from Pseudomonas aeruginosa reveals a blaVIM-1 amplification causing high-level carbapenem resistance.

Carbapenemases are a major concern for the treatment of infectious diseases caused by Gram-negative bacteria. Although plasmids are responsible for the spread of resistance genes among these pathogens, there is limited information on the nature of the mobile genetic elements carrying carbapenemases in Pseudomonas aeruginosa.We combined data from two different next-generation sequencing platforms, Illumina HiSeq2000 and PacBio RSII, to obtain the complete nucleotide sequences of two blaVIM-1-carrying plasmids (pAMBL1 and pAMBL2) isolated from P. aeruginosa clinical isolates.Plasmid pAMBL1 has 26?440 bp and carries a RepA_C family replication protein. pAMBL1 is similar to plasmids pNOR-2000 and pKLC102 from P. aeruginosa and pAX22 from Achromobacter xylosoxidans, which also carry VIM-type carbapenemases. pAMBL2 is a 24?133 bp plasmid with a replication protein that belongs to the Rep_3 family. It shows a high degree of homology with a fragment of the blaVIM-1-bearing plasmid pPC9 from Pseudomonas putida. Plasmid pAMBL2 carries three copies of the blaVIM-1 cassette in an In70 class 1 integron conferring, unlike pAMBL1, high-level resistance to carbapenems.We present two new plasmids coding for VIM-1 carbapenemase from P. aeruginosa and report that the presence of three copies of blaVIM-1 in pAMBL2 produces high-level resistance to carbapenems.© The Author 2015. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.


July 7, 2019

Identification and structural characterization of naturally-occurring broad-spectrum cyclic antibiotics isolated from Paenibacillus.

The rise of antimicrobial resistance necessitates the discovery and/or production of novel antibiotics. Isolated strains of Paenibacillus alvei were previously shown to exhibit antimicrobial activity against a number of pathogens, such as E. coli, Salmonella, and methicillin-resistant Staphylococcus aureus (MRSA). The responsible antimicrobial compounds were isolated from these Paenibacillus strains and a combination of low and high resolution mass spectrometry with multiple-stage tandem mass spectrometry was used for identification. A group of closely related cyclic lipopeptides was identified, differing primarily by fatty acid chain length and one of two possible amino acid substitutions. Variation in the fatty acid length resulted in mass differences of 14 Da and yielded groups of related MS(n) spectra. Despite the inherent complexity of MS/MS spectra of cyclic compounds, straightforward analysis of these spectra was accomplished by determining differences in complementary product ion series between compounds that differ in molecular weight by 14 Da. The primary peptide sequence assignment was confirmed through genome mining; the combination of these analytical tools represents a workflow that can be used for the identification of complex antibiotics. The compounds also share amino acid sequence similarity to a previously identified broad-spectrum antibiotic isolated from Paenibacillus. The presence of such a wide distribution of related compounds produced by the same organism represents a novel class of broad-spectrum antibiotic compounds.


July 7, 2019

Whole genome sequence of Pseudomonas aeruginosa F9676, an antagonistic bacterium isolated from rice seed.

Pseudomonas aeruginosa is a group of bacteria, which can be isolated from diverse ecological niches. P. aeruginosa strain F9676 was first isolated from a rice seed sample in 2003. It showed strong antagonism against several plant pathogens. In this study, whole genome sequencing was carried out. The total genome size of F9676 is 6368,008bp with 5586 coding genes (CDS), 67 tRNAs and 3 rRNAs. The genome sequence of F9676 may shed a light on antagonism P. aeruginosa. Copyright © 2015 Elsevier B.V. All rights reserved.


July 7, 2019

Draft genome sequence of Paenibacillus polymyxa strain Mc5Re-14, an antagonistic root endophyte of Matricaria chamomilla.

Paenibacillus polymyxa strain Mc5Re-14 was isolated from the inner root tissue of Matricaria chamomilla (German chamomile). Mc5Re-14 revealed promising in vitro antagonistic activity against plant and opportunistic human pathogens. The 6.0-Mb draft genome reveals genes putatively involved in pathogen suppression and direct and indirect plant growth promotion. Copyright © 2015 Köberl et al.


July 7, 2019

Emergence of Serotype IV group B Streptococcus adult invasive disease in Manitoba and Saskatchewan, Canada, is driven by colonal sequence type 459 strains.

Serotype IV group B Streptococcus (GBS) is emerging in Canada and the United States with rates as high as 5% of the total burden of adult invasive GBS disease. To understand this emergence, we studied the population structure and assessed the antimicrobial susceptibility of serotype IV isolates causing adult invasive infection in Manitoba and Saskatchewan, Canada, between 2010 and 2014. Whole-genome sequencing was used to determine multilocus sequence typing information and identify genes encoding antimicrobial resistance in 85 invasive serotype IV GBS strains. Antimicrobial susceptibility testing was performed by standard methods. Strain divergence was assessed using genome-wide single-nucleotide polymorphism analysis. Serotype IV strains were responsible for 16.9% of adult invasive GBS infections in Manitoba and Saskatchewan during the period. The majority of serotype IV isolates (89%) were clonally related, tetracycline-, erythromycin-, and clindamycin-resistant sequence type 459 (ST459) strains that possessed genes tetM and ermTR. Genome comparisons between ST459 and serotype V ST1 GBS identified several areas of recombination in an overall similar genomic background. Serotype IV ST459 GBS strains are expanding and causing a substantial percentage of adult invasive GBS disease. This emergence may be linked to the acquisition of resistance to tetracycline, macrolides, and lincosamides. Copyright © 2015, American Society for Microbiology. All Rights Reserved.


July 7, 2019

Keeping an eye on P. aeruginosa.

This month’s Genome Watch looks at how whole-genome sequencing (WGS) can be used to track the source of Pseudomonas aeruginosa infection and to investigate the transition and adaptation of this opportunistic pathogen from the environment to the human host.


July 7, 2019

Complete genome sequence of the novel temperate Clostridium difficile phage phiCDIF1296T.

Clostridium difficile contains many integrated and extrachromosomal genetic elements. In this study, we determined, annotated, and analyzed the complete genome of the C. difficile bacteriophage phiCDIF1296T using single-molecule real-time sequencing technology. To our knowledge, this represents the largest genome (131 kb) of a temperate C. difficile phage recognized so far. Copyright © 2015 Wittmann et al.


July 7, 2019

Complete genome sequence of Acinetobacter baumannii strain B8300, which displays high twitching motility.

Acinetobacter baumannii has emerged as an important nosocomial pathogen causing health care-associated infections. In this study, we determined the genome of a twitching-positive clinical strain, B8300, isolated from a hospital in southern India. De novo assembly of PacBio long-read sequencing data generated the B8300 genome that consists of a chromosome of 3.82 Mbp and a plasmid of 25.15 kbp. Copyright © 2015 Vijaykumar et al.


July 7, 2019

First complete genome sequence of Pseudomonas aeruginosa (Schroeter 1872) Migula 1900 (DSM 50071T), determined using PacBio Single-Molecule Real-Time Technology.

The first complete genome sequence of the type strain Pseudomonas aeruginosa (Schroeter 1872) Migula 1900 (DSM 50071(T)) was determined in a single contig by PacBio RS II. The genome (6,317,050 bp, G+C content of 66.52%) contained 10 sets of >1,000-bp identical sequence pairs and 183 tandem repeats. Copyright © 2015 Nakano et al.


July 7, 2019

Complete genome sequence of Achromobacter xylosoxidans MN001, a cystic fibrosis airway isolate.

The genome of Achromobacter xylosoxidans MN001, a strain isolated from sputum derived from an adult cystic fibrosis patient, was sequenced using combined single-molecule real-time and Illumina sequencing. Assembly of the complete genome resulted in a 5,876,039-bp chromosome, representing the smallest A. xylosoxidans genome sequenced to date. Copyright © 2015 Badalamenti and Hunter.


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