Moore, E. R. B. | Search bioRxiv

bioRxiv2022

Responses of carbapenemase-producing and non-producing carbapenem-resistant Pseudomonas aeruginosa strains to meropenem revealed by quantitative tandem mass spectrometry proteomics

Pseudomonas aeruginosa is an opportunistic pathogen with increasing incidence of multidrug-resistant strains, including resistance to last-resort antibiotics, such as carbapenems. Resistances are often due to complex interplays of naturally and acquired resistance mechanisms that are enhanced by its remarkably large regulatory network. This study describes the proteomic responses of two carbapenem-resistant P. aeruginosa strains of high-risk clones ST235 and ST395 to subminimal inhibitory concentrations (sub-MICs) of meropenem by identifying differentially expressed proteins and pathways. Strain CCUG 51971, carries a VIM-4 metallo-{beta}-lactamase or classical carbapenemase, and strain CCUG 70744 carries no known acquired carbapenem-resistance genes and exhibits non-classical carbapenem-resistance. Each strain was cultivated with different sub-MICs of meropenem, and analyzed, using quantitative shotgun proteomics, based on tandem mass tag (TMT) isobaric labeling followed by nano-liquid chromatography tandem-mass spectrometry. Exposure of both strains to sub-MICs meropenem resulted in hundreds of differentially expressed proteins, including {beta}-lactamases, proteins associated with transport, peptidoglycan metabolism, cell wall organization, and regulatory proteins. Strain CCUG 51971 showed up-regulation of intrinsic {beta}-lactamases and VIM-4 carbapenemase, while CCUG 70744 exhibited a combination of up-regulated intrinsic {beta}-lactamases, efflux pumps, penicillin-binding proteins and down-regulation of porins. All components of the H1 type VI secretion system were up-regulated in strain CCUG 51971. Enrichment analyses revealed multiple metabolic pathways affected in both strains. Sub-MICs of meropenem cause marked changes in the proteomes of carbapenem-resistant strains of P. aeruginosa exhibiting different resistance mechanisms, involving a wide range of proteins, many uncharacterized, which might play a role in the susceptibility of P. aeruginosa to meropenem.

microbiology↗

bioRxiv2020

First complete genome sequences of Streptococcus pyogenes NCTC 8198T and CCUG 4207T, the type strain of the type species of the genus Streptococcus: 100% match in length and sequence identity between PacBio solo and Illumina plus Oxford Nanopore hybrid assemblies

We present the first complete, closed genome sequences of Streptococcus pyogenes strains NCTC 8198T and CCUG 4207T, the type strain of the type species of the genus Streptococcus and an important human pathogen that causes a wide range of infectious diseases. S. pyogenes NCTC 8198T and CCUG 4207T are derived from deposit of the same strain at two different culture collections. NCTC 8198T was sequenced, using a PacBio platform; the genome sequence was assembled de novo, using HGAP. CCUG 4207T was sequenced and a de novo hybrid assembly was generated, using SPAdes, combining Illumina and Oxford Nanopore sequence reads. Both strategies, yielded closed genome sequences of 1,914,862 bp, identical in length and sequence identity. Combining short-read Illumina and long-read Oxford Nanopore sequence data circumvented the expected error rate of the nanopore sequencing technology, producing a genome sequence indistinguishable to the one determined with PacBio. Sequence analyses revealed five prophage regions, a CRISPR-Cas system, numerous virulence factors and no relevant antibiotic resistance genes. These two complete genome sequences of the type strain of S. pyogenes will effectively serve as valuable taxonomic and genomic references for infectious disease diagnostics, as well as references for future studies and applications within the genus Streptococcus.

microbiology↗