Antimicrobial efficacy of chlorhexidine-treated surfaces against clinical isolates implicated in nosocomial infections

\ua9 2025 The Authors. Introduction. Bacterial infections and antimicrobial resistance are significant threats to global public health, both of which spread through contamination of solid surfaces. We have previously developed an antimicrobial surface technology that directly bonds the broad-spectrum biocide chlorhexidine to steel surfaces. These surfaces were shown to kill bacteria within minutes of contact and to be effective against bacteria evolved in the laboratory for resistance to chlorhexidine in solution. Hypothesis/Gap Statement. We hypothesized that resistance to these surfaces could exist outside of the naive and chlorhexidine-resistant laboratory strains tested previously. We also sought to test whether strains that were resistant to chlorhexidine in solution were also resistant to chlorhexidine-based antimicrobial surfaces. Aim. To test the efficacy of these surfaces against a range of bacteria isolated from the hospital environment and to compare this to the resistance of these bacteria to chlorhexidine in solution or when dissolved in solid media. Methodology. Ninety-one isolates of mixed bacterial species were obtained from Queen Elizabeth Hospital Birmingham. The isolates, along with laboratory strains of Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus, were tested for sensitivity to chlorhexidine-coated steel surfaces in a 30-min exposure simulated splash assay. Resistance to chlorhexidine in solution was also assayed by solid and broth media MIC assays. Results. We demonstrate that within 30 min of incubation, the surfaces reduced the survival of all 91 isolates. Over 85% of these isolates were killed (exhibiting a 7–8 log reduction compared with control surfaces), whilst 12% experienced a 3–4 log reduction. We also show that resistance to the surfaces did not correlate with resistance to freely diffusible chlorhexidine in liquid or solid media. Conclusion. The results demonstrate the efficacy of chlorhexidine-coated surfaces against a broad range of bacterial isolates from the hospital environment and imply the potential for a mode of exposure to dictate the effectiveness of different antimicrobial resistance mechanisms. Future studies should investigate the genetic mechanisms providing resistance to chlorhexidine-coated surfaces and whether these differ in the capacity to provide resistance to chlorhexidine in different modes of exposure

The dissemination of multidrug-resistant and hypervirulent <em>Klebsiella pneumoniae</em> clones across the Kingdom of Saudi Arabia

\ua9 2024 The Author(s). Published by Informa UK Limited, trading as Taylor &amp; Francis Group, on behalf of Shanghai Shangyixun Cultural Communication Co., Ltd.Klebsiella pneumoniae is a Gram-negative bacterium associated with a wide range of community- and hospital-acquired infections. The emergence of clonal hypervirulent strains resistant to last-resort antimicrobial agents has become a global concern. The Kingdom of Saudi Arabia (KSA), with its diverse population and high tourism traffic, serves as a platform where the spread of multidrug-resistant (MDR) strains are facilitated. However, the knowledge of epidemiology and population diversity of MDR K. pneumoniae in KSA is scarce. We conducted a comprehensive genomic survey on 352 MDR K. pneumoniae isolates systematically collected from bloodstream and urinary tract infections in 34 hospitals across 15 major cities in KSA during 2022 and 2023. Whole-genome sequencing on the isolates was performed, followed by genomic epidemiology and phylodynamic analysis. Our study revealed a dynamic population characterized by the rapid expansion of several dominant clones, including, ST2096, ST147, and ST231, which were estimated to have emerged within the past decade. These clones exhibited widespread dissemination across hospitals and were genetically linked to global strains, particularly from the Middle East and South Asia. All major clones harboured plasmid-borne ESBLs and carbapenemase genes, with plasmidome analysis identifying multiple IncH, IncA/C and IncL plasmids underlying the MDR-hypervirulent phenotype. These plasmids were shared between major clones and became acquired on the same time scales as the expansion of the dominant clones. Our results report ST2096 as an emerging MDR-hypervirulent clone, emphasizing the need for monitoring of the circulating clones and their plasmid content in the KSA and broader West Asia

Methicillin-resistant <em>Staphylococcus aureus</em> in Saudi Arabia: genomic evidence of recent clonal expansion and plasmid-driven resistance dissemination

Copyright \ua9 2025 Alhejaili, Zhou, Halawa, Huang, Fallatah, Hirayban, Iftikhar, AlAsmari, Milner, Banzhaf, Alzaidi, Rajeh, Al-Otaiby, Alabbad, Bukhari, Aljurayyan, Aljasham, Alzeyadi, Alajel, Alanazi, Alghoribi, Almutairi, Pain, Senok, Moradigaravand and Al Salem.Objectives: Staphylococcus aureus is a leading cause of hospital-acquired infections worldwide. Over recent decades, methicillin-resistant Staphylococcus aureus (MRSA), which is resistant to multiple antimicrobials, has emerged as a significant pathogenic strain in both hospital and community settings. The rapid emergence and dissemination of MRSA clones are driven by a dynamic and evolving population, spreading swiftly across regions on epidemiological time scales. Despite the vast geographical expanse and diverse demographics of the Kingdom of Saudi Arabia and the broader West Asia region, the population diversity of MRSA in hospitals in these areas remains underexplored. Methods: We conducted a large-scale genomic analysis of a systematic Staphylococcus aureus collection obtained from 34 hospitals across all provinces of KSA, from diverse body sites between 2022 and 2024. The dataset comprised 581 MRSA and 31 methicillin-susceptible Staphylococcus aureus (MSSA) isolates, all subjected to whole-genome sequencing. A combination of phylogenetic and population genomics approaches was utilized to analyze the genomic data. Hybrid sequencing approach was employed to retrieve the complete plasmid content. Results: The population displayed remarkable diversity, comprising 48 distinct sequence types (STs), with the majority harboring community-associated SCCmec loci (types IVa, V/VII, and VI). Virulence factors associated with community-acquired MRSA (CA-MRSA), including Panton-Valentine Leukocidin (PVL) genes, were identified in 12 distinct STs. Dominant clones, including ST8-t008 (USA300), ST88-t690, ST672-t3841, ST6-t304, and ST5-t311, were associated with infections at various body sites and were widely disseminated across the country. Linezolid and vancomycin resistance were mediated by cfr-carrying plasmids and mutations in the vraR gene (involved in cell-wall stress response) and the murF gene (involved in peptidoglycan biosynthesis) in five isolates, respectively. Phylodynamic analysis revealed rapid expansion of the dominant clones, with their emergence estimated to have occurred 10–20 years ago. Plasmidome analysis uncovered a diverse repertoire of blaZ-containing plasmids and the sharing of erm(C)-encoding plasmids among major clades. The acquisition of plasmids coincided with clonal expansion. Conclusions: Our results highlight the recent concurrent expansion and geographical dissemination of CA-MRSA clones across hospitals. These findings also underscore the interplay between clonal spread and horizontal gene transfer in shaping the resistance landscape of MRSA

What Is Resistance? Impact of Phenotypic versus Molecular Drug Resistance Testing on Therapy for Multi- and Extensively Drug-Resistant Tuberculosis.

Rapid and accurate drug susceptibility testing (DST) is essential for the treatment of multi- and extensively drug-resistant tuberculosis (M/XDR-TB). We compared the utility of genotypic DST assays with phenotypic DST (pDST) using Bactec 960 MGIT or Löwenstein-Jensen to construct M/XDR-TB treatment regimens for a cohort of 25 consecutive M/XDR-TB patients and 15 possible anti-TB drugs. Genotypic DST results from Cepheid GeneXpert MTB/RIF (Xpert) and line probe assays (LPAs; Hain GenoType MTBDRplus 2.0 and MTBDRsl 2.0) and whole-genome sequencing (WGS) were translated into individual algorithm-derived treatment regimens for each patient. We further analyzed if discrepancies between the various methods were due to flaws in the genotypic or phenotypic test using MIC results. Compared with pDST, the average agreement in the number of drugs prescribed in genotypic regimens ranged from just 49% (95% confidence interval [CI], 39 to 59%) for Xpert and 63% (95% CI, 56 to 70%) for LPAs to 93% (95% CI, 88 to 98%) for WGS. Only the WGS regimens did not contain any drugs to which pDST showed resistance. Importantly, MIC testing revealed that pDST likely underestimated the true rate of resistance for key drugs (rifampin, levofloxacin, moxifloxacin, and kanamycin) because critical concentrations (CCs) were too high. WGS can be used to rule in resistance even in M/XDR strains with complex resistance patterns, but pDST for some drugs is still needed to confirm susceptibility and construct the final regimens. Some CCs for pDST need to be reexamined to avoid systematic false-susceptible results in low-level resistant isolates

Supplemental data for "Whole genome sequencing reveals high-resolution epidemiological links between clinical and environmental Klebsiella pneumoniae

Data for "Whole genome sequencing reveals high-resolution epidemiological links between clinical and environmental Klebsiella pneumoniae" Authors: Chakkaphan Runcharoen*, Danesh Moradigaravand*, Elizabeth Blane, Suporn Paksanont, Jeeranan Thammachote, Suthatip Anun, Julian Parkhill, Narisara Chantratita** and Sharon J. Peacock** * Joint first author ** Joint senior author 1- List of genes in the pan-genome of 77 Klebsiella pneumoniae isolates from Thailand 2- Multiple alignment of the genes in the pan-genom

Supplementary Data for "Population structure of multidrug resistant Klebsiella oxytoca within the UK and Ireland identifies sharing of virulence and resistance genes with K. pneumoniae"

Supplemental Data for "Population structure of multidrug resistant Klebsiella oxytoca within the UK and Ireland identifies sharing of virulence and resistance genes with K. pneumoniae" Danesh Moradigaravand, Veronique Martin, Sharon J. Peacock and Julian Parkhill 1- Multi-fasta files of genes in pan-genome 2- Metadata of genes in pan-genom

Pan-genome multi-fasta files for the Serratia marcescens population study

multifasta files for the pan-genome analysis conducted in "Recent independent emergence of multiple multi-drug resistant Serratia marcescens clones within the United Kingdom and Ireland" 2016 Authors: Danesh Moradigaravand, Christine J. Boinett, Veronique Martin, Sharon J. Peacock and Julian Parkhil

Pan-genome data for the genes in "Prediction of antibiotic resistance in Escherichia coli from large-scale pan-genome data"

The pan-genome data for the paper under review. Files are in fasta format

Assembly data for newly sequenced genomes used in "Prediction of antibiotic resistance in Escherichia coli from large-scale pan-genome data"

These are 256 assembly files for the genomes sequenced for the manuscript. The file "accession.txt" contains tags and accession number