Longitudinal fluctuations of common antimicrobial resistance genes in the gut microbiomes of healthy Dutch individuals.

The human gut microbiome is an important reservoir of antimicrobial resistance genes (ARGs), collectively termed the 'resistome'. To date, few studies have examined the dynamics of the human gut resistome in healthy individuals. Previously, the authors observed high rates of ARG acquisition and significant abundance shifts during international travel.

Infections with the SARS-CoV-2 Delta variant exhibit fourfold increased viral loads in the upper airways compared to Alpha or non-variants of concern.

There has been a growing body of evidence that the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Delta variant (B.1.617.

Supplementing SARS-CoV-2 genomic surveillance with PCR-based variant detection for real-time actionable information, the Netherlands, June to July 2021.

We evaluated routine testing with SARS-CoV-2 Delta variant-specific RT-PCR in regional hospital laboratories in addition to centralised national genomic surveillance in the Netherlands during June and July 2021. The increase of the Delta variant detected by RT-PCR correlated well with data from genomic surveillance and was available ca 2 weeks earlier. This rapid identification of the relative abundance and increase of SARS-CoV-2 variants of concern may have important benefits for implementation of local public health measures.

Prevalence and abundance of selected genes conferring macrolide resistance genes in COPD patients during maintenance treatment with azithromycin.

Objectives: Maintenance treatment with macrolide antibiotics has shown to be effective in reducing exacerbations in COPD patients. A major concern with prolonged treatment with antibiotics is the development of bacterial resistance. In this study we determined the effect of azithromycin on the development and acquisition of resistance to macrolides in the nasopharyngeal flora in COPD patients.

Detection of the plasmid-mediated colistin-resistance gene mcr-1 in faecal metagenomes of Dutch travellers.

Background: Recently, the first plasmid-mediated colistin-resistance gene, mcr-1, was reported. Colistin is increasingly used as an antibiotic of last resort for the treatment of infections caused by carbapenem-resistant bacteria, which have been rapidly disseminating worldwide in recent years.

Objectives: The reported carriage rate of mcr-1 in humans remains sporadic thus far, except for those reported in Chinese populations.

The gut resistome is highly dynamic during the first months of life.

Aim: We investigated the longitudinal development of several antibiotic resistance genes (ARGs) of the infant gut resistome during the first months after birth.

Materials & Methods: Fecal samples from 120 infants collected at the ages of 5, 13 and 31 weeks were analyzed and subjected to qPCR for the detection of several ARGs.

Results: The prevalence of ARGs significantly increased for ermB, tetM and tetQ, while it decreased for aac(6')-aph(2').

Dissemination of Antimicrobial Resistance in Microbial Ecosystems through Horizontal Gene Transfer.

The emergence and spread of antibiotic resistance among pathogenic bacteria has been a rising problem for public health in recent decades. It is becoming increasingly recognized that not only antibiotic resistance genes (ARGs) encountered in clinical pathogens are of relevance, but rather, all pathogenic, commensal as well as environmental bacteria-and also mobile genetic elements and bacteriophages-form a reservoir of ARGs (the resistome) from which pathogenic bacteria can acquire resistance via horizontal gene transfer (HGT). HGT has caused antibiotic resistance to spread from commensal and environmental species to pathogenic ones, as has been shown for some clinically important ARGs.

Citrulline Supplementation Improves Organ Perfusion and Arginine Availability under Conditions with Enhanced Arginase Activity.

Enhanced arginase-induced arginine consumption is believed to play a key role in the pathogenesis of sickle cell disease-induced end organ failure. Enhancement of arginine availability with L-arginine supplementation exhibited less consistent results; however, L-citrulline, the precursor of L-arginine, may be a promising alternative. In this study, we determined the effects of L-citrulline compared to L-arginine supplementation on arginine-nitric oxide (NO) metabolism, arginine availability and microcirculation in a murine model with acutely-enhanced arginase activity.

High rates of antimicrobial drug resistance gene acquisition after international travel, The Netherlands.

We investigated the effect of international travel on the gut resistome of 122 healthy travelers from the Netherlands by using a targeted metagenomic approach. Our results confirm high acquisition rates of the extended-spectrum β-lactamase encoding gene blaCTX-M, documenting a rise in prevalence from 9.0% before travel to 33.

Development and validation of a single-tube multiple-locus variable number tandem repeat analysis for Klebsiella pneumoniae.

Genotyping of Klebsiella pneumoniae is indispensable for management of nosocomial infections, monitoring of emerging strains--including extended-spectrum beta-lactamase (ESBL) producers-, and general epidemiology. Such objectives require a high-resolution genotyping method with a fixed scheme that allows (1) long-term retrospective and prospective assessment, (2) objective result readout and (3) library storage for database development and exchangeable results. We have developed a multiple-locus variable number tandem repeat analysis (MLVA) using a single-tube fluorescently primed multiplex PCR for 8 Variable Number Tandem Repeats (VNTRs) and automated fragment size analysis.