Whole Genome Sequencing of Extended-Spectrum- and AmpC- β-Lactamase-Positive Enterobacterales Isolated From Spinach Production in Gauteng Province, South Africa

Plasmid-mediated AmpC in Klebsiella pneumoniae and Escherichia coli from septicaemic neonates: diversity, transmission and phenotypic detection

OBJECTIVES

Presence and dissemination of plasmid-mediated AmpC genes (pAmpCs) have made bacteria cephalosporin-resistant and assessment of their prevalence and diversity is essential. Coexistence of pAmpCs with New Delhi metallo-β-lactamase (blaNDM) has facilitated their spread and NDM interferes with correct pAmpC phenotypic identification.

METHODS

Assessment of pAmpCs in different species and sequence types (STs), co-transmission with blaNDM and phenotypic detection were analysed among Klebsiella pneumoniae (n = 256) and Escherichia coli (n = 92) isolated from septicaemic neonates over 13 years.

RESULTS

pAmpCs were present in 9% (30/348) of strains, 5% in K. pneumoniae and 18% in E. coli. pAmpC genes (blaCMY and blaDHA) were detected, blaCMY-42 and blaDHA-1 variants being predominant. Strains were resistant to most antimicrobials tested. blaCMY and blaDHA were dominant among E. coli (14/17) and K. pneumoniae (9/13), respectively. pAmpC-bearing strains belonged to diverse STs, including epidemic K. pneumoniae ST11 and ST147. Some strains co-harboured carbapenemase genes, blaNDM (17/30) and blaOXA-48 (5/30). In 40% (12/30) of strains, pAmpC genes were transferred by conjugation, of which 8/12 exhibited co-transfer with blaNDM. pAmpCs were frequently found in replicons as follows: blaDHA-1 with IncHIB-M, blaCMY-4 with IncA/C, blaCMY-6 with IncA/C, and blaCMY-42 with IncFII. The combination disk-diffusion test correctly detected pAmpC in 77% (23/30) of pAmpC-bearing strains. However, correct detection of pAmpC was higher in strains that did not harbour blaNDM vs. those with blaNDM (85% vs. 71%).

CONCLUSION

Presence of pAmpCs along with carbapenemases, linkage with multiple STs, and replicon types indicated their potential for spread. pAmpCs can go undetected in the presence of blaNDM; hence, regular surveillance is required.

Prevalence of extended-spectrum β-lactamase producing Enterobacterales in Africa's water-plant-food interface: A meta-analysis (2010–2022)

Background

Multidrug-resistant extended-spectrum β-lactamase (ESBL)-producing Enterobacterales is regarded as a critical health issue, yet, surveillance in the water-plant-food interface remains low, especially in Africa.

Objectives

The objective of the study was to elucidate the distribution and prevalence of antimicrobial resistance in clinically significant members of the Enterobacterales order isolated from the water-plant-food interface in Africa.

Methods

A literature search was conducted using six online databases according to the PRISMA guidelines. All available published studies involving phenotypic and genotypic characterization of ESBL-producing Enterobacterales from water, fresh produce or soil in Africa were considered eligible. Identification and characterization methods used as well as a network analysis according to the isolation source and publication year were summarized. Analysis of Escherichia coli, Salmonella spp. and Klebsiella pneumoniae included the calculation of the multiple antibiotic resistance (MAR) index according to isolation sources and statistical analysis was performed using RStudio.

Results

Overall, 51 studies were included for further investigation. Twelve African countries were represented, with environmental AMR surveillance studies predominantly conducted in South Africa. In 76.47% of the studies, occurrence of antimicrobial resistant bacteria was investigated in irrigation water samples, while 50.98% of the studies included fresh produce samples. Analysis of bacterial phenotypic antimicrobial resistance profiles were reported in 94.12% of the studies, with the disk diffusion method predominantly used. When investigating the MAR indexes of the characterized Escherichia coli, Klebsiella pneumoniae and Salmonella spp., from different sources (water, fresh produce or soil), no significant differences were seen across the countries. The only genetic determinant identified using PCR detection in all the studies was the blaCTX − M resistance gene. Only four studies used whole genome sequence analysis for molecular isolate characterization.

Discussion

Globally, AMR surveillance programmes recognize ESBL- and carbapenemase-producing Enterobacterales as vectors of great importance in AMR gene dissemination. However, in low- and middle-income countries, such as those in Africa, challenges to implementing effective and sustainable AMR surveillance programmes remain. This review emphasizes the need for improved surveillance, standardized methods and documentation of resistance gene dissemination across the farm-to-fork continuum in Africa.

MEGARes and AMR++, v3.0: an updated comprehensive database of antimicrobial resistance determinants and an improved software pipeline for classification using high-throughput sequencing

Antimicrobial resistance (AMR) is considered a critical threat to public health, and genomic/metagenomic investigations featuring high-throughput analysis of sequence data are increasingly common and important. We previously introduced MEGARes, a comprehensive AMR database with an acyclic hierarchical annotation structure that facilitates high-throughput computational analysis, as well as AMR++, a customized bioinformatic pipeline specifically designed to use MEGARes in high-throughput analysis for characterizing AMR genes (ARGs) in metagenomic sequence data. Here, we present MEGARes v3.0, a comprehensive database of published ARG sequences for antimicrobial drugs, biocides, and metals, and AMR++ v3.0, an update to our customized bioinformatic pipeline for high-throughput analysis of metagenomic data (available at MEGLab.org). Database annotations have been expanded to include information regarding specific genomic locations for single-nucleotide polymorphisms (SNPs) and insertions and/or deletions (indels) when required by specific ARGs for resistance expression, and the updated AMR++ pipeline uses this information to check for presence of resistance-conferring genetic variants in metagenomic sequenced reads. This new information encompasses 337 ARGs, whose resistance-conferring variants could not previously be confirmed in such a manner. In MEGARes 3.0, the nodes of the acyclic hierarchical ontology include 4 antimicrobial compound types, 59 resistance classes, 233 mechanisms and 1448 gene groups that classify the 8733 accessions.

Fecal Shedding of Multidrug Resistant Escherichia coli Isolates in Dogs Fed with Raw Meat-Based Diets in Brazil

The practice of feeding dogs raw meat-based diets (RMBDs) is growing in several countries, and the risks associated with the ingestion of pathogenic and antimicrobial-resistant Escherichia coli in dogs fed these diets are largely unknown. We characterized E. coli strains isolated from dogs fed either an RMBD or a conventional dry feed, according to the phylogroup, virulence genes, and antimicrobial susceptibility profiles of the bacteria. Two hundred and sixteen E. coli strains were isolated. Dogs fed RMBDs shed E. coli strains from the phylogroup E more frequently and were positive for the E. coli heat-stable enterotoxin 1-encoding gene. Isolates from RMBD-fed dogs were also frequently positive for multidrug-resistant E. coli isolates including extended-spectrum beta-lactamase (ESBL) producers. Whole-genome sequencing of seven ESBL-producing E. coli strains revealed that they predominantly harbored blaCTX-M-55, and two strains were also positive for the colistin-resistant gene mcr-1. These results suggest that feeding an RMBD can affect the dog’s microbiota, change the frequency of certain phylogroups, and increase the shedding of diarrheagenic E. coli. Also, feeding an RMBD seemed to be linked with the fecal shedding of multidrug-resistant E. coli, including the spread of strains harboring mobilizable colistin resistance and ESBL genes. This finding is of concern for both animal and human health.