Whole genome sequence analysis of ESBL-producing Escherichia coli recovered from New Zealand freshwater sites

High-resolution genomic analysis to investigate the impact of the invasive brushtail possum (Trichosurus vulpecula) and other wildlife on microbial water quality assessments

Escherichia coli are routine indicators of fecal contamination in water quality assessments. Contrary to livestock and human activities, brushtail possums (Trichosurus vulpecula), common invasive marsupials in Aotearoa/New Zealand, have not been thoroughly studied as a source of fecal contamination in freshwater. To investigate their potential role, Escherichia spp. isolates (n = 420) were recovered from possum gut contents and feces and were compared to those from water, soil, sediment, and periphyton samples, and from birds and other introduced mammals collected within the Mākirikiri Reserve, Dannevirke. Isolates were characterized using E. coli-specific real-time PCR targeting the uidA gene, Sanger sequencing of a partial gnd PCR product to generate a gnd sequence type (gST), and for 101 isolates, whole genome sequencing. Escherichia populations from 106 animal and environmental sample enrichments were analyzed using gnd metabarcoding. The alpha diversity of Escherichia gSTs was significantly lower in possums and animals compared with aquatic environmental samples, and some gSTs were shared between sample types, e.g., gST535 (in 85% of samples) and gST258 (71%). Forty percent of isolates gnd-typed and 75% of reads obtained by metabarcoding had gSTs shared between possums, other animals, and the environment. Core-genome single nucleotide polymorphism (SNP) analysis showed limited variation between several animal and environmental isolates (<10 SNPs). Our data show at an unprecedented scale that Escherichia clones are shared between possums, other wildlife, water, and the wider environment. These findings support the potential role of possums as contributors to fecal contamination in Aotearoa/New Zealand freshwater. Our study deepens the current knowledge of Escherichia populations in under-sampled wildlife. It presents a successful application of high-resolution genomic methods for fecal source tracking, thereby broadening the analytical toolbox available to water quality managers. Phylogenetic analysis of isolates and profiling of Escherichia populations provided useful information on the source(s) of fecal contamination and suggest that comprehensive invasive species management strategies may assist in restoring not only ecosystem health but also water health where microbial water quality is compromised.

The characterisation of antimicrobial resistant Escherichia coli from dairy calves

Introduction. Dairy calves, particularly pre-weaned calves have been identified as a common source of multidrug resistant (MDR) Escherichia coli.Gap statement. E. coli strains isolated from dairy calves and the location of their resistance genes (plasmid or chromosomal) have not been well characterised.Aim. To characterise the phenotypic and genotypic features as well as the population structure of antimicrobial-resistant E. coli isolated from calves located on dairy farms that feed waste-milk to their replacement calves.Methodology. Recto-anal swab enrichments from 40 dairy calves (≤ 14 days old) located on four dairy farms were examined for tetracycline, streptomycin, ciprofloxacin, and third-generation cephalosporin resistant E. coli. Whole genome sequencing was performed using both short- and long-read technologies on selected antimicrobial resistant E. coli.Results. Fifty-eight percent (23/40) of calves harboured antimicrobial resistant E. coli: 43 % (17/40) harboured tetracycline resistant, and 23 % (9/40) harboured chromosomal mediated AmpC producing E. coli. Whole genome sequencing of 27 isolates revealed five sequence types, with ST88 being the dominant ST (17/27, 63 % of the sequenced isolates) followed by ST1308 (3/27, 11 %), along with the extraintestinal pathogenic E. coli lineages ST69 (3/27, 11 %), ST10 (2/27, 7 %), and ST58 (2/27, 7 %). Additionally, 16 isolates were MDR, harbouring additional resistance genes that were not tested phenotypically. Oxford Nanopore long-read sequencing technologies enabled the location of multiple resistant gene cassettes in IncF plasmids to be determined.Conclusion. Our study identified a high incidence of tetracycline and streptomycin-resistant E. coli in dairy calves, and highlighted the presence of multidrug-resistant strains, emphasising the need for further investigation into potential associations with farm management practices.

Multidrug-resistant extended spectrum β-lactamase (ESBL)-producing Escherichia coli from farm produce and agricultural environments in Edo State, Nigeria

Antimicrobial resistance (AMR) is a major public health concern, especially the extended-spectrum β-lactamase-producing (ESBL) Escherichia coli bacteria are emerging as a global human health hazard. This study characterized extended-spectrum β-lactamase Escherichia coli (ESBL-E. coli) isolates from farm sources and open markets in Edo State, Nigeria. A total of 254 samples were obtained in Edo State and included representatives from agricultural farms (soil, manure, irrigation water) and vegetables from open markets, which included ready-to-eat (RTE) salads and vegetables which could potentially be consumed uncooked. Samples were culturally tested for the ESBL phenotype using ESBL selective media, and isolates were further identified and characterized via polymerase chain reaction (PCR) for β-lactamase and other antibiotic resistance determinants. ESBL E. coli strains isolated from agricultural farms included 68% (17/25) from the soil, 84% (21/25) from manure and 28% (7/25) from irrigation water and 24.4% (19/78) from vegetables. ESBL E. coli were also isolated from RTE salads at 20% (12/60) and vegetables obtained from vendors and open markets at 36.6% (15/41). A total of 64 E. coli isolates were identified using PCR. Upon further characterization, 85.9% (55/64) of the isolates were resistant to ≥ 3 and ≤ 7 antimicrobial classes, which allows for characterizing these as being multidrug-resistant. The MDR isolates from this study harboured ≥1 and ≤5 AMR determinants. The MDR isolates also harboured ≥1 and ≤3 beta-lactamase genes. Findings from this study showed that fresh vegetables and salads could be contaminated with ESBL-E. coli, particularly fresh produce from farms that use untreated water for irrigation. Appropriate measures, including improving irrigation water quality and agricultural practices, need to be implemented, and global regulatory guiding principles are crucial to ensure public health and consumer safety.