Opportunistic Pathogens of Recreational Waters with Emphasis on Antimicrobial Resistance-A Possible Subject of Human Health Concern

Epidemiology of multidrug-resistant zoonotic E. coli from beef processing and retail points in Delta State, Nigeria: Public health implications

Some sorbitol non-fermenting E. coli (SN-F E. coli) and all E. coli O157 are zoonotic. Contamination of beef with zoonotic E. coli at the processing or retail point is a significant public health problem. Despite the public health importance of these organisms, there is no published data on the prevalence and antimicrobial resistance (AMR) of zoonotic E. coli from Delta State, Nigeria. Consequently, this study determined the prevalence and AMR of SN-F E. coli and E. coli O157 isolates from meat contact surfaces at the processing and retail points in the study area. The isolation, biochemical and serological characterisations and AMR status of the isolates were performed following standard microbiological methods. Overall prevalence of SN-F E. coli and E. coli O157 were 13.8% (56/406) and 1.5% (6/406), respectively. Majority of the 56 SN-F E. coli (64.3%, 36/56) and all the six E. coli O157 (10.7%, 6/56) detected in this study were found at the meat processing points. Most of the SN-F E. coli were isolated at the slaughterhouse floor (31%), meat hooks (17.2%) and meat sellers' knives (17.2%). The SN-F E. coli exhibited greater AMR to ampicillin (67.9%), gentamycin (64.3%) and tetracycline (50%) than other antimicrobial agents tested. No isolate was resistant to aztreonam. All six E. coli O157 isolates were resistant to enrofloxacin. Overall, 23 AMR patterns, comprised 14 from meat processing points and nine from meat retailing points, were observed from the 56 antimicrobial-resistant SN-F E. coli isolates. All the six E. coli O157 and 73.2% (41/56) of the SN-F E. coli isolates were multidrug-resistant. An overall mean multiple antimicrobial resistance index of 0.6 was recorded. Multidrug-resistant zoonotic E. coli were detected at meat processing and retail points in Delta State, Nigeria. The findings warrant the adoption of One Health control approach, "farm to fork" principle of food safety and prudent use of antimicrobial agents in animal agriculture. These may help to limit beef contamination with multidrug-resistant zoonotic E. coli at the processing and retailing points, for public health safety.

Integrating molecular microbial methods to improve faecal pollution management in rivers with designated bathing waters

Rivers are at risk from a variety of pollution sources. Faecal pollution is of particular concern since it disperses pathogenic microorganisms in the aquatic environment. Currently, faecal pollution levels in rivers is monitored using faecal indicator bacteria (FIB) that do not offer information about pollution sources and associated risks. This study used a combined molecular approach, along with measurements of water quality, to gain information on pollution sources, and risk levels, in a newly designated recreational bathing site in the River Wharfe (UK). Physico-chemical parameters were monitored in situ, with water quality multiparameter monitoring sondes installed during the 2021 bathing season. The molecular approach was based on quantitative PCR (qPCR)-aided Microbial Source Tracking (MST) and 16S rRNA gene metabarcoding to obtain a fingerprint of bacterial communities and identify potential bioindicators. The analysis from the water quality sondes showed that ammonium was the main parameter determining the distribution of FIB values. Lower faecal pollution levels were detected in the main river when compared to tributaries, except for samples in the river located downstream of a wastewater treatment plant. The faecal pollution type (anthropogenic vs. zoogenic) changed the diversity and the structure of bacterial communities, giving a distinctive fingerprint that can be used to inform source. DNA-based methods showed that the presence of human-derived bacteria was associated with Escherichia coli spikes, coinciding with higher bacterial diversity and the presence of potential pathogenic bacteria mainly of the genus Mycobacterium, Aeromonas and Clostridium. Samples collected after a heavy rainfall event were associated with an increase in Bacteroidales, which are markers of faecal pollution, including Bacteroides graminisolvens, a ruminant marker associated with surface run-off from agricultural sources. The combined use of qPCR and 16S rRNA sequencing was able to identify pollution sources, and novel bacterial indicators, thereby aiding decision-making and management strategies in recreational bathing rivers.

Facile Synthesis of Cu-Doped ZnO Nanoparticles for the Enhanced Photocatalytic Disinfection of Bacteria and Fungi

In this study, Cu-doped ZnO was prepared via the facile one-pot solvothermal approach. The structure and composition of the synthesized samples were characterized by XRD (X-ray diffraction), TEM (transmission electron microscopy), and XPS (X-ray photoelectron spectroscopy) analyses, revealing that the synthesized samples consisted of Cu-doped ZnO nanoparticles. Ultraviolet-visible (UV-vis) spectroscopy analysis showed that Cu-doping significantly improves the visible light absorption properties of ZnO. The photocatalytic capacity of the synthesized samples was tested via the disinfection of Escherichia coli, with the Cu-ZnO presenting enhanced disinfection compared to pure ZnO. Of the synthesized materials, 7% Cu-ZnO exhibited the best photocatalytic performance, for which the size was ~9 nm. The photocurrent density of the 7% Cu-ZnO samples was also significantly higher than that of pure ZnO. The antifungal activity for 7% Cu-ZnO was also tested on the pathogenic fungi of Fusarium graminearum. The macroconidia of F. graminearum was treated with 7% Cu-ZnO photocatalyst for 5 h, resulting in a three order of magnitude reduction at a concentration of 105 CFU/mL. Fluorescence staining tests were used to verify the survival of macroconidia before and after photocatalytic treatment. ICP-MS was used to confirm that Cu-ZnO met national standards for cu ion precipitation, indicating that Cu-ZnO are environmentally friendly materials.

Aquaculture bacterial pathogen database: Pathogen monitoring and screening in coastal waters using environmental DNA

Increasingly diverse pathogen occurrence in coastal and mariculture areas demands improved monitoring platforms to prevent economic and public health implications. Accessible databases with up-to-date knowledge and taxonomy are critical for detecting and screening environmental pathogens. Condensed from over 3000 relevant reports in peer reviewed articles, we constructed an aquaculture bacterial pathogen database that provides specialized curation of over 210 bacterial pathogenic species impacting aquaculture. Application of the aquaculture bacterial pathogen database to environmental DNA metabarcoding monitoring data in Hong Kong coastal and mariculture waters effectively characterized regional pathogen profiles over a one-year period and improved identification of new potential pathogen targets. The results highlighted the increase in potential pathogen abundance related to aquaculture activity and the associated inorganic nitrogen load, which was chiefly due to the enrichment of Vibrio during the atypical dry winter season. The value of the aquaculture bacterial pathogen database for empowering environmental DNA-based approaches in coastal marine pathogen surveillance benefits water resource management and aquaculture development on a global scale.

Antimicrobial Resistance Linked to Septic System Contamination in the Indiana Lake Michigan Watershed

Extended-spectrum β-lactamases confer resistance to a variety of β-lactam antimicrobials, and the genes for these enzymes are often found on plasmids that include additional antimicrobial resistance genes (ARG). We surveyed aquatic environments in the Indiana Lake Michigan watershed in proximity to areas with high densities of residential septic systems to determine if human fecal contamination from septic effluent correlated with the presence of antimicrobial resistance genes and phenotypically resistant bacteria. Of the 269 E. coli isolated from environmental samples and one septic source, 97 isolates were resistant to cefotaxime, a third-generation cephalosporin. A subset of those isolates showed phenotypic resistance to other β-lactams, fluoroquinolones, sulfonamides, and tetracyclines. Quantitative PCR was used to quantify human-associated Bacteroides dorei gene copies (Human Bacteroides) from water samples and to identify the presence of ARG harbored on plasmids from E. coli isolates or in environmental DNA. We found a strong correlation between the presence of ARG and human fecal concentrations, which supports our hypothesis that septic effluent is a source of ARG and resistant organisms. The observed plasmid-based resistance adds an additional level of risk, as human-associated bacteria from septic systems may expand the environmental resistome by acting as a reservoir of transmissible resistance genes.

Antimicrobial Susceptibility Profile of Pathogenic and Commensal Bacteria Recovered from Cattle and Goat Farms

The use of antibiotics in food animals results to antimicrobial resistant bacteria that complicates the ability to treat infections. The purpose of this study was to investigate the prevalence of pathogenic and commensal bacteria in soil, water, manure, and milk from cattle and goat farms. A total of 285 environmental and 81 milk samples were analyzed for Enterobacteriaceae by using biochemical and PCR techniques. Susceptibility to antibiotics was determined by the Kirby-Bauer disk diffusion technique. A total of 15 different Enterobacteriaceae species were identified from goat and cattle farms. Manure had significantly higher (p < 0.05) Enterobacteriaceae (52.0%) than soil (37.2%), trough water (5.4%), and runoff water (5.4%). There was a significant difference (p < 0.05) in Enterobacteriaceae in goat milk (53.9%) and cow milk (46.2%). Enterobacteriaceae from environment showed 100% resistance to novobiocin, erythromycin, and vancomycin E. coli O157:H7, Salmonella spp., Enterococcus spp., and Listeria monocytogenes displayed three, five, six, and ten. AMR patterns, respectively. NOV-TET-ERY-VAN was the most common phenotype observed in all isolates. Our study suggest that cattle and goat farms are reservoirs of multidrug-resistant bacteria. Food animal producers should be informed on the prudent use of antimicrobials, good agricultural practices, and biosecurity measures.