Quantitative risk analysis for potentially resistant E. coli in surface waters caused by antibiotic use in agricultural systems

Quantitative microbial risk assessment of gastrointestinal illness due to recreational exposure to E. coli and enterococci on the southern coasts of the Caspian Sea

Background

Gastrointestinal illness refers to a broad range of diseases that affect the digestive system, including infections caused by bacteria, viruses, and parasites. Quantitative Microbial Risk Assessment (QMRA) is a powerful tool used to evaluate the risks associated with microbial pathogens in various environments. The main objective of this study was to conduct a quantitative assessment of gastrointestinal illnesses that occur as a result of exposure to E. coli and enterococci during recreational activities on the southern coasts of the Caspian Sea.

Methods

Samples were collected from the recreational beaches along the border line of the Caspian Sea. The samples were analyzed for the presence and enumeration of E. coli and enterococci using the microplate method and membrane filtration techniques. Then, the annual and daily infection risks were computed using the Monte Carlo simulation approach.

Results

The results revealed that the risk of daily and annual infections on the coasts of Babolsar was higher than that on the coasts of Sari. Also, in the recreational waters of these beaches, the risk of infection by enterococci was higher than that posed by E. coli. In Babolsar, the average annual infection risk caused by E. coli and enterococci was 0.365 and 1 for children and 0.181 and 0.986 for adults. Also, in Sari, the average annual infection risk caused by E. coli and enterococci was 0.060 and 0.908 for children and 0.027 and 0.815 for adults. In addition, children were more likely than adults to become infected.

Conclusion

In light of the study's findings, due to the entry of untreated urban wastewater into the southern part of the Caspian Sea (northern Iran) and the high risk of infectious diseases for children, more control and health measures are necessary for children's swimming.

Quantitative microbial risk assessment for ingestion of antibiotic resistance genes from private wells contaminated by human and livestock fecal sources

We used quantitative microbial risk assessment to estimate ingestion risk for intI1, erm(B), sul1, tet(A), tet(W), and tet(X) in private wells contaminated by human and/or livestock feces. Genes were quantified with five human-specific and six bovine-specific microbial source-tracking (MST) markers in 138 well-water samples from a rural Wisconsin county. Daily ingestion risk (probability of swallowing ≥1 gene) was based on daily water consumption and a Poisson exposure model. Calculations were stratified by MST source and soil depth over the aquifer where wells were drilled. Relative ingestion risk was estimated using wells with no MST detections and >6.1 m soil depth as a referent category. Daily ingestion risk varied from 0 to 8.8 × 10-1 by gene and fecal source (i.e., human or bovine). The estimated number of residents ingesting target genes from private wells varied from 910 (tet(A)) to 1,500 (intI1 and tet(X)) per day out of 12,000 total. Relative risk of tet(A) ingestion was significantly higher in wells with MST markers detected, including wells with ≤6.1 m soil depth contaminated by bovine markers (2.2 [90% CI: 1.1-4.7]), wells with >6.1 m soil depth contaminated by bovine markers (1.8 [1.002-3.9]), and wells with ≤6.1 m soil depth contaminated by bovine and human markers simultaneously (3.1 [1.7-6.5]). Antibiotic resistance genes (ARGs) were not necessarily present in viable microorganisms, and ingestion is not directly associated with infection. However, results illustrate relative contributions of human and livestock fecal sources to ARG exposure and highlight rural groundwater as a significant point of exposure.IMPORTANCEAntibiotic resistance is a global public health challenge with well-known environmental dimensions, but quantitative analyses of the roles played by various natural environments in transmission of antibiotic resistance are lacking, particularly for drinking water. This study assesses risk of ingestion for several antibiotic resistance genes (ARGs) and the class 1 integron gene (intI1) in drinking water from private wells in a rural area of northeast Wisconsin, United States. Results allow comparison of drinking water as an exposure route for antibiotic resistance relative to other routes like food and recreational water. They also enable a comparison of the importance of human versus livestock fecal sources in the study area. Our study demonstrates the previously unrecognized importance of untreated rural drinking water as an exposure route for antibiotic resistance and identifies bovine fecal material as an important exposure factor in the study setting.

Health risk assessment of swimming beaches microbial contamination: a case study - Mahmoudabad, Iran

Waterborne organisms in marine water generally originate from untreated wastewater discharged into the sea. The presence of numerous leisure beaches in Mahmoudabad city, Iran, annually attracts thousands of tourists from all over the country to participate in recreational swimming activities. This study probabilistically characterized the health risks associated with recreational swimming engendered by waterborne pathogens, such as intestinal enterococci and Escherichia coli (E. coli) at 15 sampling points along the beaches of the study using quantitative microbial risk assessment (QMRA). The mean annual infection risk of E. coli in children and adults was 0.424 and 0.229, respectively. The respective risk in terms of enterococci was 0.999 and 0.997, which were higher than the level recommended by the WHO and EPA. The results show that the risk of infection for children was higher than adults. Related authorities have to consider measures to improve environmental quality to protect tourists' and residents' well-being.

Natural recreational waters and the risk that exposure to antibiotic resistant bacteria poses to human health

Antimicrobial resistance (AMR) is widely recognised as a considerable threat to human health, wellbeing and prosperity. Many clinically important antibiotic resistance genes are understood to have originated in the natural environment. However, the complex interactions between humans, animals and the environment makes the health implications of environmental AMR difficult to quantify. This narrative review focuses on the current state of knowledge regarding antibiotic resistant bacteria (ARB) in natural bathing waters and implications for human health. It considers the latest research focusing on the transmission of ARB from bathing waters to humans. The limitations of existing evidence are discussed, as well as research priorities. The authors are of the opinion that future studies should include faecally contaminated bathing waters and people exposed to these environments to accurately parameterise environment-to-human transmission.

Food animals as reservoirs and potential sources of multidrug-resistant diarrheagenic E. coli pathotypes: Focus on intensive pig farming in South Africa

Background

Diarrheagenic E. coli (DEC) strains are a major cause of diarrheal diseases in both developed and developing countries. Healthy asymptomatic animals may be reservoirs of zoonotic DEC, which may enter the food chain via the weak points in hygiene practices.

Aim

We investigated the prevalence of DEC along the pig production continuum from farm-to-fork.

Methods

A total of 417 samples were collected from specific points along the pig production system, that is, farm, transport, abattoir and food. E. coli was isolated and enumerated using Colilert. Ten isolates from each Quanti-tray were selected randomly and phenotypically identified using eosin methylene blue agar selective media. Real-time polymerase chain reaction (PCR) was used to confirm the species and to classify them into the various diarrheagenic pathotypes. Antimicrobial susceptibility was determined against a panel of 20 antibiotics using the Kirby-Bauer disk diffusion method and EUCAST guideline.

Results

The final sample size consisted of 1044 isolates, of which 45.40% (474/1044) were DEC and 73% (762/1044) were multidrug-resistant. Enteroinvasive E. coli (EIEC) was the most predominant DEC at all the sampling sites.

Conclusion

The presence of DEC in food animal production environments and food of animal origin could serve as reservoirs for transmitting these bacteria to humans, especially in occupationally exposed workers and via food. Adherence to good hygienic practices along the pig production continuum is essential for mitigating the risk of transmission and infection, and ensuring food safety.

A Streamlined Study on Chitosan-Zinc Oxide Nanomicelle Properties to Mitigate a Drug-Resistant Biofilm Protection Mechanism

The nosocomial multidrug resistant bacteria (MDR), are rapidly circulating from water surfaces to humans away from the clinical setting, forming a cyclical breeding ground of resistance, causing worldwide infections, and thus requiring urgent responses. The combination of chitosan and zinc oxide (CZNPs), with proven bactericidal effects on some MDRs, was further studied to set the stage for a broad-spectrum in vivo utilization of CZNPs. Toward ensuring CZNPs' uniformity and potency, when it faces not only biofilms but also their extracellular polymeric substances (EPS) defense mechanism, the size, zeta potential, and polydispersity index (PDI) were determined through dynamic light scattering (DLS). Furthermore, the efficacy of CZNPs was tested on the inhibition of MDR Gram-negative Escherichia coli BAA-2471 and Gram-positive Enterococcus faecium 1449 models, co-cultured in an Alvatex 3D fiber platform as a biofilm-like structure. The Biotek Synergy Neo2 fluorescent microplate reader was used to detect biofilm shrinkage. The biofilm protection mechanism was elucidated through detection of EPS using 3D confocal and transmission electronic microscopy. Results indicated that 200 μl/mL of CZNPs, made with 50 nm ZnO and 10,000 Da chitosan (N = 369.1 nm; PDI = 0.371; zeta potential = 22.8 mV), was the most promising nanocomposite for MDR biofilm reduction, when compared to CZNPs enclosing ZnO, 18 or 100 nm. This study depicts that CZNPs possess enough potency and versatility to face biofilms' defense mechanism in vivo.

Risk evaluation of groundwater leakage in coal seam goaf: a case study in the Lingxin Mining Area

It is of great importance to determine the risk grades of the leakage and non-leakage cases of concentrated saltwater from an underground reservoir for the safe operation of reservoirs and environmental protection. In this paper, the model of risk evaluation for environmental pollution of an underground reservoir stored with concentrated saltwater is established. Moreover, the effects of different influencing factors on the risk grades are investigated, along with an uncertainty analysis. In addition, the risk grade of Lingxin Mining Area is calculated, which can contribute to the prevention and control of pollution in the future for that area. The results show that the water quality complexity of mine water is the most significant indicator for risk grade determination. The certainty of weak-risk grade for environmental pollution caused by an underground reservoir when there is no leakage is more than 60% in the Lingxin Mining Area, and the risk grade becomes a strong-risk grade rapidly after concentrated saltwater leakage is considered. This research can provide a theoretical basis for risk control and management of underground reservoirs storing concentrated saltwater.

High-Throughput Detection of Bacterial Community and Its Drug-Resistance Profiling From Local Reclaimed Wastewater Plants

Treated wastewater from reclaimed facilities (WWTP) has become a reusable source for a variety of applications, such as agricultural irrigation. However, it is also a potential reservoir of clinically-relevant multidrug resistant (MDR) pathogens, including ESKAPE (Enterococcus faecium and Streptococcus surrogates, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species along with the emerging nosocomial Escherichia strains). This study was performed to decipher the bacterial community structure through Illumina high throughput 16S rRNA gene sequencing, and to determine the resistance profile using the Sensititre antimicrobial susceptibility test (AST) conforming to clinical lab standards (NCCLS). Out of 1747 bacterial strains detected from wastewater influent and effluent, Pseudomonas was the most predominant genus related to ESKAPE in influent, with sequence reads corresponding to 21.356%, followed by Streptococcus (6.445%), Acinetobacter (0.968%), Enterococcus (0.063%), Klebsiella (0.038%), Escherichia (0.028%) and Staphylococcus (0.004%). Despite the different treatment methods used, the effluent still revealed the presence of some Pseudomonas strains (0.066%), and a wide range of gram-positive cocci, including Staphylococcus (0.194%), Streptococcus (0.63%) and Enterococcus (0.037%), in addition to gram-negative Acinetobacter (0.736%), Klebsiella (0.1%), and Escherichia sub-species (0.811%). The AST results indicated that the strains Escherichia along with Klebsiella and Acinetobacter, isolated from the effluent, displayed resistance to 11 antibiotics, while Pseudomonas was resistant to 7 antibiotics, and Streptococcus along with Staphylococcus were resistant to 9 antibiotics. Results herein, proved the existence of some nosocomial MDR pathogens, known for ESKAPE, with potential drug resistance transfer to the non-pathogen microbes, requiring targeted remediation.