Methicillin-resistant Staphylococcus aureus (MRSA) detected at four U.S. wastewater treatment plants

Prevalence and molecular characterization of multidrug-resistant coagulase negative staphylococci from urban wastewater in Delhi-NCR, India

Antimicrobial resistance (AMR) is global health concern escalating rapidly in both clinical settings and environment. The effluent from pharmaceuticals and hospitals may contain diverse antibiotics, exerting selective pressure to develop AMR. To study the aquatic prevalence of drug-resistant staphylococci, sampling was done from river Yamuna (3 sites) and wastewater (7 sites) near pharmaceutical industries in Delhi-NCR, India. 59.25% (224/378) were considered presumptive staphylococci while, methicillin resistance was noted in 25% (56/224) isolates. Further, 23 methicillin-resistant coagulase negative staphylococci (MR-CoNS) of 8 different species were identified via 16S rRNA gene sequencing. Multidrug resistance (MDR) was noted in 60.87% (14/23) isolates. PCR based detection of antibiotic resistance genes revealed the number of isolates containing mecA (7/23), blaZ (6/23), msrA (10/23), aac(6')aph (2") (2/23), aph(3')-IIIa (2/23), ant(4')-Ia (1/23), dfrG (4/23), dfrA(drfS1) (3/23), tetK (1/23) and tetM (1/23). The current research highlights the concerning prevalence of MDR-CoNS in aquatic environment in Delhi.

Culex quinquefasciatus Mosquitoes Resist Acquisition of Methicillin-Resistant Staphylococcus aureus: Insights from Field and Laboratory Studies

The emergence of antimicrobial resistance (AMR) in pathogens and their spillover into the environment have become a global public health menace. Insects can acquire these pathogens from the environment and would serve as mechanical and biological vectors. The current study assessed the ability of Culex quinquefasciatus mosquitoes to acquire methicillin-resistant Staphylococcus aureus (MRSA) through the exposure of the mosquitoes to the pathogen via rearing water, blood feed, or a feeding membrane under laboratory conditions. In addition, mosquito immatures collected from their habitat in the vicinity of hospitals, veterinary dispensaries, and butcher shops at 15 study sites in Puducherry were screened for MRSA infection. All samples were subjected to the culture-based isolation of S. aureus from the surface and homogenate. The presence of the S. aureus-specific nuc gene and the genes that confer resistance to methicillin (mecA and mecC) were screened using PCR tests. MRSA was not evident either on the external surface or in the homogenate of the mosquitoes emerging from the larvae reared in the MRSA-spiked water or those fed with MRSA through blood or smeared membranes. Furthermore, the presence of MRSA was not evident in any of the field-caught mosquitoes. Hence, we conclude that C. quinquefasciatus mosquitoes are impervious to MRSA colonization.

Filling the Knowledge Gap Regarding Microbial Occupational Exposure Assessment in Waste Water Treatment Plants: A Scoping Review

BACKGROUND

Wastewater treatment plants (WWTPs) are crucial in the scope of European Commission circular economy implementation. However, bioaerosol production may be a hazard for occupational and public health. A scoping review regarding microbial contamination exposure assessment in WWTPs was performed.

METHODS

This study was performed through PRISMA methodology in PubMed, Scopus and Web of Science.

RESULTS

28 papers were selected for data extraction. The WWTPs' most common sampled sites are the aeration tank (42.86%), sludge dewatering basin (21.43%) and grit chamber. Air sampling is the preferred sampling technique and culture-based methods were the most frequently employed assays. Staphylococcus sp. (21.43%), Bacillus sp. (7.14%), Clostridium sp. (3.57%), Escherichia sp. (7.14%) and Legionella sp. (3.57%) were the most isolated bacteria and Aspergillus sp. (17.86%), Cladosporium sp. (10.71%) and Alternaria sp. (10.71%) dominated the fungal presence.

CONCLUSIONS

This study allowed the identification of the following needs: (a) common protocol from the field (sampling campaign) to the lab (assays to employ); (b) standardized contextual information to be retrieved allowing a proper risk control and management; (c) the selection of the most suitable microbial targets to serve as indicators of harmful microbial exposure. Filling these gaps with further studies will help to provide robust science to policy makers and stakeholders.

To what extent do water reuse treatments reduce antibiotic resistance indicators? A comparison of two full-scale systems

Water reuse is an essential strategy for reducing water demand from conventional sources, alleviating water stress, and promoting sustainability, but understanding the effectiveness of associated treatment processes as barriers to the spread of antibiotic resistance is an important consideration to protecting human health. We comprehensively evaluated the reduction of antibiotic resistance genes (ARGs) and antibiotic-resistant bacteria (ARB) in two field-operational water reuse systems with distinct treatment trains, one producing water for indirect potable reuse (ozone/biologically-active carbon/granular activated carbon) and the other for non-potable reuse (denitrification-filtration/chlorination) using metagenomic sequencing and culture. Relative abundances of total ARGs/clinically-relevant ARGs and cultured ARB were reduced by several logs during primary and secondary stages of wastewater treatment, but to a lesser extent during the tertiary water reuse treatments. In particular, ozonation tended to enrich multi-drug ARGs. The effect of chlorination was facility-dependent, increasing the relative abundance of ARGs when following biologically-active carbon filters, but generally providing a benefit in reduced bacterial numbers and ecological and human health resistome risk scores. Relative abundances of total ARGs and resistome risk scores were lowest in aquifer samples, although resistant Escherichia coli and Klebsiella pneumoniae were occasionally detected in the monitoring well 3-days downgradient from injection, but not 6-months downgradient. Resistant E. coli and Pseudomonas aeruginosa were occasionally detected in the nonpotable reuse distribution system, along with increased levels of multidrug, sulfonamide, phenicol, and aminoglycoside ARGs. This study illuminates specific vulnerabilities of water reuse systems to persistence, selection, and growth of ARGs and ARB and emphasizes the role of multiple treatment barriers, including aquifers and distribution systems.

Multidrug-Resistant Staphylococcus sp. and Enterococcus sp. in Municipal and Hospital Wastewater: A Longitudinal Study

The objective of the study was to detect multidrug-resistant Staphylococcus sp. and Enterococcus sp. isolates in municipal and hospital wastewater and to determine their elimination or persistence after wastewater treatment. Between August 2021 and September 2022, raw and treated wastewater samples were collected at two hospital and two community wastewater treatment plants (WWTPs). In each season of the year, two treated and two raw wastewater samples were collected in duplicate at each of the WWTPs studied. Screening and presumptive identification of staphylococci and enterococci was performed using chromoagars, and identification was performed with the Matrix Assisted Laser Desorption Ionization Time of Flight mass spectrometry (MALDI-TOF MS®). Antimicrobial susceptibility was performed using VITEK 2® automated system. There were 56 wastewater samples obtained during the study period. A total of 182 Staphylococcus sp. and 248 Enterococcus sp. were identified. The highest frequency of Staphylococcus sp. isolation was in spring and summer (n = 129, 70.8%), and for Enterococcus sp. it was in autumn and winter (n = 143, 57.7%). Sixteen isolates of Staphylococcus sp. and sixty-three of Enterococcus sp. persisted during WWTP treatments. Thirteen species of staphylococci and seven species of enterococci were identified. Thirty-one isolates of Staphylococcus sp. and ninety-four of Enterococcus sp. were multidrug-resistant. Resistance to vancomycin (1.1%), linezolid (2.7%), and daptomycin (8.2%/10.9%%), and a lower susceptibility to tigecycline (2.7%), was observed. This study evidences the presence of Staphylococcus sp. and Enterococcus sp. resistant to antibiotics of last choice of clinical treatment, in community and hospital wastewater and their ability to survive WWTP treatment systems.

Indole-based aryl sulfides target the cell wall of Staphylococcus aureus without detectable resistance

Sulfur-containing classes of the scaffold "Arylthioindoles" have been evaluated for antibacterial activity; they demonstrated excellent potency against methicillin-resistant Staphylococcus aureus (MRSA) as well as against vancomycin-resistant strains and a panel of clinical isolates of resistant strains. In this study, we have elucidated the mechanism of action of lead compounds, wherein they target the cell wall of S. aureus. Further, S. aureus failed to develop resistance against two lead compounds tested in a serial passage experiment in the presence of the compounds over a period of 40 days. Both the compounds demonstrated comparable in vivo efficacy with vancomycin in a neutropenic mice thigh infection model. The results of these antibacterial activities emphasize the excellent potential of thioethers for developing novel antibiotics and may fill in as a target for the adjustment of accessible molecules to develop new powerful antibacterial agents with fewer side effects.

The Impact of Metal and Heavy Metal Concentrations on Vancomycin Resistance in Staphylococcus aureus within Milk Produced by Cattle Farms and the Health Risk Assessment in Kurdistan Province, Iran

In today's food landscape, the paramount focus is on ensuring food safety and hygiene. Recognizing the pivotal role of the environment and its management in safeguarding animal products, this study explores vancomycin resistance in raw milk from livestock farms in the Kurdistan province and its correlation with metal and heavy metal. One hundred and sixty raw milk samples were collected from various locations, with heavy metal concentrations analyzed using ICP-MS. Identification of Staphylococcus aureus and vancomycin resistance testing were conducted through culture and the Kirby-Bauer method. This study investigates the relationship between resistance and heavy metal levels, revealing that 8.75% of milk samples contained Staphylococcus aureus, with 28.58% exhibiting vancomycin resistance. Significant variations in arsenic, iron, zinc, sodium, and aluminum concentrations were observed between resistant and sensitive samples (p < 0.01). The increase in arsenic, iron, and aluminum, along with the decrease in zinc, demonstrated a significant association with vancomycin resistance (p < 0.001). Levels of lead, cadmium, mercury, zinc, and iron exceeded permissible limits (p < 0.05). The Target Hazard Quotient (THQ) for cadmium indicated a high non-carcinogenic risk, while the Target Risk (TR) for arsenic fell within the carcinogenic range. Accumulation of heavy metals has the potential to impact antibiotic resistance in milk, underscoring the imperative to control arsenic residues for national safety.

Detection of mecA positive staphylococcal species in a wastewater treatment plant in South Africa

We investigated the prevalence of antibiotic resistant staphylococci and detection of resistant, virulence, and Spa genes in a South African wastewater treatment plant. Species identified were Staphylococcus aureus, S. lentus, S. arlettae, S. cohnii, S. haemolyticus, S. nepalensis, S. sciuri (now Mammaliicoccus sciuri), and S. xylosus. Isolates showed high resistance to methicillin (91%), ampicillin (89%), ciprofloxacin (86%), amoxycillin (80%), ceftazidime (74%), and cloxacillin (71%). Multiple antibiotic resistance (MAR) index for the isolates exceeded 0.2 (0.50-0.70). Among the isolates, 77% were mecA-positive. All S. aureus strains were positive for nuc and 7 Spa gene types. The present study highlights possibility of treated wastewaters being potential reservoir for antibiotic-resistant staphylococci. This is a cause for concern as wastewater effluents are decanted into environmental waters and these are, in many cases, used for various purposes including recreation (full contact), religious (full body submersion), and drinking water for some rural communities and water for livestock.

Absence of Staphylococcus aureus in Wild Populations of Fish Supports a Spillover Hypothesis

Staphylococcus aureus is a human commensal and opportunistic pathogen that also infects other animals. In humans and livestock, where S. aureus is most studied, strains are specialized for different host species. Recent studies have also found S. aureus in diverse wild animals. However, it remains unclear whether these isolates are also specialized for their hosts or whether their presence is due to repeated spillovers from source populations. This study focuses on S. aureus in fish, testing the spillover hypothesis in two ways. First, we examined 12 S. aureus isolates obtained from the internal and external organs of a farmed fish. While all isolates were from clonal complex 45, genomic diversity indicates repeated acquisition. The presence of a φSa3 prophage containing human immune evasion genes suggests that the source was originally human. Second, we tested for S. aureus in wild fish that were isolated from likely sources. In particular, we sampled 123 brown trout and their environment at 16 sites in the remote Scottish Highlands with variable levels of exposure to humans, birds, and livestock. This screen found no S. aureus infection in any of the wild populations or their environment. Together, these results support that the presence of S. aureus in fish and aquaculture is due to spillover from humans rather than specialization. Given the trends of increasing fish consumption, a better understanding of the dynamics of S. aureus spillover in aquaculture will mitigate future risks to fish and human health. IMPORTANCE Staphylococcus aureus is a human and livestock commensal but also an important pathogen responsible for high human mortality rates and economic losses in farming. Recent studies show that S. aureus is common in wild animals, including fish. However, we do not know whether these animals are part of the normal host range of S. aureus or whether infection is due to repeated spillover events from true S. aureus hosts. Answering this question has implications for public health and conservation. We find support for the spillover hypothesis by combining genome sequencing of S. aureus isolates from farmed fish and screens for S. aureus in isolated wild populations. The results imply that fish are unlikely to be a source of novel emergent S. aureus strains but highlight the prominence of the spillover of antibiotic-resistant bacteria from humans and livestock. This may affect both future fish disease potential and the risk of human food poisoning.

The presence of antibiotics and multidrug-resistant Staphylococcus aureus reservoir in a low-order stream spring in central Brazil

The disposal of industrial effluents strongly influences low-order streams, which makes them fragile ecosystems that can be impacted by contamination. In central Brazil, the Extrema River spring targets the dumping of pharmaceutical products from the surrounding industries. So, this work aimed to investigate the presence of antibiotics in Extrema River spring samples and the isolation of Staphylococcus aureus, a potential multidrug-resistant bacteria, verifying the antimicrobial resistance profile of these isolates. Three campaigns were carried out in different locals (P1-P3) between October and December 2021, in the dry and rainy seasons. The high-performance liquid chromatography-tandem mass spectrometry (LCMS) approach indicated the presence of sulfamethoxazole (≥ 1 ng/L), metronidazole (< 0.5 ng/L), and chloramphenicol (< 5 ng/L) in the water samples in November (rainy season). S. aureus was isolated in P1 (n = 128), P2 (n = 168), and P3 (n = 36), with greater resistance to trimethoprim-sulfamethoxazole (90%), clindamycin (70%), and gentamicin (60%). The presence of antibiotics in the Extrema River spring may cause S. aureus antibiotic resistance development. The presence of antibiotics and the high percentage of isolated multidrug-resistant S. aureus in the Extrema River spring cause concern and indicate the clandestine dumping of effluents from nearby pharmaceutical industries. Since preserving the springs of low-order streams is important for the environment and public health, we encourage monitoring the wastewater from Extrema River's nearby pharmaceutical industries and preserving the spring of this river.

Wastewater treatment plants, an "escape gate" for ESCAPE pathogens

Antibiotics are an essential tool of modern medicine, contributing to significantly decreasing mortality and morbidity rates from infectious diseases. However, persistent misuse of these drugs has accelerated the evolution of antibiotic resistance, negatively impacting clinical practice. The environment contributes to both the evolution and transmission of resistance. From all anthropically polluted aquatic environments, wastewater treatment plants (WWTPs) are probably the main reservoirs of resistant pathogens. They should be regarded as critical control points for preventing or reducing the release of antibiotics, antibiotic-resistant bacteria (ARB), and antibiotic-resistance genes (ARGs) into the natural environment. This review focuses on the fate of the pathogens Enterococcus faecium, Staphylococcus aureus, Clostridium difficile, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacteriaceae spp. (ESCAPE) in WWTPs. All ESCAPE pathogen species, including high-risk clones and resistance determinants to last-resort antibiotics such as carbapenems, colistin, and multi-drug resistance platforms, were detected in wastewater. The whole genome sequencing studies demonstrate the clonal relationships and dissemination of Gram-negative ESCAPE species into the wastewater via hospital effluents and the enrichment of virulence and resistance determinants of S. aureus and enterococci in WWTPs. Therefore, the efficiency of different wastewater treatment processes regarding the removal of clinically relevant ARB species and ARGs, as well as the influence of water quality factors on their performance, should be explored and monitored, along with the development of more effective treatments and appropriate indicators (ESCAPE bacteria and/or ARGs). This knowledge will allow the development of quality standards for point sources and effluents to consolidate the WWTP barrier role against the environmental and public health AR threats.

The development of variation-based rifampicin resistance in Staphylococcus aureus deciphered through genomic and transcriptomic study

Rifampicin (RIF) resistance imposes a challenge on the antimicrobial treatment of pathogen infections. Figuring out the development mechanism of RIF resistance is critical to improving antimicrobial therapy strategy in clinics and biological treatment strategy of RIF polluted sewage in environmental engineering. The RIF resistance development of Staphylococcus aureus (S. aureus) with exposure to RIF at sub-inhibitory concentrations was comprehensively investigated via genomic and transcriptomic approaches in this study. RIF minimal inhibitory concentration (MIC) for S. aureus rapidly increased from 0.032 to 256 mg/L. Membrane permeability decrease, biofilm formation enhancement, and ROS production increase associated with RIF resistance were observed in RIF-induced strains. Through comparative genomic analysis, mutations in rpoB and rpoC were considered to be associated with RIF resistance in S. aureus mutants. Pan-genome-wide single-nucleotide variant analysis indicated that mutations at rpoB-1412, rpoB-1451, and rpoB-1457 were prevalent in 13849 public genomes of S. aureus, while mutations at rpoB-2256, and rpoC-3092 were first discovered in this study. The panorama of adaptative alteration of cellular physiological processes was observed via transcriptomic analysis. The oxidation pressure responses, metabolism, transporters, virulence factors, and multiple steps of DNA and RNA machinery were found to be perturbed by RIF in S. aureus.

MRSA compendium of epidemiology, transmission, pathophysiology, treatment, and prevention within one health framework

Staphylococcus aureus is recognized as commensal as well as opportunistic pathogen of humans and animals. Methicillin resistant strain of S. aureus (MRSA) has emerged as a major pathogen in hospitals, community and veterinary settings that compromises the public health and livestock production. MRSA basically emerged from MSSA after acquiring SCCmec element through gene transfer containing mecA gene responsible for encoding PBP-2α. This protein renders the MRSA resistant to most of the β-lactam antibiotics. Due to the continuous increasing prevalence and transmission of MRSA in hospitals, community and veterinary settings posing a major threat to public health. Furthermore, high pathogenicity of MRSA due to a number of virulence factors produced by S. aureus along with antibiotic resistance help to breach the immunity of host and responsible for causing severe infections in humans and animals. The clinical manifestations of MRSA consist of skin and soft tissues infection to bacteremia, septicemia, toxic shock, and scalded skin syndrome. Moreover, due to the increasing resistance of MRSA to number of antibiotics, there is need to approach alternatives ways to overcome economic as well as human losses. This review is going to discuss various aspects of MRSA starting from emergence, transmission, epidemiology, pathophysiology, disease patterns in hosts, novel treatment, and control strategies.

Towards the standardization of Enterococcus culture methods for waterborne antibiotic resistance monitoring: A critical review of trends across studies

Antibiotic resistance is a major 21^st century One Health (humans, animals, environment) challenge whose spread limits options to treat bacterial infections. There is growing interest in monitoring water environments, including surface water and wastewater, which have been identified as key recipients, pathways, and sources of antibiotic resistant bacteria (ARB). Aquatic environments also facilitate the transmission and amplification of ARB. Enterococcus spp. often carry clinically-important antibiotic resistance genes and are of interest as environmental monitoring targets. Enterococcus spp. are Gram-positive bacteria that are typically of fecal origin; however, they are also found in relevant environmental niches, with various species and strains that are opportunistic human pathogens. Although the value of environmental monitoring of antibiotic-resistant Enterococcus has been recognized by both national and international organizations, lack of procedural standardization has hindered generation of comparable data needed to implement integrated surveillance programs. Here we provide a comprehensive methodological review to assess the techniques used for the culturing and characterization of antibiotic-resistant Enterococcus across water matrices for the purpose of environmental monitoring. We analyzed 117 peer-reviewed articles from 33 countries across six continents. The goal of this review is to provide a critical analysis of (i) the various methods applied globally for isolation, confirmation, and speciation of Enterococcus isolates, (ii) the different methods for profiling antibiotic resistance among enterococci, and (iii) the current prevalence of resistance to clinically-relevant antibiotics among Enterococcus spp. isolated from various environments. Finally, we provide advice regarding a path forward for standardizing culturing of Enterococcus spp. for the purpose of antibiotic resistance monitoring in wastewater and wastewater-influenced waters within a global surveillance framework.

Variations in Bacterial Communities and Antibiotic Resistance Genes Across Diverse Recycled and Surface Water Irrigation Sources in the Mid-Atlantic and Southwest United States: A CONSERVE Two-Year Field Study

Reduced availability of agricultural water has spurred increased interest in using recycled irrigation water for U.S. food crop production. However, there are significant knowledge gaps concerning the microbiological quality of these water sources. To address these gaps, we used 16S rRNA gene and metagenomic sequencing to characterize taxonomic and functional variations (e.g., antimicrobial resistance) in bacterial communities across diverse recycled and surface water irrigation sources. We collected 1 L water samples (n = 410) between 2016 and 2018 from the Mid-Atlantic (12 sites) and Southwest (10 sites) U.S. Samples were filtered, and DNA was extracted. The V3-V4 regions of the 16S rRNA gene were then PCR amplified and sequenced. Metagenomic sequencing was also performed to characterize antibiotic, metal, and biocide resistance genes. Bacterial alpha and beta diversities were significantly different (p < 0.001) across water types and seasons. Pathogenic bacteria, such as Salmonella enterica, Staphylococcus aureus, and Aeromonas hydrophilia were observed across sample types. The most common antibiotic resistance genes identified coded against macrolides/lincosamides/streptogramins, aminoglycosides, rifampin and elfamycins, and their read counts fluctuated across seasons. We also observed multi-metal and multi-biocide resistance across all water types. To our knowledge, this is the most comprehensive longitudinal study to date of U.S. recycled water and surface water used for irrigation. Our findings improve understanding of the potential differences in the risk of exposure to bacterial pathogens and antibiotic resistance genes originating from diverse irrigation water sources across seasons and U.S. regions.

Occurrence and Quantitative Microbial Risk Assessment of Methicillin-Resistant Staphylococcus aureus (MRSA) in a Sub-Catchment of the Yodo River Basin, Japan

The occurrence of Staphylococcus aureus (S. aureus) and methicillin-resistant S. aureus (MRSA) in a sub-catchment of the Yodo River Basin, a representative water system of a drinking water source in Japan, was investigated. The chromogenic enzyme-substrate medium method was used for the detection of S. aureus and MRSA by the presence or absence of antimicrobials in the medium for viable bacteria in a culture-based setting. The contributions of S. aureus and MRSA from wastewater to the rivers were estimated based on mass flux-based analysis, and quantitative microbial risk assessment (QMRA) was further conducted for S. aureus and MRSA in river environments. The mean abundance of S. aureus and MRSA was 31 and 29 CFU/mL in hospital effluent, 124 and 117 CFU/mL in sewage treatment plant (STP) influent, 16 and 13 CFU/mL in STP effluent, and 8 and 9 CFU/mL in river water, respectively. Contribution of the pollution load derived from the target STP effluent to river water ranged from 2% to 25%. The QMRA showed that to achieve the established health benchmarks, the drinking water treatment process would need to yield 1.7 log10 and 2.9 log10 inactivation in terms of infection risk and disability-adjusted life year (DALY) indexes, respectively. These findings highlight the link between medical environment and the importance of environmental risk management for antimicrobial-resistant bacteria in aquatic environments.

A comparison of soil Staphylococcus aureus and fecal indicator bacteria concentrations across land uses in a Hawaiian watershed

Staphylococcus aureus, methicillin-resistant S. aureus (MRSA), and fecal indicator bacteria (FIB; Enterococcus spp., Clostridium perfringens) concentrations increase in Hawaiian streams and estuaries following storms and pose a health threat to recreational water users. To reduce this risk, watershed bacteria sources need to be identified for management actions. This study's goals were to identify soil bacteria sources among different land uses and to determine if their concentrations were associated with different soil properties. Soil samples were collected three times on 24 d between October 2017 and November 2018 at urban, agriculture, and native-forest land uses in the Hilo Bay watershed, Hawai'i Island, Hawai'i. Soil bacteria concentrations were quantified using culturing techniques with selective media. Staphylococcus aureus, MRSA, and FIB were present in soil from all land uses. Bacteria concentrations were highest in urban soils and lowest in native-forest soils, with up to three orders of magnitude differences among land uses. Staphylococcus aureus, MRSA, and FIB soil concentrations were positively correlated with each other and with soil temperature and pH, but inversely correlated with soil moisture and organic matter content. Our results demonstrate that soils are a watershed bacteria source and that some soil properties affect their concentrations. Identifying these sources is critical for implementing management actions to reduce pathogen loads to estuaries and transmission to recreational water users.

A systematic review on chlorine tolerance among bacteria and standardization of their assessment protocol in wastewater

Though chlorine is a cost-effective disinfectant for water and wastewaters, the bacteria surviving after chlorination pose serious public health and environmental problems. This review critically assesses the mechanism of chlorine disinfection as described by various researchers; factors affecting chlorination efficacy; and the re-growth potential of microbial contaminations in treated wastewater post chlorination to arrive at meaningful doses for ensuring health safety. Literature analysis shows procedural inconsistencies in the assessment of chlorine tolerant bacteria, making it extremely difficult to compare the tolerance characteristics of different reported tolerant bacteria. A comparison of logarithmic reduction after chlorination and the concentration-time values for prominent pathogens led to the generation of a standard protocol for the assessment of chlorine tolerance. The factors that need to be critically monitored include applied chlorine doses, contact time, determination of chlorine demands of the medium, and the consideration of bacterial counts immediately after chlorination and in post chlorinated samples (regrowth). The protocol devised here appropriately assesses the chlorine-tolerant bacteria and urges the scientific community to report the regrowth characteristics as well. This would increase the confidence in data interpretation that can provide a better understanding of chlorine tolerance in bacteria and aid in formulating strategies for effective chlorination.

High Frequency of the EMRSA-15 Clone (ST22-MRSA-IV) in Hospital Wastewater

Hospital wastewaters often carry multidrug-resistant bacteria and priority pathogens, such as methicillin-resistant Staphylococcus aureus (MRSA). Pathogens and antibiotic resistance genes present in wastewaters may reach the natural environment facilitating their spread. Thus, we aimed to isolate MRSA from wastewater of 3 hospitals located in the north of Portugal and to characterize the isolates regarding the antimicrobial resistance and genetic lineages. A total of 96 wastewater samples were collected over six months. The water was filtered, and the filtration membrane was immersed in BHI broth supplemented with 6.5% of NaCl and incubated. The inoculum was streaked in ORSAB agar plates for MRSA isolation. The isolates susceptibility testing was performed against 14 antimicrobial agents. The presence of resistance and virulence genes was accessed by PCR. Molecular typing was performed in all isolates. From the 96 samples, 28 (29.2%) were MRSA-positive. Most isolates had a multidrug-resistant profile and carried the mecA, blaZ, aac(6')-Ie-aph(2″)-Ia, aph(3')-IIIa, ermA, ermB, ermC, tetL, tetM, dfrA dfrG and catpC221 genes. Most of the isolates were ascribed to the immune evasion cluster (IEC) type B. The isolates belonged to ST22-IV, ST8-IV and ST105-II and spa-types t747, t1302, t19963, t6966, t020, t008 and tOur study shows that MRSA can be found over time in hospital wastewater. The wastewater treatment processes can reduce the MRSA load. The great majority of the isolates belonged to ST22 and spa-type t747 which suggests the fitness of these genetic lineages in hospital effluents.

Prevalence and molecular characterization of extended-spectrum β-lactamase (ESBL) producing Escherichia coli isolated from dogs suffering from diarrhea in and around Kolkata

BACKGROUND

Dogs are the favorite companion animals among humans. The close interaction between dogs and people increases the risk of antibiotic resistance spreading. Surveillance for antimicrobial resistance and the identification of ESBL-producing Escherichia coli as an indicator bacterium is an important tool for managing antimicrobial drug therapy.

AIMS

The present study targeted to identify and characterize ESBL-producing E. coli among dogs suffering from diarrhea in and around Kolkata.

METHODS

Isolation and identification of E. coli from dogs suffering from diarrhea (n=70) along with screening for the production of both ESBL and AmpC. The isolates were further characterized through antimicrobial resistance profiling, resistance genes (bla _CTX-M, bla _TEM, and bla _SHV) screening, and phylogenetic group study.

RESULTS

Among the 70 isolates, 21 (30%) were confirmed ESBL producers. An antibiogram typing of ESBL-producing E. coli revealed that the majority of them were resistant to norfloxacin (85.7%) followed by tetracycline (61.90%), doxycycline (57.14%), piperacillin/tazobactam (52.38%), cotrimoxazole (47.62%), gentamicin (42.62%), amikacin (23.81%), and chloramphenicol (19.05%). Major resistance genes included bla _CTX-M (100%), bla _TEM (28.57%), and bla _SHV (9.50%). The predominant phylogenetic groups were phylogroup A (76%) followed by phylogroup D (24%).

CONCLUSION

The current investigation reported a high prevalence of both ESBL and AmpC β-lactamase (AmpC) producing E. coli, co-resistance to a distinct group of antibiotics, and co-existence of different ESBL genes in dogs. Our findings highlight the importance of diagnostic antimicrobial susceptibility testing for proper antimicrobial therapy and to prevent antimicrobial resistance from spreading to humans from dogs in Kolkata and the surrounding area.

Quantitative Microbial Risk Assessment of Antimicrobial Resistant and Susceptible Staphylococcus aureus in Reclaimed Wastewaters

The annual risks of colonization, skin infection, bloodstream infection (BSI), and disease burden from exposures to antibiotic-resistant and susceptible Staphylococcus aureus (S. aureus) were estimated using quantitative microbial risk assessment (QMRA). We estimated the probability of nasal colonization after immersion in wastewater (WW) or greywater (GW) treated across a range of treatment alternatives and subsequent infection. Horizontal gene transfer was incorporated into the treatment model but had little effect on the predicted risk. The cumulative annual probability of infection (resulting from self-inoculation) was most sensitive to the treatment log₁₀ reduction value (LRV), S. aureus concentration, and the newly calculated morbidity ratios and was below the health benchmark of 10^-4 infections per person per year (ppy) given a treatment LRV of roughly 3.0. The predicted annual disability-adjusted life years (DALYs), which were dominated by BSI, were below the health benchmark of 10^-6 DALYs ppy for resistant and susceptible S. aureus, given LRVs of 4.5 and 3.5, respectively. Thus, the estimated infection risks and disease burdens resulting from nasal colonization are below the relevant health benchmarks for risk-based, nonpotable, or potable reuse systems but possibly above for immersion in minimally treated GW or WW. Strain-specific data to characterize dose-response and concentration in WW are needed to substantiate the QMRA.

Functionalized magnetite nanoparticles with Moringa oleifera with potent antibacterial action in wastewater

Contaminations by Staphylococcus aureus in food industry environments have been extended to industrial Effluent Treatment Plant (ETP). The methodologies used in ETP for bacterial removals and quality parameters adjustment commonly use products toxic to the environment, being mostly inefficient against virulent bacteria such as S. aureus. Seeds of Moringa oleifera Lam. (MO) have potential to be used in ETP as an alternative to harmful products, as it has both the ability to regulate the physicochemical parameters of water and has antibacterial action. Functionalization of MO with magnetite magnetic nano particles (Fe₃O₄) at nano scale focusing on coagulation and flocculation of wastewater has been gaining prominence. Therefore, the present study evaluated the potential use of the magnetic coagulant MO-Fe₃O₄ in the elimination of S. aureus in synthetic dairy effluent; concomitantly sought to adjust the quality levels of physicochemical parameters. MO-Fe₃O₄ added to synthetic dairy effluent at different concentrations amounted to 16 treatments, which were evaluated for removal of color, turbidity, UV_254nm and S. aureus on the effluent surface and sludge after 30 min of sedimentation. The results confirmed the efficient elimination of S. aureus simultaneously with a significant reduction of the physicochemical values, with constant efficiency up to 30 min. Scanning electron microscopy images confirm the removal of S. aureus on the effluent surface and sludge. Thus, this study was able to present a natural coagulant capable of remove bacteria and adjust the quality levels of the effluent after 10 min of sedimentation, making this biotechnological innovation highly applicable to ETP.

Decolorization mechanism, identification of an FMN-dependent NADH-azoreductase from a moderately halotolerant Staphylococcus sp. MEH038S, and toxicity assessment of biotransformed metabolites

The application of halotolerant microorganisms capable of decolorizing is attractive. Decolorization mechanism, the effect of different parameters on the decolorization percentage, and toxicity analysis of Reactive Black 5 before and after decolorization were investigated in the present study. The decolorization percentage for live cells of Staphylococcus sp. strain MEH038S was more than dead cells, which demonstrated that Reactive Black 5 was decolorized through the degradation process. The results confirmed that an FMN-dependent NADH-azoreductase gene was responsible for the decolorization and then was identified as Staphylococcus sp. EFS01 azoreductase from a moderately halotolerant Staphylococcus strain for the first time. The maximal decolorization of 98.15% was observed at pH 6.5 and 35 ^° C for 50 mg/L of Reactive Black 5. In addition, more than 90% decolorization was achieved with 5-40 g/L of NaCl. The results of Gas chromatography-mass spectrometry and Fourier transform infrared spectroscopy showed that Reactive Black 5 was broken to the lower molecular weight compounds without any chromophoric azo groups. Phytotoxicity and fish toxicity proved that the biotransformed metabolites of Reactive Black 5 degradation were more toxic than the original dye. The moderate halotolerant strain exhibited a remarkable decolorization capability and can be applied for textile wastewater treatment. PRACTITIONER POINTS: An azoreductase gene from a moderately halotolerant Staphylococcus was identified. More than 90% decolorization efficiency was observed under high-salt conditions. Biotransformed metabolites of RB5 degradation were identified. Toxicity analysis of biotransformed metabolites was investigated.

Association of Fecal Microbiota with Irritable Bowel Syndrome-Diarrhea and Effect of Traditional Chinese Medicine for Its Management

Changes in intestinal microbiota have been linked to the development of diarrhea predominant irritable bowel syndrome (IBS-D). In order to better elucidate the relationship between intestinal microbiota changes and IBS-D, we compared fecal microbiota of IBS-D rats and healthy control using pyrosequencing of bacterial 16S rRNA gene targeted. Furthermore, we explored the effects of different traditional Chinese medicine (TCM) on intestinal microbiota of IBS-D in dose-dependent manner. Our results showed that there was no significant difference in fecal microbial community diversity among the healthy control group, IBS-D rats and IBS-D rats treated with traditional Chinese medicine, but the fecal microbial composition at different taxonomic levels have changed among these groups. Interestingly, the weight of IBS-D rats treated with moderate doses (13.4 g/kg) of TCM increased significantly, and the diarrhea-related symptoms improved significantly, which may be related to the enrichment in Deferribacteres, Proteobacteria, Tenericutes, Lachnospiraceae, and Ruminococcaceae and the reduction in Lactobacillus in fecal samples.

Quantitative microbial risk assessment for occupational health of temporary entrants and staffs equipped with various grade PPE and exposed to microbial bioaerosols in two WWTPs

PURPOSE

This study was to evaluate the occupational health risks of infection from Gram-negative bacteria and Staphylococcus aureus bioaerosols to temporary entrants and staffs equipped with various grade personal protection equipment (PPE) related to wastewater treatment plants (WWTPs).

METHODS

This study determined the emission concentrations of Gram-negative bacteria and Staphylococcus aureus bioaerosols from two WWTPs under various aeration modes. Then, a strict quantitative microbial risk assessment (QMRA) was performed on several exposure scenarios associated with occupational health risks of temporary entrants (researchers, visitors, and inspectors) and staffs (field engineer and laboratory technician).

RESULTS

Although the bioaerosol concentrations were generally regarded as safe according to existing standards, these bioaerosols' health risks were still unacceptable. The microbial bioaerosols posed considerable infection health risks in WWTPs. These risks were generally above the WHO and US EPA benchmarks. The health risks of females were always smaller than those of male of grown-up age group. Staffs that had been exposed to bioaerosols for a long time were found to have higher health risks compared with temporary entrants. In addition, field engineers equipped with PPE rendered low health risks, thus revealing that wearing PPE could effectively reduce the occupational health risks.

CONCLUSION

This study provided novel data and enriched the knowledge of microbial bioaerosol emission's health risks from various aeration modes in WWTPs. Management decisions could be executed by authorities on the basis of the results of QMRA for field engineers equipped with PPE to reduce the related occupational health risks.

Urban wastewater as a conduit for pathogenic Gram-positive bacteria and genes encoding resistance to β-lactams and glycopeptides

The emergence and spread of clinical pathogens, antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs) in the environment pose a direct threat to human and animal health worldwide. In this study, we analyzed qualitatively and quantitatively urban sewage resistome for the occurrence of genes encoding resistance to β-lactams and glycopeptides in the genomes of culturable bacteria, as well as in the wastewater metagenome of the Central Wastewater Treatment Plant in Koziegłowy (Poland). Moreover, we estimated the presence of pathogenic Gram-positive bacteria in wastewater based on analysis of species-specific virulence genes in the wastewater metagenome. The results show that the final effluent contains alarm pathogens with particularly dangerous mechanisms of antibiotic resistance, including methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE). We also noticed that during the wastewater treatment, there is an increase in the frequency of MRSA and VRE. Furthermore, the results prove the effective removal of vanA, but at the same time show that wastewater treatment increases the relative abundance of mecA and virulence genes (groES and sec), indicating the presence of clinical pathogens E. faecalis and S. aureus in the effluent released to surface waters. We also observed an increase in the relative abundance of mecA and vanA genes already in the aeration tank, which suggests accumulation of contaminants affecting enhanced selection and HGT processes in the activated sludge. Moreover, we found a relation between the taxonomic composition and the copy number of ARGs as well as the presence of pathogens at various stages of wastewater treatment. The presence of clinically relevant pathogens, ARB, including multi-resistant bacteria, and ARGs in the effluent indicates that wastewater treatment plant play a key role in the existence of pathogens and antimicrobial resistance spreading pathway in the environment and human communities, which is a direct threat to public health and environmental protection.

Characterization of methicillin-resistant Staphylococcus aureus strains in sewage treatment plants in Tehran, Iran

Multidrug-resistant Staphylococcus aureus strains have been commonly found in hospitals and communities causing wide ranges of infections among humans and animals. Typing of these strains is a key factor to reveal their clonal dissemination in different regions. We investigated the prevalence and dissemination of different clonal groups of S. aureus with resistance phenotype to multiple antibiotics in two sewage treatment plants (STPs) in Tehran, Iran over four sampling occasions. A total of 576 S. aureus were isolated from the inlet, sludge and outlet. Of these, 80 were identified as methicillin-resistant S. aureus (MRSA) and were further characterized using a combination of Phene Plate (PhP) typing, staphylococcal cassette chromosome mec (SCCmec), ccr types, prophage and antibiotic-resistant profiling. In all, eight common type (CT) and 13 single PhP type were identified in both STPs, with one major CT accounting for 38.8% of the MRSA strains. These strains belonged to three prophage patterns and five prophage types with SCCmec type III being the predominant type. Resistance to 11 out of the 17 antibiotics tested was significantly (P < 0.0059) higher among the MRSA isolates than methicillin-sensitive S. aureus (MSSA) strains. The persistence of the strains in samples collected from the outlet of both STPs was 31.9% for MRSA and 23.1% for MSSA. These data indicated that while the sewage treatment process, in general, is still useful for removing most MRSA populations, some strains with SCCmec type III may have a better ability to survive the STP process.

Degradation Kinetics of Antibiotic Resistance Gene mecA of Methicillin-Resistant Staphylococcus aureus (MRSA) during Water Disinfection with Chlorine, Ozone, and Ultraviolet Light

Degradation kinetics of antibiotic resistance genes (ARGs) by free available chlorine (FAC), ozone (O₃), and UV₂₅₄ light (UV) were investigated in phosphate buffered solutions at pH 7 using a chromosomal ARG (mecA) of methicillin-resistant Staphylococcus aureus (MRSA). For FAC, the degradation rates of extracellular mecA (extra-mecA) were accelerated with increasing FAC exposure, which could be explained by a two-step FAC reaction model. The degradation of extra-mecA by O₃ followed second-order reaction kinetics. The degradation of extra-mecA by UV exhibited tailing kinetics, which could be described by a newly proposed kinetic model considering cyclobutane pyrimidine dimer (CPD) formation, its photoreversal, and irreversible (6-4) photoproduct formation. Measured rate constants for extra-mecA increased linearly with amplicon length for FAC and O₃, or with number of intrastrand pyrimidine doublets for UV, which enabled prediction of degradation rate constants of extra-mecA amplicons based on sequence length and/or composition. In comparison to those of extra-mecA, the observed degradation rates of intracellular mecA (intra-mecA) were faster for FAC and O₃ at low oxidant exposures but significantly slower at high exposures for FAC and UV. Differences in observed extra- and intracellular kinetics could be due to decreased DNA recovery efficiency and/or the presence of MRSA aggregates protected from disinfectants.

Antibiotic-resistant staphylococci from the wastewater treatment plant and grey-water samples in Obafemi Awolowo University, Ile-Ife, Nigeria

This study examined the occurrence and molecular basis for antibiotic-resistant staphylococci from the wastewater treatment plant and grey-water samples in Obafemi Awolowo University, Nigeria. Standard microbiological techniques and molecular methods were utilized. The species identified (MALDI score >1.7) comprised S. saprophyticus (19), S. cohnii (8), S. sciuri (7), S. aureus (4), S. epidermidis (3), S. warneri (2), S. equorum (1), S. haemolyticus (1), S. nepalensis (1), S. condimenti (1), and S. pasteuri (1). Resistance to trimethoprim, tetracycline and cefoxitin were observed in 78.3% (47/60), 36.7% (22/60) and 25% (15/60) of the isolates, respectively. The rate of multidrug resistance was 53.3% (32/60) and observed in eight species from different sampling sites. Seven (S. sciuri; n = 5; S. aureus; n = 1; S. warneri; n = 1) of the 20 selected (representing the various staphylococcal species and antibiotypes) isolates were mecA-positive. Furthermore, the tetK gene was detected in nine isolates, six with dfrA, and four were positive for the dfrG gene. One S. aureus was mecA, tetK and dfrG gene positive. The study provides insights on antibiotic-resistant staphylococci from a non-clinical setting and highlights the need for active surveillance to understand the burden of antimicrobial resistance in Nigeria. This is key to improve synergy across the human, animal and environmental health sectors in Nigeria.

Evaluation of bacterial contamination and mutagenic potential of treated wastewater from Al-Samra wastewater treatment plant in Jordan

Jordan is one of the lowest countries in the world in terms of water resources. The reuse of treated wastewater is an important alternative to supply agricultural demands for water. In Jordan, Kherbet Al-Samra wastewater treatment plant (KSWWTP) is the largest and its effluent is mainly used for irrigation purposes. In this study, bacterial contamination and mutagenic potential were evaluated in six sites, beginning with KSWWTP and ending with King Tallal Dam. The results showed high contamination with many pathogenic bacteria and coliforms. The isolated pathogenic bacteria were Salmonella sp., Shigella sp., Bacillus cereus and Staphylococcus aureus. The isolated opportunistic pathogenic bacteria were Acinetobacter lwoffii, Elizabethkingia meningosepticum, Pseudomonas fluorescens and Bacillus licheniformis. These bacteria were found in all sampling sites without a specific prevalence pattern. Differences in temperature between seasons affect total coliform and other bacterial count. All water samples showed positive mutagenic activity and high bacterial pollution. Improving the disinfection efficiency in the wastewater treatment plant is important to minimize potential toxicity and exposure of public health to pathogenic bacteria, reduce water resources' contamination and environmental pollution. Increasing effluent sampling frequency from KSWWTP is required to monitor bacterial contamination and toxicity/mutagenicity level for water safety and public health risk assessments.

Treatment Processes for Microbial Resistance Mitigation: The Technological Contribution to Tackle the Problem of Antibiotic Resistance

Advances generated in medicine, science, and technology have contributed to a better quality of life in recent years; however, antimicrobial resistance has also benefited from these advances, creating various environmental and health problems. Several determinants may explain the problem of antimicrobial resistance, such as wastewater treatment plants that represent a powerful agent for the promotion of antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARG), and are an important factor in mitigating the problem. This article focuses on reviewing current technologies for ARB and ARG removal treatments, which include disinfection, constructed wetlands, advanced oxidation processes (AOP), anaerobic, aerobic, or combined treatments, and nanomaterial-based treatments. Some of these technologies are highly intensive, such as AOP; however, other technologies require long treatment times or high doses of oxidizing agents. From this review, it can be concluded that treatment technologies must be significantly enhanced before the environmental and heath problems associated with antimicrobial resistance can be effectively solved. In either case, it is necessary to achieve total removal of bacteria and genes to avoid the possibility of regrowth given by the favorable environmental conditions at treatment plant facilities.

Metabolically-active bacteria in reclaimed water and ponds revealed using bromodeoxyuridine DNA labeling coupled with 16S rRNA and shotgun sequencing

Understanding the complex microbiota of agricultural irrigation water is vital to multiple sectors of sustainable agriculture and public health. To date, microbiome characterization methods have provided comprehensive profiles of aquatic microbiotas, but have not described which taxa are likely metabolically-active. Here, we combined 5‑bromo‑2'-deoxyuridine (BrdU) labeling with 16S rRNA and shotgun sequencing to identify metabolically-active bacteria in reclaimed and agricultural pond water samples (n = 28) recovered from the Mid-Atlantic United States between March 2017 and January 2018. BrdU-treated samples were significantly less diverse (alpha diversity) compared to non-BrdU-treated samples. The most abundant taxa in the metabolically-active fraction of water samples (BrdU-treated samples) were unclassified Actinobacteria, Flavobacterium spp., Pseudomonas spp. and Aeromonas spp. Interestingly, we also observed that antimicrobial resistance and virulence gene profiles seemed to be more diverse and more abundant in non-BrdU-treated water samples compared to BrdU-treated samples. These findings raise the possibility that these genes may be associated more with relic (inactive) DNA present in the tested water types rather than viable, metabolically-active microorganisms. Our study demonstrates that the coupled use of BrdU labeling and sequencing can enhance understanding of the metabolically-active fraction of bacterial communities in alternative irrigation water sources. Agricultural pond and reclaimed waters are vital to the future of sustainable agriculture, and thus, the full understanding of the pathogenic potential of these waters is important to guide mitigation strategies that ensure appropriate water quality for intended purposes.

The prevalence of drug-resistant and virulent Staphylococcus spp. in a municipal wastewater treatment plant and their spread in the environment

Drug-resistant and pathogenic Staphylococcus spp. strains can reach surface waters and air with wastewater evacuated to the environment. These strains increase the environmental pool of genetic determinants conferring antibiotic resistance and virulence, and constitute a health risk for the employees of wastewater treatment plants (WWTP) who come into daily contact with bioaerosols. The aim of this study was to identify the genetic determinants of drug resistance and virulence in Staphylococcus spp. strains isolated from untreated (UWW) and treated wastewater (TWW), an activated sludge (AS) bioreactor, river water collected upstream and downstream from the wastewater discharge point (URW and DRW), and WWTP employees. All isolates were analysed for the presence of the rpoB gene, and were subjected to clonal analysis by ERIC fingerprinting. As a result, 249 of the 455 analysed isolates were selected for PCR. The presence of the gene encoding nuclease activity in S. aureus (nuc), the methicillin resistance gene (mecA), vancomycin resistance gene (vanA), antiseptic resistance gene (qacA/B) and virulence genes (sasX, pvl, tst1, hla, sec) was determined. The prevalence of nuc, mecA, vanA and qacA/B genes in wastewater and river water was determined by quantitative PCR (qPCR). In the group of strains isolated from wastewater and water samples, 63% were identified as S. aureus, and 20% of the strains carried the vanA gene. The hla virulence gene was present in 80% of the isolates, and the pvl gene was detected in 27% of the isolates. In the group of strains isolated from the employees, 82% were identified as S. aureus, and the presence of vanA and mecA genes was confirmed in 14% and 16% of the isolates, respectively. The most prevalent virulence gene was hla (74%), whereas pvl was observed in 43% of the isolates. The quantitative analysis revealed the highest concentrations of the studied genes in UWW samples, at 2.56x10⁴ gene copies/ml for nuc, 1.18x10³ gene copies /ml for mecA, 8.28x10⁵ gene copies /ml for vanA and 3.83x10⁵ gene copies /ml for qacA/B. Some of analysed genes were identified in the isolates from both URW and DRW samples, as well as in genomic DNA of these samples. These results indicate that wastewater is not effectively treated in the analysed WWTP, which could contribute to the dissemination of antibiotic resistance genes (ARGs) and antibiotic-resistant bacteria (ARB) to the environment. An analysis of the genetic relatedness of selected isolates revealed clusters of strains originating from UWW samples, AS samples and the employees. These observations suggest that ARGs and ARB are transmitted by wastewater bioaerosols to the upper respiratory tract mucosa of the plant's employees, thus increasing their exposure to infectious factors.

Multidrug-resistance in methicillin-resistant Staphylococcus aureus (MRSA) isolated from a subtropical river contaminated by nearby livestock industries

Methicillin-resistant Staphylococcus aureus (MRSA) is a major threat to public health that causes infections in hospitals, communities, and animal husbandry. Livestock-associated MRSA (LA-MRSA) is defined as MRSA possessing staphylococcal cassette chromosome mec (SCCmec) IV or V, both of which lacks the Panton-Valentine leukocidin (PVL) gene but has variable combinations of antimicrobial susceptibility. This study focused on Taiwan's subtropical river basin and the Puzih River, which converges from tributaries flowing through downtown and animal husbandry areas. MRSA was detected at a rate of 7.8% in the tributaries, which was higher than downstream (2.1%). The ratio of multidrug-resistant (MDR) MRSA (n = 30) to total MRSA isolates (n = 39) was 0.769, and most of the MDR MRSA isolates (66.7%, 20/30) exhibited resistance to chloramphenicol, ciprofloxacin, clindamycin, erythromycin, sulfamethoxazole-trimethoprim, and tetracycline. The number of MDR MRSA isolates in the tributaries was also higher than the downstream regions of the Puzih River. The majority of MRSA isolates (64.1%) observed in this study possessed SCCmec type IV without PVL, which is typical for LA-MRSA. Enterobacterial repetitive intergenic consensus PCR (ERIC-PCR) typing aided the discrimination of resistance patterns among SCCmec types. This study highlights the threat to human health posed by the waterborne transmission of MDR LA-MRSA.

Antibiotic-resistant Escherichia coli and Klebsiella spp. in greywater reuse systems and pond water used for agricultural irrigation in the West Bank, Palestinian Territories

Treating and reusing greywater for agricultural irrigation is becoming increasingly prevalent in water-scarce regions such as the Middle East. However, the potential for antibiotic-resistant bacteria to be introduced into food systems or the environment via greywater reuse is a potential area of concern. It is known that off-grid treated greywater often has elevated levels of bacteria, however, little is known regarding the prevalence of antibiotic-resistant bacteria in this water source. To address this knowledge gap, samples (n = 61) of off-grid, household greywater (influent), treated greywater effluent, and irrigation pond water were collected between October 2017 and June 2018 from four farms in the West Bank, Palestinian Territories. Samples were tested for pH, turbidity, dissolved oxygen, electrical conductivity, and oxidation reduction potential. Standard membrane filtration was used to enumerate presumptive Escherichia coli, and isolates (n = 88) were purified, confirmed using 16S rRNA sequencing, and subjected to antimicrobial susceptibility testing using microbroth dilution. The majority of influent (76.5%) and effluent (70.6%) samples had detectable presumptive E. coli. Interestingly, the majority of the isolates were confirmed as Klebsiella sp. (n = 37), followed by E. coli (n = 32), and the remainder were classified as other Enterobacteriaceae (n = 19). A higher percentage of effluent isolates were fully susceptible to all tested antibiotics when compared to influent isolates (28.6% vs 18.6%). Resistance was most commonly observed against ampicillin (69.3% of all isolates), trimethoprim-sulfamethoxazole (11.4%), tetracycline (9.1%), and cefazolin (7.9%), and 7.9% of isolates were observed to be multidrug-resistant. While most water quality parameters were within Israeli and Palestinian wastewater reuse requirements, E. coli levels in effluent violated available standards. These findings suggest that, despite observed decreases in bacteria and an overall decrease in isolates expressing antibiotic resistance from influent to effluent, off-grid greywater treatment systems are still a potential source of both susceptible and antibiotic-resistant bacteria in the agricultural environment.

Effects of tourist flows on antibiotic resistance in wastewater of a Greek island

AIM

Antibiotic resistance in wastewaters reflects the clinical resistome. This study aimed at investigating whether changes in the population size and composition in the popular tourist destination of Zakynthos island are associated with differentiation in the antibiotic resistance of environmental micro-organisms isolated from wastewater.

METHODS AND RESULTS

The resistance profiles of four species (Escherichia coli, Staphylococcus sp., Pseudomonas sp. and Enterococcus sp.) were studied in 124 raw and treated municipal wastewaters from November 2015 to August 2016. Isolates were tested against their susceptibility to several antibiotics of different antimicrobial categories. Data concerning the alteration in the population size and composition, due to the tourist mobility, were collected and logistic regression models were used to examine the relationships between antimicrobial resistance and population changes. The decrease in resistance of E. coli to amoxicillin-clavulanate, of enterococci to norfloxacin and ampicillin, and of pseudomonads to almost all antibiotics tested was associated with population increase due to tourist flows. In contrast, the presence of tourists was linked to an increase in quinupristin-dalfopristin resistant enterococci. Resistance of staphylococci did not change during the tourist period.

CONCLUSION

Changes in population composition in touristic areas are reflected in antibiotic resistance of environmental bacteria in wastewater.

SIGNIFICANCE AND IMPACT OF THE STUDY

In touristic areas, where people carrying different resistomes are merged, medication should be adapted accordingly.

Antimicrobial Resistance of Staphylococcus aureus Isolated from Hospital Wastewater in Kermanshah, Iran

Introduction

Hospital wastewater contains highly resistant and virulent bacteria that can spread into the environment. This study was conducted to investigate the antimicrobial resistance of methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-sensitive S. aureus (MSSA) in raw and treated hospital wastewater.

Methods

During a three-month period, 40 sewage samples were collected from the hospital sewage (Kermanshah, Iran), and S. aureus were identified using culture and biochemical tests. MRSA was detected by resistance to cefoxitin. Antibiotic resistance (AR) was determined using disk diffusion according to the Clinical and Laboratory Standards Institute (CLSI) in 20 MSSA (10 raw and 10 treated sewage) and 40 MRSA isolates (20 raw and 20 treated sewage). The antimicrobial resistance genes (ARGs) were determined by PCR.

Results

Eleven and eight percent of the isolates were MRSA in raw and treated sewage samples, respectively. Out of 60 isolates, 59 (98%) were multidrug resistant (MDR). The most common ARGs were mecA (raw=100%, treated=100%), aacA-D (raw=100%, treated=85%) and tetK (raw =95%, treated =45%) in MRSA, while the tetM gene was the most abundant gene (raw=50%, treated=80%) in MSSA. None of isolates (n=60) was positive for the vanB gene. MSSR (n=20) had the highest level of resistance against penicillin (100%), clindamycin (raw=90%, treated=90%), azithromycin (raw=80%, treated=90%). All MRSA isolates (n=40,100%) in both raw and treated sewage samples were non-susceptible to penicillin, oxacillin and azithromycin. There was no significant difference in the frequency AR and ARGs between raw and treated sewage samples (p>0.05).

Conclusion

The results indicated a high frequency of MDR and ARGs in both raw and treated sewage isolates which could be released into the environment through sewage system and pose a serious threat to public health. Hospital wastewater treatment processes should be improved in order to prevent the dissemination of the most resistant strains of S. aureus.

Antibiotic-resistant bacteria and antimicrobial residues in wastewater and process water from German pig slaughterhouses and their receiving municipal wastewater treatment plants

Slaughterhouse process- and wastewater are considered as a hotspot for antibiotic-resistant bacteria and antimicrobial residues and may thus play an important role for their dissemination into the environment. In this study, we investigated occurrence and characteristics of ESKAPE bacteria (E. faecium, S. aureus, K. pneumoniae, A. baumannii, P. aeruginosa, Enterobacter spp.) and ESBL (extended spectrum β-lactamase) -producing E. coli in water samples of different processing stages of two German pig slaughterhouses (S1/S2) as well as their municipal wastewater treatment plants (mWWTPs). Furthermore, residues of various antimicrobials were determined. A total of 103 water samples were taken in delivery and dirty areas of the slaughterhouses S1/S2 (n = 37), their in-house WWTPs (n = 30) and mWWTPs including their receiving water bodies (n = 36). The recovered isolates (n = 886) were characterized for their antimicrobial resistance pattern and its genetic basis. Targeted species were ubiquitous along the slaughtering and wastewater chains. Phenotypic and genotypic analyses revealed a broad variety of resistance phenotypes and β-lactamase genes. Carbapenemase-producing Enterobacteriaceae (CPE), vancomycin-resistant enterococci (VRE) and healthcare-associated (HA) MRSA were recovered only from mWWTPs and their preflooders. In contrast, the mcr-1 gene was exclusively detected in E. coli from S1/S2. Residues of five antimicrobials were detected in 14.9% (10/67) of S1/S2 samples in low range concentrations (≤1.30 μg/L), whereas 91.7% (33/36) of mWWTPs samples exhibited residues of 22 different antibiotics in concentrations of up to 4.20 μg/L. Target bacteria from S1/S2 and mWWTPs exhibited differences in their abundances, resistance phenotypes and genotypes as well as clonal lineages. S1/S2 samples exhibited bacteria with zoonotic potential (e.g. MRSA of CC398, E. coli of significant clones), whereas ESKAPE bacteria exhibiting resistances of clinical importance were mainly detected in mWWTPs. Municipal WWTPs seem to fail to eliminate these bacteria leading to a discharge into the preflooder and a subsequent dissemination into the surface water.

ESKAPE Bacteria and Extended-Spectrum-β-Lactamase-Producing Escherichia coli Isolated from Wastewater and Process Water from German Poultry Slaughterhouses

The wastewater of livestock slaughterhouses is considered a source of antimicrobial-resistant bacteria with clinical relevance and may thus be important for their dissemination into the environment. To get an overview of their occurrence and characteristics, we investigated process water (n = 50) from delivery and unclean areas as well as wastewater (n = 32) from the in-house wastewater treatment plants (WWTPs) of two German poultry slaughterhouses (slaughterhouses S1 and S2). The samples were screened for ESKAPE bacteria (Enterococcus spp., Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Enterobacter spp.) and Escherichia coli Their antimicrobial resistance phenotypes and the presence of extended-spectrum-β-lactamase (ESBL), carbapenemase, and mobilizable colistin resistance genes were determined. Selected ESKAPE bacteria were epidemiologically classified using different molecular typing techniques. At least one of the target species was detected in 87.5% (n = 28/32) of the wastewater samples and 86.0% (n = 43/50) of the process water samples. The vast majority of the recovered isolates (94.9%, n = 448/472) was represented by E. coli (39.4%), the A. calcoaceticus-A. baumannii (ACB) complex (32.4%), S. aureus (12.3%), and K. pneumoniae (10.8%), which were widely distributed in the delivery and unclean areas of the individual slaughterhouses, including their wastewater effluents. Enterobacter spp., Enterococcus spp., and P. aeruginosa were less abundant and made up 5.1% of the isolates. Phenotypic and genotypic analyses revealed that the recovered isolates exhibited diverse resistance phenotypes and β-lactamase genes. In conclusion, wastewater effluents from the investigated poultry slaughterhouses exhibited clinically relevant bacteria (E. coli, methicillin-resistant S. aureus, K. pneumoniae, and species of the ACB and Enterobacter cloacae complexes) that contribute to the dissemination of clinically relevant resistances (i.e., blaCTX-M or blaSHV and mcr-1) in the environment.IMPORTANCE Bacteria from livestock may be opportunistic pathogens and carriers of clinically relevant resistance genes, as many antimicrobials are used in both veterinary and human medicine. They may be released into the environment from wastewater treatment plants (WWTPs), which are influenced by wastewater from slaughterhouses, thereby endangering public health. Moreover, process water that accumulates during the slaughtering of poultry is an important reservoir for livestock-associated multidrug-resistant bacteria and may serve as a vector of transmission to occupationally exposed slaughterhouse employees. Mitigation solutions aimed at the reduction of the bacterial discharge into the production water circuit as well as interventions against their further transmission and dissemination need to be elaborated. Furthermore, the efficacy of in-house WWTPs needs to be questioned. Reliable data on the occurrence and diversity of clinically relevant bacteria within the slaughtering production chain and in the WWTP effluents in Germany will help to assess their impact on public and environmental health.

Enhanced Antibacterial Property of Sulfate-Doped Ag3PO4 Nanoparticles Supported on PAN Electrospun Nanofibers

Heterojunction nanofibers of PAN decorated with sulfate doped Ag₃PO₄ nanoparticles (SO₄²⁻-Ag₃PO₄/PAN electrospun nanofibers) were successfully fabricated by combining simple and versatile electrospinning technique with ion exchange reaction. The novel material possessing good flexibility could exhibit superior antibacterial property over sulfate undoped species (Ag₃PO₄/PAN electrospun nanofibers). FESEM, XRD, FTIR, XPS and DRS were applied to characterize the morphology, phase structure, bonding configuration, elemental composition, and optical properties of the as fabricated samples. FESEM characterization confirmed the successful incorporation of SO₄²⁻-Ag₃PO₄ nanoparticles on PAN electrospun nanofibers. The doping of SO₄²⁻ ions into Ag₃PO₄ crystal lattice by replacing PO₄³⁻ ions can provide sufficient electron-hole separation capability to the SO₄²⁻-Ag₃PO₄/PAN heterojunction to generate reactive oxygen species (ROS) under visible light irradiation and enhances its antibacterial performance. Finally, we hope this work may offer a new paradigm to design and fabricate other types of flexible self-supporting negative-ions-doped heterojunction nanofibers using electrospinning technique for bactericidal applications.

Prevalence of Methicillin-Resistant Staphylococcus aureus in Shrines

Methicillin-resistant Staphylococcus aureus (MRSA) infection in human beings and animals is concerning; it stands out as one of the leading agents causing nosocomial and community infections. Also, marginally increasing drug resistance in MRSA has limited therapeutic options. This study focuses on estimating the prevalence of MRSA in shrines, a place where human and animal interaction is frequent, sharing antibiotic-resistant bacteria, antibiotic-resistant genes, and diseases. A total of 120 environmental swabs were collected from targeted areas during the study period, March 2018 to May 2018. Staphylococcus aureus was identified by growth on mannitol salt agar (MSA), and MRSA by growth on mannitol salt agar containing 4 μg Oxacillin, Gram staining, and conventional biochemical test. Isolates of S. aureus were characterized by antibiotic susceptibility testing using the disc diffusion method. MRSA and methicillin-sensitive S. aureus (MSSA) proportion were 19% and 81%, respectively; a high rate of MRSA was observed in isolates from Thapathali (28.6%). MSSA isolates showed a high rate of resistance to erythromycin (64.7%). MRSA isolates were resistant to gentamicin (50%), cotrimoxazole (25%), erythromycin (50%), and ciprofloxacin (25%). The isolates were susceptible to linezolid (100%), clindamycin (100%), ciprofloxacin (75%), erythromycin (50%), tetracycline (100%), and cotrimoxazole (75%). Intermediate resistance was also found in gentamicin (50%). Of the 11 MSSA isolates that were erythromycin resistant and clindamycin sensitive, 6 (54.5%) showed the inducible clindamycin resistance (ICR) pattern and 2 MRSA isolates that were erythromycin resistant and clindamycin sensitive showed ICR pattern. Fifteen MSSA isolates were β-lactamase positive, whereas only two MRSA isolates showed β-lactamase production. There exists a minimal research work on infectious diseases that are shared between primates and animals. This study suggests the pervasiveness of MRSA/MSSA in the shrines, which may be a primary place for pathogen exchange between humans and primates.

Multi-drug resistance traits of methicillin-resistant Staphylococcus aureus and other Staphylococcal species from clinical and environmental sources

Multi-drug resistance traits of Staphylococcus species especially methicillin-resistant Staphylococcus aureus (MRSA) in the clinical settings are well established. Of environmental concern is hospital effluents discharging into wastewaters. This article investigated the prevalence and detection of antibiotic resistance genes in Staphylococcus species from clinical and environmental sources in Ile-Ife, Nigeria. Standard culture-based and molecular protocols were used. Seventy-six (27 clinical, 14 hospital effluent and 35 environmental) Staphylococcus isolates were recovered: 56.58% were coagulase-negative and 43.42% coagulase-positive (S. aureus). For the clinical isolates, 10, 6, 4, 4 and 1 were isolated from urine, skin, wounds, blood and pus, respectively. Isolates were resistant to methicillin and amoxycillin (91.7%), cloxacillin (88.0%), ciprofloxacin (84.0%), ofloxacin (83.3%), azithromycin (78.0%), ceftazidime (76.0%), gentamycin (75.0%), cefuroxime (75.0%) and erythromycin (72.0%). Nearly, all isolates (90.8%) had multiple antibiotic resistance (MAR) index >0.2. Overall MAR indices for Staphylococcus species isolated from the clinical, hospital effluent and environmental wastewaters were relatively similar (0.482; 0.500; 0.435). mecA, nuc and luk-pvl genes were detected in S. aureus, while mecA was detected in S. arlettae, S. sciuri, S. cohnii, S. epidermidis and S. saprophyticus. This study informs on the potential contamination of environmental waters downstream from hospitals and possible impacts that this could have on human and animal health.

Airborne Staphylococcus aureus in different environments-a review

The aim of the literature review was to describe the environments where the presence of airborne Staphylococcus aureus was confirmed and to catalogue the most often used methods and conditions of bioaerosol sampling to identify the bacteria. The basis for searching of studies on S. aureus in the bioaerosol in different environments was PubMed database resources from the years 1990-2019 (May). The review included studies which were carried on in selected environments: hospitals and other health care facilities, large-scale animal breeding, wastewater treatment plants, residential areas, educational institutions, and other public places. The highest concentrations and genetic diversity of identified S. aureus strains, including MRSA (methicillin-resistant S. aureus), have been shown in large-scale animal breeding. The role of the airborne transmission in dissemination of infection caused by these pathogens is empirically confirmed in environmental studies. Commonly available, well-described, and relatively inexpensive methods of sampling, identification, and subtyping guarantee a high reliability of results and allow to obtain fast and verifiable outcomes in environmental studies on air transmission routes of S. aureus strains.

Identification of discriminatory antibiotic resistance genes among environmental resistomes using extremely randomized tree algorithm

BACKGROUND

The interconnectivities of built and natural environments can serve as conduits for the proliferation and dissemination of antibiotic resistance genes (ARGs). Several studies have compared the broad spectrum of ARGs (i.e., "resistomes") in various environmental compartments, but there is a need to identify unique ARG occurrence patterns (i.e., "discriminatory ARGs"), characteristic of each environment. Such an approach will help to identify factors influencing ARG proliferation, facilitate development of relative comparisons of the ARGs distinguishing various environments, and help pave the way towards ranking environments based on their likelihood of contributing to the spread of clinically relevant antibiotic resistance. Here we formulate and demonstrate an approach using an extremely randomized tree (ERT) algorithm combined with a Bayesian optimization technique to capture ARG variability in environmental samples and identify the discriminatory ARGs. The potential of ERT for identifying discriminatory ARGs was first evaluated using in silico metagenomic datasets (simulated metagenomic Illumina sequencing data) with known variability. The application of ERT was then demonstrated through analyses using publicly available and in-house metagenomic datasets associated with (1) different aquatic habitats (e.g., river, wastewater influent, hospital effluent, and dairy farm effluent) to compare resistomes between distinct environments and (2) different river samples (i.e., Amazon, Kalamas, and Cam Rivers) to compare resistome characteristics of similar environments.

RESULTS

The approach was found to readily identify discriminatory ARGs in the in silico datasets. Also, it was not found to be biased towards ARGs with high relative abundance, which is a common limitation of feature projection methods, and instead only captured those ARGs that elicited significant profiles. Analyses of publicly available metagenomic datasets further demonstrated that the ERT approach can effectively differentiate real-world environmental samples and identify discriminatory ARGs based on pre-defined categorizing schemes.

CONCLUSIONS

Here a new methodology was formulated to characterize and compare variances in ARG profiles between metagenomic data sets derived from similar/dissimilar environments. Specifically, identification of discriminatory ARGs among samples representing various environments can be identified based on factors of interest. The methodology could prove to be a particularly useful tool for ARG surveillance and the assessment of the effectiveness of strategies for mitigating the spread of antibiotic resistance. The python package is hosted in the Git repository: https://github.com/gaarangoa/ExtrARG.

Longitudinal Comparison of Bacterial Diversity and Antibiotic Resistance Genes in New York City Sewage

Urban sewage or wastewater is a diverse source of bacterial growth, as well as a hot spot for the development of environmental antibiotic resistance, which can in turn influence the health of the residents of the city. As part of a larger study to characterize the urban New York City microbial metagenome, we collected raw sewage samples representing three seasonal time points spanning the five boroughs of NYC and went on to characterize the microbiome and the presence of a range of antibiotic resistance genes. Through this study, we have established a baseline microbial population and antibiotic resistance abundance in NYC sewage which can prove to be very useful in studying the load of antibiotic usage, as well as for developing effective measures in antibiotic stewardship.

Bacterial resistance to antibiotics is a pressing health issue around the world, not only in health care settings but also in the community and environment, particularly in crowded urban populations. The aim of our work was to characterize the microbial populations in sewage and the spread of antibiotic resistance within New York City (NYC). Here, we investigated the structure of the microbiome and the prevalence of antibiotic resistance genes in raw sewage samples collected from the fourteen NYC Department of Environmental Protection wastewater treatment plants, distributed across the five NYC boroughs. Sewage, a direct output of anthropogenic activity and a reservoir of microbes, provides an ecological niche to examine the spread of antibiotic resistance. Taxonomic diversity analysis revealed a largely similar and stable bacterial population structure across all the samples, which was found to be similar over three time points in an annual cycle, as well as in the five NYC boroughs. All samples were positive for the presence of the seven antibiotic resistance genes tested, based on real-time quantitative PCR assays, with higher levels observed for tetracycline resistance genes at all time points. For five of the seven genes, abundances were significantly higher in May than in February and August. This study provides characteristics of the NYC sewage resistome in the context of the overall bacterial populations.

IMPORTANCE Urban sewage or wastewater is a diverse source of bacterial growth, as well as a hot spot for the development of environmental antibiotic resistance, which can in turn influence the health of the residents of the city. As part of a larger study to characterize the urban New York City microbial metagenome, we collected raw sewage samples representing three seasonal time points spanning the five boroughs of NYC and went on to characterize the microbiome and the presence of a range of antibiotic resistance genes. Through this study, we have established a baseline microbial population and antibiotic resistance abundance in NYC sewage which can prove to be very useful in studying the load of antibiotic usage, as well as for developing effective measures in antibiotic stewardship.

Prevalence and characterization of Staphylococcus aureus in wastewater treatment plants by whole genomic sequencing

Infections with Staphylococcus aureus are being spread through contact with the community environment, but the role of wastewater treatment plants in the transmission routes is not defined. This study investigated the prevalence, types, genetic elements, and potential for transmission of S. aureus by these engineered systems. Synchronized sampling events at two wastewater treatment plants were conducted with isolates of S. aureus obtained by a selective enrichment method using acriflavine that suppressed Staphylococcus epidermidis growth. DNA was extracted from a subset of the S. aureus isolates, checked by PCR to assure the absence of S. epidermidis, and sequenced to determine the multilocus sequence type, spa type, and carriage of the methicillin resistance and Panton-Valentine leukocidin genetic elements. Sequences were analyzed for single nucleotide polymorphism differences in pairwise comparison of isolates. There were two dominant S. aureus clonal complexes identified in the isolates, one commonly identified as hospital-related (CC5) and one community-related (CC8). Both types of isolates were found at both treatment facilities, even though only one facility had significant hospital sewage inputs. The presence of S. aureus persisted through treatment, with some isolates recovered from the final processes showing genetic diversity. The presence of the Panton-Valentine leukocidin genetic element was greater than the 1-5% expected from global reports. Our results suggest that treatment provides an opportunity for genetic shift, while the persistence and release of evolved strains of S. aureus may provide an environmentally relevant pathway to new hosts in the environment.

A survey of antimicrobial resistance in Enterobacteriaceae isolated from the Chesapeake Bay and adjacent upper tributaries

In recent years, the rise in antimicrobial resistance (AR) in the healthcare setting as well as the environment has been recognized as a growing public health problem. The Chesapeake Bay (CB) and its upper tributaries (UT) is a large and biologically diverse estuary. This pilot study evaluated the presence of AR of gram‐negative bacteria isolated from water samples collected at various sites of the Chesapeake Bay. Bacterial organisms were identified and antimicrobial susceptibility testing was performed by phenotypic and genotypic methods. Ninety‐two distinctly different gram‐negative bacteria were identified; Klebsiella pneumoniae, Enterobacter cloacae, Enterobacter aerogenes, Serratia marcescens, and Escherichia coli were most often isolated. Serratia marcescens was more frequently isolated in samples from the UT compared to the CB. Antimicrobial resistance was more frequently detected in organisms from the CB by phenotypic and genotypic methods. Antimicrobial resistance to ampicillin, imipenem, tetracycline, and chloramphenicol were the most frequently observed resistance patterns. ACT‐1, CMY, and SHV genes were the most frequently detected resistance genes, with predominance in organism isolated from the CB. The results from this study emphasize the importance for further developing comprehensive surveillance programs of AR in bacterial isolates in the various environments, such as recreational and other water systems.

Water reuse, food production and public health: Adopting transdisciplinary, systems-based approaches to achieve water and food security in a changing climate

Climate change and population growth are contributing to a growing global freshwater crisis that is exacerbating agricultural water scarcity and compromising food security and public health. In light of these challenges, the increased reliance on nontraditional irrigation water sources, such as reclaimed or recycled water, is emerging as a potentially viable strategy to address water and food insecurity worldwide. This editorial provides an overview of the global need for agricultural water reuse and outlines the environmental and public health impacts associated with this practice. Policy implications, including an emphasis on "One Water" approaches, are discussed. Finally, the editorial leads off a Special Issue that includes a collection of articles reporting on the initial research and extension/outreach findings of CONSERVE: A Center of Excellence at the Nexus of Sustainable Water Reuse, Food and Health, funded by the U.S. Department of Agriculture, National Institute of Food and Agriculture. Taken together, this compilation of articles addresses the overarching theme that transdisciplinary teams are key with regard to moving the science of agricultural water reuse forward to achieve water and food security and advance public health in a changing climate.

The Impact of Climate Change on Raw and Untreated Wastewater Use for Agriculture, Especially in Arid Regions: A Review

Climate change is one of the major challenges of our time that pose unprecedented stress to the environment and threats to human health. The global impacts of climate change are vast, spanning from extreme weather events to changes in patterns and distribution of infectious diseases. Lack of rainfall associated with higher temperatures has a direct influence on agricultural production. This is compounded by a growing population forecasted to expand further with increasing needs for food and water. All this has led to the increasing use of wastewater worldwide. In this review, we more specifically discuss the use of untreated wastewater in agriculture in the Middle East and North Africa (MENA) countries, the most arid region in the world. This presents challenges for agriculture with respect to water availability and increasing wastewater use in agri-food chain. This in turn exerts pressures on the safety of food raised from such irrigated crops. Current practices in the MENA region indicate that ineffective water resource management, lack of water quality policies, and slow-paced wastewater management strategies continue to contribute to a decline in water resources and an increased unplanned use of black and graywater in agriculture. Radical actions are needed in the region to improve water and wastewater management to adapt to these impacts. In this regard, the 2006 WHO guidelines for the use of wastewater contain recommendations for the most effective solutions. They provide a step-by-step guide for series of appropriate health protection measures for microbial reduction targets of 6 log units for viral, bacterial, and protozoan pathogens, but these need to be combined with new varieties of crops that are drought and pest resistant. More research into economic local treatment procedures for wastewater in the region is warranted.