CTX-M-15-producing Escherichia coli clone B2-O25b-ST131 and Klebsiella spp. isolates in municipal wastewater treatment plant effluents

Molecular characterization and prevalence of β-lactamase-producing Enterobacterales in livestock and poultry slaughterhouses wastewater in Iran

Beta-lactamase-producing Enterobacterales bacteria cause severe hard-to-treat infections. Currently, they are spreading beyond hospitals and becoming a serious global health concern. This study investigated the prevalence and molecular characterization of extended-spectrum β-lactamase and AmpC-type β-lactamase-producing Enterobacterales (ESBL-PE, AmpC-PE) in wastewater from livestock and poultry slaughterhouses in Ardabil, Iran. A total of 80 Enterobacterales bacteria belonging to 9 species were identified. Among the isolates, Escherichia coli (n = 21/80; 26.2%) and Citrobacter spp. (n = 18/80; 22.5%) exhibited the highest frequency. Overall, 18.7% (n = 15/80) and 2.5% (n = 2/80) of Enterobacterales were found to be ESBL and AmpC producers, respectively. The most common ESBL producer isolates were E. coli (n = 9/21; 42.8%) and Klebsiella pneumoniae (n = 6/7; 85.7%). All AmpC-PE isolates belonged to E. coli strains (n = 2/21; 9.5%). In this study, 80% of ESBL-PE and 100% of AmpC-PE isolates were recovered from poultry slaughterhouse wastewater. All ESBL-PE and AmpC-PE isolates were multidrug-resistant. In total, 93.3% of ESBL-PE isolates harbored the blaCTX-M gene, with the blaCTX-M-15 being the most common subgroup. The emergence of ESBL-PE and AmpC-PE in wastewater of food-producing animals allows for zoonotic transmission to humans through contaminated food products and contaminations of the environment.

The clinical, genomic, and microbiological profile of invasive multi-drug resistant Escherichia coli in a major teaching hospital in the United Kingdom

Escherichia coli is a ubiquitous component of the human gut microbiome, but is also a common pathogen, causing around 40, 000 bloodstream infections (BSI) in the United Kingdom (UK) annually. The number of E. coli BSI has increased over the last decade in the UK, and emerging antimicrobial resistance (AMR) profiles threaten treatment options. Here, we combined clinical, epidemiological, and whole genome sequencing data with high content imaging to characterise over 300 E. coli isolates associated with BSI in a large teaching hospital in the East of England. Overall, only a limited number of sequence types (ST) were responsible for the majority of organisms causing invasive disease. The most abundant (20 % of all isolates) was ST131, of which around 90 % comprised the pandemic O25b:H4 group. ST131-O25b:H4 isolates were frequently multi-drug resistant (MDR), with a high prevalence of extended spectrum β-lactamases (ESBL) and fluoroquinolone resistance. There was no association between AMR phenotypes and the source of E. coli bacteraemia or whether the infection was healthcare-associated. Several clusters of ST131 were genetically similar, potentially suggesting a shared transmission network. However, there was no clear epidemiological associations between these cases, and they included organisms from both healthcare-associated and non-healthcare-associated origins. The majority of ST131 isolates exhibited strong binding with an anti-O25b antibody, raising the possibility of developing rapid diagnostics targeting this pathogen. In summary, our data suggest that a restricted set of MDR E. coli populations can be maintained and spread across both community and healthcare settings in this location, contributing disproportionately to invasive disease and AMR.

Comparison of antibiotic-resistant Escherichia coli and extra-intestinal pathogenic E. coli from main river basins under different levels of the sewer system development

Antimicrobial-resistant Escherichia coli in the aquatic environments is considered a strong indicator of sewage or animal waste contamination and antibiotic pollution. Sewer construction and wastewater treatment plant (WWTP) infrastructure may serve as concentrated point sources of contamination of antibiotic-resistant bacteria and antibiotic resistance genes. In this study, we focused on the distribution of antimicrobial-resistant E. coli in two rivers with large drainage areas and different urbanisation levels. E. coli from Kaoping River with drainage mainly from livestock farming had higher resistance to antibiotics (e.g. penicillins, tetracyclines, phenicols, aminoglycosides, and sulpha drugs) and presented more positive detection of antibiotic-resistance genes (e.g. ampC, blaTEM, tetA, and cmlA1) than that from Tamsui River. In Kaoping River with a lower percentage of sewer construction nearby (0-30%) in contrast to a higher percentage of sewer construction (55-92%) in Tamsui River, antimicrobial-resistant E. coli distribution was related to livestock farming waste. In Tamsui River, antimicrobial resistant E. coli isolates were found more frequently in the downstream drainage area of WWTPs with secondary water treatment than that of WWTPs with tertiary water treatment. The Enterobacterial Repetitive Intergenic Consensus (ERIC) PCR showed that the fingerprinting group was significantly related to the sampling site (p < 0.01) and sampling date (p < 0.05). By utilising ERIC-PCR in conjunction with antibiotic susceptibility and antibiotic-resistance gene detection, the relationship among different strains of E. coli could be elucidated. Furthermore, we identified the presence of six extra-intestinal pathogenic E. coli isolates and antibiotic-resistant E. coli isolates near drinking water sources, posing a potential risk to public health through community transmission. In conclusion, this study identified environmental factors related to antibiotic-resistant bacteria and antibiotic-resistance gene contamination in rivers during urban development. The results facilitate the understanding of specific management of different waste streams across different urban areas. Periodic surveillance of the effects of WWTPs and livestock waste containing antibiotic-resistant bacteria and antibiotic-resistance genes on river contamination is necessary.

Development of two microbial source tracking markers for detection of wastewater-associated Escherichia coli isolates

Escherichia coli has been used as an indicator of fecal pollution in environmental waters. However, its presence in environmental waters does not provide information on the source of water pollution. Identifying the source of water pollution is paramount to be able to effectively reduce contamination. The present study aimed to identify E. coli microbial source tracking (MST) markers that can be used to identify domestic wastewater contamination in environmental waters. We first analyzed wastewater E. coli genomes sequenced by us (n = 50) and RefSeq animal E. coli genomes of fecal origin (n = 82), and identified 144 candidate wastewater-associated marker genes. The sensitivity and specificity of the candidate marker genes were then assessed by screening the genes in 335 RefSeq wastewater E. coli genomes and 3318 RefSeq animal E. coli genomes. We finally identified two MST markers, namely W_nqrC and W_clsA_2, which could be used for detection of wastewater-associated E. coli isolates. These two markers showed higher performance than the previously developed human wastewater-associated E. coli markers H8 and H12. When used in combination, W_nqrC and W_clsA_2 showed specificity of 98.9 % and sensitivity of 25.7 %. PCR assays to detect W_nqrC and W_clsA_2 were also developed and validated. The developed PCR assays are potentially useful for detecting E. coli isolates of wastewater origin in environmental waters, though users should keep in mind that the sensitivity of these markers is not high. Further studies are needed to assess the applicability of the developed markers to a culture-independent approach.

Geographic distribution of the major clone of extended-spectrum beta-lactamase-producing Escherichia coli infection in a pediatric community in southern Taiwan

BACKGROUND

The geographic distribution of the major clone of sequence type 131 (ST131) in extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli (E. coli) infections is not known. We analyzed the clinical features, resistance mechanisms, and geographic distribution of ESBL-producing E. coli clones in 120 children.

METHODS

We studied the 120 ESBL-producing E. coli strains from children younger than 18 years. A VITEK 2 automated system was used to determine bacterial identification and ESBL production. Sequence type was determined by multi-locus sequence typing (MLST). The genetic relationship of the ESBL-producing strains was studied using pulsed-field gel electrophoresis (PFGE). Phylogenetic group and blaCTX-M group was performed using polymerase chain reaction (PCR). Multiplex PCR for detecting the common group 9 variant, CTX-M-14, and group 1 variant, CTX-M-15, was also performed. The addresses of the 120 children were collected, and plotted on the Taiwan map.

RESULTS

The groups in the center of Kaohsiung City lived mainly in urban areas with a population density of over 10,000 people per square kilometer, and the majority of the Kaohsiung groups on the outskirts of the city center lived in suburban areas with a population density of under 6000 people per square kilometer. There was no statistically significant difference between the city center and outskirt groups in terms of clinical presentation, laboratory, and imaging data. However, more ST131 clones, major pulsotype groups, and phylogenetic group B2 strains were found in the center of Kaohsiung than on the outskirts.

CONCLUSION

ESBL-producing E. coli clones may be more challenging to treat clinically. Most infections were community-acquired, and there appeared to be major pulsotype clones, mainly in urban areas. This reinforces the necessity of environmental surveillance and sanitary procedures for ESBL-producing E. coli.

Clinically Relevant β-Lactam Resistance Genes in Wastewater Treatment Plants

Antimicrobial resistance (AMR) is one of the largest global concerns due to its influence in multiple areas, which is consistent with One Health's concept of close interconnections between people, animals, plants, and their shared environments. Antibiotic-resistant bacteria (ARB) and antibiotic-resistance genes (ARGs) circulate constantly in various niches, sediments, water sources, soil, and wastes of the animal and plant sectors, and is linked to human activities. Sewage of different origins gets to the wastewater treatment plants (WWTPs), where ARB and ARG removal efficiency is still insufficient, leading to their transmission to discharge points and further dissemination. Thus, WWTPs are believed to be reservoirs of ARGs and the source of spreading AMR. According to a World Health Organization report, the most critical pathogens for public health include Gram-negative bacteria resistant to third-generation cephalosporins and carbapenems (last-choice drugs), which represent β-lactams, the most widely used antibiotics. Therefore, this paper aimed to present the available research data for ARGs in WWTPs that confer resistance to β-lactam antibiotics, with a particular emphasis on clinically important life-threatening mechanisms of resistance, including extended-spectrum β-lactamases (ESBLs) and carbapenemases (KPC, NDM).

High Carriage of Extended-Spectrum, Beta Lactamase-Producing, and Colistin-Resistant Enterobacteriaceae in Tibetan Outpatients with Diarrhea

Antibiotic-resistant bacteria (ARB) and antibiotic-resistance genes (ARGs) have been detected in human-impacted habitats, especially in densely populated cities. The Qinghai–Tibet Plateau is located far from the heavily populated regions of China, and Tibetan residents have distinct dietary habits and gut microbes. Antibiotic-resistance monitoring in the Tibetan population is rare. Here, we collected stool samples from Tibetan outpatients with diarrhea. From 59 samples, 48 antibiotic-resistant Enterobacteriaceae isolates were obtained, including 19 extended-spectrum beta lactamase (ESBL)-producing isolates from 16 patients and 29 polymyxin-resistant isolates from 22 patients. Either ESBL or mcr genes were found in 17 Escherichia coli isolates, approximately 58.8% of which were multidrug-resistant, and ten incompatible plasmid types were found. The gene bla_CTX-M was a common genotype in the ESBL-producing E. coli isolates. Four E. coli isolates contained mcr-1. The same mcr-1-carrying plasmid was found in distinct E. coli isolates obtained from the same sample, thus confirming horizontal transmission of mcr-1 between bacteria. Genomic clustering of E. coli isolates obtained from Lhasa, with strains from other regions providing evidence of clone spreading. Our results reveal a strong presence of ARB and ARGs in Tibetan outpatients with diarrhea, implying that ARB and ARGs should be monitored in the Tibetan population.

Extended-spectrum β-lactamase (ESBL)-producing Escherichia coli survey in wild seabirds at a pristine atoll in the southern Atlantic Ocean, Brazil: First report of the O25b-ST131 clone harboring blaCTX-M-8

Antimicrobial resistance is among the most serious public health threats of the 21st century, with great impact in terms of One Health. Among antimicrobial resistant bacteria (ARB), extended-spectrum ß-lactamase (ESBL)-producing Escherichia coli (ESBL-EC) represent major challenges to human healthcare. Wild birds have been commonly used as environmental bioindicators of ESBL-EC. Remote locations represent a unique opportunity to evaluate the occurrence, dissemination and epidemiology of ARB in the environment. Herein we surveyed ESBL-EC in 204 cloacal swabs from six nonsynanthropic seabird species at the pristine Rocas Atoll, Brazil. We identified ESBL-EC isolates in 2.4% (5/204) of the tested seabirds, all in magnificent frigatebirds (Fregata magnificens). We isolated strains of O25b-ST131-fimH22 harboring gene bla_CTX-M-8 (3 clones), ST117 harboring gene bla_SHV-12, and a novel ST11350 (clonal complex 349) harboring genes bla_CTX-M-55 and fosA3. All the isolates presented Extraintestinal pathogenic E. coli (ExPEC) virulence profiles. We suggest that magnificent frigatebirds may act as "flying bridges", transporting ESBL-EC and ARGs from an anthropogenically-impacted archipelago geographically close to our pristine and remote study site. The characteristics of our isolates suggest zoonotic potential and, despite the apparent good health of all the evaluated birds, may represent a hypothetical potential threat to the avian population using the atoll. To our knowledge, this is the first description of: (1) the pandemic and public health relevant ST131-O25b harboring bla_CTX-M-8 worldwide; (2) ST131-fimH22 in wild birds; and (3); fosA3 in wildlife. Our findings expand the current epidemiological knowledge regarding host and geographical distribution of ESBL-EC and ARGs in wild birds, and emphasize the disseminating characteristics and adaptability of ST131 and ST117 strains within the human-animal-interface. Herein we discuss the involvement of nonsynanthropic wild birds in the epidemiology of antimicrobial resistance and their potential as sentinels of ESBL E. coli in insular environments.

Klebsiella oxytoca Complex: Update on Taxonomy, Antimicrobial Resistance, and Virulence

Klebsiella oxytoca is actually a complex of nine species-Klebsiella grimontii, Klebsiella huaxiensis, Klebsiella michiganensis, K. oxytoca, Klebsiella pasteurii, Klebsiella spallanzanii, and three unnamed novel species. Phenotypic tests can assign isolates to the complex, but precise species identification requires genome-based analysis. The K. oxytoca complex is a human commensal but also an opportunistic pathogen causing various infections, such as antibiotic-associated hemorrhagic colitis (AAHC), urinary tract infection, and bacteremia, and has caused outbreaks. Production of the cytotoxins tilivalline and tilimycin lead to AAHC, while many virulence factors seen in Klebsiella pneumoniae, such as capsular polysaccharides and fimbriae, have been found in the complex; however, their association with pathogenicity remains unclear. Among the 5,724 K. oxytoca clinical isolates in the SENTRY surveillance system, the rates of nonsusceptibility to carbapenems, ceftriaxone, ciprofloxacin, colistin, and tigecycline were 1.8%, 12.5%, 7.1%, 0.8%, and 0.1%, respectively. Resistance to carbapenems is increasing alarmingly. In addition to the intrinsic bla_OXY, many genes encoding β-lactamases with varying spectra of hydrolysis, including extended-spectrum β-lactamases, such as a few CTX-M variants and several TEM and SHV variants, have been found. bla_KPC-2 is the most common carbapenemase gene found in the complex and is mainly seen on IncN or IncF plasmids. Due to the ability to acquire antimicrobial resistance and the carriage of multiple virulence genes, the K. oxytoca complex has the potential to become a major threat to human health.

Klebsiella spp. isolates from Houston bayous exhibit increased resistance to lead exposure and possess enhanced virulence potential

Houston watersheds are susceptible to microbial contamination as well as chemical contaminations from bordering industrial facilities. Bacterial loads in various Houston bayous were determined, and pathogenic Gram-negative bacteria were isolated for characterization. Isolates included Klebsiella aerogenes and Klebsiella pneumoniae. To determine whether environmental exposures to lead (Pb), measured in our Houston bayou samples, resulted in bacterial adaptations, we compared growth kinetics, biofilm production, oxidative stress resistance, and eukaryotic co-culture growth of environmentally isolated K. aerogenes and K. pneumoniae to their respective commercially acquired reference strains. Interestingly, the K. aerogenes environmental isolate displayed significantly better growth than the reference strain in the presence of 50 ppb of Pb. Unexpectedly, we did not observe any differences in biofilm production of the aforementioned strains when challenged with a range of Pb (0.5-50 ppb). However, when comparing our K. pneumoniae environmental isolate to its reference strain, there were significantly higher levels of biofilm produced by the environmental isolate when challenged with Pb concentrations of 10 and 50 ppb. When grown in eukaryotic cell co-culture with either BAES 2B lung cells or CCD 841 colon epithelial cells in the presence of 20 ppb Pb, the environmental isolates of K. aerogenes and K. pneumoniae had a significantly higher fold-increase over 6 h than their respective reference strains. Taken together, the environmentally isolated Klebsiella spp. appeared to be more Pb-tolerant than their respective reference strains, a possible environmental adaptation. Such enhanced tolerance can promote environmental persistence and increase the possibility of causing human disease.

The Pheno- and Genotypic Characterization of Porcine Escherichia coli Isolates

Escherichia (E.) coli is the main causative pathogen of neonatal and post-weaning diarrhea and edema disease in swine production. There is a significant health concern due to an increasing number of human infections associated with food and/or environmental-borne pathogenic and multidrug-resistant E. coli worldwide. Monitoring the presence of pathogenic and antimicrobial-resistant E. coli isolates is essential for sustainable disease management in livestock and human medicine. A total of 102 E. coli isolates of diseased pigs were characterized by antimicrobial and biocide susceptibility testing. Antimicrobial resistance genes, including mobile colistin resistance genes, were analyzed by PCR and DNA sequencing. The quinolone resistance-determining regions of gyrA and parC in ciprofloxacin-resistant isolates were analyzed. Clonal relatedness was investigated by two-locus sequence typing (CH clonotyping). Phylotyping was performed by the Clermont multiplex PCR method. Virulence determinants were analyzed by customized DNA-based microarray technology developed in this study for fast and economic molecular multiplex typing. Thirty-five isolates were selected for whole-genome sequence-based analysis. Most isolates were resistant to ampicillin and tetracycline. Twenty-one isolates displayed an ESBL phenotype and one isolate an AmpC β-lactamase-producing phenotype. Three isolates had elevated colistin minimal inhibitory concentrations and carried the mcr-1 gene. Thirty-seven isolates displayed a multi-drug resistance phenotype. The most predominant β-lactamase gene classes were bla_TEM-1 (56%) and bla_CTX-M-1 (13.71%). Mutations in QRDR were observed in 14 ciprofloxacin-resistant isolates. CH clonotyping divided all isolates into 51 CH clonotypes. The majority of isolates belonged to phylogroup A. Sixty-four isolates could be assigned to defined pathotypes wherefrom UPEC was predominant. WGS revealed that the most predominant sequence type was ST100, followed by ST10. ST131 was detected twice in our analysis. This study highlights the importance of monitoring antimicrobial resistance and virulence properties of porcine E. coli isolates. This can be achieved by applying reliable, fast, economic and easy to perform technologies such as DNA-based microarray typing. The presence of high-risk pathogenic multi-drug resistant zoonotic clones, as well as those that are resistant to critically important antibiotics for humans, can pose a risk to public health. Improved protocols may be developed in swine farms for preventing infections, as well as the maintenance and distribution of the causative isolates.

Populations of extended-spectrum β-lactamase-producing Escherichia coli and Klebsiella pneumoniae are different in human-polluted environment and food items: a multicentre European study

OBJECTIVES

To assess the extent to which food items are a source of extended-spectrum β-lactamase (ESBL) -producing Escherichia coli (ESBL-Ec) and ESBL-producing Klebsiella pneumoniae (ESBL-Kp) for humans in five European cities.

METHODS

We sampled 122 human polluted (hp)-environments (sewers and polluted rivers, as a proxy of human contamination) and 714 food items in Besançon (France), Geneva (Switzerland), Sevilla (Spain), Tübingen (Germany) and Utrecht (The Netherlands). A total of 254 ESBL-Ec and 39 ESBL-Kp isolates were cultured. All genomes were fully sequenced to compare their sequence types (ST) and core genomes, along with the distribution of bla_ESBL genes and their genetic supports (i.e. chromosome or plasmid).

RESULTS

Sequence data revealed that ESBL-Ec and ESBL-Kp isolates from hp-environments were genetically different from those contaminating food items. ESBL-Ec ST131 was widespread in the hp-environment (21.5% of the isolates) but absent from the food items tested. ESBL-Ec ST10 was in similar proportions in hp-environments and food items (15 and 10 isolates, respectively) but mostly carried reservoir-specific bla_ESBL. bla_CTX-M-1 and bla_SHV-12 predominated in food-related E. coli isolates (32% and 34% of the isolates, respectively), whereas bla_CTX-M-15 and bla_CTX-M-27 predominated in isolates from hp-environments (52% and 15% of the isolates, respectively).

CONCLUSIONS

We found a very limited connection between ESBL-Ec and ESBL-Kp populations retrieved in food items and from hp-environments and bla_ESBL. This suggests that human-to-human contamination, rather than the food chain, is possibly the most frequent route of ESBL-Ec and ESBL-Kp transmission in high-income countries.

Analysis of Wastewater Reveals the Spread of Diverse Extended-Spectrum β-Lactamase-Producing E. coli Strains in uMgungundlovu District, South Africa

Wastewater treatment plants (WWTPs) are major reservoirs of antibiotic-resistant bacteria (ARB), favouring antibiotic resistance genes (ARGs) interchange among bacteria and they can provide valuable information on ARB circulating in a community. This study characterised extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli from the influent and effluent of four WWTPs in uMgungundlovu District, KwaZulu-Natal, South Africa. E. coli was enumerated using the membrane filtration method and confirmed using the API 20E test and real-time polymerase chain reaction. ESBL-producers were phenotypically identified by their susceptibility to the third-generation cephalosporins using the disc diffusion and the double-disc synergy methods against cefotaxime (30 µg) with and without 10 µg clavulanic acid. Genotypic verification was by PCR of the TEM, SHV, and CTX-M genes. The clonality of isolates was assessed by ERIC-PCR. The highest E. coli count ranged between 1.1 × 10⁵ (influent) and 4.3 × 10³ CFU/mL (effluent). Eighty pure isolates were randomly selected, ten from the influent and effluent of each of the four WWTP. ESBLs were phenotypically confirmed in 49% (n = 39) of the isolates, of which 77% (n = 30) were genotypically confirmed. Seventy-three percent of the total isolates were multidrug-resistant (MDR). Only two isolates were susceptible to all antibiotics. Overall, resistance to first and second-generation cephalosporins was higher than to third and fourth generation cephalosporins. Also, 15% of the isolates were resistant to carbapenems. The CTX-M-type ESBL (67%; n = 20) was the most common ESBL antibiotic resistance gene (ARG) followed by TEM (57%; n = 17) and SHV-types (27%; n = 8). Also, a substantial number of isolates simultaneously carried all three ESBL genes. ERIC-PCR revealed a high diversity of isolates. The diversity of the isolates observed in the influent samples suggest the potential circulation of different ESBL-producing strains within the studied district, requiring a more comprehensive epidemiological study to prevent the spread of ESBL-producing bacteria within impoverished communities.

Application of Floating TiO2 Photocatalyst for Methylene Blue Decomposition and Salmonella typhimurium Inactivation

The growing level of wastewater as well as pollution of freshwater by various bacteria are essential worldwide issues which have to be solved. In this contribution, nanocrystalline anatase TiO2 films deposited by magnetron sputtering on high-density polystyrene (HDPE) beads were applied as floating photocatalysts for Salmonella typhimurium bacterial inactivation in water for the first time. Additionally, the photocatalytic degradation of methylene blue dye in the presence of HDPE beads with TiO2 film under UV-B irradiation was investigated. The suitability to adopt such floating photocatalyst structures for practical applications was tested in cycling experiments. The detailed surface morphology, crystal structure, elemental mapping, surface chemical composition and bond analysis of deposited TiO2 films were investigated by scanning electron microscope, X-ray diffractometer and X-ray photoelectron spectroscope techniques. The bacterial viability as well as MB decomposition experiments showed promising results by demonstrating that 6% of bacterial colonies were formed after the first run and only about 1% after the next four runs, which is an appropriate outcome for practical applications. NPN uptake results showed that the permeability of the outer membrane was significantly increased as well.

Presence of β-Lactamase-producing Enterobacterales and Salmonella Isolates in Marine Mammals

Marine mammals have been described as sentinels of the health of marine ecosystems. Therefore, the aim of this study was to investigate (i) the presence of extended-spectrum β-lactamase (ESBL)- and AmpC-producing Enterobacterales, which comprise several bacterial families important to the healthcare sector, as well as (ii) the presence of Salmonella in these coastal animals. The antimicrobial resistance pheno- and genotypes, as well as biocide susceptibility of Enterobacterales isolated from stranded marine mammals, were determined prior to their rehabilitation. All E. coli isolates (n = 27) were screened for virulence genes via DNA-based microarray, and twelve selected E. coli isolates were analyzed by whole-genome sequencing. Seventy-one percent of the Enterobacterales isolates exhibited a multidrug-resistant (MDR) pheno- and genotype. The gene bla_CMY (n = 51) was the predominant β-lactamase gene. In addition, bla_TEM-1 (n = 38), bla_SHV-33 (n = 8), bla_CTX-M-15 (n = 7), bla_OXA-1 (n = 7), bla_SHV-11 (n = 3), and bla_DHA-1 (n = 2) were detected. The most prevalent non-β-lactamase genes were sul2 (n = 38), strA (n = 34), strB (n = 34), and tet(A) (n = 34). Escherichia coli isolates belonging to the pandemic sequence types (STs) ST38, ST167, and ST648 were identified. Among Salmonella isolates (n = 18), S. Havana was the most prevalent serotype. The present study revealed a high prevalence of MDR bacteria and the presence of pandemic high-risk clones, both of which are indicators of anthropogenic antimicrobial pollution, in marine mammals.

Resistance determinants and their genetic context in enterobacteria from a longitudinal study of pigs reared under various husbandry conditions

Pigs are major reservoirs of resistant Enterobacteriaceae that can reach humans through consumption of contaminated meat or vegetables grown in manure-fertilized soil. Samples were collected from sows during lactation and their piglets at five time points spanning the production cycle. Cefotaxime-resistant bacteria were quantified and isolated from feed, feces, manures and carcasses of pigs reared with penicillin-using or antibiotic-free husbandries. The isolates were characterized by antibiotic susceptibility testing, whole genome sequencing and conjugation assays. The extended spectrum β-lactamase (ESBL) phenotype was more frequent in isolates originating from antibiotic-free animals, while the bacteria isolated from penicillin-using animals were on average resistant to a greater number of antibiotics. The ESBL-encoding genes identified were bla _CTX-M-1, bla _CTX-M-15 and bla _CMY-2 and they co-localised on plasmids with various genes encoding resistance to ß-lactams, co-trimoxazole, phenicols and tetracycline, all antibiotics used in pig production. Groups of genes conferring the observed resistance and the mobile elements disseminating multidrug resistance were determined. The observed resistance to ß-lactams was mainly due to the complementary actions of penicillin-binding proteins, an efflux pump and ß-lactamases. Most resistance determinants were shared by animals raised with or without antimicrobials. This suggests a key contribution of indigenous enterobacteria maternally transmitted along the sow lineage, regardless of antimicrobial use. It is unclear if the antimicrobial resistance observed in the enterobacteria populations of the commercial pig herds studied were present before the use of antibiotics, or the extent to which historical antimicrobial use exerted a selective pressure defining the resistant bacterial populations in farms using penicillin prophylaxis.Importance: Antimicrobial resistance is a global threat that needs to be fought on numerous fronts along the One Health continuum. Vast quantities of antimicrobials are used in agriculture to ensure animal welfare and productivity, and are arguably a driving force for the persistence of environmental and food-borne resistant bacteria. This study evaluated the impact of conventional, organic and other antibiotic-free husbandry practices on the frequency and nature of antimicrobial resistance genes and multidrug resistant enterobacteria. It provides knowledge about the relative contribution of specific resistance determinants to observed antibiotic resistance. It also showed the clear co-selection of genes coding for extended-spectrum beta-lactamases and genes coding for the resistance to antibiotics commonly used for prophylaxis or in curative treatments in pig operations.

Biosensors for wastewater-based epidemiology for monitoring public health

Public health is attracting increasing attention due to the current global pandemic, and wastewater-based epidemiology (WBE) has emerged as a powerful tool for monitoring of public health by analysis of a variety of biomarkers (e.g., chemicals and pathogens) in wastewater. Rapid development of WBE requires rapid and on-site analytical tools for monitoring of sewage biomarkers to provide immediate decision and intervention. Biosensors have been demonstrated to be highly sensitive and selective tools for the analysis of sewage biomarkers due to their fast response, ease-to-use, low cost and the potential for field-testing. This paper presents biosensors as effective tools for wastewater analysis of potential biomarkers and monitoring of public health via WBE. In particular, we discuss the use of sewage sensors for rapid detection of a range of targets, including rapid monitoring of community-wide illicit drug consumption and pathogens for early warning of infectious diseases outbreaks. Finally, we provide a perspective on the future use of the biosensor technology for WBE to enable rapid on-site monitoring of sewage, which will provide nearly real-time data for public health assessment and effective intervention.

Extended-spectrum beta-lactamase-producing Escherichia coli and antimicrobial resistance in municipal and hospital wastewaters in Czech Republic: Culture-based and metagenomic approaches

Wastewaters serve as important hot spots for antimicrobial resistance and monitoring can be used to analyse the abundance and diversity of antimicrobial resistance genes at the level of large bacterial and human populations. In this study, whole genome sequencing of beta-lactamase-producing Escherichia coli and metagenomic analysis of whole-community DNA were used to characterize the occurrence of antimicrobial resistance in hospital, municipal and river waters in the city of Brno (Czech Republic). Cefotaxime-resistant E. coli were mainly extended-spectrum beta-lactamase (ESBL) producers (95.6%, n = 158), of which the majority carried bla_CTX-M (98.7%; n = 151) and were detected in all water samples except the outflow from hospital wastewater treatment plant. A wide phylogenetic diversity was observed among the sequenced E. coli (n = 78) based on the detection of 40 sequence types and single nucleotide polymorphisms (average number 34,666 ± 15,710) between strains. The metagenomic analysis revealed a high occurrence of bacterial genera with potentially pathogenic members, including Pseudomonas, Escherichia, Klebsiella, Aeromonas, Enterobacter and Arcobacter (relative abundance >50%) in untreated hospital and municipal wastewaters and predominance of environmental bacteria in treated and river waters. Genes encoding resistance to aminoglycosides, beta-lactams, quinolones and macrolides were frequently detected, however bla_CTX-M was not found in this dataset which may be affected by insufficient sequencing depth of the samples. The study pointed out municipal treated wastewater as a possible source of multi-drug resistant E. coli and antimicrobial resistance genes for surface waters. Moreover, the combination of two different approaches provided a more holistic view on antimicrobial resistance in water environments. The culture-based approach facilitated insight into the dynamics of ESBL-producing E. coli and the metagenomics shows abundance and diversity of bacteria and antimicrobial resistance genes vary across water sites.

Antimicrobial resistance in Aeromonas species isolated from aquatic environments in Brazil

AIM

The current study was conducted to determine the antimicrobial resistance profile and genetic relatedness of Aeromonas sp. isolated from healthcare and urban effluents, wastewater treatment plant (WWTP) and river water.

METHODS AND RESULTS

We detected the presence of genes conferring resistance to β-lactam, quinolone and aminoglycoside. Multilocus sequence typing was carried out to differentiate the strains, and multilocus phylogenetic analysis was used to identify the species. A total of 28 cefotaxime-resistant Aeromonas sp. strains were identified, harbouring uncommon Guiana-extended-spectrum (GES)-type β-lactamases (GES-1, GES-5, GES-7 and GES-16). Multidrug-resistant Aeromonas sp. were found in hospital wastewater, WWTP and sanitary effluent, and A. caviae was identified as the most prevalent species (85·7%).

CONCLUSION

The release of untreated healthcare effluents, presence of antimicrobials in the environment, in addition to multidrug-resistant Aeromonas sp., are all potential factors for the spread of resistance.

SIGNIFICANCE AND IMPACT OF THE STUDY

We identified a vast repertoire of antimicrobial resistance genes (ARG) in Aeromonas sp. from diverse aquatic ecosystems, including those that encode enzymes degrading broad-spectrum antimicrobials widely used to treat healthcare-associated infections. Hospital and sanitary effluents serve as potential sources of bacteria harbouring ARG and are a threat to public health.

Distinguishing Pathovars from Nonpathovars: Escherichia coli

Escherichia coli is one of the most well-adapted and pathogenically versatile bacterial organisms. It causes a variety of human infections, including gastrointestinal illnesses and extraintestinal infections. It is also part of the intestinal commensal flora of humans and other mammals. Groups of E. coli that cause diarrhea are often described as intestinal pathogenic E. coli (IPEC), while those that cause infections outside of the gut are called extraintestinal pathogenic E. coli (ExPEC). IPEC can cause a variety of diarrheal illnesses as well as extraintestinal syndromes such as hemolytic-uremic syndrome. ExPEC cause urinary tract infections, bloodstream infection, sepsis, and neonatal meningitis. IPEC and ExPEC have thus come to be referred to as pathogenic variants of E. coli or pathovars. While IPEC can be distinguished from commensal E. coli based on their characteristic virulence factors responsible for their associated clinical manifestations, ExPEC cannot be so easily distinguished. IPEC most likely have reservoirs outside of the human intestine but it is unclear if ExPEC represent nothing more than commensal E. coli that breach a sterile barrier to cause extraintestinal infections. This question has become more complicated by the advent of whole genome sequencing (WGS) that has raised a new question about the taxonomic characterization of E. coli based on traditional clinical microbiologic and phylogenetic methods. This review discusses how molecular epidemiologic approaches have been used to address these questions, and how answers to these questions may contribute to our better understanding of the epidemiology of infections caused by E. coli. *This article is part of a curated collection.

Genotypic and phenotypic traits of blaCTX-M-carrying Escherichia coli strains from an UV-C-treated wastewater effluent

Wastewater treatment plants (WWTPs) are relevant sources of antibiotic resistance into aquatic environments. Disinfection of WWTPs' effluents (e.g. by UV-C irradiation) may attenuate this problem, though some clinically relevant bacteria have been shown to survive disinfection. In this study we characterized 25 CTX-M-producing Escherichia coli strains isolated from a WWTP's UV-C-irradiated effluent, aiming to identify putative human health hazards associated with such effluents. Molecular typing indicated that the strains belong to the phylogroups A, B2 and C and clustered into 9 multilocus sequence types (STs), namely B2:ST131 (n = 7), A:ST58 (n = 1), A:ST155 (n = 4), C:ST410 (n = 2), A:ST453 (n = 2), A:ST617 (n = 2), A:ST744 (n = 1), A:ST1284 (n = 3) and a putative novel ST (n = 3). PCR-screening identified 9 of the 20 antibiotic resistance genes investigated [i.e. sul1, sul2, sul3, tet(A), tet(B), bla_OXA-1-like, aacA4, aacA4-cr and qnrS1]. The more prevalent were sul1, sul2 (n = 15 isolates) and tet(A) (n = 14 isolates). Plasmid restriction analysis indicated diverse plasmid content among strains (14 distinct profiles) and mating assays yielded cefotaxime-resistant transconjugants for 8 strains. Two of the transconjugants displayed a multi-drug resistance (MDR) phenotype. All strains were classified as cytotoxic to Vero cells (9 significantly more cytotoxic than the positive control) and 10 of 21 strains were invasive towards this cell line (including all B2:ST131 strains). The 10 strains tested against G. mellonella larvae exhibited a virulent behaviour. Twenty-four and 7 of the 25 strains produced siderophores and haemolysins, respectively. Approximately 66% of the strains formed biofilms. Genome analysis of 6 selected strains identified several virulence genes encoding toxins, siderophores, and colonizing, adhesion and invasion factors. Freshwater microcosms assays showed that after 28 days of incubation 3 out of 6 strains were still detected by cultivation and 4 strains by qPCR. Resistance phenotypes of these strains remained unaltered. Overall, we confirmed WWTP's UV-C-treated outflow as a source of MDR and/or virulent E. coli strains, some probably capable of persisting in freshwater, and that carry conjugative antibiotic resistance plasmids. Hence, disinfected wastewater may still represent a risk for human health. More detailed evaluation of strains isolated from wastewater effluents is urgent, to design treatments that can mitigate the release of such bacteria.

Characterization of water treatment-resistant and multidrug-resistant urinary pathogenic Escherichia coli in treated wastewater

A growing body of evidence has demonstrated that extraintestinal pathogenic E. coli (ExPEC), such as the urinary pathogenic E. coli (UPEC), are common constituents of treated wastewater, and therefore represent a potential public health risk. However, no single virulence gene, or set of virulence genes, can be used to conclusively identify this genetically diverse pathotype. As such we sought to identify and characterize the public health relevance of potential UPEC found in treated sewage/wastewater using a comparative genomics approach. Presumptive wastewater UPEC (W-UPEC) were initially identified by virulence gene screening against 5 virulence genes, and for which isolates containing ≥3 virulence genes were whole genome sequenced (n = 24). Single nucleotide polymorphic (SNP) spanning tree analysis demonstrated that many of these wastewater UPEC (WUPEC) were virtually identical at the core genome (0.4 Mbp) when compared to clinical UPEC (C-UPEC) sequences obtained from NCBI, varying by as little as 1 SNP. Remarkably, at the whole genome level, W-UPEC isolates displayed >96% whole genome similarity to C-UPEC counterparts in NCBI, with one strain demonstrating 99.5% genome similarity to a particular C-UPEC strain. The W-UPEC populations were represented by sequence types (ST) known to be clinically important, including ST131, ST95, ST127 and ST640. Many of the W-UPEC carried the exact same complement of virulence genes as their most closely related C-UPEC strains. For example, O25b-ST131 W-UPEC strains possessed the same 80 virulence genes as their most closely related C-UPEC counterparts. Concerningly, W-UPEC strains also carried a plethora of antibiotic resistance genes, and O25b-ST131strains were designated as extended spectrum beta-lactamase (ESBL) producing E. coli by both genome profiling and phenotypic resistance testing. W-UPEC ST131 strains were found in the effluents of a single treatment plant at different times, as well as different wastewater treatment plants, suggesting a differentially ability to survive wastewater treatment. Indeed, in sewage samples treated with chlorine doses sufficient for inducing a ∼99.99% reduction in total E. coli levels, UPEC represented a significant proportion of the chlorine-resistant population. By contrast, no Shiga toxin-producing E. coli were observed in these chlorinated sewage libraries. Our results suggest that clinically-relevant UPEC exist in treated wastewater effluents and that they appear to be specifically adapted to survive wastewater treatment processes.

Urban brown rats (Rattus norvegicus) as possible source of multidrug-resistant Enterobacteriaceae and meticillin-resistant Staphylococcus spp., Vienna, Austria, 2016 and 2017

Background

Brown rats (Rattus norvegicus) are an important wildlife species in cities, where they live in close proximity to humans. However, few studies have investigated their role as reservoir of antimicrobial-resistant bacteria.

Aim

We intended to determine whether urban rats at two highly frequented sites in Vienna, Austria, carry extended-spectrum β-lactamase-producing Enterobacteriaceae, fluoroquinolone-resistant Enterobacteriaceae and meticillin-resistant (MR) Staphylococcus spp. (MRS).

Methods

We surveyed the presence of antimicrobial resistance in 62 urban brown rats captured in 2016 and 2017 in Vienna, Austria. Intestinal and nasopharyngeal samples were cultured on selective media. We characterised the isolates and their antimicrobial properties using microbiological and genetic methods including disk diffusion, microarray analysis, sequencing, and detection and characterisation of plasmids.

Results

Eight multidrug-resistant Escherichia coli and two extensively drug-resistant New Delhi metallo-β-lactamases-1 (NDM-1)-producing Enterobacter xiangfangensis ST114 (En. cloacae complex) were isolated from nine of 62 rats. Nine Enterobacteriaceae isolates harboured the bla_CTX-M gene and one carried a plasmid-encoded ampC gene (bla_CMY-2). Forty-four MRS were isolated from 37 rats; they belonged to seven different staphylococcal species: S. fleurettii, S. sciuri, S. aureus, S. pseudintermedius, S. epidermidis, S. haemolyticus (all mecA-positive) and mecC-positive S. xylosus.

Conclusion

Our findings suggest that brown rats in cities are a potential source of multidrug-resistant bacteria, including carbapenem-resistant En. xiangfangensis ST114. Considering the increasing worldwide urbanisation, rodent control remains an important priority for health in modern cities.

Human faeces-associated extended-spectrum β-lactamase-producing Escherichia coli discharge into sanitation systems in 2015 and 2030: a global and regional analysis

BACKGROUND

Improving management of and treatment within sanitation waste streams could slow the development and transmission of antimicrobial-resistant organisms, but the magnitude of impact has not been quantified. Extended-spectrum β-lactamase (ESBL)-producing Escherichia coli are a major cause of antimicrobial-resistant infections and are frequently detected in faecal waste streams, making them model indicators of the distribution of antimicrobial-resistant organisms that are transmitted through the faecal-oral route. We aimed to estimate the mass of faeces containing ESBL-producing E coli entering different levels of the sanitation ladder globally and by WHO region to determine the global scale at which sanitation infrastructure serves as a vehicle for dissemination of antimicrobial-resistant organisms.

METHODS

In this global and regional analysis, we used publicly available sanitation coverage data from the WHO/UNICEF Joint Monitoring Programme and most recent available scientific literature on human faecal production (2018) and carriage of ESBL-producing E coli by healthy individuals (2016) to estimate the quantity of faeces that has been discharged that contains ESBL-producing E coli for 2015 and projected for 2030. We estimated the mass of faeces containing ESBL-producing E coli by WHO region and at different levels of the Sustainable Development Goal sanitation ladder-ie, into at-least basic (ie, safely managed or basic) systems, limited systems, and unimproved systems, and via open defecation. We modelled three scenarios in which the proportion of ESBL-producing E coli among all E coli that was excreted by carriers varied on the basis of the scientific literature: 100% (scenario A), 10% (scenario B), or 1% (scenario C).

FINDINGS

Under scenario B, we estimated that approximately 19 billion kg of faeces carrying ESBL-producing E coli was excreted in 2015 globally. Approximately 65·8% (1·2-120 billion kg depending on modelled scenario) of this faecal biomass was managed in at-least basic sanitation systems, 8·4% (160 million-16 billion kg) in limited sanitation systems, 14·4% (270 million-27 billion kg) in unimproved sanitation systems, and 11·4% (220 million-22 billion kg) was openly defecated. The regions with the highest proportion of openly defecated faeces containing ESBL-producing E coli were the South-East Asia (29·4%) and African (21·8%) regions. The South-East Asia, Western Pacific, and African regions produced 524 billion kg (63%) of the total global human faecal biomass, but 16·9 billion kg (90%) of faeces containing ESBL-producing E coli under scenario B. By 2030, estimates under scenario B will have approximately doubled to 37·6 billion kg of faeces carrying ESBL-producing E coli under the most conservative projections.

INTERPRETATION

At-least basic sanitation does not guarantee effective removal or inactivation of antimicrobial-resistant organisms from faecal biomass. However, our findings indicate the need for mitigating transport of antimicrobial-resistant organisms via sanitation systems that are not safely managed, including open defecation, which might result in direct environmental discharge and subsequent risk of transmission back to humans.

FUNDING

None.

Widespread high-risk clones of multidrug-resistant extended-spectrum β-lactamase-producing Escherichia coli B2-ST131 and F-ST648 in public aquatic environments

Aquatic environments are considered a reservoir for the dissemination of multidrug-resistant (MDR) bacteria, principally Escherichia coli, with the consequent spread of acquired antimicrobial resistance genes (ARGs). Widespread high-risk clones of MDR E. coli are responsible for human infections worldwide. This study aimed to characterise, through whole-genome sequencing (WGS), isolates of MDR E. coli harbouring ARGs obtained from public aquatic environments in Brazil. MDR E. coli isolates were obtained from rivers, streams and lakes that presented different Water Quality Index records and were submitted to WGS. The resistome, mobilome and virulome showed a great diversity of ARGs, plasmids and virulence genes, respectively. In addition, mutations in the quinolone resistance-determining regions of GyrA, ParC and ParE as well as several metal resistance genes (MRGs) and antibacterial biocide resistance genes (ABGs) were detected. Typing and subtyping of MDR E. coli revealed different lineages, with two belonging to widespread high-risk clones (i.e. B2-ST131-fimH30 and F-ST648-fimH27), which are grouped by core genome multilocus sequence typing (cgMLST) in clusters with E. coli lineages obtained from different sources distributed worldwide. MDR bacteria carrying MRGs and ABGs have emerged as a global human and environmental health problem. Detection of widespread high-risk clones calls for attention to the dissemination of fluoroquinolone-resistant QnrS1- and CTX-M-producing E. coli lineages associated with human infections in public aquatic environments.

Antibiogram and beta-lactamase genes among cefotaxime resistant E. coli from wastewater treatment plant

BACKGROUND

The World Health Organization (WHO) recently classified Enterobacteriaceae resistance to third-generation cephalosporin into the group of pathogens with critical criteria for future research.

METHODS

A study to assess the antibiogram and beta-lactamase genes among the cefotaxime resistant E. coli (CREc) from a South African wastewater treatment plant (WWTP) was conducted using standard phenotypic and molecular biology characterization methods.

RESULTS

Approximate total E. coli (TEc) concentration (log₁₀ CFU/mL) ranged between 5.7 and 6.8 among which cefotaxime resistant E. coli were between 1.8 and 4.8 (log₁₀ CFU/mL) for cefotaxime antibiotic concentration of 4 and 8 mg/L in the influent samples. Effluent samples, heavily influenced by the chlorination had only 0.3 log₁₀ CFU/mL of TEc. Fifty-one cefotaxime resistant isolates were selected out of an overall of 75 isolates, and subjected to a new round of testing, with a follow up of 36 and 48 isolates for both colistin and gentamicin, respectively as guided by initial results. Selected CREc exhibited resistance to amoxicillin-clavulanic acid (35.3%; n = 51), colistin sulphate (76.5%; n = 36), ciprofloxacin (47.1%; n = 51), gentamicin (87.5%; n = 48) and intermediate-resistance to meropenem (11.8%; n = 51). Extended spectrum-beta-lactamase genes detected, viz.: bla_CTX-M (52.6%; n = 38) and bla_TEM (84.2%; n = 38) and concurrent bla_CTX-M + bla_TEM (36.8%; n = 38), but no bla_SHV was detected. Carbapenem resistance genes, blaKPC-2 (15.8%; n = 38), blaOXA-1 (57.9%; n = 38), blaNDM-1 (15.8%; n = 38) were also detected. Approximately, 10.5 - 36.8% (n = 38) co-occurrence of two or more beta-lactamase genes was detected in some isolates. Out of the selected number (n = 30), 7(23.3%) were enterotoxigenic E. coli (ETEC), 14 (46.7%) were Enteroaggregative E. coli (EAEC), but no enteropathogenic E. coli (EPEC) was detected.

CONCLUSION

Resistance to cefotaxime and the presence of a wide range of beta-lactamase genes exposed the potential risks associated with these pathogens via occupational and domestic exposure during the reuse of treated wastewater.

A Comprehensive Account of Escherichia coli Sequence Type 131 in Wastewater Reveals an Abundance of Fluoroquinolone-Resistant Clade A Strains

In the ten years since its discovery, the Escherichia coli clone sequence type 131 (ST131) has become a major international health threat, with the multidrug-resistant and extended-spectrum β-lactamase (ESBL)-producing clade C emerging as the globally dominant form. ST131 has previously been isolated from wastewater; however, most of these studies selectively screened for ESBL-producing organisms, thereby missing the majority of remaining ST131 clades. In this study, we used a high-throughput PCR-based screening strategy to comprehensively examine wastewater for the presence of ST131 over a 1-year period. Additional multiplex PCRs were used to differentiate clades and obtain an unbiased account of the total ST131 population structure within the collection. Furthermore, antimicrobial susceptibility profiles of all ST131-positive samples were tested against a range of commonly used antibiotics. From a total of over 3,762 E. coli wastewater samples, 1.86% (n = 70) tested positive for ST131, with the majority being clade A isolates. In total, 63% (n = 44) were clade A, 29% (n = 20) were clade B, 1% (n = 1) were clade C0, 6% (n = 4) were clade C1, and 1% (n = 1) were clade C2. In addition, a very high rate of resistance to commonly used antibiotics among wastewater isolates is reported, with 72.7% (n = 32) of clade A resistant to ciprofloxacin and high rates of resistance to gentamicin, sulfamethoxazole-trimethoprim, and tetracycline in clades that are typically sensitive to antibiotics.IMPORTANCE ST131 is a global pathogen. This clone causes urinary tract infections and is frequently isolated from human sources. However, little is known about ST131 from environmental sources. With the widely reported increase in antibiotic concentrations found in wastewater, there is additional selection pressure for the emergence of antibiotic-resistant ST131 in this niche. The unbiased screening approach reported herein revealed that previously antibiotic-sensitive lineages of ST131 are now resistant to commonly used antibiotics present in wastewater systems and may be capable of surviving UV sterilization. This is the most comprehensive account of ST131 in the wastewater niche to date and an important step in better understanding the ecology of this global pathogen.

Extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae in cattle production - a threat around the world

Food producing animal is a global challenge in terms of antimicrobial resistance spread. Extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae are relevant opportunistic pathogens that may spread in many ecological niches of the One Health approach as human, animal and environment due to intestinal selection of antimicrobial resistant commensals in food production animals. Cattle production is a relevant ecological niche for selection of commensal bacteria with antimicrobial resistance from microbiota. Enterobacteriaceae show importance in terms of circulation of resistant-bacteria and antimicrobial resistance genes via food chain creating a resistance reservoir, setting up a threat for colonization of humans and consequent health risk. ESBL-producing Enterobacteriaceae are a threat in terms of human health responsible for life threatening outbreaks and silent enteric colonization of community populations namely the elder population. Food associated colonization is a risk difficult to handle and control. In a time of globalization of food trading, population intestinal colonization is a mirror of food production and in that sense this work aims to make a picture of ESBL-producing Enterobacteriaceae in animal production for food over the world in order to make some light in this reality of selection of resistant threats in food producing animal.

Antibiotic-Resistant Escherichia coli in Drinking Water Samples from Rural Andean Households in Cajamarca, Peru

Antibiotic resistance in pathogenic bacteria is a serious public health issue. The growing threat is a cause for concern and action to prevent the emergence of new resistant strains and the spread of existing ones to humans via the environment. This study aimed at identifying fecal pathogens in drinking water obtained from rural Andean households from Cajamarca, Peru, and measuring the antibiotic resistance profile of Escherichia coli. The study was embedded within a community-randomized controlled trial among 102 communities in the northern highlands of the Cajamarca region, Peru. Of 314 samples, 55.4% (95% CI [49.7, 61.0], n = 174) were identified as thermotolerant coliforms. Among the samples positive for thermotolerant coliform, E. coli was isolated in 37.3% (n = 117), Klebsiella spp. in 8.0% (n = 25), Enterobacter spp. in 5.1% (n = 16), and Citrobacter spp. in 2.5% (n = 8). Of the 117 E. coli samples, 48.7% (95% CI [39.4, 58.1], n = 57) showed resistance to any antibiotic. The E. coli antibiotic resistance profile showed highest resistance against tetracycline (37.6%), ampicillin (34.2%), sulfamethoxazole-trimethoprim (21.4%), and nalidixic acid (13%). Some 19.7% (95% CI [12.9, 28.0], n = 23) of the E. coli isolates displayed multidrug resistance, defined as resistance to at least three classes of antibiotics. The CTX-M-3 gene, which encodes extended-spectrum resistance to beta-lactamase antibiotics, was found in one isolate. The high prevalence of fecal contamination in drinking water highlights the importance of household water treatment methods. Likewise, the high levels of antibiotic resistance found indicate a need for further research to identify the origins of potential environmental contamination, misuse, or inadequate disposal of antibiotics.

A One Health Study of the Genetic Relatedness of Klebsiella pneumoniae and Their Mobile Elements in the East of England

BACKGROUND

Klebsiella pneumoniae is a human, animal, and environmental commensal and a leading cause of nosocomial infections, which are often caused by multiresistant strains. We evaluate putative sources of K. pneumoniae that are carried by and infect hospital patients.

METHODS

We conducted a 6-month survey on 2 hematology wards at Addenbrooke's Hospital, Cambridge, United Kingdom, in 2015 to isolate K. pneumoniae from stool, blood, and the environment. We conducted cross-sectional surveys of K. pneumoniae from 29 livestock farms, 97 meat products, the hospital sewer, and 20 municipal wastewater treatment plants in the East of England between 2014 and 2015. Isolates were sequenced and their genomes compared.

RESULTS

Klebsiella pneumoniae was isolated from stool of 17/149 (11%) patients and 18/922 swabs of their environment, together with 1 bloodstream infection during the study and 4 others over a 24-month period. Each patient carried 1 or more lineages that was unique to them, but 2 broad environmental contamination events and patient-environment transmission were identified. Klebsiella pneumoniae was isolated from cattle, poultry, hospital sewage, and 12/20 wastewater treatment plants. There was low genetic relatedness between isolates from patients/their hospital environment vs isolates from elsewhere. Identical genes encoding cephalosporin resistance were carried by isolates from humans/environment and elsewhere but were carried on different plasmids.

CONCLUSION

We identified no patient-to-patient transmission and no evidence for livestock as a source of K. pneumoniae infecting humans. However, our findings reaffirm the importance of the hospital environment as a source of K. pneumoniae associated with serious human infection.

Comparative distribution of extended-spectrum beta-lactamase-producing Escherichia coli from urine infections and environmental waters

Extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli have been reported in natural environments, and may be released through wastewater. In this study, the genetic relationship between ESBL-producing E. coli collected from patient urine samples (n = 45, both hospitalized patients and out-patients) and from environmental water (n = 82, from five locations), during the same time period, was investigated. Three independent water samples were collected from the municipal wastewater treatment plant, both incoming water and treated effluent water; the receiving river and lake; and a bird sanctuary near the lake, on two different occasions. The water was filtered and cultured on selective chromID ESBL agar plates in order to detect and isolate ESBL-producing E. coli. Illumina whole genome sequencing was performed on all bacterial isolates (n = 127). Phylogenetic group B2 was more common among the clinical isolates than the environmental isolates (44.4% vs. 17.1%, p < 0.01) due to a significantly higher prevalence of sequence type (ST) 131 (33.3% vs. 13.4%, p < 0.01). ST131 was, however, one of the most prevalent STs among the environmental isolates. There was no significant difference in diversity between the clinical isolates (DI 0.872 (0.790-0.953)) and the environmental isolates (DI 0.947 (0.920-0.969)). The distribution of ESBL genes was similar: blaCTX-M-15 dominated, followed by blaCTX-M-14 and blaCTX-M-27 in both the clinical (60.0%, 8.9%, and 6.7%) and the environmental isolates (62.2%, 12.2%, and 8.5%). Core genome multi-locus sequence typing showed that five environmental isolates, from incoming wastewater, treated wastewater, Svartån river and Hjälmaren lake, were indistinguishable or closely related (≤10 allele differences) to clinical isolates. Isolates of ST131, serotype O25:H4 and fimtype H30, from the environment were as closely related to the clinical isolates as the isolates from different patients were. This study confirms that ESBL-producing E. coli are common in the aquatic environment even in low-endemic regions and suggests that wastewater discharge is an important route for the release of ESBL-producing E. coli into the aquatic environment.

Genomic surveillance of Escherichia coli in municipal wastewater treatment plants as an indicator of clinically relevant pathogens and their resistance genes

We examined whether genomic surveillance of Escherichia coli in wastewater could capture the dominant E. coli lineages associated with bloodstream infection and livestock in the East of England, together with the antibiotic-resistance genes circulating in the wider E. coli population. Treated and untreated wastewater was taken from 20 municipal treatment plants in the East of England, half in direct receipt of acute hospital waste. All samples were culture positive for E. coli, and all but one were positive for extended-spectrum β-lactamase (ESBL)-producing E. coli. The most stringent wastewater treatment (tertiary including UV light) did not eradicate ESBL-E. coli in 2/3 cases. We sequenced 388 E. coli (192 ESBL, 196 non-ESBL). Multilocus sequence type (ST) diversity was similar between plants in direct receipt of hospital waste versus the remainder (93 vs 95 STs, respectively). We compared the genomes of wastewater E. coli with isolates from bloodstream infection (n=437), and livestock farms and retail meat (n=431) in the East of England. A total of 19/20 wastewater plants contained one or more of the three most common STs associated with bloodstream infection (ST131, ST73, ST95), and 14/20 contained the most common livestock ST (ST10). In an analysis of 1254 genomes (2 cryptic E. coli were excluded), wastewater isolates were distributed across the phylogeny and intermixed with isolates from humans and livestock. Ten blaCTX-M elements were identified in E. coli isolated from wastewater, together with a further 47 genes encoding resistance to the major antibiotic drug groups. Genes encoding resistance to colistin and the carbapenems were not detected. Genomic surveillance of E. coli in wastewater could be used to monitor new and circulating lineages and resistance determinants of public-health importance.

Mobile antibiotic resistome in wastewater treatment plants revealed by Nanopore metagenomic sequencing

BACKGROUND

Wastewater treatment plants (WWTPs) are recognized as hotspots for horizontal gene transfer (HGT) of antibiotic resistance genes (ARGs). Despite our understanding of the composition and distribution of ARGs in WWTPs, the genetic location, host, and fate of ARGs remain largely unknown.

RESULTS

In this study, we combined Oxford Nanopore and Illumina metagenomics sequencing to comprehensively uncover the resistome context of influent, activated sludge, and effluent of three WWTPs and simultaneously track the hosts of the ARGs. The results showed that most of the ARGs detected in all compartments of the WWTPs were carried by plasmids. Transposons and integrons also showed higher prevalence on plasmids than on the ARG-carrying chromosome. Notably, integrative and conjugative elements (ICEs) carrying five types of ARGs were detected, and they may play an important role in facilitating the transfer of ARGs, particularly for tetracycline and macrolide-lincosamide-streptogramin (MLS). A broad spectrum of ARGs carried by plasmids (29 subtypes) and ICEs (4 subtypes) was persistent across the WWTPs. Host tracking showed a variety of antibiotic-resistant bacteria in the effluent, suggesting the high potential for their dissemination into receiving environments. Importantly, phenotype-genotype analysis confirmed the significant role of conjugative plasmids in facilitating the survival and persistence of multidrug-resistant bacteria in the WWTPs. At last, the consistency in the quantitative results for major ARGs types revealed by Nanopore and Illumina sequencing platforms demonstrated the feasibility of Nanopore sequencing for resistome quantification.

CONCLUSION

Overall, these findings substantially expand our current knowledge of resistome in WWTPs, and help establish a baseline analysis framework to study ARGs in the environment.

Fate of cefotaxime-resistant Enterobacteriaceae and ESBL-producers over a full-scale wastewater treatment process with UV disinfection

Disinfection by UV radiation is one of the most promising solutions to reduce the bacterial load and antibiotic resistance in the final effluents of urban wastewater treatment plants (UWTP). Our aim was to evaluate the fate of cefotaxime-resistant Enterobacteriaceae and Extended Spectrum Beta-Lactamase (ESBL) producers in a full-scale system that includes UV-C disinfection. Over treatment, the abundance of cefotaxime-resistant Enterobacteriaceae was reduced, with reductions of 1.9 log units after secondary treatment (STW samples) and 1.8 log following UV disinfection (UTW samples). These reductions, did not reflect the variations in the prevalence of cefotaxime-resistant Enterobacteriaceae, estimated to be of 3% in raw wastewater (RW), 18% in STW and 3% in UTW. A significant increase of cefotaxime-resistant bacterial counts (0.5 log; p < 0.05) was observed after 3 days of storage. In a total of 1799 cefotaxime-resistant Enterobacteriaceae isolates, 15% harboured bla_CTX-M (n = 274), 11% bla_TEM (n = 194) and 4% bla_SHV (n = 72). While the ESBL gene prevalence decreased over treatment, the prevalence of the intI1 gene decreased after ST but slightly increased in UTW samples. The bla_CTX-M-carriers were identified as Escherichia coli and Klebsiella pneumoniae, mostly multi-drug resistant (90.5%) and carrying integrase genes (82.8%). The bla_CTX-M gene variants (48 bla_CTX-M-15, 9 bla_CTX-M-32, 8 bla_CTX-M-1, 5 bla_CTX-M-27, and 2 bla_CTX-M-14) were flanked by ISEcp1, ISEcp1/IS26, IS903 and ORF477 in 8 different arrangements. The IncF plasmid replicon type was highly prevalent among bla_CTX-M-carrying Escherichia coli (74.5%) while IncR predominated among K. pneumoniae (54.5%). Our results confirmed the potential of UV-C disinfection to remove antibiotic resistant bacteria. Still, resistant Enterobacteriaceae (about 30 × 10⁶ cells per m³ of water), presenting traits that might potentiate antibiotic resistance spread, are released in the final effluent. In addition, a significant regrowth was observed after storage. These results suggest that improvements of wastewater disinfection are still required to minimize the risks associated with UWTP discharges.

Extensive Genetic Commonality among Wildlife, Wastewater, Community, and Nosocomial Isolates of Escherichia coli Sequence Type 131 (H30R1 and H30Rx Subclones) That Carry blaCTX-M-27 or blaCTX-M-15

Escherichia coli sequence type 131 (ST131) is currently one of the leading causes of multidrug-resistant extraintestinal infections globally. Here, we analyzed the phenotypic and genotypic characteristics of 169 ST131 isolates from various sources (wildlife, wastewater, companion animals, community, and hospitals) to determine whether wildlife and the environment share similar strains with humans, supporting transmission of ST131 between different ecological niches. Susceptibility to 32 antimicrobials was tested by disc diffusion and broth microdilution. Antibiotic resistance genes, integrons, plasmid replicons, 52 virulence genes, and fimH-based subtypes were detected by PCR and DNA sequencing. Genomic relatedness was determined by pulsed-field gel electrophoresis (PFGE). The genetic context and plasmid versus chromosomal location of extended-spectrum beta-lactamase and AmpC beta-lactamase genes was determined by PCR and probe hybridization, respectively. The 169 ST131 study isolates segregated predominantly into bla_CTX-M-15H30Rx (60%) and bla_CTX-M-27H30R1 (25%) subclones. Within each subclone, isolates from different source groups were categorized into distinct PFGE clusters; genotypic characteristics were fairly well conserved within each major PFGE cluster. Irrespective of source, the bla_CTX-M-15H30Rx isolates typically exhibited virotype A (89%), an F2:A1:B- replicon (84%), and a 1.7-kb class 1 integron (92%) and had diverse structures upstream of the bla_CTX-M region. In contrast, the bla_CTX-M-27H30R1 isolates typically exhibited virotype C (86%), an F1:A2:B20 replicon (76%), and a conserved IS26-ΔISEcp1-bla_CTX-M-like structure. Despite considerable overall genetic diversity, our data demonstrate significant commonality between E. coli ST131 isolates from diverse environments, supporting transmission between different sources, including humans, environment, and wildlife.

Extended Spectrum Beta-Lactamase (ESBL)-producing bacteria isolated from hospital wastewaters, rivers and aquaculture sources in Nigeria

Untreated wastewater is a risk factor for the spread of antibiotic resistance in the environment. However, little is known about the contribution of untreated wastewater to the burden of antibiotic resistance in the Nigerian environment. In this study, a total of 143 ceftazidime-/cefpodoxime-resistant bacteria isolated from untreated wastewater and untreated wastewater-contaminated surface and groundwater in Nigeria were screened for extended-spectrum β-lactamase (ESBL) genes, integrons and integron gene cassettes by PCR. The genetic environment of bla _CTX-M-15 was mapped by PCR and potentially conjugative plasmids were detected among the isolates by degenerate primer MOB typing (DPMT). ESBL production was confirmed in 114 (79.7%) isolates and ESBL genes (bla _SHV, bla _CTX-M-15 and bla _TEM) were detected in 85 (74.6%) ESBL-producing isolates. bla _CTX-M-15 was associated with ISEcp1 and with orf477 in 12 isolates and with ISEcp1, IS26 and orf477 in six others. To the best of our knowledge, this is the first report of bla _CTX-M-15 in hand-dug wells and borehole serving as sources of drinking water and a first report of the genetic environment of bla _CTX-M-15 in environmental bacteria from Nigeria. The results of this study confirm untreated wastewater as an important medium for the spread of ESBL-producing bacteria within the Nigerian environment. Hence, the widespread practice of discharging untreated wastewater into the aquatic ecosystem in Nigeria is a serious risk to public health.

Vancomycin-resistant enterococci with vanA gene in treated municipal wastewater and their association with human hospital strains

Vancomycin-resistant enterococci (VRE) are pathogens of increasing medical importance. In Brno, Czech Republic, we collected 37 samples from the effluent of a wastewater treatment plant (WWTP), 21 surface swabs from hospital settings, and 59 fecal samples from hospitalized patients and staff. Moreover, we collected 284 gull cloacal swabs from the colony situated 35km downstream the WWTP. Samples were cultured selectively. Enterococci were identified using MALDI-TOF MS, phenotypically tested for susceptibility to antibiotics, and by PCR for occurrence of resistance and virulence genes. Pulsed-field gel electrophoresis (PFGE) and multi-locus sequence typing (MLST) were used to examine genotypic diversity. VRE carrying the vanA gene were found in 32 (86%, n=37) wastewater samples, from which we obtained 49 isolates: Enterococcus faecium (44) and Enterococcus gallinarum (2), Enterococcus casseliflavus (2), and Enterococcus raffinosus (1). From 33 (69%) of 48 inpatient stool samples, we obtained 39 vanA-carrying VRE, which belonged to E. faecium (33 isolates), Enterococcus faecalis (4), and Enterococcus raffinosus (2). Nearly one-third of the samples from hospital surfaces contained VRE with the vanA gene. VRE were not detected among gulls. Sixty-seven (84%, n=80) E. faecium isolates carried virulence genes hyl and/or esp. Virulence of E. faecalis was encoded by gelE, asa1, and cylA genes. A majority of the E. faecium isolates belonged to the clinically important sequence types ST17 (WWTP: 10 isolates; hospital: 4 isolates), ST18 (9;8), and ST78 (5;0). The remaining isolates belonged to ST555 (2;0), ST262 (1;6), ST273 (3;0), ST275 (1;0), ST549 (2;0), ST19 (0;1), ST323 (3;0), and ST884 (7;17). Clinically important enterococci carrying the vanA gene were almost continually detectable in the effluent of the WWTP, indicating insufficient removal of VRE during wastewater treatment and permanent shedding of these antibiotic resistant pathogens into the environment from this source. This represents a risk of their transmission to the environment.

Extended-spectrum β-lactamase-producing Escherichia coli in wastewaters and refugee camp in Lebanon

AIM

To evaluate the effects of population influx of refugees on the prevalence of extended-spectrum β-lactamase-producing Escherichia coli in wastewater networks in Lebanon.

MATERIALS & METHODS

Pulsed-field gel electrophoresis, multilocus sequence typing and antibiotic resistance genes typing were performed.

RESULTS

53.1% of isolates recovered from Al-Qaa refugee camp were positive for the tested resistant determinants compared with 49.1% from river effluents. All isolates carried aac(6)-1b and/or aac(3)-II; none carried armA, rmtB, ant(4')-Iia, aph(3')-Ia or carbapenemases. CTX-M-15, TEM-1, OXA-1, CMY-2 and SHV-12 were detected. Single and/or double substitutions were detected in GyrA and ParC. Phylogenetic group B2 and ST6470 were the most prevalent. Pulsed-field gel electrophoresis revealed 19 XbaI patterns and 17 pulsotypes.

CONCLUSION

The introduction of novel resistance patterns into the wastewater network requires effective control.

Occurrence of Clinically Important Lineages, Including the Sequence Type 131 C1-M27 Subclone, among Extended-Spectrum-β-Lactamase-Producing Escherichia coli in Wastewater

Contamination of environmental waters by extended-spectrum-β-lactamase (ESBL)-producing Escherichia coli (ESBLEC) is of great concern. Wastewater treatment plants (WWTPs) and hospitals release large amounts of ESBLEC into the environment. In the present study, we isolated ESBLEC strains from wastewater collected from a WWTP and a hospital in Japan and performed whole-genome sequencing to characterize these strains. Genomic analysis of 54 strains (32 from the WWTP and 22 from hospital wastewater) revealed the occurrence of clinically important clonal groups with extraintestinal pathogenic E. coli status in the WWTP and hospital wastewater. Fine-scale phylogenetic analysis was performed to further characterize 15 sequence type 131 (ST131) complex strains (11 from the WWTP and 4 from hospital wastewater). These ST131 complex strains were comprised of the following different subgroups: clade A (n = 2), C1-M27 (n = 8), and C1 (non-C1-M27) (n = 1) for strains from the WWTP and clade A (n = 2), C1-M27 (n = 1), and C1 (non-C1-M27) (n = 1) for strains from hospital wastewater. The results indicate that ESBLEC strains belonging to clinically important lineages, including the C1-M27 clade, may disseminate into the environment through wastewater, highlighting the need to monitor for antibiotic resistance in wastewater.

Extended-Spectrum β-Lactamase-Producing Klebsiella pneumoniae from Pharmaceutical Wastewaters in South-Western Nigeria

Emergence and spread of Klebsiella pneumoniae isolates producing extended-spectrum β-lactamases (ESBLs) present a major threat to public health. In this study, we characterized β-lactam-resistant K. pneumoniae isolates from six wastewater samples obtained from two pharmaceutical industries located in Lagos and Ogun States, Nigeria. Bacteria were isolated by using MacConkey agar; species identification and antibacterial susceptibility testing were performed by Vitek 2. Etest was used for ESBL phenotype confirmation. The presence of β-lactamase genes was investigated by PCR and sequencing. Bacterial strain typing was done by XbaI-macrorestriction and subsequent pulsed-field gel electrophoresis (PFGE) as well as multilocus sequence typing (MLST). Thirty-five bacterial species were isolated from the six samples; among them, we identified seven K. pneumoniae isolates with resistance to β-lactams and co-resistance to fluoroquinolones, aminoglycosides, and folate pathway inhibitors. The ESBL phenotype was confirmed in six K. pneumoniae isolates that harbored ESBL genes bla_CTX-M-15 (n = 5), bla_SHV-2 (n = 1), and bla_SHV-12 (n = 1). PFGE and MLST analysis revealed five clones belonging to four sequence types (ST11, ST15, ST37, ST101), and clone K. pneumoniae-ST101 was present in the wastewater samples from two different pharmaceutical industries. Additionally performed conjugation assays confirmed the location of β-lactamase genes on conjugative plasmids. This is the first confirmation of K. pneumoniae isolates producing CTX-M-15-ESBL from pharmaceutical wastewaters in Nigeria. The co-resistance observed might be a reflection of the different drugs produced by these industries. Continuous surveillance of the environmental reservoirs of multidrug-resistant bacteria is necessary to prevent their further spread.

The ecology of extended-spectrum β-lactamases (ESBLs) in the developed world

BACKGROUND

Since the initial appearance in the 1980s, Enterobacteriaceae producing extended-spectrum β-lactamase (ESBL) have increased in prevalence and emerged as a major antimicrobial-resistant pathogen. The source of these antimicrobial-resistant bacteria in the developed world is an area of active investigation.

METHODS

A standard internet search was conducted with a focus on the epidemiology and potential sources of ESBL-producing Enterobacteriaceae in the developed world.

RESULTS

The last decade has witnessed several major changes in the epidemiology of these bacteria: replacement of TEM and SHV-type ESBLs by CTX-M-family ESBLs, emergence of Escherichia coli ST131 as a prevalent vehicle of ESBL, and spread of ESBL-producing E. coli in the community. The most studied potential sources of ESBL-producing Enterobacteriaceae in humans in the community include food and companion animals, the environment and person-to-person transmission, though definitive links are yet to be established. Evidence is emerging that international travel may serve as a major source of introduction of ESBL-producing Enterobacteriaceae into the developed world.

CONCLUSIONS

ESBL-producing Enterobacteriaceae has become a major multidrug-resistant pathogen in the last two decades, especially in the community settings. The multifactorial nature of its expansion poses a major challenge in the efforts to control them.

Characterization of CTX-M enzymes, quinolone resistance determinants, and antimicrobial residues from hospital sewage, wastewater treatment plant, and river water

Multidrug-resistant (MDR) bacteria are widespread in hospitals and have been increasingly isolated from aquatic environments. The aim of the present study was to characterize extended-spectrum β-lactamase (ESBL) and quinolone-resistant Enterobacteriaceae from a hospital effluent, sanitary effluent, inflow sewage, aeration tank, and outflow sewage within a wastewater treatment plant (WWTP), as well as river water upstream and downstream (URW and DRW, respectively), of the point where the WWTP treated effluent was discharged. β-lactamase (bla) genes, plasmid-mediated quinolone resistance (PMQR), and quinolone resistance-determining regions (QRDRs) were assessed by amplification and sequencing in 55 ESBL-positive and/or quinolone-resistant isolates. Ciprofloxacin residue was evaluated by high performance liquid chromatography. ESBL-producing isolates were identified in both raw (n=29) and treated (n=26) water; they included Escherichia coli (32), Klebsiella pneumoniae (22) and Klebsiella oxytoca (1). Resistance to both cephalosporins and quinolone was observed in 34.4% of E. coli and 27.3% of K. pneumoniae. Resistance to carbapenems was found in 5.4% of K. pneumoniae and in K. oxytoca. Results indicate the presence of bla_CTX-M (51/55, 92.7%) and bla_SHV (8/55, 14.5%) ESBLs, and bla_GES (2/55, 3.6%) carbapenemase-encoding resistance determinants. Genes conferring quinolone resistance were detected at all sites, except in the inflow sewage and aeration tanks. Quinolone resistance was primarily attributed to amino acid substitutions in the QRDR of GyrA (47%) or to the presence of PMQR (aac-(6')-Ib-cr, oqxAB, qnrS, and/or qnrB; 52.9%) determinants. Ciprofloxacin residue was absent only from URW. Our results have shown strains carrying ESBL genes, PMQR determinants, and mutations in the gyrA QRDR genes mainly in hospital effluent, URW, and DRW samples. Antimicrobial use, and the inefficient removal of MDR bacteria and antibiotic residue during sewage treatment, may contribute to the emergence and spreading of resistance in the environment, making this a natural reservoir.

Characteristics of Quinolone Resistance in Escherichia coli Isolates from Humans, Animals, and the Environment in the Czech Republic

Escherichia coli is a common commensal bacterial species of humans and animals that may become a troublesome pathogen causing serious diseases. The aim of this study was to characterize the quinolone resistance phenotypes and genotypes in E. coli isolates of different origin from one area of the Czech Republic. E. coli isolates were obtained from hospitalized patients and outpatients, chicken farms, retailed turkeys, rooks wintering in the area, and wastewaters. Susceptibility of the isolates grown on the MacConkey agar with ciprofloxacin (0.05 mg/L) to 23 antimicrobial agents was determined. The presence of plasmid-mediated quinolone resistance (PMQR) and ESBL genes was tested by PCR and sequencing. Specific mutations in gyrA, gyrB, parC, and parE were also examined. Multilocus sequence typing and pulsed-field gel electrophoresis were performed to assess the clonal relationship. In total, 1050 E. coli isolates were obtained, including 303 isolates from humans, 156 from chickens, 105 from turkeys, 114 from the rooks, and 372 from wastewater samples. PMQR genes were detected in 262 (25%) isolates. The highest occurrence was observed in isolates from retailed turkey (49% of the isolates were positive) and inpatients (32%). The qnrS1 gene was the most common PMQR determinant identified in 146 (56%) followed by aac(6')-Ib-cr in 77 (29%), qnrB19 in 41 (16%), and qnrB1 in 9 (3%) isolates. All isolates with high level of ciprofloxacin resistance (>32 mg/L) carried double or triple mutations in gyrA combined with single or double mutations in parC. The most frequently identified substitutions were Ser(83)Leu; Asp(87)Asn in GyrA, together with Ser(80)Ile, or Glu(84)Val in ParC. Majority of these isolates showed resistance to beta-lactams and multiresistance phenotype was found in 95% isolates. Forty-eight different sequence types among 144 isolates analyzed were found, including five major clones ST131 (26), ST355 (19), ST48 (13), ST95 (10), and ST10 (5). No isolates sharing 100% relatedness and originating from different areas were identified. In conclusion, our study identified PMQR genes in E. coli isolates in all areas studied, including highly virulent multiresistant clones such as ST131 producing CTX-M-15 beta-lactamases.

Anthropogenic antibiotic resistance genes mobilization to the polar regions

Anthropogenic influences in the southern polar region have been rare, but lately microorganisms associated with humans have reached Antarctica, possibly from military bases, fishing boats, scientific expeditions, and/or ship-borne tourism. Studies of seawater in areas of human intervention and proximal to fresh penguin feces revealed the presence of Escherichia coli strains least resistant to antibiotics in penguins, whereas E. coli from seawater elsewhere showed resistance to one or more of the following antibiotics: ampicillin, tetracycline, streptomycin, and trim-sulfa. In seawater samples, bacteria were found carrying extended-spectrum β-lactamase (ESBL)-type CTX-M genes in which multilocus sequencing typing (MLST) showed different sequence types (STs), previously reported in humans. In the Arctic, on the contrary, people have been present for a long time, and the presence of antibiotic resistance genes (ARGs) appears to be much more wide-spread than was previously reported. Studies of E coli from Arctic birds (Bering Strait) revealed reduced susceptibility to antibiotics, but one globally spreading clone of E. coli genotype O25b-ST131, carrying genes of ESBL-type CTX-M, was identified. In the few years between sample collections in the same area, differences in resistance pattern were observed, with E. coli from birds showing resistance to a maximum of five different antibiotics. Presence of resistance-type ESBLs (TEM, SHV, and CTX-M) in E. coli and Klebsiella pneumoniae was also confirmed by specified PCR methods. MLST revealed that those bacteria carried STs that connect them to previously described strains in humans. In conclusion, bacteria previously related to humans could be found in relatively pristine environments, and presently human-associated, antibiotic-resistant bacteria have reached a high global level of distribution that they are now found even in the polar regions.

Free water surface constructed wetlands limit the dissemination of extended-spectrum beta-lactamase producing Escherichia coli in the natural environment

The fates of Escherichia coli and extended-spectrum beta-lactamase-producing E. coli (ESBL E. coli) were studied over a period of one year in a free water surface constructed wetland (FWS CW) with a succession of open water zones and vegetation ponds (Typha or Phragmites), that received the effluent from a wastewater treatment plant. ESBL E. coli were detected and isolated from all sampling areas of the FWS CW throughout the study period. They represented 1‰ of the total E. coli population regardless of the origin of samples. Two main factors affected the log removal of E. coli and of ESBL E. coli: the season and the presence of vegetation. Between the inlet and the outlet of the FWS CW, the log removal of E. coli ranged from 1.5 in the warmer season (summer and fall) to 3.0 in the colder season (winter and spring). The concentrations of E. coli decreased significantly in the vegetated areas during the colder season, but increased in the warmer season, suggesting an effect of the plant growth stage on the survival of E. coli. Among the 369 ESBL E. coli isolates collected during our study, 84% harbored the CTX-M-ESBL type and 55.3% carried bla genes on plasmid DNA. Furthermore, 93% of the ESBL E. coli isolates were multidrug resistant but the proportion of resistant strains did not change significantly along the FWS CW. ESBL E. coli were characterized by MLST analysis using the 7 genes based Achtman Scheme. ESBL E. coli isolated from water, sediments, roots and feces of myocastors collected in the FWS CW and in the recipient river were genotypically related, suggesting persistence and circulation of the ESBL producing E. coli throughout the FWS CW and in the receiving river. Overall, these observations show that FWS CW could be an efficient treatment for ESBL E. coli disinfection of wastewater and could limit their dissemination in the aquatic environment.

The Risk of Some Veterinary Antimicrobial Agents on Public Health Associated with Antimicrobial Resistance and their Molecular Basis

The risk of antimicrobial agents used in food-producing animals on public health associated with antimicrobial resistance continues to be a current topic of discussion as related to animal and human public health. In the present review, resistance monitoring data, and risk assessment results of some important antimicrobial agents were cited to elucidate the possible association of antimicrobial use in food animals and antimicrobial resistance in humans. From the selected examples, it was apparent from reviewing the published scientific literature that the ban on use of some antimicrobial agents (e.g., avoparcin, fluoroquinolone, tetracyclines) did not change drug resistance patterns and did not mitigate the intended goal of minimizing antimicrobial resistance. The use of some antimicrobial agents (e.g., virginiamycin, macrolides, and cephalosporins) in food animals may have an impact on the antimicrobial resistance in humans, but it was largely depended on the pattern of drug usage in different geographical regions. The epidemiological characteristics of resistant bacteria were closely related to molecular mechanisms involved in the development, fitness, and transmission of antimicrobial resistance.

Reservoirs of Extraintestinal Pathogenic Escherichia coli

Several potential reservoirs for the Escherichia coli strains that cause most human extraintestinal infections (extraintestinal pathogenic E. coli; ExPEC) have been identified, including the human intestinal tract and various non-human reservoirs, such as companion animals, food animals, retail meat products, sewage, and other environmental sources. Understanding ExPEC reservoirs, chains of transmission, transmission dynamics, and epidemiologic associations will assist greatly in finding ways to reduce the ExPEC-associated disease burden. The need to clarify the ecological behavior of ExPEC is all the more urgent because environmental reservoirs may contribute to acquisition of antimicrobial resistance determinants and selection for and amplification of resistant ExPEC. In this chapter, we review the evidence for different ExPEC reservoirs, with particular attention to food and food animals, and discuss the public health implications of these reservoirs for ExPEC dissemination and transmission.