Abstract
The goal of this study was to determine how surface and wastewater contribute to the contamination of the environment with an extended-spectrum β-lactamase-producing Escherichia coli (ESBL E. coli). Water samples (n = 32) were collected from eight different locations of Islamabad and processed for microbiological and molecular analyses of E. coli and ESBL E. coli. Antimicrobial susceptibility testing was carried out to determine the resistance pattern of the isolates. A total of 21 water samples were contaminated with E. coli and 15 isolates were identified as ESBL producers harboring blaTEM (40%) and blaCTX-M (33.33%) genes. Interestingly, all the ESBL E. coli isolates showed the least resistance against second-generation Cephalosporins compared to other generations. Moreover, the study showed that the aquatic environment is harboring multidrug-resistant E. coli; therefore, it may act as a source of transmission to humans. The recovery of ESBL E. coli isolates resistant to higher generation Cephalosporins, Monobactam, and Carbapenems from water samples indicated an alarming situation. Thus, there is an urgent need to treat water efficiently for microbial decontamination to minimize the transmission of antimicrobial-resistant (AMR) bacteria.
HIGHLIGHTS
This is the first study of its type from Pakistan which describes the occurrence of AMR bacteria in a water body starting from upstream to its subsequent downstreams.
All (100%) of the ESBL E. coli isolates had multidrug resistance.
The most commonly detected ESBL-encoding gene in ESBL E. coli isolates was blaTEM.
ESBL E. coli isolates resistant to last-resort antibiotics were recovered during the study.
Graphical Abstract
INTRODUCTION
Antibiotic resistance especially against third-generation Cephalosporins and Carbapenems has become a threat for the global healthcare system. The most important resistance mechanism that undermines the efficacy of expanded spectrum Cephalosporins in the members of Enterobacteriaceae family is based on the production of plasmid-mediated enzymes, the extended-spectrum β-lactamases (ESBLs). These enzymes inactivate the said antibiotic compounds by disrupting their β-lactam rings (Zurfluh et al. 2013).
Escherichia coli (E. coli) is one of the most significant members of the family Enterobacteriaceae which have been affected with the emergence of ESBLs. Similarly, some strains of E. coli disseminating high levels of β-lactamases by the mutations of genes have been considered as an important group globally. E. coli is an outstanding indicator species to investigate the transmission of antimicrobial resistance through fecal contamination of water (Mohsin et al. 2017).
Antibiotic resistance has formerly been considered as a clinical problem, but recently natural ecosystems have been viewed as a crucial reservoir of antibiotic-resistant genes. The occurrence of antibiotic-resistant bacteria in aquatic environments is increasing consistently (Bouki et al. 2013). The water bodies, after receiving huge amounts of urban wastewater, hospital waste, and animal waste, represent the repository of diverse E. coli. These water bodies play a pivotal role in transferring and spreading of the resistance genes in public health significant pathogens and emerging unique resistance mechanism in them (Bajaj et al. 2015).
A recent study indicated in vitro transmission of ESBL-encoding multidrug-resistant (MDR) plasmids from ESBL E. coli recovered from water to susceptible E. coli making them antimicrobial-resistant (AMR) organisms (Gekenidis et al. 2020). Therefore, there is a possibility that ESBL E. coli isolates which are not resistant to antibiotics phenotypically but carry ESBL-encoding genes that may be involved in horizontal transmission of ESBL-encoding genes to other bacteria in the wastewater (Lenart-Boroń et al. 2020).
Only a few countrywide studies regarding the occurrence of ESBL E. coli in wastewater are reported; however, due to lack of any large-scale epidemiological study, the current understanding on environmental AMR reservoirs is very poor in Pakistan. Therefore, the current study was planned to (i) assess the occurrence of ESBL E. coli in wastewater of Islamabad Capital Territory (ICT) of the country and (ii) to determine the percentage of most important β-lactamase (ESBL) genes, i.e. blaCTX-M, blaSHV, blaTEM in the isolates obtained during the study and to estimate the current situation of antimicrobial resistance in E. coli isolates recovered during the study.
MATERIALS AND METHODS
Sample description
Water samples were collected from different locations of the Korang River and its tributaries (upstream Shangrilla Park, upstream Shahdara, downstream Baharakahu, and downstream G-6), Lai stream, wet markets, and wastewater treatment plant (WWTP) of the ICT. Sampling locations and their coordinates are shown in Figure 1 and Table 1.
GPS coordinates of locations from where the water samples were taken
Serial no. . | Sample location . | Coordinates . |
---|---|---|
1 | Upstream Shangrilla Park | 33°53′38.7″N, 73°22'15.8″E |
2 | Downstream Baharakahu | 33.7068°N, 73.0870°E |
3 | Wet market Baharakahu | 33.7068°N, 73.0870°E |
4 | Upstream Shahdara | 33.7068°N, 73.0870°E |
5 | Downstream G-6 | 33°38′32.6″N, 73°07′46.7″E |
6 | Wet market G-6 | 33°38′32.6″N, 73°07′46.7″E |
7 | I-9 treatment plant | 33°39′09.7″N, 73°03′20.6″E |
8 | Lai stream | 33°36′10.4″N, 73°04′25.1″E |
Serial no. . | Sample location . | Coordinates . |
---|---|---|
1 | Upstream Shangrilla Park | 33°53′38.7″N, 73°22'15.8″E |
2 | Downstream Baharakahu | 33.7068°N, 73.0870°E |
3 | Wet market Baharakahu | 33.7068°N, 73.0870°E |
4 | Upstream Shahdara | 33.7068°N, 73.0870°E |
5 | Downstream G-6 | 33°38′32.6″N, 73°07′46.7″E |
6 | Wet market G-6 | 33°38′32.6″N, 73°07′46.7″E |
7 | I-9 treatment plant | 33°39′09.7″N, 73°03′20.6″E |
8 | Lai stream | 33°36′10.4″N, 73°04′25.1″E |
Map showing water sampling locations in Islamabad Capital Territory.
Sampling was carried out fortnightly from May to October 2018. During this period, a total of 32 water samples were collected. Each sampling site was visited up to six times. The samples were taken in 1,000 ml sterilized glass bottles following the APHA, 2012 standard protocols. The samples were brought to the laboratory maintaining the cold chain and analyzed in the laboratory within 24 h.
Microbiological analysis for isolation of E. coli
Water samples were processed for microbiological analysis following APHA, 2012 guidelines. Briefly, samples were diluted in phosphate buffer saline (PBS) using a 10-fold serial dilution (up to 10−5) and spread on tryptone bile X-glucuronide agar (TBX) and MacConkey agar supplemented with ceftriaxone (4 μg/ml) and incubated at 37 °C for 24 h. Presumptive E. coli colonies were identified and confirmed using Gram's staining and biochemical tests including Indole, Methyl Red, Voges Proskauer, Citrate, and Triple sugar iron (TSI).
Identification of ESBL E. coli
Isolates identified as E. coli using Gram's staining and biochemical tests were analyzed for ESBL-producing characteristic using double-disk diffusion test (DDDT) and double-disk synergy test (DDST) (Clinical and Laboratory Standards Institute (CLSI) 2013; Garrec et al. 2013).
Double-Disk Diffusion Test
Briefly, DDDT was performed by placing antibiotic disks of cefotaxime (with and without clavulanic acid) and ceftazidime (with and without clavulanic acid) on Muller Hinton agar (MHA) at a distance of 30 mm (center to center) from one another. The E. coli strain for which the zone of inhibition against the disks containing clavulanic acid was more in size (at least 5 mm) was considered an ESBL E. coli (Clinical and Laboratory Standards Institute (CLSI) 2013).
Double-Disk Synergy Test
Briefly, DDST was performed by placing ceftriaxone (30 μg), ceftazidime (30 μg), aztreonam (30 μg), cefixime (30 μg), and cefepime (30 μg) disks on MHA at a distance of 30 mm center to center from amoxicillin–clavulanic acid (AMC 30) disk. The detection of ESBL strain was confirmed when any of the five antibiotic disks showed synergism toward the AMC disk, resulting in a typical ‘keyhole-shaped’ or ‘ellipsis-shaped’ zone (Clinical and Laboratory Standards Institute (CLSI) 2013).
Antibiotic resistance profile
Phenotypically confirmed ESBL E. coli isolates were tested for antibiotic susceptibility to 17 different antibiotics of veterinary and human clinical relevance using the disk diffusion method (Kassim et al. 2016). The antibiotics tested were amoxicillin, ampicillin, aztreonam, cephradine, cefepime, cefixime, cefoxitin, ciprofloxacin, doxycycline, enrofloxacin, gentamicin, imipenem, lincomycin, neomycin, oxytetracycline, penicillin G, and streptomycin. Antimicrobial resistance against the tested disks was determined using CLSI breakpoints (Clinical and Laboratory Standards Institute (CLSI) 2013).
Molecular detection of ESBL-encoding genes
DNA was extracted from each of ESBL E. coli isolate using the boiling method (Irshad et al. 2012). Briefly, one ESBL E. coli colony was re-suspended in 200 μl of autoclaved distilled water in a micro-centrifuge tube. This suspension was incubated at 95 °C in a heat block for 10 min and transferred to a freezer for 2 min for a clod shock. After centrifugation at 10,000 g for 5 min, the supernatant (containing DNA) was transferred to a fresh tube, stored at −20 °C, and was used as a template in PCR reaction. The DNA was analyzed using PCR for the presence of blaTEM (Gangoué-Piéboji et al. 2005), blaSHV (Colom et al. 2003), and blaCTX-M genes (Kaftandzieva et al. 2011). The PCR reaction mixture and thermal profile are given in Table 2.
PCR condition for detection of CTX, TEM, and SHV genes in ESBL E. coli isolates from water samples collected from eight different locations of Islamabad Capital Territory during May–October 2018
Gene . | PCR conditions . | PCR reaction volume . | Amplicon size . | Reference . |
---|---|---|---|---|
CTX gene | 1 cycle: 94 °C–5 min 35 cycles: 95 °C–30 s 54 °C–1 min 72 °C–1 min 1 cycle: 72 °C–8 min | 2.5 μl of 10× PCR buffer 1.5 mM MgCl2 0.2 mM of each dNTP (Thermoscientific, Waltham, USA) 1 μM of each primer (Macrogen, Seoul, South Korea) 1 unit of Taq DNA Polymerase (Thermoscientific, Waltham, USA) 5 μl of DNA Final volume of 25 μl with nuclease free water | 588 | Kaftandzieva et al. (2011) |
TEM gene | 1 cycle: 95 °C–5 min 35 cycles: 95 °C–30 s 56 °C–30 s 72 °C–1 min 1 cycle: 72 °C–10 min | 2 .5 μl of 10× PCR buffer 2 mM MgCl2 0.2 mM of each dNTP (Thermoscientific, Waltham, USA) 2 μM of each primer (Macrogen, Seoul, South Korea) 1 unit of Taq DNA Polymerase (Thermoscientific, Waltham, USA) 5 μl of DNA Final volume of 25 μl with nuclease free water | 465 | Gangoué-Piéboji et al. (2005) |
SHV gene | 1 cycle: 94 °C–2 min 35 cycles: 94 °C–20 s 56 °C–60 s 72 °C–60 s 1 cycle: 72 °C–5 min | 2.5 μl of 10× PCR buffer 1.5 mM MgCl2 0.2 mM of each dNTP (Thermoscientific, Waltham, USA) 1 μM of each primer (Macrogen, Seoul, South Korea) 1 unit of Taq DNA Polymerase (Thermoscientific, Waltham, USA) 5 μl of DNA Final volume of 20 μl with nuclease-free water | 392 | Colom et al. (2003) |
Gene . | PCR conditions . | PCR reaction volume . | Amplicon size . | Reference . |
---|---|---|---|---|
CTX gene | 1 cycle: 94 °C–5 min 35 cycles: 95 °C–30 s 54 °C–1 min 72 °C–1 min 1 cycle: 72 °C–8 min | 2.5 μl of 10× PCR buffer 1.5 mM MgCl2 0.2 mM of each dNTP (Thermoscientific, Waltham, USA) 1 μM of each primer (Macrogen, Seoul, South Korea) 1 unit of Taq DNA Polymerase (Thermoscientific, Waltham, USA) 5 μl of DNA Final volume of 25 μl with nuclease free water | 588 | Kaftandzieva et al. (2011) |
TEM gene | 1 cycle: 95 °C–5 min 35 cycles: 95 °C–30 s 56 °C–30 s 72 °C–1 min 1 cycle: 72 °C–10 min | 2 .5 μl of 10× PCR buffer 2 mM MgCl2 0.2 mM of each dNTP (Thermoscientific, Waltham, USA) 2 μM of each primer (Macrogen, Seoul, South Korea) 1 unit of Taq DNA Polymerase (Thermoscientific, Waltham, USA) 5 μl of DNA Final volume of 25 μl with nuclease free water | 465 | Gangoué-Piéboji et al. (2005) |
SHV gene | 1 cycle: 94 °C–2 min 35 cycles: 94 °C–20 s 56 °C–60 s 72 °C–60 s 1 cycle: 72 °C–5 min | 2.5 μl of 10× PCR buffer 1.5 mM MgCl2 0.2 mM of each dNTP (Thermoscientific, Waltham, USA) 1 μM of each primer (Macrogen, Seoul, South Korea) 1 unit of Taq DNA Polymerase (Thermoscientific, Waltham, USA) 5 μl of DNA Final volume of 20 μl with nuclease-free water | 392 | Colom et al. (2003) |
All the PCR reactions were carried out in PCR system Veriti (Applied Biosystems, Waltham, MA, USA).
RESULTS
Identification of E. coli isolates
In total 26 E. coli isolates were recovered from 32 water samples. The water samples from both upstreams (Shahdara and Shangrilla Park) were free from E. coli contamination. However, all of the water samples from wet markets and WWTP were heavily contaminated with E. coli. The details of E. coli contamination found in water samples from various sources are given in Table 3.
Water samples (n = 32) were collected from eight different sites of Islamabad Capital Territory between May and October 2018
Serial no. . | Sampling site . | No. of samples collected . | E. coli isolates recovered from samples . | No. of E. coli isolates positive for ESBL . |
---|---|---|---|---|
1 | Upstream Shangrilla park | 2 | 0/2 (0%) | 0 (0%) |
2 | Downstream Baharakahu | 6 | 5/6 (83.33%) | 3/5 (60%) |
3 | Wet market Baharakahu | 6 | 6/6 (100%) | 3/6 (50%) |
4 | Upstream Shahdara | 2 | 0/2 (0%) | 0 (0%) |
5 | Downstream G-6 | 6 | 6/6 (100%) | 3/6 (50%) |
6 | Wet market G-6 | 6 | 6/6 (100%) | 4/6 (66.66%) |
7 | I-9 treatment plant | 2 | 2/2 (100%) | 1/2 (50%) |
8 | Lai stream | 2 | 1/2 (50%) | 1/1 (100%) |
Serial no. . | Sampling site . | No. of samples collected . | E. coli isolates recovered from samples . | No. of E. coli isolates positive for ESBL . |
---|---|---|---|---|
1 | Upstream Shangrilla park | 2 | 0/2 (0%) | 0 (0%) |
2 | Downstream Baharakahu | 6 | 5/6 (83.33%) | 3/5 (60%) |
3 | Wet market Baharakahu | 6 | 6/6 (100%) | 3/6 (50%) |
4 | Upstream Shahdara | 2 | 0/2 (0%) | 0 (0%) |
5 | Downstream G-6 | 6 | 6/6 (100%) | 3/6 (50%) |
6 | Wet market G-6 | 6 | 6/6 (100%) | 4/6 (66.66%) |
7 | I-9 treatment plant | 2 | 2/2 (100%) | 1/2 (50%) |
8 | Lai stream | 2 | 1/2 (50%) | 1/1 (100%) |
The samples were analyzed for the presence of E. coli and ESBL E. coli isolates.
Occurrence of ESBL E. coli in wastewater
In total, 15 of 26 (57.69%) E. coli isolates recovered during the study period were found to be ESBL producers. Almost half of the E. coli isolates (13/23; 56.52%) recovered from downstream and wet markets were ESBL producers. This showed dissemination of AMR E. coli into environment. E. coli isolates recovered from WWTP and subsequent downstream (Lai stream) were also detected as ESBL producers (2/3; 66.67%)). The details of isolation of ESBL E. coli are given in Table 3.
Antibiotic resistance patterns
The range of antimicronial resistance (AMR) shown by ESBL E. coli isolates was 13.3–100%. All the ESBL E. coli isolates (n = 15) recovered during the study showed 100% resistance to streptomycin, neomycin (class Aminoglycosides), enrofloxacin (class Fluoroquinolones), lincomycin (class Lincosamides), ampicillin, penicillin G (class Penicillin), and oxytetracycline (class Tetracycline). Moreover, the resistance of the isolates against doxycycline, ciprofloxacin, and gentamicin was 86.66, 80, and 46.66%, respectively. The results of Antimicrobial Susceptibility Testing (AST) against Cephalosporins were interesting as all isolates of ESBL E. coli showed least resistance against second-generation Cephalosporins (Cefoxitin; 26.66%), followed by fourth-generation Cephalosporins (Cefepime; 33.33%), first-generation Cephalosporins (Cephradine; 100%), and third generation Cephalosporins (Cefixime; 100%), whereas they exhibited high susceptibility to Carbapenems (Imipenem; 86.67%) and amoxicillin with clavulanic acid (73.34%) (Figure 2).
Antibiotic susceptibility profile of ESBL E. coli isolates against 17 different antibiotics of veterinary and human clinical relevance using the disk diffusion method. The isolates were recovered from water samples collected from eight different locations of Islamabad Capital Territory during May–October 2018.
Antibiotic susceptibility profile of ESBL E. coli isolates against 17 different antibiotics of veterinary and human clinical relevance using the disk diffusion method. The isolates were recovered from water samples collected from eight different locations of Islamabad Capital Territory during May–October 2018.
Frequency and diversity of ESBL-encoding genes
The most commonly detected ESBL-encoding gene in ESBL E. coli isolates was blaTEM (06/15; 40%) followed by blaCTX-M gene (05/15; 33.33%). The combination of blaTEM and blaCTX-M was observed in only 2 of 15 (13.33%) ESBL E. coli isolates. None of the ESBL E. coli isolates carried blaSHV gene, whereas 4 of 15 (26.66%) ESBL E. coli isolates were negative for all three tested ESBL-encoding genes.
DISCUSSION
The water bodies have been considered as the key reservoir of antimicrobial-resistant bacteria. It has been demonstrated that fecal bacterial species, i.e. E. coli, Salmonella, and Campylobacter are being transmitted through water. This dissemination of the said fecal bacterial species with acquired AMR is a serious public health concern (Blaak et al. 2015). These AMR bacteria may be a source of transmission of resistance genes to other bacteria (Lenart-Boroń et al. 2020). In addition, these AMR bacteria may reach humans through direct contact with contaminated water or indirectly through surface water into food chain and then to humans causing serious infections which are difficult to treat (Blaak et al. 2015). Moreover, E. coli species have been suggested for monitoring AMR in the environment (Mohsin et al. 2017). Therefore, keeping in mind the significance of this bacteria in the aquatic environment, the study was carried out to assess the burden of ESBL E. coli and its antibiotic resistance in surface and wastewater of ICT.
In total, 26 of 32 (81.25%) E. coli and 15 of 26 (57.69%) ESBL E. coli were recovered from water samples collected during this study. The water samples from upstream (Shangrilla Park and Shahdara) had no E. coli contamination. This may be due to limited or no anthropogenic activities in these areas. However, when the same water enters downstream of densely populated areas, i.e. Baharakahu and G-6, it was found to be contaminated with E. coli (91.66%) as these streams receive water from wet markets (poultry meat shops). It is a well-known fact that E. coli is a normal inhabitant of the gastrointestinal tract of poultry and other food animals (Seiffert et al. 2013). Therefore, excreta from these animals entering into the water of the streams may be the source of transmission of ESBL E. coli and other AMR bacteria into these streams. Furthermore, because ESBL E. coli are abundant in food animals, particularly broilers and calves, animal dung may also have a role in the transmission. Moreover, wild animal feces, such as those of birds, may introduce ESBL E. coli into surface water (Guenther et al. 2011).
All of the water samples from WWTP and its subsequent stream (Lai stream) were found polluted with AMR bacteria. Upon investigation from the WWTP management, it was revealed that wastewater is only treated for heavy metals and microbial decontamination procedure is not being carried out at present. Thus, there is an urgent need to treat water efficiently at treatment plants so that the transmission of AMR bacteria may be reduced.
High occurrence (57%) of ESBL E. coli from surface and wastewater was observed in this study which is consistent with previous studies of ESBL E. coli in India (64%) and Bangladesh (75%) (Haque et al. 2014; Johnson et al. 2020). This incidence of ESBL E. coli was in contrary to the incidence rates of ESBL E. coli from other sources in Pakistan, i.e. 38.80% from poultry farm environmental samples (Rahman et al. 2018) and 17.30% from migratory birds (Mohsin et al. 2017). However, the occurrence of ESBL E. coli in the current study was similar with that from humans (54%) in Pakistan (Hassan et al. 2011). Furthermore, we could not find any published data of ESBL E. coli from wastewater downstream and WWTP effluents in Pakistan to compare our results.
AST indicated that ESBL E. coli isolates were completely resistant to antibiotics which are considered as the first line of defense against infections. The AMR pattern of ESBL E. coli isolates observed against Cephalosporins during the study period was very interesting. As per general understanding, ESBL E. coli isolates should be least resistant to fourth-generation Cephalosporins followed by respective generations of the Cephalosporins. Nevertheless, the lowest resistance was seen against second-generation Cephalosporins (26.66%) followed by fourth-generation Cephalosporins (33.33%). The third- and first-generation Cephalosporins showed 100% resistance against the antibiotics tested in this study. One of the possible causes of this unusual resistance pattern could be the excessive and irrational usage of broad-spectrum and advanced generation Cephalosporins in the medical as well as in the veterinary/poultry sector.
Another finding of the study was the appearance of resistance in ESBL E. coli isolates against aztreonam (40%) and imipenem (13. 33%). However, in a previous study carried out in Islamabad where E. coli isolates were recovered from meat samples obtained from retail meat showed high sensitivity (100%) against these antibiotics (Irshad et al. 2020). These antibiotics are costly and are deemed as the last choice antibiotics; therefore, they are hardly used in food animals (Irshad et al. 2020). The recovery of ESBL E. coli isolates resistant to aztreonam and imipenem from water samples in this study indicated that these streams of ICT may have received hospital waste effluents where these drugs are extensively used (Chantziaras et al. 2014).
The most prevalent gene found in 15 ESBL E. coli isolates from water samples during the current study was blaTEM (40%, n = 6), followed by blaCTX-M (33.33%, n = 5) which concurs previous report from Pakistan (Irfan et al. 2021). However, blaSHV gene could not be detected in the tested ESBL E. coli isolates in this study. Similar occurrence of ESBL-encoding genes was reported in Germany except for blaSHV gene (Savin et al. 2020). However, one study in contrary to the current study reported blaCTX-M as the most prevalent gene in Pakistan (Abrar et al. 2018).
ESBL E. coli isolates negative for all the genes indicated that ESBL-encoding genes other than the three tested in the current study are also present in them. However, we tested for only three genes due to their widespread occurrence and clinical relevance in human population (Tissera & Lee 2013). These findings indicated that the ESBL E. coli isolates should be analyzed for other ESBL-encoding genes to understand the true distribution of ESBL-encoding genes in E. coli isolates.
The results of ESBL-encoding genes in the current study were quite interesting as the most prevalent gene was blaTEM in the current study. Previously, blaCTX-M is considered as the most predominant gene present in the region (Abrar et al. 2019). This change in genomic epidemiology of ESBL E. coli suggested that the bacterial population in the environment may be facing selection pressure. The situation of AMR may become worse if it is true and this world can face a new pandemic in the form of AMR in near future.
The high occurrence of ESBL E. coli in water bodies of developing countries like Pakistan is a serious public health threat as antimicrobial usage is not being regulated in the medical as well as in the veterinary sector (Rahman et al. 2018). All (100%) of the ESBL E. coli isolates in the current study were resistant to multiple antimicrobial drugs simultaneously. This multiple drug resistance depicted the worrisome situation as the water bodies can be a source of transmission of these bacteria to humans. Moreover, a large diversity in the AMR pattern observed in this study is an indication of vulnerability and environmental pressure which bacterial species are facing in water streams (Bessa et al. 2014).
The study provided useful information about the occurrence of ESBL E. coli in water samples collected from different streams of ICT. Some of these isolates were resistant to more than two antibiotics indicating the presence of MDR bacteria in streams of ICT. However, ESBL E. coli isolates could not be recovered from the upstream water of Shangrilla and Shahdara where there is a limited anthropogenic activity. Although the study provided useful information about contamination of stream water of ICT with E. coli isolates but it was a small-scale study. Therefore, a large-scale study is required to completely understand the factors responsible for the occurrence of high level of E. coli in water of Korang River and its tributaries. The information would help in devising appropriate control strategies to reduce the prevalence of ESBL E. coli in environment and thus reaching humans.
CONCLUSION
This study showed that the aquatic environment is harboring MDR E. coli; and therefore may act as a source of transmission to humans. The recovery of ESBL E. coli isolates resistant to higher generation Cephalosporins, Monobactam, and Carbapenems from water samples indicated an alarming situation. Thus, there is an urgent need to treat water efficiently for microbial decontamination to minimize the transmission of AMR bacteria.
ACKNOWLEDGEMENTS
We acknowledge International Foundation of Science (IFS) as a part of this study was supported by the IFS grant no. I-3-B-6121-1.
CONFLICT OF INTEREST
There is no conflict of interest to declare.
AUTHORS’ CONTRIBUTION
A.A. administrated the project, analyzed the samples and data, and wrote and edited the manuscript; T.A.U.R. collected the samples and data, and analyzed the samples; H.I. conceptualized, visualized, supervised, and analyzed the data, and wrote and edited the manuscript; M.A.S. analyzed the samples and data, and edited the manuscript; A.S. analyzed the samples and data; A.J. conceptualized and collected the samples; A.D. analyzed the samples.
DATA AVAILABILITY STATEMENT
All relevant data are included in the paper or its Supplementary Information.