Molecular detection of beta-lactamase blaCTX-M group 1 in Escherichia coli isolated from drinking water in Khartoum State

This study aimed to detect the blaCTX-M group 1 in Escherichia coli (E. coli) isolated from drinking water in Khartoum State. Two hundred and eighty water samples were collected randomly from different areas, places, and sources from the state and examined for the presence of E. coli as a fecal contamination indicator. Isolation and identification of E. coli were performed using culture characteristics on different culture media and biochemical reactions. An antimicrobial sensitivity test was performed for all isolated E. coli using agar disk diffusion method. DNA was extracted by boiling method, and bacterial genomic DNA used as a template to detect blaCTX-M group 1 by PCR. Results showed 86 (30.7%) E. coliwere isolated out of 280 water samples. Antimicrobial susceptibility testing revealed the highest resistant percentage was 59% for tetracycline, followed by 35% for gentamycin, while for chloramphenicol and cefotaxime was 22 and 20%, respectively. blaCTX-M group 1 was detected in about 40% of all isolates. This study concludes that drinking water in Khartoum State may be contaminated with feces and might be a possible source for transferring resistant bacteria. Thus, it may be one of the critical causes of increasing reports of antimicrobial resistance in Khartoum State.


INTRODUCTION
There is global concern about antibiotic resistance phenomena with serious significance on the treatment of infections.
The increase in this problem results from widespread uses or misuses of antibiotics in human medicine as well as veterinary and agriculture spheres (WHO ). As a result, there is rapid growth in antibiotic resistance in bacteria that cause community infections and hospital-acquired infections (Peters et al. ). Previously, infection by Escherichia coli (E. coli) had an effective antibiotic therapy; there were no signs of E. coli on morbidity, mortality, and health care, but this condition has been altered due to accumulation of the occurrence of antimicrobial resistance by E. coli (Njage & Buys ). Although beta-lactamase has been commonly used in the treatment of E. coli infection in both human and animal medicine, extended-spectrum beta-lactamase (ESBLs) producing E. coli are increasing rapidly (Ali et al. ). ESBLs belong to class A betalactamases, and their genes include TEM, SHV, CTX-M Furthermore, the presence of E. coli in drinking water or the environment is an indicator for fecal contamination (WGO ). Antimicrobial-resistant bacteria can contaminate natural and drinking water sources by some human activities such as generating wastewater settlements, farms, and hospitals. Also, increased risk of groundwater contamination, as well as natural activities such as storm water runoff, may be washed into rivers or groundwater since the soil contains bacteria as a result of using cow dung extensively as fertilizer (Rashid et al. ). In addition, wastewater usage plant sites offer a promising situation for the multiplication of resistant bacteria (Rizzo et al. ).
Thus, water does not only serve as a reservoir for the distribution of antibiotic-resistant microorganisms among human and animal populations but also is used as a system by which the resistance genes are presented into the natural bacteria ecosystem, spreading resistant genes to non-resistant bacteria (Rizzo et al. ).
Consequently, this will lead to a wide epidemic and endemic spread of multidrug-resistant bacteria (Coleman et al. , ). Antimicrobial-resistant E. coli has been reported in several areas, including drinking water.
Therefore, the ingestion of this polluted water can lead to the spread of resistant strains in humans (Coleman et al. ). In Sudan, attention has not been given to the potential role of drinking water in the dissemination of antibioticresistant bacteria in the population, although evidence shows that it may be an essential pathway for gene transfer to human pathogenic and commensal strains (Sanganyado & Gwenzi ). Moreover, drinking water in Khartoum State comes from groundwater that might be polluted from septic tanks and pit latrines, and surface water comes from municipal water systems which distribute water through old pipelines after being treated by chlorination

Study design and sample collection
In this cross-sectional study, 280 water samples were collected randomly from three localities in Khartoum State Water samples were collected under aseptic conditions from various water sources (160 tap water and 120 house tanks). The tap spout was sterilized first by burning around the pipe using a cotton swab moistened with alcohol to avoid contamination from the environment. Then, the water was allowed to run down for 2 to 3 minutes, after which about 50 mL of water was collected into sterile screw cap bottles containing about 50 mL of lauryl tryptose broth media and an inverted Durham tube. Collected samples were transported immediately in plastic boxes with icepacks (Cheesbrough ).

Bacteriological analysis
The bottles containing water samples and lauryl tryptose broth were incubated at 37 C for 48 hours aerobically.
After incubation the bottle with gas production was sub-

Statistics analysis
Data were analyzed by using the statistical package for the Social Sciences (SPSS) version 20. Chi-squared tests were performed to find the probable relationship between

E. coli isolation
In the present study, a total of 280 water samples were col-
There was no statistically significant association between the presence of bla CTX-M-1 group and different variables (Khartoum State provinces, sources of water samples, and antimicrobials susceptibility) (p-value >0.05).

According to the recommendations by the World Health
Organization (WHO ), the presence of E. coli in drinking water was used as an indicator for testing water quality and fecal contamination. In this study, 30.7% (86/280) isolates of E. coli were detected in Khartoum State drinking  In the present study, we detected a high prevalence of bla CTX-M-1 group in E. coli isolated from drinking water (40%). This result is less than an earlier study which isolated E. coli from water environments in northern Thailand, which stated that the most common extended-spectrum β-lactamase-encoding gene was bla CTX-M group 1 (75%)

DATA AVAILABILITY STATEMENT
All relevant data are included in the paper or its Supplementary Information.