Detection, Identification and Antibiogram Studies of Drinking Water Bacteria in Ground Wells at Al-Khums City, Libya

Groundwater as a vital source of drinking water is currently become under threat from chemical and microbiological contamination. The region around Al-Khums City, Libya, suffers from disorganized residential communities and limited supplies of safe drinking water that are often contaminated by bacterial infections. It is concerning when this is combined with rising rates of microbial antibiotic resistance. The current study was concerned with isolation, identification and diagnosis of pathogenic bacteria from 100 groundwater wells in Al-Khums City to determine whether the water is suitable for drinking or not. Most probable number (MPN) technique was applied to determine the quality of water samples. Total bacterial count (TB) and total coliforms (TCs) were also investigated. Bacterial isolates were biochemically identified using API20E test. Agar disc diffusion method was used to test the bacterial resistance in the pathogenic bacterial isolates. The overall coliform readings for the contaminated wells were 7.02 × 101 ± 4.25 × 101 MPN/100mL. The highest recorded values of TB were 5.74 × 104 ± 3.06× 104 CFU/mL. From the water samples, a variety of harmful bacteria were recorded, including Escherichia coli, Klebsiella pneumoniae, Enterobacter aerogenes, Citrobacter freundii and Serratia marcescens. The highest levels of bacterial resistance against the tested antibiotics were recorded against cephalexin (89.2%), cefazolin (88.2%), and cephalothin (70.6%). On the other hand, gentamycin, with a resistance level of 28.2%, and kanamycin, with a level of 38.2%, were the most active antibiotics against the bacterial isolates.