Chemical effect of chlorination process on antibiotic resistant bacteria

Abstract

CURRENT study was conducted to evaluate the effectiveness of chlorine as a simple and cheap application to inactivate antibiotic resistant bacteria. To achieve this aim, different doses of chlorine (1.0, 1.5, 2.0, 2.5 and 3mg/l) were introduced to antibiotic resistant and sensitive isolates of Salmonella typhimurium as an example of Gram negative bacteria for 20 min contact time. The same chlorine doses were introduced to both antibiotic resistant and sensitive isolates of Staphylococcus aureus as an example of Gram positive bacteria for the same contact time. The antibiotic resistant isolates were obtained from antibiotic resistance genetic transformation experiment, which proves that antibiotic resistance in the aquatic environments was occurred by horizontal gene transfer(mainly genetic transformation). The obtained results showed that, antibiotic resistant and sensitive bacteria have the same chlorine susceptibility in either Gram negative and positive pathogenic bacteria. Whereas, the chlorine susceptibility in antibiotic sensitive and resistant isolates of Salmonella typhimurium (Gram negative bacteria) was relatively higher than chlorine susceptibility in antibiotic sensitive and resistant isolates Staphylococcus aureus (Gram positive bacteria). Where, 3gm/l chlorine dose was able to make complete reduction of each of resistant and sensitive Salmonella typhimurium at 20 min contact time. Whereas, at the same chlorine dose (3mg/l) and contact time (20min), Staphylococcus aureus still culturable (7.0x10 and 9.0x10 CFU/ml) for sensitive and resistant isolates, respectively. And statistical analysis found that there was inverse proportion between chlorine dose and the bacterial counts in both pathogenic bacterial isolates (antibiotic sensitive and resistant).