Elimination of oxacillin, its toxicity and antibacterial activity by using ionizing radiation

The chemical changes caused by electron beam and gamma irradiations and the biochemical characteristics of degradation products of a frequently used antibiotic oxacillin were investigated and compared with those of cloxacillin by applying pulse radiolysis, chemical and biochemical oxygen demand, total organic carbon content, oxygen uptake rate, toxicity and antibacterial activity measurements. Oxacillin was found to be non-toxic, but poorly biodegradable by the mixed microbial population of the activated sludge of a wastewater treatment plant. Therefore, it can significantly contribute to the spread of beta-lactam antibiotic resistant bacteria. However, the products formed by gamma-irradiation were more easily biodegradable as they were utilized as nutrient source by the microbes of the activated sludge and the products did not show antibacterial activity. During irradiation treatment of aerated aqueous solutions mainly hydroxyl radicals induce the elimination of antimicrobial activity by making alterations at the bicyclic beta-lactam part of these antibiotics. Since the beta-lactam part is the same in oxacillin and cloxacillin, the biochemical characteristics of products of the two antibiotics are similar. The attack of hydrated electron takes place on the carbonyl groups. When the irradiation is made under anoxic conditions

Automated summary

The study found that oxacillin is poorly biodegradable and non-toxic, potentially contributing to the spread of beta-lactam antibiotic resistant bacteria. In contrast, the products formed by gamma-irradiation were easily biodegradable and did not show antibacterial activity. The attack of hydrated electron takes place on the carbonyl groups in both antibiotics.