Zanotto Carlo, Bissa Massimiliano, Illiano Elena, Mezzanotte Valeria, Marazzi Francesca, Turolla Andrea, Antonelli Manuela, De Giuli Morghen Carlo, Radaelli Antonia
Department of Medical Biotechnologies and Translational Medicine, University of Milan, Via Vanvitelli, 32, 20129, Milan, Italy.
Department of Pharmacological and Biomolecular Sciences, University of Milan, Via Balzaretti, 9, 20133, Milan, Italy.
Chemosphere. 2016 Dec;164:627-633. doi: 10.1016/j.chemosphere.2016.08.040. Epub 2016 Sep 13.
The emergence and diffusion of antibiotic-resistant bacteria has been a major public health problem for many years now. In this study, antibiotic-resistance of coliforms and Escherichia coli were investigated after their isolation from samples collected in a municipal wastewater treatment plant in the Milan area (Italy) along different points of the treatment sequence: inflow to biological treatment; outflow from biological treatment following rapid sand filtration; and outflow from peracetic acid disinfection. The presence of E. coli that showed resistance to ampicillin (AMP) and chloramphenicol (CAF), used as representative antibiotics for the efficacy against Gram-positive and Gram-negative bacteria, was evaluated. After determining E. coli survival using increasing AMP and CAF concentrations, specific single-resistant (AMP or CAF) and double-resistant (AMP/CAF) strains were identified among E. coli colonies, through amplification of the β-lactamase Tem-1 (bla) and acetyl-transferase catA1 (cat) gene sequences. While a limited number of CAF bacteria was observed, most AMP colonies showed the specific resistance genes to both antibiotics, which was mainly due to the presence of the bla gene sequence. The peracetic acid, used as disinfection agent, showed to be very effective in reducing bacteria at the negligible levels of less than 10 CFU/100 mL, compatible with those admitted for the irrigation use of treated waters.
多年来，抗生素耐药菌的出现和传播一直是一个重大的公共卫生问题。在本研究中，从意大利米兰地区一个城市污水处理厂不同处理阶段采集的样本中分离出大肠菌群和大肠杆菌后，对其抗生素耐药性进行了调查：生物处理的进水；快速砂滤后生物处理的出水；以及过氧乙酸消毒后的出水。评估了对氨苄青霉素（AMP）和氯霉素（CAF）耐药的大肠杆菌的存在情况，这两种抗生素分别作为抗革兰氏阳性菌和革兰氏阴性菌效力的代表性抗生素。在使用递增浓度的AMP和CAF测定大肠杆菌存活率后，通过扩增β-内酰胺酶Tem-1（bla）和乙酰转移酶catA1（cat）基因序列，在大肠杆菌菌落中鉴定出特定的单耐药（AMP或CAF）和双耐药（AMP/CAF）菌株。虽然观察到的CAF耐药菌数量有限，但大多数AMP耐药菌落对这两种抗生素都显示出特定的耐药基因，这主要是由于bla基因序列的存在。用作消毒剂的过氧乙酸在将细菌数量减少到低于10 CFU/100 mL的可忽略水平方面显示出非常有效，这与处理后水用于灌溉的许可水平相符。
