Effect of alkaline pretreatment on cephalosporin degradation and microbial susceptibility in wastewater of cephalosporin drug manufacturing plant

Wastewater treatment plants can act as a reservoir of antibiotic-resistant bacteria, antibiotic-resistance genes, and antibiotic residues. The study aims to investigate the status of the microorganism present in a built wastewater pretreatment plant (WWPTP) during degradation of cephalosporin antibiotics by NaOH at pH around 10.00–13.00 discharged from a drug manufacturing plant. The resistance phenomena of the in situ bacteria present in WWPTP were investigated by a modified disc diffusion technique below the detectability of the analytical procedure (0.05 ppm) with the treatment strategy set in the laboratory. Four different cephalosporins (Cefadroxil, Cefaclor, Ceftriaxone, and Cefepime) were used to prepare the antibiotic discs for the experiments against two common bacterial strains named staphylococcus aureus (ATCC 29213) and Escherichia coli (ATCC 25922). These two bacteria were cultured and evaluated in different pH environments (pH @ 6.00 and pH @ 11.00) with variable treated cephalosporins (high and low concentration), LOQ level cephalosporins (0.1 ppm). There was no stressor effect found against these strains based on bacterial growth and zone of inhibition (ZOI) on Muller Hinton Agar (MHA) media. For instance, the standard bacterial strains were susceptible in presence of LOQ level or NaOH treated cephalosporin antibiotics solution. The same experiment was repeated with the mostly native microorganism found during wastewater pretreatment executed in situ into the WWPTP. The laboratory-developed pretreatment method effectively degrades cephalosporins, reducing their concentration to a level (e.g., LOQ) where they no longer constitute a primary stressor for resistance.