en Anti-microbial agents, resistance and treatment protocols Anti-microbial agents, resistance and treatment protocols Original article Original article <b><span style="font-size:10.0pt"><span style="line-height:107%"><span new="" roman="" style="font-family:" times="">Introduction</span></span></span></b><span style="font-size:10.0pt"><span style="line-height:107%"><span new="" roman="" style="font-family:" times="">: Hospitals are breeding grounds for multidrug-resistant (MDR) bacteria, posing treatment challenges and increasing the risk of spreading &quot;superbugs.&quot; This study investigates the prevalence of colistin-resistant bacteria, a last-resort antibiotic, in wastewater from tertiary hospitals in Enugu, Nigeria. <b>Methods</b></span></span></span><span style="font-size:10.0pt"><span style="line-height:107%"><span new="" roman="" style="font-family:" times="">: Twenty wastewater samples were collected over three months from two tertiary hospitals in Enugu. A standardized protocol by the American Public Health Association (APHA) was followed. Samples were collected aseptically from key drainage points and transported to the lab within 2 hours. Bacteria were isolated using the pour-plate method and characterized by morphological and biochemical tests, including Catalase, Oxidase, and Glucose Fermentation. Antibiotic susceptibility was assessed using Kirby-Bauer disc diffusion, and colistin resistance was confirmed via broth microdilution. Multiplex PCR detected <i>mcr</i> genes indicating plasmid-mediated resistance. Data were analyzed using SPSS version 23 with Chi-Square and ANOVA tests at a significance level of <i>P </i>< 0.05</span></span></span><span style="font-size:10.0pt"><span style="line-height:107%"><span new="" roman="" style="font-family:" times="">.</span></span></span><span style="font-size:10.0pt"><span style="line-height:107%"><span new="" roman="" style="font-family:" times=""> <b>Results</b></span></span></span><span style="font-size:10.0pt"><span style="line-height:107%"><span new="" roman="" style="font-family:" times="">: Gram-negative bacteria were isolated from 63.1% of samples, with <i>Klebsiella</i> spp. being the most prevalent, accounting for 24.6%. Colistin resistance was phenotypically observed in <i>E. coli</i> (83%), <i>Klebsiella</i> spp. (75%), and <i>Pseudomonas aeruginosa</i> (100%). Genotypically, <i>E. coli</i> harbored <i>mcr-1</i> (17%) and <i>mcr-3</i> (83%), while all <i>Klebsiella</i> and <i>Pseudomonas</i> isolates carried multiple <i>mcr</i> genes. Additionally, these bacteria showed resistance to multiple antibiotics, including Septrin, Gentamycin, and Ceftriaxone</span></span></span><span style="font-size:10.0pt"><span style="line-height:107%"><span new="" roman="" style="font-family:" times="">. <b>Conclusion</b>: The significant presence of colistin-resistant bacteria, especially <i>E. coli</i> and <i>Klebsiella</i>, poses a public health concern, potentially leading to treatment failures and spreading resistance genes. Stricter monitoring of hospital wastewater is necessary to identify emerging resistance trends and improve antibiotic practices in hospitals.</span></span></span> Colistin resistance, Antibiotic resistance, Enterobacteriaceae, Hospital wastewater, mcr-1 gene, mcr-2 gene, mcr-3 gene, Multidrug resistance, Nigeria 110 120 http://jommid.pasteur.ac.ir/browse.php?a_code=A-10-588-1&slc_lang=en&sid=1 Oluchi AGBO agbo.oluchi2024@gmail.com 0009-0001-4904-9492 Yes Department of Pharmaceutics, University of Nigeria, Nsukka, PMB 410001, Enugu State, Nigeria Mumuni Momoh audu.momoh@unn.edu.ng 0000-0002-3715-9977 No Department of Pharmaceutics, University of Nigeria, Nsukka, PMB 410001, Enugu State, Nigeria Damian Odimegwu damian.odimegwu@unn.edu.ng 0000-0001-6537-9160 No Department of Pharmaceutics, University of Nigeria, Nsukka, PMB 410001, Enugu State, Nigeria Cyril Adonu adonucyril@gmail.com 0000-0002-3486-8137 No Department of Pharmaceutical Microbiology and Biotechnology, Enugu State University of Science and Technology, PMB 01660, Enugu State, Nigeria