RESUMO
Wastewater discharged from hospitals is a recognized contributor to the dissemination of antibiotic-resistant bacteria and their associated genetic traits into the environment. This study focused on the analysis of ß-lactamase-producing pathogenic bacteria within untreated biomedical wastewater originating from various hospitals in Dhaka City, Bangladesh, as well as in silico evaluation and structural activity relationship mentioned antibiotics were evaluated. In silico drug design techniques were applied to identify the relationship with how the functional group impacts the binding energy. Out of the 184 isolates obtained from well-established hospital sewage discharge points in Dhaka, 89 were identified as ß-lactamase positive. These bacteria were subjected to antimicrobial susceptibility testing using the VITEK-2 assay, and their profiles of extended-spectrum beta-lactamase (ESBL) production were determined through molecular methodologies. Among the ß-lactamase-positive isolates, considerable resistance was observed, particularly against ampicillin, Ceftriaxone, Cefuroxime, and Meropenem. The predominant resistant species included Escherichia coli, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter cloacae. The study identified the prevalence of ESBL-producing genes, with blaNDM-1 being the most prevalent, followed by blaOXA-1, blaSHV, blaCTX-M, and blaKPC. None of the isolates carried the blaTEM gene. In addition to characterizing these bacteria, the research explored ways to enhance the binding energy of four existing antibiotics as new inhibitors through computational studies. The findings revealed significant improvements in binding energy. Specifically, Meropenem initially exhibited a binding energy of -7.5 kcal/mol, notably increasing to -8.3 kcal/mol after modification. With an initial binding energy was only -7.9 kcal/mol, Ampicillin experienced an enhancement, reaching -8.0 kcal/mol post-modification. Similarly, Ceftriaxone, with an initial binding energy of -8.2 kcal/mol, increased to -8.5 kcal/mol following structural adjustments. Finally, Cefuroxime, initially registering a binding energy of -7.1 kcal/mol, substantially increased to -8.9 kcal/mol after modification. This finding establishes a foundation for future investigations in the development of modified antibiotics to address the issue of antibiotic resistance. It presents prospective remedies for the persistent problem of antibiotic-resistant bacteria in healthcare and the environment.
RESUMO
A total of 39 Vibrio cholerae non O1 non O139 strains were isolated from surface waters of different parts of Dhaka City, Bangladesh. All these strains showed lack of ctx or zot gene, as demonstrated by the PCR analysis. Eighteen representative strains were tested for enterotoxin production using a rabbit ileal loop model, of which live cells of 8 strains and culture filtrates of 6 strains produced fluid accumulation in ileal loops. However, none of them produced heat stable toxin (ST), as detected by suckling mouse assay. On the other hand, 15% of isolates produced cytotoxin as detected by the Chinese Hamster Ovary (CHO) cell assay. Fifty times concentrated culture filtrates of the representative strains did not give any precipitin band against the anti-cholera toxin, suggesting the strains produced an enterotoxin, which is antigenically different from known cholera toxin (CT). Eighty percent of the total isolates were found to be positive for heat labile haemolysin detected by tube method, whereas, 39% were found positive by the Christie-Atkins-Munch-Petersen (CAMP) method. However, 87% of the isolates were positive for haemagglutinin/protease and all of the strains were positive for mannose-sensitive-haemagglutinin assay.
