Microbiological Assessment of Biomedical Waste, Environmental Monitoring and Sterilization Effectiveness with Antibiotic Profile in a Specialized Eye Hospital of Dhaka City, Bangladesh

Abstract

Hospital environments, biomedical waste, and water sources can act as potential reservoirs for microorganisms that contribute to healthcare-associated infections (HAIs). Ensuring effective sterilization, water safety, and environmental hygiene is therefore crucial for infection prevention and patient safety. This study aimed to assess the microbiological presence of hospital drinking water, biomedical waste, and operating theatre (OT) environments, as well as to evaluate sterilization effectiveness and antibiotic susceptibility patterns of the isolated microorganisms. Samples were collected from hospital drinking water, biomedical waste bins, and OT surfaces, including beds, floors, and trays. Microorganisms were isolated and identified by standard microbiological methods using Nutrient Agar and different types of selective and differential media, along with Gram staining. Antibiotic susceptibility was determined by the Kirby-Bauer disc diffusion method. Sterilization performance was evaluated over 17 autoclave cycles using both Class N and Class B autoclaves. Physical, chemical (Bowie-Dick test, Class 5 integrator, and autoclave tape), and biological indicators containing Geobacillus stearothermophilus spores were employed for process validation. Escherichia coli was isolated from hospital drinking water, Klebsiella spp. from biomedical waste, and Staphylococcus aureus from OT surfaces. E. coli showed complete sensitivity to all tested antibiotics, whereas Klebsiella spp. displayed resistance to Cefuroxime but remained sensitive to other antibiotics. Staphylococcus aureus, identified as a normal environmental flora, was found on OT beds and floors that were regularly disinfected with formaldehyde. Sterilization tests confirmed 100% effectiveness across all autoclave cycles, indicating optimal sterilization performance and reliability of all indicator systems. Overall, the findings emphasize that rigorous sterilization procedures, proper biomedical waste management, and regular environmental disinfection substantially minimize microbial contamination in healthcare facilities. Continuous microbiological monitoring and antibiotic susceptibility testing are essential to detect resistant organisms early and sustain a safe, infection-free hospital environment.

Stam. J. Microbiol. 2025;15(1):63-68