Comprehensive Study on Antibiotic Resistance, Antibiotic Residues, and Quality of the Municipal Solid Waste Compost in Sri Lanka
摘要
Composting for Municipal Solid Waste (MSW) helps divert organic waste from landfills and provides a cost-effective method for producing agricultural materials. This research aimed to assess compost quality, analyze antibiotic residues, determine antibiotic resistance, and conduct antibiotic susceptibility tests on bacteria isolated from MSW and commercially available compost. MSW compost samples were collected from controlled open dump sites in Horana, Mathugama, Mirigama, Seethawaka, Kaduwela, and Karadiyana, while five commercially available compost products were purchased from the market. The quality assessment followed the Sri Lanka Standard Institution (SLSI) guidelines, evaluating physical and chemical characteristics. None of the samples exceeded Cd (0.01- 0.09 ppm), Pb (0.24- 0.84 ppm), and Cr (0.42- 4.17 ppm) concentrations above the SLSI standard for Cd (3 ppm), Pb (50 ppm), and Cr (50 ppm). None of the samples showed detectable levels of Amoxicillin (AMX), Tetracycline (TET), Cloxacillin (CLOX), or Ciprofloxacin (CIP). Since the detection limit of the High-Performance Liquid Chromatography (HPLC) was 0.05 ppm, any antibiotic concentrations below this threshold could not be measured, indicating that they were below the detection limit (0.05 ppm) of the HPLC. MSW compost Total Viable Count (TVC);224 × 104–368 × 104 CFU/mL: Antibiotic Resistant Bacteria (ARB);20 × 104–47 × 104 CFU/mL counts were more significant than the commercially available compost TVC;50 × 104–198 × 104 CFU/mL: ARB;2.5 × 104–18 × 104 CFU/mL counts. The highest percentage of ARB was found for Amoxicillin (37%) and Cloxacillin (35%). Over 50% of the ARB had a Minimum Inhibitory Concentration (MIC) greater than 660 μg/mL. These findings highlight potential health risks from using contaminated compost, emphasizing the need for proper guidelines and policies to protect human health.