Risk of pharmaceutical contaminations; Cloxacillin contamination and prevalence of cloxacillin resistant bacteria in environmental samples, Sri Lanka

Abstract

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Antibiotics are an important group of pharmaceuticals used extensively in health care for the treatment and prevention of microbial infections. Antibiotic resistance has become a major health concern; thus, there is a growing interest in exploring the occurrence of antibiotic resistant bacteria in environment. Cloxacillin (CLOX), a broad spectrum penicillin type antibiotic, is commonly used for community acquired pneumonia, superficial skin infections, cellulitis etc. The present study focused on quantification of CLOX and isolation of cloxacillin-resistant (CLOX1) bacteria from ten wastewater discharge drains in some selected hospitals, Sri Lanka. Solid-Phase Extraction (SPE) and High Performance Liquid Chromatography (HPLC) were employed to quantify CLOX. Isolation of CLOXr bacteria was done by standard pour plate method, after 14 days of enrichment. Minimum Inhibitory Concentration (MIC) was observed at 60- 720 ppm via 96-well plate method and pour plate method. Among selected locations the highest concentration of CLOX was recorded as 8.815±0.002 ppm in Karapitiya hospital effluent and contamination was ranged between 8.815±0.002 ppm to 0 ppm. CLOXr bacteria were identified (>360ppm MICs) as Staphylococcus aureus, Escherichia coli, Enterobacter ludwigii, Bacillus sp., Bacillus cereus and Pseudomonas aeruginosa by 16S rRNA sequencing. MIC values for each bacterial strain were recorded as 540 ppm, 660 ppm, 600 ppm, 660 ppm, 660 ppm and 540 ppm respectively. The antibiotic concentrations observed in most effluent water samples have exceeded the maximum permissible level (< 0.001 ppmwater) given by the World Health Organization for aquatic environment. Thus, continuous monitoring and further studies are needed to get baseline information on contamination status of antibiotics, in order to prepare guidelines and strategic plan for the country to minimize health issues related to antibiotic resistance.