Abstract
This study had investigated contaminants and control of antimicrobial-resistant microorganisms (AMR) from hospitals and pig farms. In the study of pig farms, the questionnaire survey was conducted at four farms nearby the surface water body in Prachinburi province. It shows that 50% of the farms use antibiotics for disease prevention and treatment, while that 50% mix antibiotics with feed. The commonly used antibiotics are Amoxycillin (100%), Enrofloxacin (50%), and colistin (25%). The residual antibiotics found during the rainy season were Amoxycillin (54%), Florfenicol (14%), and Tiamulin (13%), of which the concentrations were significantly higher than those found during the summer season (P<0.05). The detection of antibiotic resistance among 143 isolates of E. coli, 29% was in pig manure, 36% in wastewater, and 33% in treated water. Nevertheless, the antibiotics that those isolates were found more than 50% resistant against were Ampicillin (90%), Florfenicol (67%), and Tetracycline (66%), 13% of ESBL. None was of Imipenem resistance. The resistant genes of E. coli were found higher for beta-lactamase followed by Tetracycline (tetA, tetB) and Aminoglycoside (aadA1, aadA2, aadB), while no mcr1 gene showed in all samples. The probability that microorganisms having identical genes of 1 pair (100%) and 80% similarity was about 20%. The study of treatment efficacy of activated sludge (AS) wastewater treatment plant of Chao Phraya Abhaibhubejhr hospital revealed 68-69% removals of basic pollutants, and 20-100% removals of 13 types of antibiotics. A similar AMR population (60-100%) to 20 antibiotics of E. coli, K. pneumoniae, and A. baumannii appeared in wastewater and the AS effluent. The study of pilot-scale membrane bioreactor (MBR) operated without excess sludge wastage in hospital wastewater treatment revealed 79-100% removals of basic pollutants and 32-100% removals of antibiotics. The MBR could effectively remove microorganisms (100%). Antimicrobial resistant test in the MBR sludge revealed higher percentages of sensitive colonies, especially those of K. pneumoniae and A. baumannii >80% were sensitive to 75-85% of tested antibiotics. The 1-2 log reduction of antibiotic resistance genes (ARGs) in the influent with 106-1010 copies/ml by the MBR had been achieved. The use of post-chlorination and ozonation slightly improved in removals of ARGs.
