Detection and genotyping of vancomycin-resistant Enterococcus spp. by multiplex polymerase chain reaction in Korean aquatic environmental samples

• Published in: International journal of hygiene and environmental health 2013-07, Vol.216 (4), p.421-427
• Main Authors: Nam, Sehee, Kim, Min-jeong, Park, Chulmin, Park, Jong-Geun, Maeng, Pil Jae, Lee, Gyu-Cheol
• Format: Article
• Language: English
• Subjects: Air. Soil. Water. Waste. Feeding; Aquatic environments; Bacterial Load; Bacterial Proteins - genetics; Biological and medical sciences; DNA, Bacterial - genetics; Enterococcus; Enterococcus - genetics; Enterococcus - isolation & purification; Enterococcus spp; Environment. Living conditions; Environmental Monitoring - methods; Genotype; Medical sciences; Miscellaneous; Multiplex PCR; Multiplex Polymerase Chain Reaction; Public health. Hygiene; Public health. Hygiene-occupational medicine; Republic of Korea; Rivers - microbiology; Teicoplanin; Toxicology; Vancomycin; Vancomycin Resistance - genetics; VRE; Water Pollutants - isolation & purification
• ISSN: 1438-4639; 1618-131X
• DOI: 10.1016/j.ijheh.2012.12.004

The distribution characteristics of Enterococcus spp., which are indicators of fecal pollution, were investigated at 33 sites within the 3 major water systems of Korea. Enterococci were detected at concentrations ranging from 1 to 37 CFU/100mL in 41 of 132 samples (31.1%) from the 3 major water systems. The overall average detected concentration was 1.2 CFU/100mL, while the average concentration for all detection sites was 5.3 CFU/100mL. After optimized multiplex polymerase chain reaction (PCR) was performed with newly developed VanA, VanB, VanC-1, and VanC-2/3 primers, concentrations of vancomycin-resistant Enterococcus spp. (VRE) ranging from 1 to 23 CFU/100mL were detected in 17 of 132 samples (12.9%). Of 216 individual enterococcal colonies, 64 (29.6%) displayed the VanC genotype. The results of a susceptibility test to vancomycin showed that the range of the minimal inhibitory concentration (MIC), an indicator of bacterial resistance, was 4 to 24μg/mL, with the average MIC at 9.2±4.5μg/mL. Of the bacterial isolates, 1 colony with the VanC-1 genotype was identified as E. gallinarum by 16S rDNA sequencing, whereas the other 63 colonies had the VanC-2/3 genotype and were identified as E. casseliflavus. Although these results imply that the major head bays of Korea are not contaminated with the highly vancomycin-resistant VanA- or VanB-type VREs, the misuse of antibiotics should be prohibited to minimize the presence of VREs and to maintain a safe water supply for protecting the health of the general population. Based on the study results, we also recommend the implementation of a continuous, broad-spectrum inspection program for Enterococcus spp. and VRE contamination in the major head bays. Furthermore, the multiplex PCR method described in this study can be used effectively for this purpose.