Abstract
The management of pathogenic bacteria in waterways is a public health issue. Here, we investigated the concentrations of potentially pathogenic bacteria, Arcobacter spp. and Campylobacter spp., and Escherichia coli, by quantifying species-specific genes in surface water samples from canals and the Chao Phraya River from June 2017 to June 2018 in Bangkok, Thailand. We assessed the relationship between the specific bacterial concentrations, water quality, and seasonal changes. Arcobacter spp. were detected at high density in all samples and showed seasonal fluctuations according to analyses based on 16S rDNA and the invasion gene ciaB. High levels of 16S rDNA and dut gene of E. coli were detected in the polluted drainage canals. A high correlation was observed between E. coli and chemical and biochemical oxygen demand (COD and BOD), suggesting that untreated domestic wastewater was the source of the E. coli. In contrast, Arcobacter spp. were detected with high density even in water samples with relatively low COD, suggesting that Arcobacter spp. are more likely than E. coli to survive in the water environment. The analysis of 16S rDNA and ciaB gene sequence analyses indicated that the Arcobacter spp. isolated from the drainage canals were A. butzleri and A. cryaerophilus.
Highlights
Arcobacter spp. have, in recent years, received increasing interest as emerging enteropathogens and potential zoonotic agents (Rasmussen et al 2013)
To gather basic information for quality management of surface water, we investigated the relationship between the concentrations of these bacteria and water quality standard items [e.g., pH, dissolved oxygen (DO), biochemical oxygen demand (BOD), chemical oxygen demand (COD), oxidation–reduction potential (ORP), NH4-N, NO3-N, and E. coli colony forming units (CFU)]
This concentration range is close to the average concentration of cultivatable E. coli CFU (1.5 Â 102 cells mLÀ1) that we found in the current survey in the Chao Phraya River in Bangkok city
Summary
Arcobacter spp. have, in recent years, received increasing interest as emerging enteropathogens and potential zoonotic agents (Rasmussen et al 2013). A. butzleri (Lau et al 2002) and A. cryaerophilus (Hsueh et al 1997) have been detected in patients with bacteremia. Taylor et al (1991) reported that A. cryaerophilus was detected in a child with diarrhea in Thailand, and Morita et al (2004) isolated A. butzleri from a drainage canal in Bangkok. Both A. butzleri and A. cryaerophilus have been detected in high concentrations in domestic sewage (Kirs et al 2017; Cui et al 2019). Since the waterways in Bangkok may be widely contaminated with Arcobacter spp., it is important to investigate the concentrations of Arcobacter spp. in canals and rivers close to areas of human habitation in Thailand
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