Antibiotic-resistant heterotrophic plate count bacteria and amoeba-resistant bacteria in aquifers of the Mooi River, North West province, South Africa Alewyn Carstens, Catheleen Bartie, Rainier Dennis and Carlos Bezuidenhout ABSTRACT Groundwater in the Mooi River catchment is prone to mining, agricultural, municipal and septic tank pollution. In this study physico-chemical and microbiological parameters were determined using appropriate methods. Bacterial isolates were identified by 16S rRNA sequencing (heterotrophic plate count (HPC) bacteria and amoeba-resistant bacteria (ARB)) and multiplex polymerase chain reaction (Escherichia coli). Antibiotic resistance tests were also performed. Physico-chemical parameters were generally within target water quality ranges for drinking water. HPC bacteria ranged between 10 5 and 10 7 colony-forming units (cfu)/ml. E. coli were enumerated from Trimpark, School and Cemetery. The Blaauwbank borehole was negative for faecal streptococci. Pseudomonas spp. were most abundant in the bulk water. Opportunistic pathogens isolated included Pseudomonas aeruginosa, Acinetobacter, Aeromonas, Alcaligenes, Flavobacterium, Bacillus cereus and Mycobacterium spp. Varying patterns of antibiotic resistance were observed. Most HPC bacterial isolates were resistant to cephalothin and/or amoxicillin and a few were resistant to erythromycin and streptomycin. Pseudomonas spp. was also the most abundant ARB. Other ARBs included Alcaligenes faecalis, Ochrobactrum sp. and Achromobacter sp. ARBs were resistant to streptomycin, chloramphenicol, cephalothin, and/or amoxicillin compared to HPCs. The presence of E. coli and ARB in these groundwater sources indicates potential human health risks. These risks should be further investigated and quantified, and groundwater should be treated before use. Alewyn Carstens Rainier Dennis Carlos Bezuidenhout (corresponding author) Unit for Environmental Sciences and Management, North-West University: Potchefstroom Campus, South Africa E-mail: carlos.bezuidenhout@nwu.ac.za Catheleen Bartie National Institute for Occupational Health, PO Box 4788, Johannesburg, 2000, South Africa Key words | antibiotic resistance, ARB, groundwater, HPC bacteria, opportunistic pathogens INTRODUCTION People living in rural areas in the Northern provinces of South Africa are largely dependent on groundwater resources to meet the demand for water for domestic purposes. In the North West province, this amounts to 65% of 3.5 million people (Department of Water Affairs (DWA) ). As groundwater is generally considered to be of good physico- chemical quality, this resource is usually supplied to commu- nities without prior treatment (Momba et al. ). However, the microbiological quality may be impaired (Mpenyana- Monyatsi & Momba ). Testing for this aspect is generally neglected by authorities as well as individual households. Ingestion of contaminated water may lead to infection by pathogens causing illnesses such as cholera, typhoid fever, para- typhoid fever and bacillary dysentery (Fourie & van Ryneveld ; Lawrence et al. ). Microbiological tests, based on faecal indicator bacteria, such as faecal coliforms, specifically Escherichia coli, are used to indicate the possibility that patho- genic species of faecal origin could be present (Department of Water Affairs & Forestry (DWAF) ; Atlas & Bartha ; World Health Organization (WHO) ). Heterotrophic plate count (HPC) bacteria include all naturally occurring bac- teria that utilise organic nutrients at low concentrations 835 © IWA Publishing 2014 Journal of Water and Health | 12.4 | 2014 doi: 10.2166/wh.2014.226 Downloaded from http://iwaponline.com/jwh/article-pdf/12/4/835/395880/835.pdf by guest on 15 July 2022