Fluctuations of indicator and index microbes as indication of pollution over three years in the Plankenburg and Eerste Rivers, Western Cape, South Africa

Abstract

The Plankenburg and Eerste Rivers (Western Cape) have been reported to be contaminated with faecal coliforms. Water is drawn from both rivers for irrigation of fresh produce. The potential risk in the use of these rivers as irrigation sources was assessed by determining the fluctuations of 'indicator' and 'index' microbes over 3 years. Selected physico-chemical (water temperature, pH, COD, conductivity and alkalinity) and microbiological parameters, including coliforms, faecal coliforms, Escherichia coli and enterococci, as 'indicators' of faecal pollution, and Salmonella, Listeria and Staphylococcus, as 'index' of the presence of potential pathogens, were monitored.No correlation was found between water temperature and COD (r 2 = 0.0003), whereas for temperature and pH a significant trend (p = 0.0004), but low correlation (r 2 = 0.108), was observed. With the exception of the faecal coliforms (E. coli), no significant trends and no correlations between temperature and the dependent variables were found. For the faecal coliforms there was a significant trend (p = 0.0289) with temperature but not a good correlation (r 2 = 0.0434), but the impact of temperature over time was significant (p = 0.0047). This is important, when the World Health Organisation (WHO) and South African Department of Water Affairs (DWA) guidelines for faecal coliforms are applied, as it indicates that temperature does impact the faecal coliform numbers. The presence of indicator organisms did not only indicate unsanitary conditions, but also the presence of potential pathogens such as Staphylococcus, Klebsiella, Listeria and Salmonella. Based on these results the microbial quality of these rivers was found to be unacceptable and does not meet the WHO and DWA guidelines for safe irrigation. There was also a high risk of exposure to human pathogens when water from these rivers is used to irrigate produce that is consumed without further processing.

Microbial study of household hygiene conditions and associated Listeria monocytogenes infection risks for Peruvian women

“…In areas like the shanty town community participating in this study, L. monoyctogenes is likely associated with wastewater, graywater and presence and persistence in the natural environment. L. monocytogenes and other pathogens have been detected in natural waters in other parts of the world where these waters were known to be contaminated , and L. monocytogenes can survive in soil, faecal matter, water and animal feed for days to months .…”

Escherichia coli with virulence factors and multidrug resistance in the Plankenburg River

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“…The rivers were frequently polluted by sewage, refuse, potentially pathogenic microorganisms from the river bank dwellers running off into the river from rainfall. The studies by Lotter (); Britz et al () confirmed the presence of Listeria monocytogenes , Listeria ivanovii , Listeria grayi , Listeria innocua , and Listeria welshimeri isolated from these rivers. Likewise, Huisamen () also isolated Listeria monocytogenes , Listeria ivanovii , Listeria grayi and Listeria seeligeri in his studies on these rivers and his report revealed a direct link in the incidence of Listeria species and the pollution of the rivers.…”