Browsing by Author "Romanis, Marco"
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- ItemEscherichia coli with virulence factors and multidrug resistance in the Plankenburg River(Academy of Science of South Africa, 2014) Lamprecht, Corne; Romanis, Marco; Huisamen, Nicola; Carinus, Anneri; Schoeman, Nika; Sigge, G. O.; Britz, Trevor J.Escherichia coli is a natural inhabitant of the gut and E. coli levels in water are considered internationally to be an indication of faecal contamination. Although not usually pathogenic, E. coli has been linked to numerous foodborne disease outbreaks, especially those associated with fresh produce. One of the most common ways through which E. coli can be transferred onto fresh produce is if contaminated water is used for irrigation. In this study, a total of 81 confirmed E. coli strains were isolated from the Plankenburg River as part of three separate studies over 3 years. During sampling, E. coli levels in the river were above the accepted levels set by the World Health Organization and the South African Department of Water Affairs and Forestry for safe irrigation of fresh produce, which indicates that transfer of E. coli during irrigation is highly probable. Multiplex polymerase chain reaction screening for pathogenic gene sequences revealed one enteroaggregative positive strain and four enteropathogenic positive strains. The four enteropathogenic strains were also found to be resistant to three or more critically and highly important antibiotics and were therefore classified as multidrug resistant strains. These results show that E. coli with enteropathogenic potential and multiple antimicrobial resistance properties has persisted over time in the Plankenburg River.
- ItemEvaluation of agricultural effluents and irrigation water as sources of antimicrobial resistant Escherichia coli(Stellenbosch : Stellenbosch University, 2013-12) Romanis, Marco; Britz, T. J.; Lamprecht, Corne; Stellenbosch University. Faculty of AgriSciences. Dept. of Food Science.ENGLISH ABSTRACT: Food-borne disease outbreaks caused by Escherichia coli have been linked to the use of faecally-polluted irrigation waters. Thus the overall aim of this research was to evaluate irrigation water and agricultural effluents as sources of antibiotic resistant E. coli in the Western Cape. The aim of the first study was to enumerate and characterise E. coli present in irrigation water and in potential contamination sources. Maximum total coliform and E. coli counts for irrigation sites was log 7.862 and log 5.364 MPN.100 mL-1, respectively. Five out of seven irrigation sites had E. coli counts exceeding national and international guidelines for ‘safe’ irrigation water (<1 000 counts.100 mL-1), making it unsafe for the irrigation of fresh produce. In this study, 46.6% of the E. coli strains were characterised in phylogenetic group B1. It has been shown that E. coli in group B1 have the ability to survive and persist in the external environment. Group B1 was also the most common group among isolates from irrigation sites (79.4%), while isolates from environmental sites grouped mainly in group A0 (54.1%). It was concluded that the wide variation of E. coli types present in irrigation water is a concern that should be further investigated. This raises human health implications since the increased exposure to faecal organisms increases the risk of food-borne outbreaks. The E. coli isolates (n = 120) and the marker (n = 37) and reference strains (n = 6), were evaluated for antibiotic resistance to seven medically-important antibiotics from different classes using the Kirby-Bauer disc diffusion method. Thirty-five strains (35/163 = 21.5%) exhibited resistance to one or more antibiotics. Piggery effluent was found to harbour the most antibiotic resistant E. coli isolates (9/35 = 25.7%). Among the resistant E. coli strains, the highest occurrence of antibiotic resistance was to trimethoprim (2.5 μg) (68.6%), tetracycline (30 μg) (57.1%), ampicillin (10 μg) (45.7%) and chloramphenicol (30 μg) (34.3%). Seventy-four percent (26/35) exhibited multiple antibiotic resistances to two or more antibiotics. The antibiotic resistant E. coli strains were evaluated for the presence of pathotypes using Polymerase Chain Reaction analysis to detect Intestinal Pathogenic E. coli (InPEC) and Extra-intestinal Pathogenic E. coli (ExPEC). Five InPEC strains were characterised as four Entero-Pathogenic E. coli (EPEC) strains resistant to three or four antibiotics and one Entero-Aggregative E. coli (EAEC) strain resistant to trimethoprim. The antibiotic resistant EAEC strain also possessed the ExPEC-related gene iutA. Two E. coli isolated from the Mosselbank River were both resistant to chloramphenicol and trimethoprim and also possessed the ExPEC-related gene iutA. It was concluded that the diverse antibiotic resistances of E. coli pathotypes present in irrigation water is a concern that should be further investigated.