Microbial Contamination in Vegetables at the Farm Gate Due to Irrigation with Wastewater in the Tamale Metropolis of Northern Ghana

Abstract

The rational for this study was to assess the microbial quality of fresh vegetables at the farm gate of the Water Works road vegetable farm at Gumbihini in the Tamale Metropolis. A total of thirty-six (36) vegetables comprising lettuce, amarantus and cabbages and eight (8) wastewater samples were collected at random and analysed for a period of four months, to assess the microbial contamination level. Samples were analysed for total coliforms, faecal coliforms, E. coli and helminthes eggs. All vegetables sampled during the study period recorded high levels of total and faecal coliform bacteria. Mean faecal coliforms for the various vegetables were as follows; lettuce 3.7 ± 0.5 CFU·g −1 , amarantus 3.5 ± 0.6 CFU·g −1 and cabbage 3.1 ± 0.6 log CFU·g −1 fresh weight. FC levels were above the International Commission on Microbiological Specifications for Foods (ICMSF) recommended level of 3 log CFU·g −1 fresh weight. E. coli were recorded in lettuce (3.3 ± 0.6 log CFU·g −1 fresh weight) and amarantus (0.6 ± 0.1 log CFU·g −1 fresh weight) but not in cabbages. Lettuce generally recorded high levels of microbial contamination because of the large surface area occupied by its leaves. Two helminth eggs (Strongiloides stercoralis) were identified in lettuce while four (Ascaris lumbricoides) were identified in wastewater. Microbial loads recorded in wastewater were generally higher than that of vegetables. Since most of these vegetables are eaten fresh or slightly cooked, there is course for concern as public health will be adversely affected. Education of farmers and consumers on food safety has to be intensified to avert a possible outbreak.

Assessment of the Risk of Microbial Contamination of an Urban Crop in the City of Daloa (Côte d'Ivoire): Case of Lettuce (Lactuca sativa L.)

“…High loads of these microfloras were also reported in other studies. Fecal coliforms were found in lettuce at production sites with loads ranging from 10 3 to 10 5 CFU/g and 10 3 to 10 4 CFU/g respectively, in Ghana in the works of Cobbina et al (2013) and Ethiopia those Woldetsadik et al (2017). Mesophilic aerobic germs (3x10 5 to 1.1x10 6 CFU/g) and fungal flora (2x10 3 to 2x10 4 ) were reported in lettuce grown in Romania (Soendjojo, 2012).…”

“…Contamination of vegetables is one of the potential risks of infection with enteropathogenic bacteria such as Salmonella and Escherichia coli. This contamination occurs from an environmental, animal or human source at the time of planting, harvesting or handling vegetable prior to consumption (Cobbina et al, 2013;Wognin et al, 2013). Considered as a contamination of plant surfaces, recent work has shown that certain pathogens such as salmonella are able to infect and multiply in the mesophyll of certain plants such as lettuce (Kroupitski et al, 2009;Guchi et al, 2010;Pelletier et al, 2011;Schikora et al, 2011).…”

Occurrence of Escherichia coli in Brassica rapa L. chinensis irrigated with low quality water in urban areas of Morogoro, Tanzania

“…The faecal pathogens may cause diseases to farmers, consumers and communities (Abakpa et al, 2013;Cobbina et al, 2013). These studies reported faecal bacterial contamination in vegetables including lettuce and Swiss chards irrigated with LQIW.…”

Division of methods for counting helminths’ eggs and the problem of efficiency of these methods

“…For this purpose, chambers of general use are applied, e.g. Fuchs-Rosenthal (which is also used in cytology, haematology, microbiological and protozoological examinations) [28,29], Sedgwick-Rafter [30,31], or Doncaster chambers -most often used in hydrobiology and sanitary engineering, more rarely in veterinary medicine while counting developmental forms of parasites -mainly the eggs of helminths [32].…”