Contamination of Tomatoes with Coliforms and Escherichia coli on Farms and in Markets of Northwest Nigeria

Abstract

Although recent reports indicated that produce contamination with foodborne pathogens is widespread in Nigeria, the sources and magnitude of microbial contamination of fruits and vegetables on farms and in markets have not been thoroughly identified. To ascertain possible pathways of contamination, the frequency and magnitude of coliform and Escherichia coli contamination of tomatoes produced in northwest Nigeria was assessed on farms and in markets. Eight hundred twenty-six tomato fruit samples and 36 irrigation water samples were collected and assessed for fecal indicator organisms. In addition, the awareness and use of food safety practices by tomato farmers and marketers were determined. Median concentration of coliforms on all field- and market-sourced tomato fruit samples, as well as in irrigation water sources, in Kaduna, Kano, and Katsina states exceeded 1,000 most probable number (MPN) per g. Median E. coli counts from 73 (17%) of 420 field samples and 231 (57%) of 406 market tomato fruit samples exceeded 100 MPN/g. Median E. coli concentrations on tomato fruits were higher (P < 0.01) in the rainy season (2.45 Log MPN/g), when irrigation was not practiced than in the dry (1.10 Log MPN/g) and early dry (0.92 Log MPN/g) seasons. Eighteen (50%) of 36 irrigation water samples had E. coli counts higher than 126 MPN/100 ml. Median E. coli contamination on market tomato fruit samples (2.66 Log MPN/g) were higher (P < 0.001) than those from tomatoes collected on farms (0.92 Log MPN/g). Farmers and marketers were generally unaware of the relationship between food safety practices and microbial contamination on fresh produce. Good agricultural practices pertaining to food safety on farms and in local markets were seldom used. Adoption of food safety practices on-farm, during transport, and during marketing could improve the microbial quality of tomatoes available to the public in this region of the world.

Simultaneous multifrequency: A possible alternative to improve the efficacy of ultrasound treatment on cherry tomato during storage

“…Sanitizers have been used for decontamination of pathogens; however, food safety and environmental concerns limit their use in agricultural produce (Lo & Martinez‐lo, ). Also, they are not highly effective for decontamination of food pathogens and often result in less than a 2‐log unit reduction of pathogens (Shenge, ). These reasons and many others such as the adverse effect of thermal treatment on the nutritional quality of food has increased the need for alternative means such as nonthermal treatment (Yang, Cao, Yang, Cai, & Zheng, ).…”

The implementation of the five keys to safer food in campus cafeterias and the effects on <em>Escherichia coli</em> contamination

“…A study in Nigeria found that 50% of 336 irrigation water samples used for farming contaminated by E. coli > 126 MPN/100. The median value of E. coli contamination of tomatoes sold in a supermarket was 2.66 Log MP/g, which was higher than the contamination levels of tomatoes in farming areas (0.92 Log MPN/g) (Shenge et al, 2015). These studies suggest that E. coli contamination can occur in raw materials.…”

Evaluation of irrigation suitability potential of brewery effluent post treated in a pilot horizontal subsurface flow constructed wetland system: implications for sustainable urban agriculture

“…Similarly, the healthy and matured tomato fruit yield (FY) on each of the three treatment groups was measured in kilograms per square meter (kgm −2 ). Tomato fruit was collected using UV - sterile plastic bags and taken to the laboratory for immediate TC analysis following a serial dilution method ( Shenge et al, 2015 ).…”