“Garri” as popularly known in Nigeria is a staple food for most Nigerians. It is prepared by fermenting grated fresh cassava (Manihot esculenta (rantz) roots. This cassava originated from tropical America and is cultivated today in all tropical regions of the World (Scolt et al., 2000). It could be eaten, by reconstituting with  hot  water, stirred to form a thick paste and eaten with soup or stew and could be eaten dried or mixed with cold water and sugar- /milk, taken as a snack (Nweke, 1988).

In Nigeria, the sales and distribution of garri in local markets is associated with practice such as displaying of the products in open buckets, bowls and mats at points of sales and the use of bare hands during handling and sales. These unhygienic practices, may lead to microbial contamination due to deposition of bioaerosols on exposed products (Amadi and Adebola, 2008).

There are many factors that could result to food contamination. Trickett (1992), listed his own sources of contamination. According to him, the larger the surface area of the food exposed, the higher the load of micro organism, as well as the greater availability of oxygen for the metabolic activities of aerosol organisms.

Microorganism, especially bacteria vary from species to species in nutritional requirement (Asegbeloyin and Onyimonyi, 2007). Their presence in food at any stage, depend on the nutritional status of the food at that stage,

temperature, water content, pH as well as the nature of the organism. The bacteria that cause food poisoning have a similar nutritional requirement with that of human (Baine, 2000). He also states that food poisoning could have been minimized, if the food producers and processors are trained in safe – food – handling and consumers are better adviced in the choice of food.

Microorganism associated with food exposed to environment are Salmonella Typhi which was incriminated in Salmonella food poisoning outbreak in Germany and Great Britain in 1988 and 1971 respectively (Tietjen and Fung, 1980), Shigella flaxner associated with food contaminated with feacal materials. Others include: Bacillus cerus, pseudomonas spp.; clostridium spp.; Klebsiella spp.; and S. aureus (Nkanga and Nduka, 1980; Ijebadeniyi, 2007). In Nigeria, it has become a common practice to eat garri raw or as snacks especially among students who resort to it as faster alternative to preparation of cooked food, without considering the bacteriological implication. This work therefore is aimed at investigating the bacterial contamination of garri due to exposure in the market, as well as to establish the hygiene status of garri taken as snacks by many Nigerians.    

Sample collection

Garri samples used for this study were purchased randomly on two spaced time points between the month of January and November 2012 from sellers in five selective open markets: Eke-ukwu, Relief, Eke-Mmegbu, Orji and IMSU gate, as well as from different local garri processing factory within the locality to serve as control. A total of one hundred and ten (110) samples were obtained, twenty (20) samples from each market and ten from factories. The samples were collected into sterile polyethylene bags, using standard procedure and were transported to the microbiology laboratory of the   Department   of    Medical   Laboratory   Science,   Imo    State University, Owerri for analysis within 3 h of collection.

Preparation of samples

Ten (10) grams proportion of each sample was aseptically weighed after thorough mixing, transferred into a sterile 500 ml beaker containing 90 ml of peptone water and allowed to soak for 5 minwith occasional stirring using sterile glass rod. The supernatant was decanted into another sterile beaker and 10 fold serial dilutions of the sample supernatant were prepared by transferring successively 1 ml aliquot of the supernatant into 9 ml of sterile distilled water up to 10^-3 dilutions (Osoagbaka, 1996).

Cultivation of samples    

0.1 ml aliquot of each dilution was plated on nutrient agar (Biotec) for total viable heterotrophic bacterial counts and MacConkey agar (Biotec) for total coliform counts by pour plate method. The plates were incubated at 30°C for 24 h. At the end the incubation period, descrete colonies were enumerated and expressed as log of colony – forming units per gram (log CFU/g) of sample.

Representative bacterial colonies obtained after incubation were purified by subculturing on nutrient agar using the streak method. The purity of isolates was determined using the Gram’s stain reaction. The purified isolates were then characterized and identified using their colonial morphologies and biochemical characteristics as described by Cheesbrough (2000) and with reference to the bergey’s Manual of Determinative Bacteriology (Holt et al., 1994).

Statistical analysis

Chi-square statistical method was adopted to determine if there is a significant difference between the five markets. 

Table 1 shows the prevalence of Bacterial contamination distribution among the different market samples; relief market recorded 100% contamination, followed by Eke-Ukwu (90%) and IMSU gate with the least contamination of 75%.Table 2 shows specific sites of bacterial conta-minants. This indicates that Staphylococcus was the predominate isolate, while E. coli was isolated from four out of the five markets. B.cereus and Staphylococcus epidemidis were isolated from three different market each and Klebsiella aerogenes was isolated from only one market.

Figure 1 shows the rate of occurrence of the different isolate. S. saprophyticus occurred in 35 representing 37% occurrence, E. coli in 24 (25.5%), B. cereus 18(19.2%), K. aerogenes 10 (10.6%) and S. epidemidis 7(97.5%).The heterotrophic count when compared with the control showed a statistical significant increase at P>0.05.

The coliform count of Eke- Ukwu, Relief, Eke-Mmegbu and Orji when compared with the control showed a statistical significant increase at P > 0.05 while that of IMSU gate showed a statistical decrease at P< 0.05.

In addition to death and ill health caused by food poisoning, individuals, families, health care system and society, as well as commercial enterprises incure tremendous economic lost. These lost include, loss of income due to the cost of medical care, the cost of investigating food contamination outbreaks, loss of income due to closure of business, legal costs and fine (Baine, 2000). Hence taking “Garri” dry as snacks or with cold water is exposure to health risk due to the microbial status.

This study reveals high prevalence of bacterial contamination of samples from different markets, when compared with that of control. Relief market has the highest prevalence of 100%. This may be attributed to dirty environment associated with these markets. Indiscriminate dumping of refuse is a common practice around these markets. This is in agreement with the results of Trickett (1992) who listed his own sources of food contamination among other factors to include, dust, and waste products from the environment.

The 20% prevalence recorded against the control can be attributed to the unskilled nature of the garri producers who introduce contaminants to their products, especially during the cooling and packaging phase of their production. This corroborates the reports of Baine (2000) who states that food poisoning could have been reduced if the food producers and processors are educated and trained in safe food handling and consumers are better adviced in their choice of food.

The coliform count of IMSU gate when compared with that of control showed significant difference against other markets. This decrease can be attributed to the fact that IMSU gate market is not a large market, rather a mini market and so does not accommodate large population. Refuse disposal in this market is more properly managed than what is obtainable in other markets. The major source of contamination in this market is likely to be from the sellers and the aerosols. This supports the observation of Mankee et al. (2003) who states that the vendors can be carriers of pathrogens like E. coli, Salmonella, Shigella, Campylobacter and S. aureus, who eventually transfer these food borne harzards to consumers.

The distribution of the organism varied from the different markets. Eke – Ukwu market is located at the heart of the town with great number of people coming in for marketing purpose. Relief market though not completely at the heart of the town, harbours many refuse dumps, gutters and water logged areas containing stagnant water from sewages, hence, recorded more contamination than others. This corroborates Almeida, (1994) who attributes the variation in distribution of organisms to environmental condition and practice of the food handlers.

From the result of this work, Staphylococcus spp. (S. epidermidis and S. aureus) had the highest rate of occurrence with a total of 44.7% (37.2 and 7.5 respectively). They might have found their way into the garri through carriers, since the organisms are found around the nose, throats, hands and clottings of these carriers (Cheesbrough, 2000).

The isolation of E. coli and K. aerogenes from some of the markets, though, bellow infection causing value (E.coli: ≥1.0 x 10⁶ and Klebsiella erogenous ≥ 5.9x10³) (Solberg et al., 1976) indicates recent feacal contamination which can be attributed to the refuse dumps as well as the stagnant waters from sewages seen around some of these markets. This is in agreement with the results of Dike- Ndudim et al. (2014) who attribute the isolation of the same organisms from smoked fish sold in Owerri to feacal contamination of water sources in Owerri.

The result of this study has proven that “Garri” which were sold in Owerri markets are highly contaminated with pathogenic organism. Although, the coliform (CFU/G) fall below the value that can result to infection, this implies that, increase intake of garri as snacks among people of Owerri may lead to a disease condition such as gastro enteritis.

We therefore suggest that the state government establishes standard garri processing industries to be managed by trained personnel in food handling, to reduce contamination due to poor handling. Also, environmental sanitation should be taken as a priority project to reduced food-borne disease. Finally, residents of the state should be educated on the dangers of food poisoning to enhance personal hygiene.

Authors did not declare any conflict of interest.