1. *Aminu Maryam and Barira Saidu B
ISOLATION OF E. COLI 0157:H7 FROM VEGETABLES AND WATER USED TO IRRIGATE VEGETABLE FARMS WITHIN SABON GARI, ZARIA, KADUNA STATE
*Aminu Maryam and Barira Saidu B
Department of Microbiology, Faculty of Science, Ahmadu Bello University, Zaria-Nigeria
Corresponding Author: Dr. Maryam Aminu;
1. INTRODUCTION
Table 1: MPN result for coliforms in water samples collected from the three vegetable farms.
5. DISCUSSION
Escherichia coli is a member of the family Enterobacteriacaea, which are a major source of food contamination worldwide. Escherichia coli 0157, which is a strain of the enterohaemorrhagic E. coli group is recognized as an organism whose presence in any food material can lead to serious public health implications. Concern for pathogens in vegetables has risen because of increasing number of outbreaks of food borne illnesses caused by consumption of fresh and minimally processed vegetables. The bacterium Escherichia coli (E. coli) 0157:H7 is of particular concern because of its hardiness and the severe consequence of infection. In Nigeria, there is no sufficient information about the outbreaks of diseases caused by the verotoxic E. coli which has emerged as food borne pathogen that can cause severe and potentially fatal human illness.
The data obtained in this study have shown that 1 sample of vegetable (3.03) of the total of 33 samples obtained from vegetable farms in Sabon Gari local government was contaminated with E. coli 0157:H7. The coliform index which were all above 2300 showed that E. coli was abundant on the surface of vegetables and the water was highly contaminated with coliforms. The higher E. coli count recorded from Zango and Sabo might be due to the water used for irrigation in these areas. The water is gotten from a nearby river which runs through the town and the river is highly polluted with waste matter from households and faeces from both humans and animals. The isolation rate on SMAC which was 3.03% is higher than Jalil Khandagh, who obtained 0.35% in Iran but lower than Rubeglio et al. (2012) who obtained 5.1% prevalence of E. coli 0157:H7 in Argentina. The minimum count obtained on EMB was above the acceptable limit and this high count is of public health concern.
Location
10ml
1ml
0.1ml
MPN Index
Zango 5+
2300
Dam
Sabo
Table 2: Mean E.coli counts of five different vegetables in zaria. E.coli counts (log10 CFU/g)
Farms
Tomatoes
Lettuce
Spinach
Cabbage
Carrot
Zango
6.30
6.39 * -
7.56
Dam
6.65
6.82
6.63
6.93
Sabo
7.11
6.72
6.90
6.74
Total
13.41
19.76
13.72
13.37
20.79
Mean
4.47
6.59
4.57
4.46
2. AIM
The aim of this study is to isolate 0157:H7 from vegetables and water used to irrigate vegetable farms within Sabon Gari Local Government area in Zaria, Kaduna State.
3. METHODS
A total of 33 samples (30 vegetables and 3 samples of water) were collected from vegetable farms in Sabon Gari Local Gov’t area of Kaduna state. The vegetable and water samples were collected in sterile polythene bags and conical flasks respectively and transported to the laboratory immediately for analysis. Most probable number index was used for the water analysis. 0.1ml of the 10-5 dilution factor of homogenized vegetable was taken and spread onto EMB agar plates. Colonies positive for E. coli were then inoculated onto nutrient agar slants and incubated at 370C for 24 hours. Biochemical test was carried out using triple sugar iron (TSI), Citrate, Urea, MR-VP, Indole and Motility based on the method of Cowan and Steel (2010). Isolates that are biochemically characterized to be E. coli were inoculated onto cefixime raminos Sorbitol MacConkey agar (CR-SMAC) and incubated at 37°C for 24hours.
6. CONCLUSION
Due to low level of sanitary practices observed in the study area and lack of adequate data on the trend of the infection, the organism could spread easily without early detection and as such it is important to take seriously the isolation of the organism in food. It is recommended that consumers wash and cook vegetables and wash fruits properly before they are consumed. Provision of basic amenities, public enlightenment and proper enforcement of surveillance system should be taken as priority by the government.
Table 3: Isolation of E.coli on EMB and SMAC, and Biochemical characterization.
Location
Total
Positive (%)
Isolation
Biochemical
SMAC
Zango 11 8
8 (72.7)
0 (0.00)
0 (0.00)
Dam 5
5 (45.5)
Sabo
1 (12.5)
1 (9.1) 33 21
21 (63.6)
1 (4.8)
1 (3.03)
8. REFERENCES
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Vogt and Dippold. (2005). Escherichia coli 0157:H7 outbreak associated with consumption of ground beef, June-July Public Health Report 120(2):
4. RESULTS
High coliform contamination was observed in water samples collected from all the sampling points. The highest mean E. coli count was recorded with carrots while cabbage is lowest. The organism was more isolated from samples collected from Zango and Sabo which both had 72.7% while the sample from Sabo had confirmatory E. coli 0157:H7.
7. ACKNOWLEDGEMENTS
We acknowledge all the farmers whose farms were used as sampling points for this research.