|Year : 2014 | Volume
| Issue : 2 | Page : 169-171
Assessment of bacteriological quality of ready to eat food vended in streets of Silchar city, Assam, India
I Sharma, JA Mazumdar
Department of Microbiology, Assam University, Silchar - 788 011, Assam, India
|Date of Submission||14-Mar-2013|
|Date of Acceptance||25-Oct-2013|
|Date of Web Publication||2-Apr-2014|
Department of Microbiology, Assam University, Silchar - 788 011, Assam
Source of Support: None, Conflict of Interest: None
A total of 37 street vended food samples were examined for bacterial and the colony forming units counts ranged from 4.5 × 10 5 to 1.12 × 10 6 . The isolates were identified as Escherichia coli (37.5%), Pseudomonas aeruginosa (3.57%), Staphylococcus aureus (14.20%), Salmonella sp. (5.36%), Klebsiella sp. (10.71%), Shigella sp. (19.64%) and Enterobacter sp. (8.93%) respectively. All the 56 isolates were susceptible to ciprofloxacin while their susceptibility to the other drugs varied. These findings demonstrated that the ready-to-eat foods vended in Silchar city constitute an important potential hazard to human health and provision of health education to the vendors would improve quality of street foods.
Keywords: bacterial contamination, food safety, hazard analysis and critical control points, street vended food
|How to cite this article:|
Sharma I, Mazumdar J A. Assessment of bacteriological quality of ready to eat food vended in streets of Silchar city, Assam, India. Indian J Med Microbiol 2014;32:169-71
|How to cite this URL:|
Sharma I, Mazumdar J A. Assessment of bacteriological quality of ready to eat food vended in streets of Silchar city, Assam, India. Indian J Med Microbiol [serial online] 2014 [cited 2019 Jun 18];32:169-71. Available from: http://www.ijmm.org/text.asp?2014/32/2/169/129809
| ~ Introduction|| |
According to the Food and Agriculture Organization, street foods are 'ready to eat foods and beverages prepared and sold by vendors especially in streets and similar public places.'  The street food industry plays an important role in cities and towns of many developing countries both economically and in meeting food demands of city dwellers. 
The street vended foods are prepared under unhygienic conditions and displayed openly leading to a high degree of contamination. Thus, from the health point of view, the microbiological quality of street vended foods becomes important as food can act as a major source for transmission of food borne infections and intoxications. The faecal-oral route has been recognized as the most important mode of transmission for pathogenic microbes from food handlers to food.  The potential for the contamination of street foods with pathogenic micro-organisms has been well-documented and several disease outbreaks have been traced to consumption of contaminated street foods.  The street foods are contaminated with enteropathogens such as Escherichia, Salmonella, Shigella and Enterobacter along with toxin producing bacteria such as Staphylococcus and Clostridium species. Apart from these, food may also be contaminated with Pseudomonas, Bacillus, Vibrio and Klebsiella sp. Around 250 different foodborne diseases have been described by Centre for Disease Control in 2011.  Furthermore in the recent years, a substantial increase in antibiotic resistance has been observed; mainly in developing countries  because of self-medication and general public are unaware of the effects antibiotics hold. Thus it is essential to monitor the antibiotic susceptibility of foodborne pathogens.
Today, street food has become one of the major concerns of public health  and a focus for governments and scientists to raise public awareness. Hence, taking these factors into account this study was undertaken to assess the bacteriological quality of various street foods consumed lavishly at street sides in Silchar city, Assam, India.
| ~ Materials and Methods|| |
The samples for the present study were collected from popular Indian street vended food items (panipuri, chaats and eggrolls) vended in various parts of Silchar city, Assam (India) from the month of January to June 2012.
Collection of sample
The food samples were purchased randomly from various street-food vendors collected aseptically in sterilised containers and was maintained in chilled state using coolants (ice pack). The pH of the samples was measured using a digital pH metre and then the samples were processed for further studies.
Enumeration of bacterial load in each sample was done by statistical process control method where the colony forming units (CFUg−1 /CFUml−1 ) of the food samples were determined. 1 g (for solid food i.e., chaat, eggroll and panipuri) or 1 ml (for liquid food, i.e., panipuri water) of the food sample was measured and added to 9 ml of sterilized saline (0.85% NaCl), mixed well to make a dilution of 10 fold. From the 10−1 dilution further dilutions of 10−2 , 10−3 , 10−4 , 10−5 and 10−6 were prepared. A spread plate of each dilution was done on plate count agar plates and incubated at 37°C for 16-18 h. After incubation, the plates were analysed and CFUs were counted for appropriate plates.
The CFU/g of the sample was calculated by using the following formula:
Statistical analysis of bacterial load in all the three types of food samples had been done using analysis of variance (ANOVA). The variance in CFUs for each type of sample was calculated and the probability, i.e., P value determined accordingly.
For isolating the bacteria, enrichment culture was done by inoculating 0.5 g (for solid samples) or 0.5 ml (for liquid samples) of the food sample in 4.5 ml peptone water broth and incubated for 6 to 8 h at 37°C. The growth in the medium was depicted as turbidity in the broth. An loopful from broth was streaked on nutrient agar, eosin methylene blue agar, MacConkey agar, Mannitol salt agar, Cetrimide agar and deoxycholate citrate agar plates were incubated at 35-37°C for 24 h and pure cultures of isolated bacteria were obtained. Microscopic examination and biochemical characterisation of the isolates was carried out as per the standard laboratory protocol  and the isolates were identified using Bergey's manual of determinative bacteriology, 9 th edition.
Antibiotic susceptibility test
The isolates were tested for antibiotic susceptibility pattern using Bauer et al.,  disc diffusion method. The antibiotics used in the test included ampicillin (10 mcg), pipericillin/tazobactam (15 mcg), chloramphenicol (50 mcg), imipenem (30 mcg), co-trimoxazole (15 mcg), cefadroxil (20 mcg), gentamicin (20 mcg), ciprofloxacillin (15 mcg), amikacin (15 mcg) and penicillin (30 mcg).
| ~ Results|| |
The pH of the samples ranged from 3.2 to 6.5 at a temperature of 34°C. The CFU counts of the samples ranged from 4.5 × 10 5 to 1.12 × 10 6 , thus indicating a high rate of contamination. Statistical analysis using ANOVA showed a P value of 0.0089 (which is <0.05) thus indicating a statistically significant difference between the bacterial load in the three types of food samples.
Both the Gram-positive and Gram-negative isolates were subjected to a series of biochemical tests that is indole, methyl red, voges-proskauer, citrate, catalase, oxidase, urease, triple sugar iron, nitrate reduction, gelatine liquefaction, deoxyribonuclease, carbohydrate fermentation and coagulase tests (for Staphylococcus). The isolates were identified using Bergey's manual of determinative bacteriology, 9 th edition. Seven different genera of bacteria were isolated from street vended foods. The isolates were identified as Escherichia coli (37.5%), Pseudomonas aeruginosa (3.57%), Staphylococcus aureus (14.20%), Salmonella sp. (5.36%), Klebsiella sp. (10.71%), Shigella sp. (19.64%) and Enterobacter sp. (8.93%) respectively.
The food samples showed a high load of E. coli followed by Shigella and Staphylococcus and the panipuri samples were more contaminated followed by chaat and egg roll. The isolates showed a varied response towards other drugs, but all the 56 isolates were 100% susceptible to ciprofloxacin while most all of them were resistance to ampicillin.
| ~ Discussion|| |
This study clearly indicated considerable levels of contamination in street vended foods of Silchar city. Many of these contaminants have been found to be pathogenic and the occurrence of bacterial species in the studied samples paralleled with several other studies conducted in various parts of the world. ,,
Quantitative analysis of the food samples showed a high load of bacteria ranging from 4.5 × 10 5 to 1.12 × 10 6 CFUs, which is relevant to the findings of other similar studies conducted on street foods. , The contamination of the street foods vended in Silchar city can be attributed to a number of factors such as hygienic condition of food handlers, unclean surroundings and utensils, contaminated water, improper handling and processing of food items and lack of proper storage as well as unhygienic display of food. The qualitative analysis of the samples revealed a wide range of bacterial contaminants. Some of the isolates were food spoiling organisms such as Pseudomonas while others were coliforms like E. coli, Klebsiella and Enterobacter and some were pathogenic bacteria such as Gram-positive Staphylococcus and Gram-negative enteropathogens like Shigella and Salmonella. In this study, E. coli was observed as a major contaminant indicating faecal contamination of the food items. The presence of respiratory pathogen such as Klebsiella in panipuri water may be suggestive of bacterial aerosols that might be generated during sneezing and coughing at public places. Different susceptibility patterns against various antibiotics were observed from this study and such responses had widely been reported for E. coli isolated from vendor foods.  All the E. coli isolates and many others including Salmonella showed a higher degree of resistance towards ampicillin, but all the isolates were highly susceptible to ciprofloxacin thus making it a good choice for treatment of food borne illness.
These findings demonstrate that the ready-to-eat food vended in Silchar city constitute an important potential hazard to human health which needs to be addressed. Provision of health education to the vendors and enforcing implementation of appropriate hygienic practices would improve bacteriological quality of street vended foods. Regular monitoring of the street food is suggested as this will help improving their quality and will also make the general public aware of the microbiological status of the vended street foods. Most importantly, relevant agencies such as consumer protection rights and others need to ensure and enforce strict compliance to hazard analysis and critical control points in all food production sectors in India.
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