Chotpoti is a popular street food in the major areas of Bangladesh. Street foods play an important role in people’s daily food options as well as their regular nutritional requirements are dependent on these foods, as their ever-growing busy schedule takes away the opportunity to eat of homemade food. Due to the expedient availability, these street foods are one of the primary food options for city peoples. The present study was undertaken to investigate the microbiological quality of Chotpoti sold by different street vendor at Savar area, Dhaka, Bangladesh. Microbial quality was assessed by total viable count (TVC), total coliform count (TCC); samples were inoculated into various selective media such as Nutrient agar, Eosin Methylene Blue (EMB) agar, Salmonella Shigella (SS) agar, Thiosulfate Citrate Bile Salts Sucrose (TCBS) agar and Mac Conkey’s agar. Gram negative bacteria were isolated and identified from the samples. The TVC in Chotpoti sample was ranged from 6 × 105 CFU/g to TNTC and TCC was ranged from 6 × 105 CFU/g to 3 × 106 CFU/g. Antibiotic sensitivity test showed that the isolates were sensitive to antibiotics such as antibiotic against Streptomycin, Chloramphenicol. Data of this study indicated that Chotpoti sold at street around Savar region harbor multidrug resistant food borne bacteria which might cause public health hazards.
Street food is ready-to-eat food in a street or other public place, such as a market or fair, by a hawker or vender, often from a portable food booth [
Over the years, many food-borne diseases have been reported due to contaminated non-homemade food consumption. Street food was widely utilized by poor urban residents of ancient Rome whose tenement homes did not have ovens or hearths, with chickpea soup being one of the common meals along with bread and grain paste [
Bangladesh is populated with many vendors of street foods of different kinds. Like all developing countries, street food preparation and selling in Bangladesh provides a regular source of income for millions of men and women with limited education or skills. Almost all of the bacteria are pathogenic to human at various degrees and infections caused by some bacteria are even hard to treat with increase the rate of antibiotic resistance in the community [
Presence of antibiotic resistant bacteria in street-foods has become a global health concern. Street food vending has become an important public health issue and a great concern to everybody. Microbial food borne illness is the major health problem associated with street foods [
The study was conducted during the period from June to December 2014, in the Department of Microbiology, Gono Bishwabidyalay, Savar, Dhaka. Chotpoti samples were collected from different street vendors at Ghorapir Mazar stand (23˚55'31.7"N 90˚14'41.4"E), Pollybidut stand (23˚54'49.5"N 90˚15'29.0"E) and Nabinagar bus stand (23˚54'49.5"N 90˚15'29.0"E). All the samples of this study were collected aseptically using sterile instruments and transferred carefully to appropriate containers. The samples were carefully handled and kept in box. Due aseptic care was taken during transportation and the samples were kept in sterile container until they are prepared for bacteriological analysis.
The media used for bacteriological analysis were MacConkey agar, Eosin-Methylene-Blue (EMB) agar, Salmonella-Shigella (SS) agar, Thiosulfate Citrate Bile Salts Sucrose (TCBS) agar, Muller Hinton agar, Nutrient broth (NB) and Peptone broth. The reagents used during the study were Lacto phenol-cotton-blue solution, Crystal violet, Gram’s iodine, Safranin, 95% Ethyl alcohol,3% hydrogen peroxide, Kovac’s & indole reagent, Burritt’s reagent A and B, normal physiological saline solution. Muller Hinton Agar plates, Phosphate buffered saline (PBS) solution, normal saline and distilled water, etc.
Portions of Chotpoti samples were uniformly homogenized in mortar and pastel using sterile diluents as per recommendation of ISO. A quantity of 10 gm homogenized sample of each Chotpoti was taken aseptically with a sterile spoon and transferred carefully into a sterile pestle containing 90 ml of PBS. Later on using whirly mixture machine different serial dilutions ranging from 10-2 to 10-4 were prepared according to the standard method.
Homogenized samples were enriched into alkaline peptone water by overnight incubation at 37˚C. Overnight enriched culture was streaked and spreaded onto Salmonella-Shigella (SS) agar, Thiosulfate Citrate Bile Salts Sucrose (TCBS) agar and incubated at 37˚C for 24 hrs. The cultural examination of Chotpoti samples for bacteriological analysis was done according to the standard method. Identification of bacteria was performed on the basis of colony morphology; Gram’s staining reaction and biochemical test.
Commercially available antibiotic disc has been used for the test to determine the drug sensitivity pattern. The commercially media were prepared according to the direction of the manufactures and the non-commercial media were prepared in the laboratory (
0.1 ml of each ten-fold dilution was transferred and spread on duplicate onto NA, EMB and MacConkey using a micropipette for each dilution for the determination of total bacterial count. The diluted samples were spread as quickly as possible on the surface of the plate with sterile glass spreader. The plates were kept in an incubator at 37˚C for 24 hours. The results of the total bacterial count were expressed as the number of colony forming units (CFU) per gram of food samples.
Colony characteristics such as shape, size, surface texture, edge and elevation, color and opacity developed on various selective media after 24 hrs of incubation at 37˚C were recorded.
Gram’s staining of the pure culture was performed according to method described
SL. NO. | Antimicrobial agents | Symbol | Disc concentration (µg/disc) |
---|---|---|---|
1 | Penicillin G | P | 10 |
2 | Chloramphenicol | CL | 30 |
3 | Streptomycin | S | 10 |
4 | Tetracycline | TE | 30 |
5 | Vancomycin | VA | 30 |
by Aneja et al. (2003). Briefly, a single colony was picked up with a bacteriological loop, smeared on separate glass slide and fixed by gentle heating. Crystal violet was then applied on each smear to stain for two minutes and then washed with running tap water. Few drops of Gram’s iodine were then added for few seconds. After washing with water, Safranin was added as counter stain and allowed to stain for 2 minutes. The slides were then washed with water, blotted and dried in air and then examined by a light microscope (100×).
Biochemical tests were done in accordance to standard procedure [
This test is used to different those bacteria that produce the enzyme catalase. To perform the test an amount of 2 - 3 ml of 3% hydrogen peroxide solution was poured into a test tube. If the organisms are catalase producer, bubbles of oxygen are released.
The sugar fermentation test was performed by inoculating a loop full of NB culture of the organisms into each tube containing three basic sugars (e.g. Dextrose) separately and incubated for 24 hours at 37˚C. Acid production was indicated by the color change from reddish to yellow in the medium.
Five milliliter of peptone water was inoculated with the 5 ml of bacterial culture and incubated at 37˚C for 48 hours. Kovac’s reagent (0.5 ml) was added, shaked well and examined after 1 minute. A red color in the reagent layer indicates indole.
Five milliliter sterile glucose peptone water was inoculated with the 5 ml of test organisms. It was incubated at 37˚C for 48 hours.
This tube medium is used to identified Gram negative enteric bacteria based on few biochemical characteristics includes―glucose indicated by yellow butt, lactose fermentation-indicated by yellow slant and gas production indicated by presence of a crack or gas space, etc.
This tube medium is used to identify Gram negative enteric based on the ability of the organism to produce the enzyme urease within 2 to 4 hours (rapid) or within 24 hours (late) of incubation. If the organism produces urease, this splits urea into ammonium, carbon-di-oxide and water.
Antimicrobial drug susceptibility against two commonly used antibiotics was performed by disc diffusion method. The procedure of disc diffusion method is the isolated microbial colony was inoculating into Nutrient-Broth and incubated at 37˚C for 24 hours. The plates were inverted and incubated at 37˚C temperature for overnight. After incubation the diameter of the zone of complete inhibition (including diameter of the discs) was measured in millimeters with a ruler.
The TVC of Chotpoti samples collected from different vendors are presented in
The TCC of Chotpoti samples collected from different vendors are presented in
The isolation of coliform bacteria from Chotpoti sample indicates fecal contamination. Presence of coliforms in the present study might be due to poor quality
Sample No: | Vendor places | Media plate | TVC (CFU/g) | Acceptable or not Acceptable |
---|---|---|---|---|
1 | Pollybidut bus stand vendor | Nutrient Agar | 3 × 105 | Not acceptable |
2 | GhorapirMazar stand | Nutrient Agar | TNTC | Not acceptable |
3 | Nabinagar bus stand | Nutrient Agar | TNTC | Not acceptable |
Sample no: | Vendor places | Media plate | TVC (CFU/gm) | Acceptable or not acceptable |
---|---|---|---|---|
1 | Pollybidut bus stand vendor | EMB agar | TNTC | Not acceptable |
2 | GhorapirMazar stand | EMB agar | 6 × 105 | Not acceptable |
3 | Nabinagar bus stand | EMB agar | 3 × 106 | Not acceptable |
EMB = Eosin Methylene Blue.
of water used for washing of fruits, vegetables and utensils, inadequate storage of these at ambient temperatures in unhygienic places, maintenance of premises and personal hygienic of vendors. Microbiological studies carried out on street-food vending in several developing countries have reported high bacteria counts in food [
The cultural characteristics of isolated bacteria exhibited on the selective media are presented in
A total of 08 isolates of 04 genera such as Escherichia coli, spp Klebsiella spp., Salmonella and Shigella spp. were subjected to antibiotic sensitivity assay. The results of antibiotic sensitivity assay are presented in
In this antibiogram sensitivity test some specific commonly used antibiotics
Name of source | Bacterial type (n) | Isolate number |
---|---|---|
Pollybidut bus stand vendor | 02 | 1 (A, B) |
Ghorapir Maza1 stand vendor | 05 | 2 (A, B, C, D, E) |
Nabinagar bus stand vendor | 01 | 3 (A) |
Serial No. | Name of selective media | Colony characteristics |
---|---|---|
1 | MacConkey agar | Pink colony |
2 | EMB agar | Metallic sheen colony |
3 | EMB agar | Brown mucoid colony |
4 | TCBS agar | Not grow |
Isolate NO. | Name of antibiotic disc | ||||
---|---|---|---|---|---|
P | S | TE | C | V | |
1 (A) | R | 22 mm | R | 20 mm | R |
1 (B) | R | 20 mm | 17 mm | 26 mm | R |
2 (A) | R | 20 mm | 17 mm | 25 mm | R |
2 (B) | R | 22 mm | R | 29 mm | R |
2 (C) | R | 21 mm | 15 mm | 15 mm | R |
2 (D) | R | 20 mm | 17 mm | 26 mm | R |
2 (E) | R | 22 mm | R | 15 mm | 18 mm |
3 (A) | R | 22 mm | R | 20 mm | R |
Interpretation: R = resistant, S = sensitive.
are used against the specific microorganism. In this study, gram negative bacteria were found multidrug resistant. Antibiotic against which bacterial isolates of Chotpoti were found resistant were Penicillin G, Tetracycline and Vancomycin.
In this study, microbiological methods were used to identify bacteria isolated from Chotpoti samples. The results of cultural characteristics, Gram’s staining, used to identify Escherichia coli, Klebsiella spp., Salmonella spp. and Shigella spp. were identified.
The biochemical identification of E. coli, Klebsiella spp. and Salmonella spp. were done by performing the biochemical test. The biochemical test was done as started on Bargen’s manual of Determination Bacteriology. In many other studies, E. coli was detected frequently in street food samples [
Street foods are very much popular in the recent days. Improper personal hygiene can facilitate the transmission of the pathogenic bacteria found in environment and on people’s hands via food to humans. Street foods have unique flavor, are easily accessible and cheap [
Isolate No. | Gram’s stain & Shape | Carbohydrate Fermentation | H²S Production | NO³ Reduction | Indole Production | MR Reaction | VP Reaction | Citrate Use | Urease Activity | Catalase Activity | Oxidase Activity | Gelatin Liquefaction | Microorganisms | ||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Lactose | Dextrose | Sucrose | |||||||||||||
1 (A) | Rod − | AG | AG | − | − | + | + | + | − | − | − | + | − | − | Escherichia coli |
1 (B) | Rod − | AG | AG | AG | − | + | − | + | + | + | + | + | − | − | Klebsiella spp. |
2 (A) | Rod − | − | AG | A | + | + | − | + | − | + | − | + | − | − | Salmonella spp. |
2 (B) | Rod − | AG | AG | A | − | + | + | + | − | − | − | + | − | − | Escherichia coli |
2 (C) | Rod − | AG | AG | AG | − | + | − | + | + | + | + | + | − | − | Klebsiella spp. |
2 (D) | Rod − | AG | AG | AG | − | + | − | + | + | + | + | + | − | − | Klebsiella spp. |
2 (E) | Rod − | − | A | A | − | + | − | + | − | − | − | + | − | − | Shigella spp. |
3 (A) | Rod − | − | AG | A | + | + | − | + | − | + | − | + | − | − | Salmonella spp. |
MR: Methyl red; VP: Voges-Proskauer; AG: Acid and gas; A: Acid; (+) = positive; (−) = negative. Comments: Isolate number: 1 (A), 2 (B) = Escherichia coli; Isolate number: 1 (B), 2 (C), 2 (D) = Klebsiella spp.; Isolate number: 2 (A), 3 (A) = Salmonella spp.; Isolate number: 2 (E) = Shigella spp.
their nutrient intake [
The authors declared no potential conflicts of the interest with respect to the research, authorship and/or publication of this article.
Happy, A.H., Alam, M.G., Mahmud, S., Imran, M.A.S., Rony, M.H., Azim, M.A.A., Islam, M.M., Sarker, M.K.D., Akter, P., Mondol, G.C., Hossain, T., Rahman, M.M., Islam, M.M., Roy, A., Das, S., Ahmed, M.R. and Uddin, M.E. (2018) Isolation, Identification & Characterization of Gram Negative Bacteria from Popular Street Food (Chotpoti) at Savar Area, Dhaka, Bangladesh. Open Access Library Journal, 5: e4986. https://doi.org/10.4236/oalib.1104986