Portage of Bacteria Responsible of Foodborne Illness in Scholarly Canteens (Republic of Benin)

doi:10.4236/aim.2012.23041

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Advances in Microbiology, 2012, 2, 340-344

http://dx.doi.org/10.4236/aim.2012.23041 Published Online September 2012 (http://www.SciRP.org/journal/aim)

Portage of Bacteria Responsible of Foodborne Illness

in Scholarly Canteens (Republic of Benin)

Honoré Sourou Bankolé1,2, Tossou Jacques Dougnon1, Patrick Aléodjrodo Edorh3,4,

Tamègnon Victorien Dougnon1,4*, Magloire Legonou2, Jean Robert Klotoé1, Frédéric Loko1,2

1Polytechnic School of Abomey-Calavi, Research Laboratory in Applied Biology,

University of Abomey-Calavi, Cotonou, Benin

2Laboratory of Food Microbiology, Ministry of Health, Cotonou, Benin

3Faculty of Science and Technology, Department of Biochemistry and Cellular Biology,

University of Abomey-Calavi (UAC), Cotonou, Benin

4Interfaculty Center of Formation and Research in Environment for the Sustainable Development,

Laboratory of Toxicology and Environmental Health, University of Abomey-Calavi (UAC), Cotonou, Benin

Email: *[email protected]

Received June 17, 2012; revised July 17, 2012; accepted July 26, 2012

ABSTRACT

This study has determined the portage of bacteria responsible for foodborne illness in the school canteen staff. 336

samples taken on the nose, mouth and hands were collected. Microbiological analyses were realized and several patho-

genic bacterial strains were isolated from the vendors: Staphylococcus aureus (26/122), sulphite-reducing clostridia

(14/122) and Escherichia coli (10/122). The food vendors in th e school canteen may be the vectors of germs that cause

food poisoning among young students.

Keywords: Portage; Bacteria; Food; Escherichia coli; Disease

1. Introduction

Foodborne diseases are, by the world, a major public

health problem. Although most often manifested by di-

arrhea with an estimated three million deaths a year in

children under five years of age, they have other serious

consequences such as kidney and liver failure, brain dis-

orders and neurological disorders and death [1,2].

According to WHO, almost one third of people in de-

veloped countries have an infection caused by foods. In

less developed countries, diarrheal diseases transmitted

through water and foods are major causes of morbidity

and mortality. They cause about 2.2 million deaths per

year especially in children [3].

In Benin, the number of cases of diarrheal diseases is

estimated at 309.944 with 331 deaths per year [4].

Deeply concerned by this situation, the 53rd World

Health Assembly adopted a resolution in May 2000 to

develop a global strategy to reduce the burden of food-

borne illness. Estimates of the overall number of epi-

sodes of foodborne illness are helpful for allocating re-

sources and prioritizing interventions. However, arriving

at these estimates is challenging because food may be-

come contaminated by many agents (a variety of bacteria,

viruses, parasites, and chemicals), transmission can occur

by nonfood mechanisms (e.g., contact with animals or

consumption of contaminated water), the proportion of

disease transmitted by food differs by pathogen and by

host factors (age and immunity), and only a small pro-

portion of illnesses are confirmed by laboratory testing

and reported to public health agencies [5].

Laboratory-based surveillance provides crucial infor-

mation for assessing foodborne disease trends. However,

because only a small proportion of illnesses are diag-

nosed and reported, periodic assessments of total epi-

sodes of illness are also needed [5]. Several countries

have conducted prospective population-based or cross-

sectional studies to sup plement surveillance and estimate

the overall number of foodborne illnesses [6]. In 2007,

the World Health Organization launched an initiative to

estimate the global burd en of foodborne diseases [7].

Most often, when cases of foodborne illness are re-

ported, only consumed foods are involved. The catering

staff which is the more in contact with food than others is

not usually investigated [8].

This observation justifies the present study entitled

“Portage of bacteria responsible of foodborne illness in

restaurants and school canteens”. It aims to determine the

*Corresponding a uthor.

H. S. BANKOLÉ ET AL. 341

involvement of catering staff in food contamination.

2. Materials and Methods

2.1. Material

Biological material was composed of 336 samples ob-

tained by swabbing the nostrils, mouth and hands. Petri

dishes, swabs, hemolysis tubes, tubes, autoclaves, mi-

croscopes, refrigerators, lyophilized rabbit plasma, hy-

drogen peroxide, Kovacs reagent, hard oxidase, hydro-

chloric acid, gentian violet, fuchsin, lugol, Eosin Me-

thylene Blue agar, Chapman, peptone water buffered

agar, Hektoen, etc. have been used among others.

2.2. Methods

A cross-sectional study was conducted from November

2011 to June 2012. Samples were collected from nine

primary schools and three colleges randomly selected in

the 8th, 9th and 13th districts of Cotonou.

The study population was composed of 112 women in

canteens of primary schools and colleges. Nasal swabs,

mouth and hands were performed by swabbing. Ethical

approval has been received and only volunteers were

included in the study. All women underwent a medical

examination and only those who were visibly in good

health (no flu, cough) were allowed to be taken.

For nasal swabs, we left swab from its package, tilt the

patient’s head slightly back, inserted the swab into the

nostril, rotated it and print the swab in a tube containing

0.5 ml buffered peptone water in compliance with aseptic

conditions.

About mouth swabs, the swab must be introduced into

the mouth of the patient. After rubbing teeth and tongue,

print the swab into a tube containing 0.5 ml buffered

peptone water.

About hands samples, we left the swab from its pack-

age, moisten it with sterile distilled water and printed it

into a tube containing 0.5 ml buffered peptone water.

All samples were transported to the laboratory in a

cooler at 4˚C. Microbiological analyzes were performed

on five days:

2.3. First day

2.3.1. F re s h State

Two drops of each of the resulting suspensions were de-

posited on a slide and covered with a coverslip. The

preparation thus obtained was observed under an optical

microscope with ×40 objective.

2.3.2. Colored Sta te

A smear was made from each suspension obtained, Gram

stained and observed microscopically at the immersion

objective.

2.3.3. Culture

The culture media were selected and seeded based on the

results of microscopic observation. The culture media

were incubated seeded according to culture condition of

suspected bacteria.

2.3.4. Pre-Enrichment for the Isolation of Salmonella

and Shigella

The suspensions obtained in peptone water were incu-

bated in an oven at 37˚C for 18 hours.

2.4. Second Day

2.4.1. Re ading

All culture media seeded the previous day were reviewed.

The colonies on selective agar media were counted. Mi-

croscopic observation of control was performed on each

culture medium.

2.4.2. Identification

The isolated bacteria were identified based on biochemi-

cal characteristics obtained through the use of the API 20

E and some biochemical tests: looking for catalase, cy-

tochrome oxidase research and research of free staphy-

locoagulase. These tests were performed following the

methodolog y adopted by [9].

2.4.3. Enrichment of Salmonella and Shigella

A volume of 0.5 ml of the culture pre-enrichment was

introduced in 4 ml of Rappaport broth. The whole was

incubated at 37˚C for 24 hours.

2.5. Day Three

2.5.1. Reading Galleries

Reading the API 20 E was conducted in accordance with

the methodology adopted by [9].

2.5.2. Isolation of Salmonella and Shigella

SS and Hektoen agars were inoculated from the enrich-

ment broth.

2.6. Day Four

Api 20 E galleries were inoculated from SS and Hektoen

agar with bacterial colonies.

2.7. Fifth Day

It was devoted to reading galleries and identification of a

possible presence of bacteria.

Statistical Analyses

The prevalence of germs found was calculated. Microsoft

Excel 2010 and XL Stat 2011 were used as software.

H. S. BANKOLÉ ET AL.

342

3. Results

3.1. Point of Bacterial Strains Isolated during the

Study

About bacterial strains isolated during this study, the

results are on Figure 1. On manipulated samples, 122

bacterial strains were isolated and identified. Gram-posi-

tive cocci are leading with 47.54% followed by 29.51%

with enterobacteria.

Specifically, among the enterobacteriaceae, Klebsiella

pneumonia e is the most isolated (38. 89%) while the only

non-enterobacteriaceae isolated microorganism is Pseu-

domonas aeruginosa. Among the Gram-positive cocci,

the most isolated is Staphylococcus aureus (44.83%).

Other bacteria most frequently isolated are sulphite-re-

ducing clostridia (Figure 2).

3.2. Point of Bacterial Strains Isolated from the

Mouths of Vendors

About the distribution of bacterial strains isolated from

the mouths of vendors, the results are as shown in Figure

3. 33 bacterial strains were isolated and identified. Gram-

positive cocci are leading with 54.55% followed by

30.30%. of Enterobacteriacea e.

Figure 1. Number of bacterial strains isolated during this

study.

Figure 2. Point of isolated bacterial species.

3.3. Point of Bacterial Strains Isolated from the

Hands of Vendors

About the distribution of bacterial strains isolated from

the hands of vendors, the results are presented in Figure

4. 37 bacterial strains were isolated and identified. En-

terobacteriaceae are leading with 45.95% followed by

24.32% with non-Enterobacteriaceae.

3.4. Point of Bacterial Strains Isolated from the

Nose of Vendors

Relative to the nose of the vendors, the results are pre-

sented in Figure 5. 52 bacterial strains were isolated and

identified. Gram-positive cocci are leading with 64.70%

followed by 17.65% with enterobacteria.

4. Discussion

This study contribute to the determination of the in-

volvement of catering staff in schools and colleges about

food contamination. Control of all aspects of quality and

food security is possible only if the operator is trained

and aware. Most vendors were educated. [10] made the

same remar k in Ghana.

The results of microbiological analyzes revealed the

Figure 3. Number of bacterial strains isolated from the

mouths of vendors.

Figure 4. Number of bacterial strains isolated from the

hands of vendors.

H. S. BANKOLÉ ET AL. 343

Figure 5. Number of bacterial strains isolated from the nose

of vendors.

presence of microorganisms involved in food poisoning

(Staphylococcus aureus, Escherichia coli and sulphite-

reducing clostridia); of spoilage microorganisms (Pseu-

domonas aeruginosa) and microorganisms from testify-

ing faecal contamination (Klebsiella pneumoniae, Citro-

bacter freundii, E. cloacae, P. mirabis, Providencia rett-

geri, Acinetobacter spp and streptococcus D). A study in

USA showed the same conclusions [11]. It has been in-

vestigated an outbreak in which a food handler, food

specimen, and three ill patrons were culture positive for

the same toxin-producing strain of Staphylococcus aureus

[11]. In the hands of vendors, the predominant microor-

ganism is Klebsiella pneumoniae. The presence of this

organism is soil-borne or fecal [12]. This raises the prob-

lem of compliance with the rules of hygiene by vendors

in Cotonou.

[13] reported that the role of hand-range transmission

of bacteria of fecal origin is demonstrated. This could be

explained by the lack of regular monitoring and aware-

ness of women.

The species Staphyloccoccus aureus were isolated in

18% of samples from the nose of the vendors. Although

the nasal cavity is a reservoir of this organism and that

30% of adults harbor this organism permanently, 50%

intermittently, the immaturity of about 15% of the ven-

dors induced that the risk of contamination could be high

[9]. Indeed, from the nose, the germ can spread to the

skin, hands and the environment. A survey conducted by

[14] showed that the main sources of microorganisms in

food are animal and feces [15]. In addition, Staphylo-

coccus aureus causes food-poisoning by the production

of one or more heat-stable extracellular toxins, which are

wholly responsible for the symptoms of the disease.

Foods most often incriminated in staphylococcal food-

borne disease include cooked meat, fish, poultry, bakery

foods (especially those with cream or custard fillings),

dairy produce, fruit, vegetables, and salads [16]. Methods

of food handling by vendors from preparation to the sale

do not guarantee the elimination of contamination and

microbial growth potential.

[17] showed that Staphylococcus aureus and Bacillus

cereus were often highlighted in food samples. Given the

fact that the spread of staphylococci in the environment

is possible from the nasal cavity of healthy carriers and

patients [14], we can assess the risks to students, food

consumers manipulated by these women.

Foods favor the growth of staphylococci and toxin

production are protein-rich products and products with a

pH close to neutral [18]. The majority of vendors han-

dling food are favorable to the growth of staphylococci.

Under these conditions, considering that 20 minutes is

enough for one generation [18], if the food is already

prepared at 7 o’clock in the morning and put on sale at

10 a.m, a microorganism that would contaminate the

food immediately after preparation due to poor hygiene

practice, would have had time to multiply and give ac-

cording to the formula:

Xn = Xo · 2n

Xn = 1 × 29 bacte r ia.

1 × 29 bacteria is equivalent to 512 bacteria so about 5,

102 bacteria. As shown, a sneeze could propel billions of

microorganisms in the environment, the probability of

having 106 to 1010 microorganisms per gram of food is

great, which proves that children in schools are every day

at risk of food poisoning linked to the status of porting

vendors.

Following this study, were isolated and identified in

the food vendors in school canteens bacterial strains of

food poisoning, Staphylococcus aureus, Escherichia coli

and sulphite-reducing clostridia; of food spoilage bacte-

ria (Pseudomonas aeruginosa) and bacteria indicating

fecal contamination, Klebsiella pneumoniae, Citrobacter

freundii, Enterobacter cloacae, Proteus mirabis, Provi-

dencia rettgeri, Acinetobacter spp and streptococcus D.

This situation poses not on ly a problem of hygienic qual-

ity of food sold b y the women but also a potential risk of

foodborne illness among students.

5. Acknowledgements

We thank all the staff of the National Laboratory of

Health Ministry/Benin who works ev ery da y for the well-

being of peopl e .

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