Original Articles
 
Intestinal bacterial and parasitic infections among food handlers in a tertiary care hospital of North India
 
Sumeeta Khurana, Neelam Taneja, Rajni Thapar, Meera Sharma, Nancy Malla
Departments of Parasitology & Medical Microbiology,
PGIMER,
Chandigarh, India


Corresponding Author
: Dr. Nancy Malla
Email: drnancymalla@yahoo.com


Abstract

Background: Intestinal infection is still an important public health problem in developing countries like India. Food handlers may be infected by a wide range of enteropathogens and have been implicated in the transmission of many infections to the public in the community and to patients in hospitals.
 
Aim: To study the presence of enteropathogenic bacteria and parasites in food handlers working in the food service establishments of a tertiary care centre in North India.
 
Method: The stool samples received from food handlers during January 2001 to December 2006 were examined by wet mount, iodine mount and modified acid fast staining directly and after formol ether concentration technique for parasites. For enteropathogenic bacteria, samples were inoculated onto MacConkey’s agar, Deoxycholate Citrate Agar, Xylose Lysine Deoxycholate agar (XLD) as per the WHO protocol.
 
Results: During the years 2001-2006 respectively, 8.75%, 16%, 1.4%, 6.75%, 2.56% and 6.75% food handlers were infected with enteropathogens. The parasitic infections in our study were 1.3 to 7% while the enteropathogenic bacteria were reported from 0% to 13.3% during the years 2001-6. Giardia was the most common parasite while Shigella was the most common bacteria isolated from food handlers. During the year 2001, there was an outbreak of ETEC in the neonatal ICU, Advanced Paediatric Centre, PGIMER, which was traced back to a food handler involved in the preparation of the milk feed. 

Conclusion: Routine screening of food handlers is a valuable tool for prevention of nosocomial food-borne infections.

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Intestinal infection is still a widely prevalent public health problem in developing countries like India. Food handlers come in contact with food from the time of preparation to the time of serving. They may be infected by a wide range of enteropathogens and have been implicated in the transmission of many infections to the public in the community and to patients in the hospital setting. One of the historically notorious examples is that of the American cook “Typhoid Mary” (Mary Malon) who was responsible for 7 epidemics of typhoid affecting more than 200 persons.[1] A study conducted in Malaysia showed that approximately 10-20% food-borne outbreaks in the community are due to food handlers.[2]
 
Since medical institutions are supposed to provide a model for healthy practices, including food services, it is expected that the food service establishments in their boundary and food handlers working there should not act as sources for food-borne diseases. Thus the present study reports the presence of enteropathogenic bacteria and parasites in food handlers working in the food service establishments of a tertiary care centre of North India and emphasises the need for routine screening of food handlers especially in hospitals in endemic countries.
 
Methods
Stool samples collected from food handlers during January 2001 to December 2006 each year were sent to the Departments of Parasitology and Medical Microbiology, PGIMER, Chandigarh, India, to test for the presence of enteropathogenic bacteria and parasites. These food handlers were catering to the patients admitted in the wards
of Nehru Hospital, and its various sub-centres. Freshly passed stool samples were collected in wide-mouthed containers for parasites and in Cary Blair medium for isolation of pathogenic bacteria. For parasites at least 2 samples were collected and examined by wet mount, iodine mount and modified acid fast staining directly and after the formol ether concentration technique.[3] For enteropathogenic bacteria, samples were inoculated onto MacConkey’s agar, Deoxycholate Citrate Agar, Xylose Lysine Deoxycholate Agar (XLD) and also inoculated into Selenite F broth for enrichment and subcultured onto XLD and MacConkey’s agar after 6 hours incubation at 37°C as per the WHO protocol.[4] Both the primary plates as well as the subcultured plates from the enrichment media were examined for pale non-lactose fermenting colonies on MacConkey and red colonies on XLD media the next day. The bacteria were identified by standard techniques using a battery of biochemical tests and serotyped using antisera from Denka & Seiken, Japan. For enterotoxigenic Escherichia coli, Reverse Passive Latex Agglutination was carried out to detect the heat labile toxin while ELISA with commercially available kit (Denka & Seiken) was used to detect the heat stable enterotoxin. The tests were carried out as per the manufacturer’s instructions. Whenever any sample was found positive for a pathogen, we initiated appropriate antimicrobial therapy and performed repeat cultures thrice on alternate days after the cessation of treatment. The food handler was kept off work whenever a bacterial pathogen was isolated and allowed to join work only after follow up cultures turned negative. The follow up samples for parasites were examined a week after the anti-parasite therapy was instituted.
 
Observations

During the years 2001-2006, 8.75%, 16%, 1.4%, 6.75%, 2.56% and 6.75% food handlers, respectively, were infected with enteropathogens. The rate of parasitic infections was 1.3% to 7% while the rate of enteropathogenic bacterial infections was reported from 0% to 13.3% during the years 2001-06. Giardia was the most common parasite while Shigella was the most common bacteria isolated from food handlers. The year-wise breakup is shown in the Table 1.




Discussion

The prevalence of enteropathogens in a community varies according to the geographical area. Reports from Chandigarh have shown 12.5% to 19.3% prevalence rates of intestinal parasites.5-7 The rate of infection in food handlers is expected to be much lower than that prevalent in the community. The prevalence of enteroparasites among food handlers (1.4-16%) observed in the present study is in accordance with the figures reported by Mohan et al in 2006[8] who reported parasites in 12.9% of food handlers in health and educational institutions in Amritsar, India, but is much lower than those reported by Malhotra et al in the same year[9] (41.1%) and by Chitnis et al[10] in 1986 (44.5%). This may be due to the higher standards of education, better wages, better personal hygiene, stricter policies of adhering to personal hygiene measures and frequent hand-washing of the food handlers engaged in our hospital. Most of the recent studies reported from Turkey[11] (29.3%). and Brazil[12] (17%) have shown figures similar to ours while one reported an even higher figure of 40.7%[13]
 
In our study, rates of 5%, 13.3%, 1.4%, 0%, 1.2%, and 0% enteropathogenic bacterial infection were reported during the years 2001-2006, respectively. During the year 2001, there was an outbreak of ETEC in the neonatal ICU Advanced Paediatric Centre, PGIMER; this was traced back to a food handler involved in the preparation of milk feeds.[14] Subsequent to this outbreak, screening for ETEC was introduced. The outbreak was curtailed once the source was identified as a cook who was temporarily withdrawn from duty and education regarding hygiene and transmission of infection was imparted.
 
Maximum enteropathogens (13.3%) were isolated in our study subjects during the year 2002. All subjects were asymptomatic. The reason for this acute increase in bacterial pathogens was perhaps due to renovation, during which time the kitchen was temporarily shifted to a place next to the washrooms where the walls were leaking. Subsequently the kitchen was shifted; food handlers were treated and given health advice with regard to personal hygiene and foodhygiene. In the subsequent years there was only the occasional food handler who was detected carrying a bacterial enteropathogen.
 
Asymptomatic infections and carriers pose greater danger to the public because the worker keeps on working unmindful of the infection he is transmitting. Around 4.6% of Salmonella infected individuals may remain unidentified.[15] The bacteria important for transmission by food handlers include Salmonella Typhi, Shigella, Campylobacter, enterohaemorrhagic E. coli, and enterotoxigenic E.coli. Various parasites important for food-borne transmission include Giardia, Entamoeba histolytica and Cryptosporidium.
 
In our hospital, screening of food handlers for various intestinal pathogens is undertaken every year. Routine screening of food handlers is imperative, especially during the summer and rainy seasons, when transmission of enteropathogens is at its peak.
 
References
 
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