Contamination of Household Refrigerators by
Listeria Species in Ahvaz, Iran
Jundishapur Journal of Microbiology: 6 (3); 301-5
April 30, 2013
Article Type: Rapid Communication
November 22, 2011
June 19, 2012
K. Contamination of Household Refrigerators by Listeria Species in Ahvaz, Iran,
Jundishapur J Microbiol.
Online ahead of Print
Listeria monocytogenes has been isolated from various foods and environments in temperate areas, tropical countries and different parts of Iran. The bacterium as a psychrotrophic organism is capable of growth at refrigeration temperatures.
The current study was conducted to determine the incidence of Listeria spp. on the surfaces of domestic refrigerators in Ahvaz city as a tropic area, to provide insights in to true burden of, and the risks posed by the bacterium in domestic refrigeration systems.
Materials and Methods:
During December 2009 June 2010, 180 refrigerators located at student accommodations and private homes in Ahvaz, were sampled for the presence of Listeria spp. The temperature of each refrigerator was measured and owners were asked to fill out a questionnaire regarding the method of cleaning. All samples were tested by culture in Listeria enrichment broth (LEB), Oxford agar and PALCAM agar using standard methods. Suspected colonies were identified by biochemical tests.
L. monocytogenes was present in 1 domestic refrigerator out of the 180 investigated (0.5 %) and L. innocua was also isolated from 2 refrigerators (1.2%). It was demonstrated that a significant number of the investigated refrigerators were operating at a temperature that can compromise the safety of the foods stored inside them. Also, most owners used mixture of water and dishwasher and some of them used water alone to clean their refrigerators.
Although the incidence of L. monocytogenes in domestic refrigerators in Ahvaz is low contamination of the stored food in refrigerator by the bacterium is still a concern. Two of the isolated Listeria were from student accommodations. It was found that most of the refrigerators used in student accommodations in comparison to private homes, were not cleaned in low frequency and had higher temperature.
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