Microbiological Safety of Domestic Refrigerators and the Dishcloths Used To Clean Them in Guadalajara, Jalisco, Mexico

Abstract

Household refrigerators are a potential pathogen contamination source for foods. An evaluation of the microbiological safety of 200 refrigerators in Guadalajara, Jalisco, Mexico, was made by visual inspection, ATP-bioluminescence levels, indicator microorganisms including Escherichia coli and Staphylococcus aureus, and the presence of Listeria monocytogenes and Salmonella. Additionally, interviews of the owners of the refrigerators were carried out to determine relationships between food storage practices, demographic aspects, and microbiological status. Dishcloths used to clean refrigerators were also analyzed. Operational conditions (cleanliness, fullness, organization, frequency of cleaning, and temperature) were evaluated by trained observers. Results showed deficient cleanliness in 55% of refrigerators, 22% were completely full, 43% very disorganized, 28% were usually cleaned only once in 3 to 6 months, and 53% had internal temperatures >7.1°C. ATP-bioluminescence levels were >300 relative light units on 67 and 74% of shelves and drawers, respectively, indicating that surfaces were dirty according to the luminometer manufacturer. Psychrotrophic aerobic bacteria counts on shelves, drawers, and dishcloths were 6.3, 5.2, and 6.3 log CFU/cm(2); for coliform bacteria, 5.2, 3.9, and 4.7 CFU/cm(2); for E. coli, 3.7, 3.5, and 4.8 CFU/cm(2); and for Staphylococcus aureus, 2.1, 2.5, and 2.3 CFU/cm(2), respectively. L. monocytogenes and Salmonella were isolated from 59.5, 20.5, and 17% and 32.5, 8.0 and 12.5% of shelves, drawers, and dishcloths, respectively. Four Salmonella serotypes and nine serogroups (partially serotyped isolates) were identified. The most prevalent were Salmonella Anatum (39.5%), Salmonella group E1 (19.7%), and Salmonella group E1 monophasic (12.5%). Operational conditions and microbiological status were clearly deficient in sampled refrigerators, highlighting the consequent risk of foodborne disease among users. Educational programs are needed to improve the domestic food safety in Mexico.

A preventative approach to promote food safety

“…Listeria is capable to attach to surfaces and disseminate from contaminated foods, which is associated to an increase in resistance toward sanitizers and other antimicrobial agents (Ahmed et al, 2004, Frank, 1991, Frank and Koffi, 1990, Jackson et al, 2007, Somers et al, 1994. Moreover, Mexican, Irish and Sudanian researchers obtained high incidences of L. monocytogenes on the surfaces, shelves, and vegetable drawers of the examined refrigerators , Macias-Rodriguez et al, 2013, Abdalla et al, 2008. These bacteria have been isolated previously from the internal surfaces of refrigerators and rubber gaskets around the door of fridges (Azevedo et al, 2005, Jackson et al, 2007, James et al, 2008, Mena et al, 2004, Mafu et al, 1990.…”

“…The refrigerators were inspected by using a food safety evaluation checklist which was adapted for refrigerators (Macias-Rodriguez et al, 2013, Godwin et al, 2006. Point scores were assigned to three aspects by a trained expert (Clean = 2, Dirty = 1, and Very dirty = 0), the organization level referring to packaging, and correct placement of food (raw and cooked) within the refrigerator (Organized =2, Disorganized = 1, and Very disorganized = 0).…”

“…The thermometer based on a protocol was placed in the geometric center (the point of the exact middle of the second shelf), the door was closed for 5 min, and at the end of time, the temperature was recorded (James et al, 2008, O'BRIEN, 1997, Godwin et al, 2007, Fight, 2015, Altunatmaz et al, 2012, Macias-Rodriguez et al, 2013.…”

“…By using PCR-based assays, amplification and detection of very small quantities of pathogens is possible (Hosseini et al, 2012). Therefore, PCR can be mentioned as one of the applicable instruments for evaluation of the surfaces, cleanliness in a reliable and rapid way (Macias-Rodriguez et al, 2013). Although PCR may increase experimental costs, because of mentioned advantages, in comparison with conventional methods, it can be used for evaluation of the refrigerator hygiene and efficiency of employed cleaning approaches (Olsen et al, 1995, Shahraz et al, 2012.…”

Co-occurrence of free-living protozoa and foodborne pathogens on dishcloths: Implications for food safety

“…Foodborne bacteria are also commonly present in kitchens and households (Jackson et al, 2007;Macias-Rodriguez et al, 2013;Scott et al, 2008) and form an important source of foodborne illness (Luber, 2009;Newell et al, 2010). High bacterial concentrations (up to 5 log 10 cfu/ml) have been reported from dishcloths (Gorman et al, 2002).…”