Evaluation of Three Swabbing Devices for Detection of Listeria monocytogenes on Different Types of Food Contact Surfaces

Abstract

Listeria monocytogenes can adhere to different types of food contact surfaces within a food processing environment. Therefore, environmental sampling devices should be capable of detecting unacceptable contamination. In this study, a sponge-stick, foam spatula and an environmental swab were evaluated on their ability to detect low concentrations of L. monocytogenes on different types of food contact surfaces. A cocktail of four L. monocytogenes serotypes was inoculated with a concentration of 100 CFU/250 cm2 onto stainless steel (SS), high density polyethylene (HDPE) and rubber surfaces in a 250 cm2 area. Immediately after inoculation and after 1 h exposure, the surfaces were swabbed with the different swabbing devices. The results of the study show only minor differences in the ability of the swabbing devices to detect L. monocytogenes. All devices were capable to detect the contamination immediately after inoculation. However, when the surfaces were allowed to air-dry for 1 h, L. monocytogenes was undetected in 11.1% of the samples (n = 27) with the sponge stick, in 7.4% of the samples (n = 27) with the foam spatula and in 3.7% of the samples (n = 27) with the environmental swab, especially on SS surfaces. The detection ability of the different devices for L. monocytogenes can be concluded to be rather high on different types of food contact surfaces.

Loop-mediated isothermal amplification (LAMP) coupled with bioluminescence for the detection of Listeria monocytogenes at low levels on food contact surfaces

“…Another possible reason might be the applied swab method, which was formerly reported as ineffective for removal of L. monocytogenes from SS coupons (Kang et al, 2007). Although, the 3M Enviro Swab was found to be the best swabbing device, among the tested tools, for the detection of low numbers of L. monocytogenes with plating technique on different types of food contact surfaces, a slight reduction in the detection efficiency for 3M Enviro Swab (3.7%, n ¼ 27) was reported especially for SS surfaces after 1 h long drying (Lahou & Uyttendaele, 2014), which is an analogous procedure to the one used in a present experiment.…”

“…In this study, LAMP-based and ISO methods were equally effective in L. monocytogenes detection, regardless of applied surfaces and organic residues. However, it is known that the condition of environmental surface (dry/wet, contaminated/clean) and the material type (stainless steel versus polymers) may influence the detection efficiency of foodborne pathogens (Lahou & Uyttendaele, 2014;Martinon et al, 2012). Slightly higher numbers of true positive (T pos ) results obtained in this study with reference ISO method at 10 1 CFU/100 cm 2 for PE compared to SS and for the surfaces with OL compared to the clear ones, could be explained with some previous findings.…”

Pseudomonas aeruginosa in CF and non-CF homes is found predominantly in drains

“…observed low recovery of Pseudomonas from non-drain surfaces may be due to a failure of swabbing to detect biofilm Pseudomonas, studies of biofilms of Listeria monocytogenes and Salmonella enteritidis indicate swabbing yields good recovery of biofilm bacteria [29,30].…”

House microbiotas as sources of lactic acid bacteria and yeasts in traditional Italian sourdoughs

“…Walls of the room wherein the sourdoughs were back-slopped, storage boxes, and clean buckets of dough mixer of the four bakeries were surface swabbed. In details, sterile rayon tip swabs (Nuova Aptaca Srl, Canelli, Asti, Italy) were moistened with sterile saline (NaCl, 9 g/ L) solution and streaked across a 100 cm 2 square area of the target surface (Lahou and Uyttendaele, 2014). Swabs were inserted into tubes containing 3.5 mL of Amies gel transport medium without charcoal, in order to protect microorganisms from adverse conditions until plate count analysis (MacFaddin, 1985).…”