Purpose: This study aimed to characterize the microbiota of CBs and compare the efficacy of domestic treatments to disinfect CBs.
Methods: Briefly, used glass, plastic, and wooden CBs were collected from various households and cut into slabs of 25 cm2. Microorganisms were recovered from the slabs using the swabbing method. Swabs were rinsed in sterile buffered saline and the rinsate was plated onto appropriate media to enumerate counts of mesophilic aerobic bacteria (MAB), yeasts and molds (YM), Escherichia coli (EC) and Listeria spp. Fungal species were identified by sequencing and phylogenetic analyses. To compare the efficacy of different domestic treatments, sterilized glass, plastic, and wooden CBs were inoculated with Escherichia coli ATCC 25922 (EC) or Listeria innocua ATCC 33090 (LI) to a final population density of ~ 3 log cfu/cm2 and subjected to one of five treatments (dishwashing detergent, chloroxylenol-based disinfectant (Dettol), hot water (65°C), chlorine-based disinfectant (bleach) and white vinegar). Treatment was followed by rinsing with sterile water. The bactericidal efficacy (BE) of the different treatments was computed as: population density before treatment – population density after treatment.
Results: Mean population density of MAB, YM, EC and listeriae recovered from CBs were as follows: 3.6, 2.2, 1.8 and 2.4 log cfu/cm2 (plastic), 3.3, 3.0, 1.6 and 1.5 log cfu/cm2 (wood) and 2.6, 2.3, 1.9 and 1.7 log cfu/cm2 (glass), respectively. Isolated fungi were identified as Penicillium critinum, Peyronellaea glomerata, and Cladosporium halotolerans. Vinegar and bleach were the two most effective treatments and significantly (P < 0.05) reduced EC and LI counts by a maximum of 1.5-1.6 and 1.2-1.5 log cfu/cm2, respectively.
Significance: Vinegar and bleach can potentially disinfect CBs to minimize risks of microbial cross-contamination.