Toxin Gene Profiles and Toxin Production Ability of Food-borne Pathogens Isolated from Indoor Air from Lunchrooms at Child Care Centers

Abstract

Objectives: This study was conducted in order to evaluate the microbiological contamination of the indoor air of the lunchrooms at child care centers and investigate the toxin genes and toxin production ability of food-borne pathogens. Methods: A total of 64 child care centers were sampled to test total aerobic bacteria, coliform bacteria, fungi, Staphylococcus aureus, Bacillus cereus and Salmonella spp. according to the Korea Food Code. All toxin genes of pathogens were detected using the Polymerase Chain Reaction method. The Sthaph. aureus enterotoxin was detected by a Staphylococcus aureus enterotoxin-reversed passive latex agglutination kit. The heamolysin BL (HBL) and non-heamolytic enterotoxin (NHE) produced by B. cereus were detected using a B. cereus enterotoxinreversed passive latex agglutination kit and Bacillus diarrheal enterotoxin visual immunoassay kit, respectively. Results: The means of total aerobic bacteria and coliform bacteria were 1.91 ± 1.84 log CFU/plate and 0.47 ± 0.62 log CFU/plate, respectively. The mean of fungi also showed 0.59 ± 0.71 log CFU/plate. Among the pathogenic bacteria tested in this study, Staphy. aureus and B. cereus were detected in four (6.3%) and 21 (32.8%) out of 64 indoor air samples from lunchrooms in child care centers, respectively. All Staphy. aureus tested in this study possessed no toxin genes and did not produce enterotoxin. The detection rate of nheABC, hblCDA, entFM and ces toxin gene in B. cereus was 100, 57.1, 76.2 and 0%, respectively. B. cereus isolates were classified into four groups according to the presence or absence of toxin genes. The nheABC gene was the major toxin gene among B. cereus tested in this study. The HBL was detected in 11 out of 21 B. cereus isolates (52.4%) and three B. cereus isolates produced NHE (14.3%). Conclusion: The results indicated that the contamination by microorganisms in the indoor air of lunchrooms was unqualified to supply safe catering in child care centers. The ongoing control of indoor air quality is required.

Toxin gene and antibiotic resistance of Staphylococcus aureus and Bacillus cereus isolated from kitchen cleaning tools in child care centers

“…Since acute food poisoning in such a large number of people can be fatal to children and infants with weak immunity and physical development, it is important to prevent food poisoning by analyzing the harmful factors affecting meals at childcare facilities. Previous research on toxic genes and antibiotic resistance at cafeterias in childcare centers have focused on airborne microorganisms and bacteria identified in the hands working in cafeterias (Kim et al, 2012). However, research on food poisoning bacteria isolated from washing Korean J Food Preserv, 29(4) ( 2022) tools, such as dishcloths and scourers, which are the main sources of food poisoning due to crosscontamination, is insufficient.…”