Assessing Cleaning and Disinfection Regime in a Slaughterhouse against Carcasses Contamination

Cleaning and disinfection regime effectiveness in a slaughterhouse was evaluated against the recovery of environmentally-robust zoonotic enteric pathogens such as E. coli and Salmonella. About 64%, 59% of carcass samples (Muscles, Lymph nodes, Organs as Liver and Spleen), and 55%, 52% of environmental samples (Wall, Floor swabs and Water) were tested positive to E. coli and Salmonella spp.; respectively after applying routine disinfection procedures in the slaughterhouse. Two experimental designs (dry and wet models) were used in an attempt to mimic the conditions of disinfection regime used in the slaughterhouse. Carbolic acid was tested at the concentrations 5%, 6.5% (recommended conc.) and 10%, while crude carbolic acid was tested at the concentrations 3% (recommended cons.); 5%; 8% and 10%. Carbolic acid wet models: 6.5% achieved 100% (P < 0.01) efficacy after 4 h; 10% achieved 100% (P > 0.05) efficacy after 2 h. Carbolic acid dry models: 6.5%; 10% achieved 97% (P < 0.01); 100% (P > 0.05) efficacy after 4 h; respectively. Sodium hypochlorite wet model: 3% achieved 47.5% (P > 0.05) efficacy after 4 h; 5%; 8% and 10% achieved 78% (P < 0.01); 94% (P < 0.01), and 100% (P > 0.05) efficacy after 4 h; respectively. Meanwhile; Sodium hypochlorite dry models: 3%; 5%; 8% and 10% achieved 46%; 73%; 86% and 100% (P < 0.01) efficacy at 4 h, respectively. In conclusion; recommended carbolic acid (6.5%) and sodium hypochlorite (3%) concentrations failed to achieve the required efficacy; thus correction of concentrations up to 10%; 8%; respectively for 4 hours contact is required. Application of green disinfectants should be considered.