Ninety random samples of fresh beef were collected from cattle carcasses slaughtered at 3 different abattoirs in Menufia governorate (30 sample of each). The sampling site was represented by neck region (chuck) of each carcass in 2018. The obtained results revealed that the efficacy of five different disinfectants against some food poisoning bacteria including E. coli O26: H11, S. Typhimurium and Klebsiella pneumonia which were isolated and serotyped at abattoir level. In vitro infected samples (3.0×106/ cm2) were examined under effect of different concentrations of disinfectants within contact time 120 minute. Disinfectant (A) at concentration 1% was effective against 100% of E. coli O26: H11 and Klebsiella pneumoniae, while 1.5% concentration was required for elimination of 100% S. Typhimurium, followed by B, C, D and E disinfectants, respectively. On the other D and E disinfectants even in 2% concentration and contact time 120 minutes reduce about 99% of the infection.