Phenotypic and molecular characterization of Salmonella serotypes in cow raw milk and milk products in Nigeria

Abstract

The prese nce of Salm monella and human pathogens in u unpasteurize d milk remains a publ ic health hazard. Th e study repo orted the ph enotypic and molecular characteriza ation of Sal onella serotypes in m cow raw milk, cheese a and traditional yoghurt m marketed fo r man’s con nsumption in Nigeria. Iso olation of Salmonella was done o on Salmonel la and Shigella agar by pour plate m e method at 37 °C. Suscep ptibility to antibiotics was determ ined by the disc diffusi n method. M o Molecular ch haracterization of the Sa almonella serotypes a and detectio n of some target gene es was done by the pol lymerase ch hain reactio n. All the isolates we ere sensitiv e to ofloxacin and nalidixic acid. Resistance e to antibio otics was i n varying proportions s with amox xicillin (95.2% ), tetracyclline (90.4%) and augum mentin (28.5% %). Ten (10) different multiple an ntibiotic resis stance patte rns were o served among the ser b otypes. The serotypes identified include Sa lmonella typ phi, Salmon nella typhimu urium and Salmonella enteritidis, and the se rogroups include D (28.6%), B (52.4%), D1 (28.6%), respectively. The invA g genes were amplified i n all the Salmonella serotypes while fliC an nd fliB gene es were absent. The rfb bJ gene was s detected only in S. Typhimuriu um. The recovery of mul tiple antibio tic resistant t pathogenic c Salmonella serotypes i n cheese and yoghu t samples in the study is r s of great hea alth concern.