Study of Distribution of Biofilm Producing Genes in Staphylococcus aureus Isolated from Local Cheese Samples in Maragheh City

Abstract

Background: Staphylococcus aureus is one of the main causes of food poisoning in the world. This pathogen has the ability to create biofilms that can lead to food contamination. The presence of biofilm producing genes in this bacterium plays a very important role in its virulence and pathogenicity and even prevents the penetration of antibiotics in pathogenicity time. The aim of this study was to investigate the distribution of biofilm producing genes in Staphylococcus aureus isolated from local cheese samples in Maragheh city. Methods: 20 Staphylococcus aureus isolates from local cheese samples in Maragheh city that had been identified phenotypically by biochemical tests for confirmatory diagnosis were identified by multiplication of species-specific thermonuclease gene (nuc) by PCR method. Specific primers for each gene were used for detection of biofilm producing genes icaA, icaD, fnbA, and clfB by PCR method. Results: 17 isolates (85%) were identified as Staphylococcus aureus by multiplying of thermonuclease (nuc) species-specific gene. The frequency of each gene separately in tested isolates was icaA (76.47%), icaD (58.82%), fnbA (64.7%), and clfB (76.47%). 5 isolates (29.41%) contained all of the tested genes simultaneously. The most frequency of tested genes combinationally was associated with icaA, icaD, and clfB genes (41.17%). None of the Staphylococcus aureus samples was negative regarding the presence of four tested genes. Conclusions: Molecular confirmation of 85% of Staphylococcus aureus strains by PCR method represents more accuracy of this method compared to biochemical methods. High frequency of biofilm producing genes in tested isolates indicates high potential of this bacterium in biofilm forming. The difference in the dispersion of effective genes in biofilm forming among different Staphylococcus aureus strains probably originates in geographical differences and differences in ecological origin of isolated bacteria.