Molecular characterization of intercellular adhesion gene in Staphylococcus aureus isolated from bovine mastitic milk

Abstract

Biofilm formation in Staphylococcus aureus is considered an important virulence factor in bovine mastitis. Intercellular adhesion gene A (icaA) is a significant genetic determinant that contributes in biofilm formation. The aim of the present study was to determine the presence of the icaA gene in S. aureus isolated from bovine mastitis from seven states of India. A total of 88 out of 150 Staphylococcus aureus strains were found to be positive for biofilm marker icaA gene by PCR. The icaA gene was confirmed by dot blot hybridization in 41 of 150 S. aureus strains tested. Results obtained with dot blot hybridization were comparable to those obtained with PCR. Partial sequences of the icaA gene of the two S. aureus isolates showed deletion of some bases in different positions that might reduce/stop transcription leading to no biofilm formation. PCR was found to be a rapid test but dot blot hybridization was more accurate than PCR for detection of icaA genes. This study showed that detection of biofilm marker the icaA gene in S. aureus would allow the detection of virulence factors present in mastitis and early application of corrective measures.

Occurrence, Antibiotic Susceptibility, Biofilm Formation and Molecular Characterization of Staphylococcus aureus Isolated from Raw Shrimp in China

“…Overall, the rate of biofilm producer isolates in the present study was higher than previous reports of all S. aureus isolates obtained from shrimp samples which showed the ability to produce biofilm with moderate or strong biofilm production capability [20,[53][54][55][56]. In addition, through whole-genome analysis, it was found that all these isolates carry biofilm-related genes, including ica genes (icaA, icaB, icaC, icaD and icaR) and another set of adhesion genes, such as fnbA, fnbB, cna, map and ebp, as well as clfA and clfB.…”

A 3-year long study of Staphylococcus aureus isolates from subclinical mastitis in three Azawak zebu herds at the Sahelian experimental farm of Toukounous, Niger

“…Finally, the frequency of the icaA gene in S. aureus isolated from bovine mastitis can be highly different between studies: 15 % (Darwish and Asfour 2013), 58 % (Chavhan et al 2012), 86 % (Ote et al 2011), 98 % (Castelani et al 2015 vs. 76 % in the present study. Biofilm production by the 57 icaA-positive isolates was strong for 8 isolates (belonging to different pulsotypes), moderate for 31 isolates (including most A and B pulsotype isolates) but weak for 18 isolates (including all 8 D pulsotype isolates) (Table 6), emphasizing not only that the icaA gene may not be expressed by one third of the positive isolates in this in vitro assay but also that this lack of expression could be related to the pulsotype.…”