Battling the Methicillin-Resistant Staphylococcus aureus Biofilm Challenge with Vancoplus

Of 55 MRSA, 47 isolates were biofilm producers and 8 isolates were non-biofilm producers. Of 47 biofilm producers, 24 (51.0%), 14 (29.8%) and 9 (19.1%) produced strong (OD570 ≥ 0.5), medium (OD570 ≥ 0.2 to <0.5), weak (OD570 0 to <0.2) biofilm, respectively. Of the 47 isolates, eight determinants (genes) (eno, hla, hlb, clfA, fnaA, icaA, agrII and sar) were found predominantly among 70 to 80% isolates whereas cna was observed only in 21.3%, finbB in 10.6% and ebps in 32% isolates. Amongst the strong biofilm producers (51%), the lowest MIC values obtained with Vancoplus (2-4 μg/ml) >linezolid (128 to 256 μg/ml) >daptomycin, clindamycin and teicoplanin (256 to 512 μg/ml). Biofilms eradication rate was also observed in the same order with Vancoplus (87%) >linezolid (51.8%) >clindamycin (31.9%) >daptomycin (27.5%) >teicoplanin (26.5%). Our results showed that the percentage of finbA, hla, eno, clfA and fib genes expressions down-regulation after Vancoplus treatment was 64.0 ± 5.9, 63.8 ± 5.8, 73.0 ± 7.4, 72.8 ± 7.8 and 71.9 ± 7.8%, respectively as compared to the control among strong biofilm producing MRSA whereas teicoplanin produced only 30.3 ± 2.7 to 34.5 ± 3.8% down regulation in fnbA, hla, eno, clfA and fib genes expression. The other comparator drugs, vancomycin, linezolid and daptomycin, demonstrated variable effects on these genes varying from 4.9 ± 3.9 to 30.3 ± 2.7%.