Antimicrobial resistance and its relationship with biofilm production and virulence-related factors in biotype 1A.

The aim of the present study was to determine antimicrobial susceptibilities, biofilm production and, to discern a relationship between antimicrobial resistance, biofilm potential and virulence-related genes in strains of biotype 1A. Thirty strains of biotype 1A including clinical and non-clinical strains were investigated. Antimicrobial susceptibility for 15 antibiotics (representing different classes) was determined by disk-diffusion assay. Biofilm potential was determined on two different culture media using crystal violet assay. Also, a co-relation was studied between antimicrobial susceptibilities, biofilm production and virulence-related genes. All strains of biotype 1A produced biofilms and exhibited varied level of susceptibilities for different antibiotics. More than 60% of the strains were strong to moderate biofilm producers and, were exclusively associated with REP/ERIC clonal group B. Moderate and strong biofilm producers exhibited both sensitive and resistant phenotypes towards different antibiotics. Interestingly, weak biofilm producers were resistant to amoxicillin, amoxicillin-clavulanate and cefazolin. Analysis of antimicrobial susceptibilities, biofilm potential and virulence-related genes did not reveal any unequivocal relationships. The differential biofilm potential of Indian strains of biotype 1A, suggests that biotype 1A strains are heterogeneous in nature.