Biofilm Formation by Clinical Isolates of S. aureus and S. epidermidis in Prosthetic Joint Infection

Clinical Microbiology and Antimicrobial Chemotherapy. 2014; 16(2):149-156

Type
Journal article

Objective.

Objectives. In vitro study of biofilm forming capacity of S. aureus and S. epidermidis strains, most common etiological agents of PJI following orthopedic surgeries, depending on source of strain, species of etiological agent and methicillin susceptibility.

Materials and Methods.

241 S. aureus and 153 S. epidermidis strains, isolated from the tissue biopsies, the join aspirates and removed orthopedic prosthesis in 2012 year from 321 patients with PJI were investigated. Antibiotic susceptibility was estimated according to EUCAST criteria, version 1.3. The biofilm forming capacity was tested according to Christensen’s method (1985). When OD≥0,2 strains were considered as strong biofilm forming strains. Statistical analysis was performed with Z-criterion tested.

Results.

40,9% of strains were found to be strong biofilm forming strains. The most strong biofilm forming capacity was shown for 60,9% of S. epidermidis strains and 43,3% of S. aureus strains isolated from removed prosthesis. The strains of both species, isolated from tissue biopsies and removed orthopedic implants (OI), possessed strong biofilm forming capacity more often than isolates from aspirates (p<0,05). MRSA amounted to 30,7% and MRSE — 77,8%. The percentage of strong biofilm forming strains was more among MRSE strains compared to MRSA strains (47,9 vs 31,1%; p<0,05). The percentage of MR strains, isolated from biological samples, was higher than one for strains from removed OI (p<0.01).

Conclusions.

Staphylococcus spp., etiological agents of PJI, in 40,9% causes possessed strong biofilm forming capacity. The strong forming biofilm strains and methicillin resistant strains were seen more often among S. epidermidis strains, but any correlation between these properties was not revealed. The strong biofilm forming capacity was more typical for S. epidermidis strains and also for strains from OI and tissue biopsies compared to isolates from aspirates irrespective of staphylococcus species.

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