Abstract
BackgroundStaphylococcus aureus is a primary pathogen of orthopedic infections. By mediating antimicrobial resistance, S. aureus biofilm plays an important role in the recalcitrance of orthopedic infections, especially for the intractable osteomyelitis (OM). This study investigated the relationship between biofilm production and various genetic or phenotypic characteristics among orthopedic S. aureus strains.MethodsA total of 137 orthopedic S. aureus isolates were enrolled and divided into OM and non-OM groups. Biofilm production was evaluated using the crystal violet assay. Genetic and phenotypic characteristics including MRSA identification, MLST and spa typing, carriage of virulence genes, drug resistance, and patients’ inflammatory responses indicators were characterized. The relationship between biofilm production and above-mentioned features was respectively analyzed among all isolates and compared between OM and non-OM isolates.ResultsBiofilm production presented no significant difference between OM (including 9 MRSA isolates) and non-OM (including 21 MRSA isolates) strains. We found that ST88, t377 and ST630-MSSA-t377 strains produced very strong biofilms, while MLST types of ST15, ST25, ST398, ST5, ST59 and spa types of t002, t2325, t437 tended to produce weaker biofilms. Strains with the following profiles produced stronger biofilms: fib(+)-hlgv(+)-lukED(+)-sei(-)-sem(-)-seo(-) for all isolates, sei(-)-sem(-)-seo(-) for OM isolates, and cna (+)-fib (+)-hlgv (+)-lukED (+)-seb(-)-sed(-) for non-OM isolates. In addition, not any single drug resistance was found to be related to biofilm production. We also observed that, among OM patients, strains with stronger biofilms caused weaker inflammatory responses.ConclusionSome genetic or phenotypic characteristics of orthopedic strains were associated with biofilm production, and this association could be different among OM and non-OM strains. The results are of great significance for better understanding, evaluating and managing different kinds of biofilm-associated orthopedic infections, and provide potential targets for biofilm clearance.
Highlights
Staphylococcus aureus is a common and versatile grampositive pathogen in orthopedic patients [1, 2]
The distribution of OD492 values between OM and non-OM groups showed no significant difference either (P = 0.946, Table 1). These results provided the basis for analyzing the relationship between biofilm production and molecular types among all the orthopedic isolates
For ST59, one of the most prevalent MRSA clones in Asia, Yang X et al reported that ST59-SCCmecIV strains isolated from Chinese children were more likely to form strong biofilm [21], our results showed that ST59-MRSA-SCCmecI produced significantly stronger biofilms than ST59-MRSASCCmecIV strains (Fig. 1d), suggesting that different environments or specimen sources might affect the biofilm-forming capacity
Summary
Staphylococcus aureus is a common and versatile grampositive pathogen in orthopedic patients [1, 2]. Biofilm is an important tool of pathogenic bacteria, and. The problem of S. aureus biofilm becomes more intractable when a patient suffers from OM infection [8, 10]. The contribution of biofilm to S. aureus pathogenicity has been widely studied, few studies focused on exploring the relationship between biofilm production and genetic or phenotypic characteristics of orthopedic S. aureus isolates, especially for S. aureus OM isolates. Staphylococcus aureus is a primary pathogen of orthopedic infections. S. aureus biofilm plays an important role in the recalcitrance of orthopedic infections, especially for the intractable osteomyelitis (OM). This study investigated the relationship between biofilm production and various genetic or phenotypic characteristics among orthopedic S. aureus strains
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