Staphylococcus haemolyticus attenuates the antibacterial effect of teicoplanin via aggregates and biofilms.

ABSTRACT

OBJECTIVES: This study aimed to determine the inhibitory and bactericidal effects of teicoplanin (TEC) on TEC-susceptible Staphylococcus haemolyticus isolated from a patient with cancer in whom infection persisted despite TEC therapy. We also focused on the biofilm-forming ability of the isolate in vitro. METHODS: S. haemolyticus clinical isolate (strain 1369A) and its control strain, ATCC 29970 were cultured in Luria-Bertani (LB) broth with TEC. The inhibitory and bactericidal effects of TEC on planktonic, adherent, biofilm-dispersed, and biofilm-embedded cells of these strains were analyzed by using a biofilm formation/viability assay kit. The expression of biofilm-related genes was measured using quantitative real-time polymerase chain reaction (qRT-PCR). Biofilm formation was determined by using scanning electron microscopy (SEM). RESULTS: The clinical isolate of S. haemolyticus had enhanced ability to bacterial growth, adherence, aggregation, and biofilm formation, thus the inhibitory and bactericidal effects of TEC on planktonic, adherent, biofilm-dispersed, and biofilm-embedded cells of the isolate were attenuated. Additionally, TEC induced cell aggregation, biofilm formation, and some biofilm-related gene expression of the isolate. CONCLUSION: The clinical isolate of S. haemolyticus is resistant to TEC treatment due to cell aggregation and biofilm formation.