Staphylococcus lugdunensis in Acute Oral Infection

ABSTRACT

To investigate the pathogenicity, genomic pattern, and o-like hemolysin of Staphylococcus lugdunensis (S. lugdunensis) in acute oral infection, S. lugdunensis was isolated from patients with an acute oral infection and from healthy persons. Antibiotic susceptibility, in vitro cellular toxicity, in vivo virulence, and hemolytic activity were tested, and plasmid DNA and restriction pattern of whole genomic DNA were analyzed to characterize the staphylococci. The dot blot and Southern blot hybridization analysis of staphylococcal DNA were performed with o-hemolysin gene probe. The isolation ratio of S. lugdunensis in the patients was higher than that in the healthy persons. S. lugdunensis from the patients with an acute oral infection showed resistance to penicillin, ampicillin, methicillin, cephalothin, and clindamycin. In the analysis of plasmid, there was a clear band about 6.5 kb in three strains of S. lugdunensis isolated from the patients with infection. S. lugdunensis in the patients had cellular toxicity in vitro and virulence in vivo. All strains of S. lugdunensis had o-like hemolysin activity against rabbit erythrocytes. Four of the six strains of S. lugdunensis gave synergistic hemolysis with Staphylococcus aureus (S. aureus) on sheep blood agar plates. In the analysis of genomic pattern, four strains of S. lugdunensis that gave synergistic hemolysis with S. aureus showed a similar genetic pattern with HindIII enzyme digests. In dot blot analysis, all strains of S. lugdunensis showed a positive reaction with the probe of 5-hemolysin gene in S. aureus. In Southern blot analysis, a 7.3 kb HindIII fragment was observed in DNA of S. lugdunensis that gave synergistic hemolysis with S. aureus, and a 2.5 kb band was observed in HindIII digests of S. aureus in the patients. These results suggest that S. lugdunensis may be an important pathogen in an acute oral infection and the 7.3 kb HindIII fragment from S. lugdunensis DNA may contain o-like hemolysin gene.