Catalase-Negative Staphylococcus lugdunensis Strain with a Novel Point Mutation in the Catalase Gene Isolated from a Patient with Chronic Suppurative Otitis Media

Abstract

dThis report describes the results of the sequence analysis of a methicillin-susceptible strain of catalase-negative Staphylococcus lugdunensis. Molecular characterization of the deduced sequence revealed a novel point mutation in the catalase gene. To our knowledge, this is the first report of a catalase-negative S. lugdunensis strain, although catalase-negative isolates of Staphylococcus aureus and Staphylococcus epidermidis have been previously reported. CASE REPORTA 22-year-old woman presented to the Department of Otolaryngology with chronic suppurative otitis media. A pus sample was collected from her ear canal for routine microbial cultivation. The sample was inoculated in sheep blood agar and chocolate agar and incubated anaerobically and aerobically at 37°C for 24 h. After incubation, 1-to 2-mm creamy white colonies without hemolytic reaction were detected on sheep blood agar and chocolate agar plates maintained under aerobic atmospheric conditions. The bacterium was found to be catalase negative on analysis with 3% H 2 O 2 , and Gram staining showed the presence of Gram-positive staphylococcal clusters. The bacterium was again tested for the next 2 generations for catalase activity after subculturing on sheep blood agar and chocolate agar; the results remained negative for each generation. In addition, the isolate showed negative results for the slide and tube coagulase tests (performed with EDTAhuman plasma) with the primary and subculturing cultures.