RESUMO
Actinomyces naeslundii is a commensal flora of the oral cavity and is generally considered as an avirulent saprophytic bacterium in immunocompetent patients. It can become an opportunistic anaerobic pathogen in oral cavity in patients with poor oral hygiene or tooth extraction and can cause periodontal disease. Pulmonary Actinomycosis is a rare manifestation and may be suspected in middle-aged male patients with cough and hemoptysis showing radiological findings of a peripheral mass or chronic consolidation in whom repeated aerobic cultures have yielded negative results. Here, we report isolation of A. naeslundii from the bronchoalveolar lavage sample from an immunocompetent patient who presented with chronic nonresolving pneumonia of 6 months duration.
RESUMO
Methicillin-resistant Staphylococcus aureus colony variants (SCVs) are frequently auxotrophic for hemin, menadione, thiamine, and CO2 involved in biosynthesis of the electron transport chain element. This phenotype grows slowly, and forms very small, nonhemolytic colonies in routine culture, so it may be led to the misidentification of this organism. We isolated an organism with catalase-positive, gram-positive cocci in cluster from the urine of a 55-years-old woman with persistent and relapsing bladder stone, who had undergone the antibiotic treatment with cefotaxime, ceftizoxime, amikacin, and/or micronomicin, intermittently for three years. The possibility of SCVs should have been ruled out because this organism didn't grow on Mueller-Hinton agar (MHA) for the susceptibility test. It formed small colonies on blood agar plate overnight, and grew only on MHA with supplement of hemin, or with 5% CO2. This organism was coagulase-positive, DNase-positive, manitol-salt positive, and identified as S. aureus with VITEK GPI card. The susceptibility test could be performed after adding hemin(1mg/mL) into bacterial suspension and showed susceptibility against vancomycin, teicoplanin, and rifampin. Because these phenotypes can be misidentifide as other non-pathogenic organisms due to their atypical characteristics, we should consider SCVs in case of small, nonhemolytic colonies with catalase-positive, gram-positive cocci in cluster, showing no growth on MHA. In addition, infections caused by SCVs are recently recognized in relation to persistent and relapsing infection, so they could be isolated from the patients with long-term antibiotic therapy.