Antibiotic Susceptibility of the First Streptococcus Constellatus Isolated from Epidural Abscess in Dakar

Abstract

Streptococcus constellatus is member of the Streptococcus anginosus Group (SAG) that are considered commensal organisms; however, they can sometimes cause serious invasive infections of the liver, lung, brain abscesses, bacteraemia, endocarditis and intra-abdominal infections. S. intermedius and S. constellatus are the main causes of deep abscess. SAG is generally considered to be susceptible to beta-lactam antibiotics and macrolides; however, increasingly we are seeing the emergence of viridans and beta-haemolytic Streptococci resistant to antibiotics. In a 59-year-old patient hospitalized in intensive unit care for an epidural abscess, pus was collected and cultures were grown. Bacterial identification was performed by routine laboratory methods including Gram stain, catalase reaction and biochemical analysis using the API 20 Strep test (BioMérieux Vitek 2). Antimicrobial susceptibility testing was performed using standard disk diffusion method. Antibiotic disks of penicillin, vancomycin, teicoplanin, gentamycin, erythromycin, lincomycin, pristinamycin, norfloxacin, and rifampicin were placed on inoculated plates. Minimum inhibitory concentration (MIC) was determined by using the BioMérieux Vitek 2. S. constellatus was identified in abscess and was resistant to penicillin, aminoglycosides, macrolides, lincomycin, fluoroquinolones. This isolate was sensitive only to vancomycin, pristinamycin and rifampin. Difficulties in identification strains isolates of the SAG have caused confusion in determining their pathogenic potential, but using new powerful tool for rapid identification bacteria, makes accurate diagnosis and differentiatiation possible. Thus, it is necessary to equip the laboratories for good management of infectious diseases. This is the first known report of S. Constellatus from abscess in Dakar. SAG are generally susceptible to penicillin, other beta-lactam antibiotics and macrolides. However, in our study S. Constellatus were resistant to penicillin, aminoglycosides, macrolides, lincomycin and fluoroquinolones, demonstrating antibiotic resistance among SAG isolates.