2002-2011 Yılları Arasında Hastalardan İzole Edilmiş Nocardia Türlerinin Biyokimyasal ve Moleküler Yöntemlerle Tanımlanması
Celalettin Uner, Mahmut
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Nocardia species are found in soil, water, air and in decomposing plant materials as saprophytes. They also cause local and systemic infections in humans and animals. Human infections are rare and commonly presented as subacute or chronic suppurative or granulomatous diseases. Variable clinical manifestations and antibiotic susceptibility profiles can be seen according to the Nocardia species. In this study, previously identified 45 Nocardia strains isolated from clinical samples in Clinical Microbiology Laboratory of Hacettepe University Hospitals between 2002 and 2011 were identified by using biochemical and moleculer tests and the antimicrobial resistance were determined. Most of the strains were isolated from respiratory samples (37.7 %) which was followed by brain abscess (17.7 %) and pus (15.5 %). By using biochemical tests, only N. farcinica (n:12) and N. otitidiscaviarum (n:4) could be identified to the species level. DNA sequencing test identified; N. cyriacigeorgica (n: 26), N. farcinica (n:12), N. otitidiscaviarum (n:4), N. asteroides (n:2) and N. abscessus (n:1) were to the species level. The ribotyping of the strains performed by automated device revealed that all of the Nocardia isolates had common 3.2 kb band patterns. Besides, distinctive band profiles were evaluated among the different Nocardia species. According to the recommendations of CLSI (Clinical and Laboratory Standards Institute), antibiotic susceptibility tests of these isolates were performed by broth microdilution method. In this method five antimicrobial agents (amikacin, ciprofloxacin, trimethoprim/ sulfamethoxazole, ceftriaxone, linezolide) were used. There was no resistance against amikacin and linezolide. The resistance rates against trimethoprim-sulfamethoxazole, ceftriaxone and ciprofloxacin were 15.5 %, 37.7 % and 82.2 %, respectively. In this study the resistance of N. farcinica to the trimethoprim-sulfamethoxazole was 16.6 % and because of this low resistance, this drug still keeps its place in treatment. Comparative evaluation of broth microdilution and disk diffusion methods indicated no consistency for TMP-SMX susceptibility profiles. In this study, for identification of Nocardia species, the importance of molecular methods such as DNA sequencing was shown. The importance of establishment a library of Nocardia species by ribotyping was also emphasized. It was clearly understood that for the antibiotic susceptibility testing of Nocardia species, broth microdilution method should be the method of choice.