Klebsiella pneumoniae Suşlarında OXA-48 ve Alt Türevlerinin Araştırılması ve Fenotipik Yansıma

Abstract

The number of infections caused by carbapenem-resistant Gram negative bacteria is increasing among nosocomial infections. These bacteria are a serious threat to health because they are usually resistant to other antibiotics. This study was aimed to determine the carbapenemase resistance of OXA-48 and its subderivatives in Klebsiella pneumoniae isolates isolated from various clinical samples by phenotypic and genotypic methods and to investigate the presence of OXA-48 gene region genotypically in isolates without resistance. A total of 127 K.pneumoniae strains isolated from patients treated in various clinics and intensive care units were included in this study from March 2015 to March 2016. The isolates were identified and susceptibilities were tested using BD Phoenix automated system and also with Kirby-Bauer disk diffusion method. The presence of resistance was examined phenotypically with the disk of temosillin, which is considered to indicate the presence of OXA-48 type enzymes. The presence of OXA-48 type enzyme was investigated by “in-house” polymerase chain reaction (PCR) in all isolates and the presence of OXA-48 variant was investigated by DNA sequencing analysis on positive isolates. Carbapenem resistance rate was 35 % and ESBL positivity was determined as 46 %. The sensitivity of temocillin disk method in the identification of OXA-48 gene presence in K. pneumoniae strains was found to be 88 %, and specificity 89 %. Ertapenem was the best carbapenem with sensitivity and specificity balance to detect carbapenem resistance caused by OXA-48. The presence of blaOXA-48 gene region was 80 % in K. pneumoniae isolates detected as resistant to carbapenems by an automated system. All sequences obtained by DNA sequence analysis of 42 OXA-48 positive isolates were OXA-48 and there was no variant OXA-48 gene among the sequences. It was observed that the phenotypic reflection of resistance did not occur immediately in three isolates genotypically having OXA-48 gene region. The presence of blaOXA-48 gene region in carbapenems-resistant K.pneumoniae isolates is common. In addition, in some isolates having OXA-48 gene region, should be kept in mind in patients who do not recover despite treatment, due to phenotypic reflection of resistance does not occur immediately