Publication: Klebsiella pneumoniae izolatlarının genişlemiş spektrumlu beta-laktamaz profilinin genotipik ve fenotipik yöntemlerle araştırılması
Abstract
Amaç: Çalışmamızda, hastanemizde izole edilen klinik Klebsiella pneumoniae izolatlarında genişlemiş spektrumlu beta-laktamaz üretiminin, fenotipik ve genotipik yöntemlerle tespitini ve bölümümüzde yeni geliştirilen kolorimetrik-GSBL testinin performansının değerlendirilmesi amaçlanmıştır. Gereç ve Yöntem: 2018-2023 yılları arasında hastanemizde izole edilen seftazidim ve seftriakson MİK’leri GSBL tarama sınır değeri (>1mg/ L) üzerinde olan 100; altında (≤1mg/ L) olan 20 K. pneumoniae izolatı çalışmaya dahil edilmiştir. İzolatlarda GSBL pozitifliği ve negatifliği, kombinasyon disk testi ile konfirme edilmiştir. İzolatların DNA’ları ekstrakte edilerek üç GSBL geni, blaTEM, blaSHV ve blaCTX-M, için spesifik primerlerle PZR yapılmıştır. PZR testinde GSBL genlerinden en az biri saptanan izolatlarda kolorimetrik-GSBL testinin, GSBL saptamadaki performansı değerlendirilmiştir. Kolorimetrik-GSBL testi, belirli konsantrasyonlarda sefotaksim/ seftriakson ve pH indikatörü olarak fenol-kırmızısı içeren bir tüpte gerçekleştirilmiştir. Bulgular: Tarama testinde MİK’leri >1 mg/ L üzerinde olan 100 K. pneumoniae izolatın tamamı kombinasyon disk testi ile GSBL pozitif olarak doğrulanmıştır. İzolatların %97’sinde PZR ile araştırılan GSBL genlerinden en az biri saptanmıştır. En sıklıkla rastlanan GSBL geni, tek başına veya diğer bir GSBL geni ile birlikte blaCTX-M (%95,9) olmuştur. İzolatlardaki blaTEM geninin oranı %55,7 ve blaSHV geninin oranı %50,5 olarak saptanmıştır. Üç geni bir arada taşıyan izolatların oranı %28,9’dur. PZR test sonuçlarını göre, PZR pozitif 97 izolatın 94’ü kolorimetrik-GSBL testi ile pozitif sonuç vermiştir. PZR negatif 20 izolatın ise kolorimetrik-GSBL testi ile hepsi GSBL negatif bulunmuştur. Sonuç: Çalışmamızda, K. pneumoniae izolatlarımızda en yaygın GSBL geninin blaCTX-M olduğu ve izolatların yarısından çoğunda ikili veya üçlü GSBL gen kombinasyonlarının varlığı belirlenmiştir. Kolorimetrik-GSBL testinin, blaCTX-M, blaSHV ve blaTEM, genlerini saptamadaki duyarlılığının ve özgüllüğünün yüksek olduğunu kaydedilmiştir.
Objective: The aim of this study is to detect the production of extended spectrum beta-lactamase (ESBL) in clinical isolates of Klebsiella pneumoniae isolated from our hospital using phenotypic and genotypic methods and to evaluate the performance of a newly developed colorimetric ESBL test in our department. Materials and Methods: Between 2018 and 2023, 100 K. pneumoniae isolates with ceftazidime and ceftriaxone MICs above the ESBL screening breakpoint (>1 mg/ L) and 20 K. pneumoniae isolates with MICs below the breakpoint (≤1mg/ L) that were isolated in our hospital were included in the study. The ESBL positivity and negativity of the isolates was confirmed by a combination disk test. The DNA of the isolates was extracted and PCR was performed with specific primers for three ESBL genes: blaTEM, blaSHV and blaCTX-M. The performance of the colorimetric-ESBL test in detecting ESBL in isolates in which at least one of the ESBL genes was detected in the PCR test was evaluated. The colorimetric-ESBL test was performed in a tube containing specific concentrations of cefotaxime/ ceftriaxone and phenol red as a pH indicator. Results: Using the VITEK® 2 Compact automated system, 100 K. pneumoniae isolates with MICs above >1 mg/ L in the screening test were confirmed as ESBL positive using the combination disk test. At least one of the ESBL genes tested by PCR was detected in 97 % of the isolates. The most frequently occurring ESBL gene was blaCTX-M (95.9 %), alone or in combination with another ESBL gene. The proportion of isolates carrying all three genes together was 28.9 %. According to the PCR test results, 94 of 97 PCR-positive isolates showed positive results in the colorimetric-ESBL test. Of the 20 PCR-negative isolates, all were found to be ESBL-negative in the colorimetric-ESBL test. Conclusion: Our study showed that the most common ESBL gene in our K. pneumoniae isolates was blaCTX-M and more than half of the isolates had a double or triple ESBL gene combination. The evaluation of extensive studies showed that the sensitivity and specificity of the colorimetric-ESBL test in detecting the blaCTX-M, blaSHV and blaTEM genes were high.
Objective: The aim of this study is to detect the production of extended spectrum beta-lactamase (ESBL) in clinical isolates of Klebsiella pneumoniae isolated from our hospital using phenotypic and genotypic methods and to evaluate the performance of a newly developed colorimetric ESBL test in our department. Materials and Methods: Between 2018 and 2023, 100 K. pneumoniae isolates with ceftazidime and ceftriaxone MICs above the ESBL screening breakpoint (>1 mg/ L) and 20 K. pneumoniae isolates with MICs below the breakpoint (≤1mg/ L) that were isolated in our hospital were included in the study. The ESBL positivity and negativity of the isolates was confirmed by a combination disk test. The DNA of the isolates was extracted and PCR was performed with specific primers for three ESBL genes: blaTEM, blaSHV and blaCTX-M. The performance of the colorimetric-ESBL test in detecting ESBL in isolates in which at least one of the ESBL genes was detected in the PCR test was evaluated. The colorimetric-ESBL test was performed in a tube containing specific concentrations of cefotaxime/ ceftriaxone and phenol red as a pH indicator. Results: Using the VITEK® 2 Compact automated system, 100 K. pneumoniae isolates with MICs above >1 mg/ L in the screening test were confirmed as ESBL positive using the combination disk test. At least one of the ESBL genes tested by PCR was detected in 97 % of the isolates. The most frequently occurring ESBL gene was blaCTX-M (95.9 %), alone or in combination with another ESBL gene. The proportion of isolates carrying all three genes together was 28.9 %. According to the PCR test results, 94 of 97 PCR-positive isolates showed positive results in the colorimetric-ESBL test. Of the 20 PCR-negative isolates, all were found to be ESBL-negative in the colorimetric-ESBL test. Conclusion: Our study showed that the most common ESBL gene in our K. pneumoniae isolates was blaCTX-M and more than half of the isolates had a double or triple ESBL gene combination. The evaluation of extensive studies showed that the sensitivity and specificity of the colorimetric-ESBL test in detecting the blaCTX-M, blaSHV and blaTEM genes were high.