Ayşe Nuriye VARIŞLI, Gülşen ÇETIN HAZIROLAN, Altan AKSOY, Neriman AKSU KOCA

İdrar örneklerinden MALDI-TOF MS sistemi ile direkt bakteri tanımlanması

Amaç: Üriner sistem enfeksiyonları (ÜSE)’deetken bakterinin erken saptanması; uygun antibiyotiktedavisine kısa sürede başlanması ve maliyet açısındanoldukça önemlidir. ÜSE’nin tanısında idrar kültürü altınstandarttır. Kültür ve antibiyotik duyarlılık testi 48-72 saat sürmektedir. Matriks aracılı lazer dezorpsiyoniyonizasyon uçuş zamanı kütle spektrometresi (MALDITOF MS) ile kültürde üretilen bakteriler birkaç dakikaiçinde tanımlanırken, direkt klinik örnekten tanımlamagenellikle iki saat gibi kısa bir zaman içinde yapılmaktadır.Bu çalışmanın amacı, idrar örneklerinden MALDI-TOFMS sistemi ile bakterinin direkt olarak tanımlanmasıve tedaviye olabildiğince erken başlanmasına katkısağlamasıdır.Yöntem: Hastanemizin mikrobiyoloji laboratuvarına01 Temmuz - 30 Kasım 2015 tarihleri arasında ÜSEşikayetiyle gönderilen 152 idrar örneği çalışmayaalınmıştır. Rastgele seçilen örneklerin bir kısmınadeneysel olarak Gram boyama yapılırken bir kısmınayapılmamıştır. Direkt idrar örneklerinden MALDI-TOF MSsistemi ile bakteri tanımlanması için örneklere formikasit ekstraksiyon metodu uygulanmıştır. Bu örneklereeş zamanlı olarak idrar kültürü de yapılmıştır. 37 °C’deaerobik ve %5 CO2’li ortamda 18-24 saatlik inkübasyondansonra anlamlı üreme saptanan plaklardaki kolonilerintanımlanması MALDI-TOF MS sistemi ile yapılmıştır.Bulgular: İdrar örneklerinden direkt bakteritanımlanmasında, MALDI-TOF MS sisteminin duyarlılığı%76 olarak bulunmuştur. MALDI-TOF MS sistemi ileekstraksiyon öncesinde bakteriyel yükü belirlemede,Gram boyama yapılmasının test sonuçlarına etkisininbelirlenmesi amacıyla istatistiksel analiz yapılmıştır.Buna göre Gram boyama uygulamasının MALDI-TOF MSsisteminin tanı performansı üzerine etkisi istatistikselolarak anlamlı bulunmuştur (p

Definition of direct bacteria by MALDI-TOF MS system from urinary examples

Objective: Rapid identification of bacterial pathogens from urine specimens are essential to establish an adequate antibiotic therapy to treat urinary tract infections and it is very important in terms of cost.Urine culture is gold standard in the diagnosis of UTI (Urinary Track Infection).Urine culture and antibiogram usually takes 48–72 h.The bacteria produced in culture identified within a few minutes while the clinical samples are identified in a short time like two hours by Matrix-assisted laser desorption and ionization time-of-flight mass spectrometry (MALDI-TOF MS).The aim of this study is to contribute identification of the direct bacteria by MALDI-TOF MS system and to start early effective treatment of urine specimens. Methods: We analyzed 152 urine samples with UTI complaints were submitted to the microbiology laboratory between July to November 2015.While some of the samples were experimentally Gram stained, some were not.Formal acid extraction method was applied to urine specimens for direct bacterial identification with MALDI-TOF MS system.In this example, the urine culture was also performed simultaneously. Identification of the colonies in plaque,which was incubated in media at 37 °C in aerobic and 5% CO2 for 18-24 hours of incubation,were performed with the MALDI-TOF MS system. Results: The sensitivity of direct sample from MALDI-TOF MS system was found to be 76%.Statistical analysis was performed to determine whether the Gram stain had any effect on the bacterial load and consequently on the identification of the MALDI-TOF MS system.According to this, there was a significant difference between Gram staining group and non - Gram staining group (p

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