Evaluation of Diagnostics Colistin MIC-Strip Test for Colistin Susceptibility Testing

Year 2021, , 9 - 13, 29.04.2021

Gülşen Altınkanat Gelmez , Elvan Sayin , Ufuk Hasdemir Güner Söyletir

https://doi.org/10.5222/ankem.2021.009

Cited By: 1

Abstract

Due to the limited number of antimicrobials to be used in the treatment of infections caused by Gram-negative microorganisms with multi-drug resistance recently, old antibiotics such as colistin have started to be preferred frequently. However, some problems are encountered in antibiotic susceptibility tests (disk diffusion, gradient test, automated systems) which are frequently used in the routine laboratory due to the cationic nature of colistin. For this reason, only the broth microdilution test is recommended by European Committee on Antimicrobial Susceptibility Testing (EUCAST) and Clinical and Laboratory Standards Institute (CLSI) for the detection of colistin susceptibility. Since broth microdilution tests are time consuming and inconvenient, tests that can provide fast and reliable colistin susceptibility result is needed in routine laboratories. In this study, it was aimed to evaluate the performance of the commercially produced Diagnostics MIC-COL test (Diagnostics I.n.c, Galanta, Slovakia) for the detection of colistin susceptibility in Klebsiella pneumoniae and Acinetobacter baumannii strains. The strains of K.pneumoniae (n = 22) and A.baumannii (n = 28) isolated from various clinical specimens between 2016 and 2019 in our routine laboratory were included in the study. Colistin minimum inhibitory concentrations (MIC) of the strains were studied with both the reference broth microdilution method and the commercially produced Diagnostics Colistin MIC-COL test. The essential agreement, categorical agreement, major error, and very major error rates of the test were calculated by comparing the obtained results. The essential agreement of the Diagnostics Colistin MIC-Strip test was determined as 84 %, categorical agreement as 98 %, and major error rate as 3.8 %, while no very major error was detected. İt is very important to guide antimicrobial treatment with rapid and reliable detection of colistin susceptibility. The commercial test used in our study is easy to use and not time-consuming. Also, due to its strip from, each isolate can be studied separately. Because of the major error rate being above the expected values, it will be useful to re-evaluate these rates with further studies to be conducted with a larger number of strains with different resistance levels.

Keywords

A.baumannii, colistin susceptibility, diagnostics MIC-COL-strip, K.pneumoniae

KOLİSTİN DUYARLILIK TESTİ İÇİN DIAGNOSTICS COLISTIN MIC-STRIP TESTİNİN DEĞERLENDİRİLMESİ

Abstract

Günümüzde çoklu ilaç direncine sahip Gram negatif mikroorganizmaların neden olduğu enfeksiyonların tedavisinde kullanılacak antimikrobiyallerin kısıtlı olması nedeniyle kolistin gibi eski antibiyotikler sıklıkla tercih edilmeye başlanmıştır. Ancak, kolistinin katyonik yapısı nedeniyle rutin laboratuvarda sıklıkla kullanılan antibiyotik duyarlılık testlerinde (disk difüzyon, gradient test, otomatize sistemler) birtakım sorunlar yaşanmaktadır. Bu nedenle European Committee on Antimicrobial Susceptibility Testing (EUCAST) ve Clinical and Laboratory Standards Institute (CLSI) tarafından kolistin duyarlılığını saptamak için sadece sıvı mikrodilüsyon testi önerilmektedir. Ancak sıvı mikrodilüsyon testlerinin zaman alıcı ve zahmetli olması nedeniyle rutin laboratuvarlarında hızlı ve güvenilir kolistin duyarlılığı sonucu sağlayabilen testlere ihtiyaç duyulmaktadır. Bu çalışmada, Klebsiella pneumoniae ve Acinetobacter baumannii kökenlerinde kolistin duyarlılığının saptanmasında ticari olarak hazır olarak üretilen Diagnostics MIC-COL (Diagnostics I.n.c., Galanta, Slovakya) testinin performansının değerlendirilmesi amaçlanmıştır. Rutin laboratuvarımızda 2016-2019 yılları arasında çeşitli klinik örneklerden izole edilen K.pneumoniae (n=22) ve A.baumannii (n=28) kökenleri çalışmaya dahil edilmiştir. Kökenlerin kolistin minimum inhibitör konsantrasyonları (MİK) hem referans yöntem olan sıvı mikrodilüsyon yöntemi ile hem de ticari olarak üretilen Diagnostics MIC-COL testi ile çalışılmıştır. Elde edilen sonuçlar karşılaştırılarak testin temel uyum, kategorik uyum, büyük hata ve çok büyük hata oranları hesaplanmıştır. Sıvı mikrodilüsyon yöntemi ile karşılaştırıldığında Diagnostics MIC-COL testinin temel uyumu % 84, kategorik uyumu % 98, büyük hata oranı % 3,8 olarak tespit edilirken çok büyük hata tespit edilmemiştir. Rutin laboratuvarlarda hızlı ve güvenilir kolistin duyarlılığının tespit edilerek tedavinin yönlendirilmesi oldukça önemlidir. Çalışmamızda kullanılan ticari test kullanımı kolay ve zaman alıcı olmayan bir testtir. Ayrıca strip şeklinde olması sayesinde her izolat ayrı çalışılabilmektedir. Büyük hata oranının beklenilen değerlerin üzerinde olması nedeniyle daha fazla sayıda ve farklı direnç düzeylerine sahip kökenlerle yapılacak ileri çalışmalarla bu oranların yeniden değerlendirilmesi faydalı olacaktır.

Keywords

A.baumannii, diagnostics MIC-COL-strip, kolistin duyarlılığı, K.pneumoniae

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