Comparison of PBP2a latex agglutination test with disk diffusion, mecA PCR and Vitek for the detection of methicillin resistant Staphylococcus aureus isolates

Metisiline dirençli Staphylococcus aureus (MRSA) izolatlannin saptanmasında genotipik vefenotipikyöntemlerin güvenilirliği araştırılmıştır. Bu amaçla çeşitli klinik örneklerden izole edilen 111 S.aureus izolatınm oksasiline duyarlılıkları dört farklı yöntem [1- NCCLS disk difüzyon testi, 2- Vitek GPS 101 (bioMerieux, Fransa) kartları ile duyarlılık saptanması, 3- MRSA-Screen (Denka Seiken, Japonya) ile direkt PBP2a belirlenmesi ve 4- PCR ile mecA geni varlığının gösterilmesi] kullanılarak incelenmiştir. Metisiline dirençli izolatların sayısı disk difüzyon yönteminde 80, Vitek sistemi ile 85, MRSA-Screen test ile 81 ve mecA gen analizi ile 76 olarak bulunmuştur. mecA gen analizi sonuçlarına göre disk difüzyon, Vitek ve MRSA-Screen testinin duyarlılık ve özgüllükleri sırasıyla % 100 ve % 90; % 100 ve % 80; %100ve% 88 olarak bulunmuştur. Gerek fenotipik gerekse genotipik yöntemler arasında sonuçların uyumsuz olduğu örnekler yeniden çalışıldığında, sonuçların MRSA-Screen ile örtüşecek şekilde değiştiği gözlenmiştir. NCCLS disk difüzyon yönteminin ve Vıtek sisteminin inokulum miktarına dikkat edilerek kullanıldığı takdirde rutin laboratuvarlarda MRSA belirlenmesinde kullanılabilecek güvenilir yöntemler olduğu saptanmıştır. Ayrıca, MRSA-Screen testinin hızlı, kolay ve güvenilir bir yöntem olduğu, doğrulama testi olarak tercih edilebileceği düşünülmüştür.

Anahtar Kelimeler:

Mikrobiyal duyarlılık testleri, Staphylococcus aureus, Metisilin direnci, Lateks fiksasyon testleri, Polimeraz zincir reaksiyonu, Oksasilin

Metisiline dirençli Staphylococcus aureus izolatlarında PBP2a lateks aglutinasyon testinin disk difüzyon ve Vitek ile karşılaştırılması

To determine the most accurate genotypic orphenotypic method for the detection ofMRSA, oxacillin susceptibility of 111 S. aureus isolates recovered from various clinical specimens were studied by 4 different methods: 1. NCCLS disk diffusion test; 2. Susceptibility determination by the Vitek GPS 101 (bioMerieux, France) cards; 3. Direct detection of PBP2a with MRSA-Screen (Denka Seiken, Japan) test; 4. mecA gene detection by PCR. The numbers of isolates found to be methicillin resistant were 80 by the disk diffusion test, 85 by the Vitek system, 81 by the MRSA-Screen test, and 76 by the mecA gene analysis. According to mecA gene analysis, sensitivity and specificity of disk diffusion, Vitek, and MRSA-Screen tests were found as 100 % and 90 %;100 % and 80 %; 100 % and 88 %, respectively. When the isolates which had shown discrepancies with both phenotypic and genotypic methods were re-studied, it was observed that all results were in complete agreement with MRSA-Screen test. NCCLS disk diffusion test and Vitek system, providing that all recommendations were followed carefully, are suitable tests to be used in routine laboratories io detect MRSA isolates, whereas MRSA-Screen test can be preferred as a verification tool due to its being a fast, easy and dependable method.

Keywords:

Microbial Sensitivity Tests, Staphylococcus aureus, Methicillin Resistance, Latex Fixation Tests, Polymerase Chain Reaction, Oxacillin,

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