Metisiline dirençli stafilokok suşlarında tigesiklin etkinliğinin araştırılması

Öz

Amaç: Amaç Metisiline dirençli Staphylococcus aureus MRSA ve metisiline dirençli koagülaz negatif stafilokoklar MRKNS dünya genelinde önemli enfeksiyon etkenleridir. Vankomisin ve diğer glikopeptit antibiyotikler MRSA ve MRKNS ile oluşan enfeksiyonların tedavisinde kullanılan belli başlı antibiyotiklerdir. Metisiline dirençli stafilokok suşlarının yüksek prevelansı, vankomisin kullanımında artışa yol açmıştır. Bu durum ise metisiline dirençli stafiloklarda glikopeptitlere duyarlılığın azalmasına neden olmuştur. Vankomisine duyarlılığı azalmış olan MRSA suşlarının yol açtığı enfeksiyonların tedavi seçenekleri sınırlıdır. Tigesiklin MRSA ve/veya MRKNS’ nin yol açtığı enfeksiyonların antimikrobiyal tedavileri için alternatif olarak göz önünde tutulmalıdır. Bu çalışmanın amacı tigesiklinin çeşitli kliniklerden izole edilen metisiline dirençli stafilokok suşlarına karşı in vitro antimikrobiyal aktivitesinin belirlenmesidir. Yöntem: Stafilokok suşları Ocak ve Aralık 2010 tarihleri arasında Konya Eğitim ve Araştırma Hastanesi Mikrobiyoloji Laboratuvarında izole edilmiştir. İzole edilen suşlar konvansiyonel metodlar ve tam otomatik bakteri identifikasyon ve duyarlılık sisteminin Phoenix 100, BD, Sparks, USA her ikisi kullanılarak tanımlanmıştır. Metisilin direnci disk difüzyon yöntemi oksasilin 1 µg ve sefoksitin 30 µg diskleri Klinik ve Laboratuvar Standartları Enstitüsü’nün Clinical and Laboratory Standards Institute-CLSI talimatlarına göre uygulanmış ve değerlendirilmiştir. İzole edilen suşlar için tigesiklinin minimum inhibitör konsantrasyon MİK değerleri E-test metodu bio-Merieux Marcy l’Etoile, France ile belirlenmiştir. Bulgular: Seksen beş dirençli stafilokok suşunda 35 %41 ’i Staphylococcus aureus ve 50 %59 ’si koagülaz negatif stafilokok olarak tanımlanmıştır. Otuz beş MRSA izolatı için tigesiklinin MİK değerleri şu şekilde bulunmuştur: MİK50: 0,094 µg/ml, MİK90: 0,5 µg/ml, 50 MRKNS izolatı için ise MİK50: 0,047 µg/ml, MİK90: 0,25. Bütün izolatların tamamı tigesikline duyarlı %100 bulunmuştur. Sonuç: Bu çalışmanın sonuçları tigesiklinin MRSA ve MRKNS izolatlarının her ikisine karşı etkili in vitro antimikrobiyal aktiviteye sahip olduğunu göstermektedir. Tigesiklin, dirençli MRSA ve MRKNS etkenlerinin yol açtığı enfeksiyonların tedavisinde alternatif antibiyotiklerin tamamının dirençli olduğu durumlarda son seçenek olarak tercih edilebilir.

Anahtar Kelimeler

• Tigesiklin, Metisiline dirençli Staphylococcus aureus, Metisiline dirençli koagülaz-negatif stafilokok, E-test.

Investigation of activity of tigecycline against methicillin-resistant staphylococci strains

Abstract

Objective: Methicillin-resistant Staphylococcus aureus MRSA and Methicillin-resistant coagulase negative staphylococci MRCNS are important cause of infections worldwide. Vancomycin and other glycopeptide antibiotics are mainstay of therapy for infections caused by MRSA and MRCNS. High prevalence of methicillin resistant staphylococci strains led to increased use of vancomycin. This situation caused to reduction of glycopeptide susceptibility in methicillinresistant staphylococci. Treatment options of infections due to MRSA with reduced susceptibility to vancomycin are limited. Tigecycline should be take into consideration as an antimicobial therapeutic alternative for infecitons caused by MRSA and/or MRCNS. The aim of this study was to determine in vitro antimicrobial activity of tigecycline against methicillin-resistant staphylococci strains isolated from various clinical specimens. Method: Staphylococcus strains isolated at the Microbiology Laboratory of Konya Education and Research Hospital in between January and December in 2010. The isolated strains were identified by using both conventional methods and fully automated bacteria identification and susceptibility system Phoenix 100, BD, Sparks, USA . Methicillin resistance was determined and evaluated according to Clinical and Laboratory Standards Institute CLSI instrucions by using disc diffusion method oxacillin 1 µg and cefoxitin 30 µg discs Minimum inhibitory concentration MIC values of tigecycline for isolated strains were detected with E-test method bio-Merieux Marcy l’Etoile, France . Results: Of all the eighty five methicillin-resistant staphylococci strains 35 41% were identified as Staphylococcus aureus and 50 59% coagulase negative staphylococci. MIC values of tigecycline for the 35 MRSA isolates were MIC50: 0.094 µg/ml, MIC90: 0.5 µg/ml and for the 50 MRCNS isolates were MIC50: 0.047 µg/ml, MIC90: 0.25 µg/ml. All isolates 100% were found to be sensitive to tigecycline. Conclusion: Results of this study showed that tigecycline was effective in vitro antimicrobial activity against both MRSA and MRCNS isolates. Tigecycline may be preferred as a last choice in the treatment of resistant infections due to the MRSA and MRCNS that alternative antibiotics were all resistant.

Keywords

• Tigecycline, Methicillin-resistant Staphylococcus aureus, Methicillin-resistant coagulase negative staphylococci, E-test.

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