Orhan BEDİR, Gürkan MERT, Ahmet Celal BAŞUSTAOĞLU, Abdullah KILIÇ

Clinical signifi cance and staphylococcal cassette chromosome mec (SCCmec) characterization of coagulase-negative staphylococci isolated from blood cultures

Amaç: Çalışmanın birinci amacı gerçek KNS bakteriyemi oranını kontaminasyon ile karşılaştırarak tanımlamaktır. İkinci amaç ise on aylık çalışma süresince, metisiline dirençli KNS (MRKNS) ve metisiline dirençli Staphylococcus aureus (MRSA) izolatları arasındaki farklılıkları değerlendirmek ve metisiline dirençli stafi lokoklarda SCCmec tiplerini belirlemektir. Yöntem ve gereç: Gerçek KNS bakteriyemi ya da kan dolaşımı enfeksiyonları CDC tarafından önceki çalışmalarda tarif edilmiş ve belirlenmiştir. Çalışmada, SCCmec tipleri real-time PCR yöntemi kullanılarak belirlenmiştir. Toplam 462 pozitif kan kültürü örneğinden 357 stafi lokok (313’ü KNS ve 44’ü S. aureus) izole edildi. Bulgular: 231 hastada oluşan 249 KNS bakteriyemi epizotu değerlendirildi. KNS bakteriyemi epizotu tanımlanmış olan 41 hastanın 45 epizotu (% 18,1) gerçek KNS bakteriyemisi olarak düşünülürken, 190 hastada tanımlanan 204 epizot kontaminasyon olarak değerlendirildi. Çalışmada, tüm MRSA suşları sadece SCCmec III tipini barındırmasına karşın MRKNSlar farklı SCCmec tipleri ve özellikle tip IV’ü en yaygın olarak barındırmaktaydı. Sonuç: Çalışmada gerçek KNS bakteriyemi oranları literatür ile uyumludur. Kurumumuzda, çoğunlukla SCCmec tip IV taşıyan MRKNS izolatlarının sadece SCCmec tip III taşıyan MRSA izolatları ile ilişkili olmadığı sonucuna varılmıştır.

Kan kültürlerinden izole edilen koagulaz negatif stafi lokokların klinik önemi ve stafi lokokal kaset kromozom (SCCmec) özellikleri

Aim: To describe the true coagulase-negative staphylococci (CoNS) bacteremia rate compared with contaminants, and to determine the SCCmec types in methicillin-resistant staphylococci and evaluate the diversity between methicillin-resistant CoNS (MRCoNS) and methicillin-resistant Staphylococcus aureus (MRSA) isolates during a 10-month study period. Materials and methods: The true CoNS bacteremia or bloodstream infection episode was defi ned on the basis of previous studies on CoNS bacteremia and the definitions of the Centers for Disease Control and Prevention. SCCmec types were determined by using the real-time PCR method. A total of 357 staphylococci isolates, including 313 CoNS and 44 S. aureus, were obtained from 462 positive blood culture samples. Results: A total of 249 CoNS bacteremia episodes in 231 patients were evaluated. Of these episodes, 45 (18.1%) in 41 patients were considered to be true CoNS bacteremia, whereas 204 in 190 patients were found to be contaminant. In the present study, all of the MRSA isolates harbored only SCCmec type III, but MRCoNS strains harbored different SCCmec types and SCCmec type IV was the most prevalent. Conclusion: The true CoNS bacteremia rate was consistently within the range reported in the literature. We also concluded that MRCoNS isolates carrying mostly SCCmec type IV elements may not be related to the presence of MRSA isolates carrying only SCCmec type III element in our institution.

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