Staphylococcus türlerinde farklı yöntemlerle metisilin direncinin saptanması ve SCCmec tiplendirmesi
Detection of methicillin resistance in staphylococcus species with different methods and SCCmec typing
Yazar: EMİNE SEVGİCAN
Danışman: PROF.DR. SUNA GEDİKOĞLU
Uludağ Üniversitesi / Tıp Fakültesi / Klinik Bakteriyoloji ve Enfeksiyon Hastalıkları Ana Bilim Dalı
Derece: Tıpta Uzmanlık, 2006
Konu: Mikrobiyoloji = Microbiology

Özet:
ÖZETMetisilin dirençli stafilokoklar, giderek artan sâºklâºkta ciddi nozokomiyalve toplum kökenli enfeksiyonlara neden olmaktadâºr. Antistafilokokal beta-laktam antibiyotiklere fenotipik heterojen ilaç direnci (heterorezistans),duyarlâºlâºk testlerinin sonuçlarâºnâº etkilemektedir. Rutin oksasilin disk difüzyontestleri, metisiline dirençli stafilokoklarda heterojen direnci belirlemedeyetersiz kalabilmektedir.Bu çalâºï¬mada 100 metisiline dirençli S aureus (MRSA) ve 100 koagülaznegatif stafilokok klinik izolatâºnda, bir sefamisin antibiyotik olan sefoksitin(30Âµg) (BD) kullanâºlarak disk difüzyon yöntemiyle deÂ¤erlendirmesi yapâºldâº.Stafilokoklarda metisilin direncini tarama amacâºyla; oksasilin (1 Âµg) (BD),sefoksitin (30 Âµg) (BD) disk difüzyon ve oksasilin, sefoksitin E-testi (ABBiodisk Sonia, Sweden) çalâºï¬âºlarak sonuçlar karï¬âºlaï¬tâºrâºldâº. Farklâº yöntemlerinperformanslarâº irdelendi ve diÂ¤er testler ile karï¬âºlaï¬tâºrâºldâº. Sonuçlar; sefoksitindisk difüzyon testinin, oksasilin disk difüzyon ve E-test yöntemleri ileirdelendiÂ¤inde, metisilin direncini saptamak için rutin çalâºï¬madakullanâºlabileceÂ¤ini gösterdi. PCR (Polymerase Chain Reaction) ile mecAgeninin saptanmasâº altâºn standart olarak kabul edilmektedir. Metisilin direncinikodlayan mecA genini içeren ve staphylococcal cassette chromosome mec(SCCmec) olarak isimlendirilen mobil genetik elementin tiplendirilmesi yapâºldâº.SCCmec tiplendirilmesinde multiplex PCR yöntemi kullanâºlarak, 100 MRSAsuï¬undan 93'ünde tip III SCCmec saptandâº, beï¬ suï¬ tiplendirilemedi ve 2suï¬da mecA geni saptanmadâº.Anahtar Kelimeler: Metisilin direnci, SCCmec, multipleks PCRii

Abstract:
SUMMARYMethicillin-resistant staphylococci are responsible for an increasingnumber of serious nosocomial and community-acquired infections. Phenotypicheterogeneous drug resistance to antistaphylococcal beta-lactams affects theresults of susceptibility testing. Routine oxacillin disk diffusion tests often failto detect heterogeneous methicillin-resistant staphylococcus populations.In the present study, a recently proposed disk diffusion method thatemploys a cephamycin antibiotic (cefoxitin 30 Âµg; BD) was evaluated using100 clinical isolates of Meticillin-Resistant Staphylococcus aureus (MRSA)and 100 clinical isolates of Coagulase-Negative Staphylococci (CoNS). Theresults were compared with those of other Methicillin-resistant Staphylococciscreening techniques: a disk diffusion test with oxacillin 1 Âµg and cefoxitin 30Âµg (BD), an E-test with oxacillin and cefoxitin (AB Biodisk Sonia, Sweden).The performances of the different methods were determined and comparedwith each other. The results showed that the cefoxitin disk diffusion test issuitable to the oxacillin disk diffusion and E-test method for routine screeningto detect methicillin-resistant staphylococci. Detection of the mecA gene bypolymerase chain reaction was considered the gold standard. SCCmec typinganalyzes a mobile genetic element called the staphylococcal cassettechromosome mec (SCCmec), which contains the mecA gene encodingmethicillin resistance. The SCCmec types were determined by a multiplexPCR strategy, out of the total of 100 strains, 93 had SCCmec type III. Fivestrains were nontypeable and two strains had not found mecA gene.Key words: Methicillin resistance, SCCmec, multiplex PCRiii