Pseudomonas aeruginosa strains, especially multidrug resistant, have great of importance among nosocomial infection isolates. Production of beta-lactamase is an important mechanism in gram-negative bacteria for resistance to beta-lactam antibiotics. PER-1 and OXA-10 like beta-lactamases (OXA-11-14-16) were first reported from Turkey, and caused ceftazidime resistance in P. aeruginosa.In this study, our aim was to identify PER-1 and OXA-10 like beta-lactamase enzymes which caused ceftazidime resistance in nosocomial P. aeruginosa strains as fast and correctly by molecular methods, to determine the prevalance of these enzymes and to get the nosocomial infections under control by determining their clonal relationship.PER-1 and OXA-10 presence was sought by PCR in 50 ceftazidime resistant P. aeruginosa strains. Clonal relationship of strains was determined by RAPD-PCR and epidemilogic analysis of isolates was investigated by PFGE. Types of PER-1 and OXA-10 like beta-lactamases were analysed by RFLP.PER-1 and OXA-10 like beta-lactamases were detected in 46 % and 78 % of P. aeruginosa strains, respectively. RAPD-PCR results releaved dissemination that the four main clones which were determined among P. aeruginosa isolates are responsible for the high prevalence. The determination of three main clones by PFGE also supported that the isolates are nearly related. PER-1 and OXA-10 11-14-16 types were identified by RFLP analyse. We concluded that, the prevalence of PER-1 and OXA-10 enzymes among ceftazidime resistant P. aeruginosa isolate was high in our hospital. PER-1 and OXA-10 producers were being transmitted horizontally as most of the isolates are clonally related.Key Word: Pseudomonas aeruginosa, beta-lactamases, PER-1, OXA-10, molecular epidemiology.

Pseudomonas aeruginosa'nın özellikle çoklu ilaca dirençli suşları hastane infeksiyonu etkenleri arasında önemli bir yere sahiptir. Beta-laktamaz üretimi, gram-negatif bakterilerde beta-laktam antibiyotiklere dirençte önemli bir mekanizmadır. Türkiye kaynaklı olan PER-1 ve OXA-10 grubu beta-laktamazlar (OXA-11/14/16) P. aeruginosa'da seftazidim direncine neden olurlar.Bu çalışmada, hastane infeksiyonu etkeni P. aeruginosa suşlarında seftazidim direncine neden olan PER-1 ve OXA-10 grubu beta-laktamaz enzimlerini moleküler yöntemler ile hızlı ve güvenilir olarak tanımlamak, görülme sıklıklarını ortaya koymak ve bu izolatların klonal yakınlıklarını saptayarak yeni oluşacak hastane infeksiyonu olgularını kontrol altına almak hedeflenmektedir.Seftazidime dirençli 50 adet P. aeruginosa izolatında PER-1 ve OXA-10 grubu gen bölgeleri PZR ile tespit edildi. Suşların klonal yakınlıkları RAPD-PZR yöntemiyle belirlendi ve PFGE ile epidemiyolojik analizleri yapıldı. PER ve OXA-10 grubu gen bölgelerinin restriksiyon analizleri yapılarak tipleri belirlendi.İncelenen suşlarda %46 oranında PER-1 ve %78 oranında OXA-10 enzimi tespit edildi. P. aeruginosa izolatları arasında saptanan dört ana klonun yüksek prevalanstan sorumlu olduğu RAPD-PZR sonuçları ile ortaya kondu. PFGE yönteminde de üç ana klonun belirlenmesi izolatların büyük oranda ilişkili olduğunu destekledi. RFLP analizi ile PER-1 ve OXA-11/14/16 enzim genotipleri tanımlandı. Ondokuz Mayıs Ünversitesi Tıp Fakültesi Hastanesi'nde izole edilen seftazidim dirençli P. aeruginosa suşlarında PER-1 ve OXA-10 enzimlerinin yaygın olduğu ve bu enzimi üreten birçok suşun ?klonal ilişkili? oluşunun horizontal yayılıma işaret ettiği sonucuna varıldı.ABSTRACTDETERMINATION OF PER-1 AND OXA-10-LIKE BETA-LACTAMASES IN CEFTAZIDIME-RESISTANT PSEUDOMONAS AERUGINOSA ISOLATES BY MOLECULAR METHODSMehtap ÜNLÜ SÖĞÜT, Ph.D. ThesisUniversity of Ondokuz Mayıs Samsun, June 2008Pseudomonas aeruginosa strains, especially multidrug resistant, have great of importance among nosocomial infection isolates. Production of beta-lactamase is an important mechanism in gram-negative bacteria for resistance to beta-lactam antibiotics. PER-1 and OXA-10 like beta-lactamases (OXA-11-14-16) were first reported from Turkey, and caused ceftazidime resistance in P. aeruginosa.In this study, our aim was to identify PER-1 and OXA-10 like beta-lactamase enzymes which caused ceftazidime resistance in nosocomial P. aeruginosa strains as fast and correctly by molecular methods, to determine the prevalance of these enzymes and to get the nosocomial infections under control by determining their clonal relationship.PER-1 and OXA-10 presence was sought by PCR in 50 ceftazidime resistant P. aeruginosa strains. Clonal relationship of strains was determined by RAPD-PCR and epidemilogic analysis of isolates was investigated by PFGE. Types of PER-1 and OXA-10 like beta-lactamases were analysed by RFLP.PER-1 and OXA-10 like beta-lactamases were detected in 46 % and 78 % of P. aeruginosa strains, respectively. RAPD-PCR results releaved dissemination that the four main clones which were determined among P. aeruginosa isolates are responsible for the high prevalence. The determination of three main clones by PFGE also supported that the isolates are nearly related. PER-1 and OXA-10 11-14-16 types were identified by RFLP analyse. We concluded that, the prevalence of PER-1 and OXA-10 enzymes among ceftazidime resistant P. aeruginosa isolate was high in our hospital. PER-1 and OXA-10 producers were being transmitted horizontally as most of the isolates are clonally related.Key Word: Pseudomonas aeruginosa, beta-lactamases, PER-1, OXA-10, molecular epidemiology.