Extended Spectrum B-lactamases and antimicrobial susceptibility among clinical isolates of Pseudomonas aeruginosa in the West Bank, Palestine

Journal of Microbiology 56 Essawiand T, etInfectious al. Ceftazidime Diseases resistance / and OXA-type Oxacillinases in P. aeruginosa 2013; 3 (2): 56-60 JMID doi: 10.5799/ahinjs.02.2013.02.0081 RESE ARCH ARTICLE Extended Spectrum β-lactamases and antimicrobial susceptibility among clinical isolates of Pseudomonas aeruginosa in the West Bank, Palestine Tamer Essawi, Israr Sabri, Mohammad A. Farraj Master Program in Clinical Laboratory Science, Birzeit University, Birzeit, Palestine ABSTRACT Objectives: Class D oxacillinases are frequently acquired by gram negative bacteria in general and P. aeruginosa in particular. P. aeruginosa is commonly implicated in causing nosocomial infections. The evolution of antibiotic resistance in P. aeruginosa and the acquisition of blaOXA genes interfere with successful treatment. Methods: A total of 49 clinical isolates of P. aeruginosa were obtained from Rafidia Hospital, West Bank, Palestine. Antimicrobial susceptibility testing of the isolates was performed by the standard disc diffusion method following the guidelines of CLSI. The prevalence of class D β-lactamases (OXA groups I, II and III) as well as the pseudomonas specific enzymes (CARB-3) were determined by PCR. Results: Susceptibility of P. aeruginosa to carbapenems was the highest 89%, and lowest to ticarcillin/clavulanic acid 70%. This study revealed that P. aeruginosa produced oxacillinase enzymes at rates of: OXA-10 (40.8%), OXA-2 (20.4%) and OXA-1 (18.4%). All ceftazidime resistant strains expressed OXA-1 and OXA-2, 18.4%. PSE group was expressed in 10.2%. Conclusions: This is the first research conducted to investigate the correlation between OXA genes (blaOXA-1, blaOXA-2 and blaOXA-10) and antimicrobial resistance among P. aeruginosa clinical isolates in Palestine. The results obtained could contribute to better treatment and reduction of the evolution of resistant strains. In addition, it will provide important information regarding the geographical distribution of class D β-lactamases. J Microbiol Infect Dis 2013; 3(2): 56-60 Key words: P. aeruginosa, β-lactamase, susceptibility, oxacillinases, blaOXA genes. Filistin, Batı Şeria’da izole edilen Pseudomonas aeruginosa izolatlarında β-laktamaz varlığı ve antibiyotik duyarlılıkları ÖZET Amaç: D sınıfı oksasilinazlar gram negatif basiller içinde ve de özellikle P. aeruginosa kökenlerinde yaygındır. P. aeruginosa hastane enfeksiyonlarının sık nedenlerinden biridir. P. aeruginosa kökenlerinde antibiyotik direncinin ve blaOXA genlerinin kazanılması tedavi başarısını etkiler. Bu çalışmada P. aeruginosa kökenlerinde antibiyotik direnci ve blaOXA gen varlığının tedavi başarısı üzerine etkileri araştırıldı. Yöntemler: Toplam 49 klinik P. aeruginosa izolatı Filistin’de bulunan Rafidia Hastanesinden elde edildi. Antimikrobiyal duyarlılık testleri standart disk difüzyon metodu ile CLSI standartlarına göre yapıldı. D grubu β-lactamaz (OXA grop I, II ve III) sıklığı ve pseudomonasa özgün enzimlerin (CARB-3) varlığı PCR yöntemiyle araştırıldı. Bulgular: P. aeruginosa kökenlerinde en yüksek duyarlılık karbapenemlere (%89) ve en düşük duyarlılık ise tikarsilin/ klavulanik aside (%70) karşı saptandı. Bu çalışmanın sonuçlarına göre; P. aeruginosa kökenlerinde OXA-10 oranı %40,8, OXA-2 %20,4 ve OXA-1 %18,4. Seftazidime dirençli kökenlerin hepsi OXA-1 taşırken %18,4’ü OXA-11 taşıyorlardı. PSE grubu salgılanması ise %10,2 idi. Sonuç: Bu çalışma Filistin’deki P. aeruginosa izolatları üzerinde yapılan ve OXA genleriyle (blaOXA-1, blaOXA-2 ve blaOXA-10 ) antimikrobiyal direnç arasındaki ilişkiyi araştıran ilk çalışmadır. Sonuçlarımız dirençli kökenlerdeki tedavi prensiplerini anlamaya yardımcı oldu ve D grubu β-laktamazların coğrafi dağılımı hakkında bilgi sahibi olmamızı sağladı. Anahtar kelimeler: P. aeruginosa, β-laktamaz, Duyarlılık, Oksasilinaz, blaOXA genleri. Correspondence: Tamer Essawi, Master Program in Clinical Laboratory Science, Birzeit University, Birzeit, Palestine Email: Received: 27 November, 2012 Accepted: 28 May, 2013 and Infectious Diseases 2013, All rights reserved J Microbiol Infect DisCopyright © Journal of Microbiology www.jmidonline.org Vol 3, No 2, June 2013 Essawi T, et al. Ceftazidime resistance and OXA-type Oxacillinases in P. aeruginosa INTRODUCTION Pseudomonas aeruginosa is an opportunistic pathogen commonly involved in infections of the immunosuppressed patients and a major cause of nosocomial infections.1-4 P. aeruginosa is intrinsically resistant to various classes of antibiotics through constitutive expression of various efflux pumps, production of β-lactamases and decreased permeability of the outer membrane.5-7 Acquired resistance by P. aeruginosa is mediated by the acquisition of resistance genes for β-lactamases, mutations and fluoroquinolones, over expression of the efflux pumps and decreased expression of porin proteins. Resistance of P. aeruginosa to aminoglycosides involves their inactivation by several modifying enzymes which inhibit the binding of these antibiotics to their target.2,6-8 P. aeruginosa is capable of developing multidrug resistance causing treatment failure and resulting in increased rates of morbidity and mortality.9,10 Although extended spectrum β-lactamases (ESBLs) of classes A, B and D have recently been reported in P. aeruginosa, OXA and PSE types are the most prevalent β-lactamases encountered.11,12 Genes encoding oxacillinase enzymes are intrinsic in gram negative bacteria including P. aeruginosa.13 The acquired OXA genes can have a narrow or expanded spectrum of hydrolysis of antibiotics.14 The prevalence of OXA type β-lactamases in P. aeruginosa had never been investigated in Palestine. The aim of this study was to assess the antimicrobial susceptibility of clinical isolates of P. aeruginosa, the rate of Ambler group A and Ambler group D β-lactamases in our isolates. METHODS Bacterial isolates A total of 49 isolates of P. aeruginosa were obtained in 2010 from various clinical sources including wounds (21), sputum (8), urine (6), sores (4), Ear (4), blood (3), CSF (1) and other sites (2). There were 20 isolates from the burn unit, 13 isolates from the intensive care unit, 7 from surgical ward and 9 from outpatient clinics. The ages of the patients ranged from newborn babies to 77 years with 28 females and 21 males. To avoid duplication, one sample for each patient was obtained. The isolates were J Microbiol Infect Dis 57 obtained from Rafidia Surgical Hospital in Nablus, West Bank, Palestine. Antimicrobial susceptibility testing Antimicrobial susceptibility testing of P. aeruginosa isolates was determined by disc diffusion following the recommendations and guidelines of the Clinical Laboratory Standard Institute (CLSI).15,16 The antibiotics tested were: Imipenem (10 ug), meropenem (10 ug), gentamicin (10 ug), ceftazidime (30 ug), ciprofloxacin (5 ug), ticarcillin (75 ug) and ticarcillin/ clavulanic acid (75 ug/10 ug), (all from Oxoid, Bakingstoke, United Kingdom). P. (...truncated)