Emergence of Raoultella ornithinolytica producing AmpC -Beta lactamases in the different clinical specimens

Abstract

The incidence of AmpC β –lactamases producing member of Enterobacteriaceae is increasing in recent years. The aim of this study was to evaluate AmpC β –lactamases production by clinical isolates of Raoultella  ornithinolytica by phenotypic detection (AmpC  disc  test (ADT) and modified three dimensional test(MTDT)) . Twenty isolates(8.73%) of Raoultella sp. were identified among 229 (70.89%) different bacteria (gram negative and gram positive) that isolated from different clinical specimens (urine 8(9.8%), burns 5(12.19%), wound5(6.3%) and stool 2(8.6%)) .Three species of Raoultella were isolated in this study that included Raoultella  ornithinolytica (16(6.98%)), Raoultella  terrigena (3 (1.31%)) and Raoultella planticola(1(0.43%)). Thirteen (81%) and10(62.5%) of Raoultella  ornithinolytica were resist to cefoxitin and amoxicillin-clavulanate respectively,10 out of 13 cefoxitin resistant and all isolates that resistant to   amoxicillin-clavulanate were produced AmpC β –lactamases by two  phenotypic tests .The AmpC β – lactamases producers were distributed to 3(100%) from burns ,6(75%)from urine and 1(33.3%) from wounds .The study showed AmpC β – lactamases producers were also high resist to other antibiotics that included tetracycline (90%) and ciprofloxacin(80%),and all isolates (100%) were sensitive to imipenem .

KEYWORDS: Raoultella ornithinolytica, AmpC β –lactamases, clinical specimens,