Isolation and characterization of Raoultella ornithinolytica from Clinical Specimens in Hilla city, Iraq
 
Samir M. Al-Hulu, Alaa H. Al-Charrakh, Mohammed A.K. Al-Saadi
     Med. J. Babylon,  7(4) : 42-47. 2009.

Abstract:
 A total of 720 clinical samples were collected from three main hospitals in Hilla city/ Babylon province, Iraq. Samples were screened for presence of Raoultella spp., as well as studying their expression of virulence factors. A total of 144 bacterial isolates were recovered and identified as Klebsiella-like organisms. Out of these, 11 isolates were identified as Raoultella ornithinolytica, which represent 7.6% of all Klebsiella-like organisms found. Many virulence factors expressed by R. ornithinolytica were studied in vitro. All isolates produced capsule and expressed CFA/I, and CFA/III.
 
 
Nine isolates (81.8%) were able to produce siderophores. Four isolates (36.6%) were able to produce bacteriocin. All R. ornithinolytica isolates were unable to produce extracellular protease, hemolysin, and histamine. All isolates of R. ornithinolytica were resistant to penicillin, ampicillin, gentamicin, chloramphenicol, rifampin, cephalothin, cephotaxime, streptomycin, amoxicillin.,but they showed high sensitivity to nitrofurantoin and ciprofloxacin, and all them were completely sensitive to meropenem. R. ornithinolytica expressed a high degree of sensitivity to the effect of human serum when they grew in human serum at 37 oC for 3 hrs. The present study represented the first record of occurrence of R. ornithinolytica in human clinical samples in Iraq.
 
Introduction:
   The genus Raoultella (formerly Klebsiella) is a member of the family Enterobactericeae.The  data  from  the  sequence  analyses  of  the  16S  rRNA  along  with  previously  reported biochemical  and  DNAnDNA  hybridization  data  confirmed  that  the  genus  Klebsiella  is heterogeneous and composed of species which form three clusters that also included membersof other genera. These data support the division of the genus Klebsiella into two genera. The name Raoultella is proposed as a genus name for species of cluster II which contained Klebsiella  ornithinolytica,  Klebsiella  planticola,  and  Klebsiella  terrigena,  organisms.