Authors
1 Department of Medical Microbiology/ College of Health Sciences/ Hawler Medical University/ Iraq
2 Department of Microbiology/ School of Medicine/ University of Sulaimani/ Iraq
Abstract
Background: -lactamases (MBLs) are emerging worldwide as powerful resistance determinants in Gram negative bacteria Rapid dissemination and spread between different bacterial species by large gene transfer favor by globalization and travel represent a high risk of worldwide pandemic among Enterobacteriaceae Objective:This study design to screen for phenotypic detection of MBL and genes coding for metallo - lactamase(MBL) such as, blaVIM, blaIMP and bla NDM among infected burn wound patients in Sulaimani city /Iraq. Materials and Methods: Out of 230 burn wound samples, 201 wound swabs and 29 tissue biopsy were collected from hospitalized burn patients with second and third degrees burnfrom Burn and Plastic Surgery Hospital in Sulaimani city from the period of April to October 2011. According to direct gram stain , bacterial cultural , biochemical tests, analytic profile identification(API) system and vitek 2 Compact system , antimicrobial susceptibility Testing by using Kirby-Bauer disk diffusion method and vitek compact system, -lactamase by Double disk synergy test and Combined EDTA disk test and Modified Hodge test and -lactamase enzyme by using polymerase chain reaction. Results: Out of 230 burn wound samples177 samples gram negative bacteria were isolated; inflammatory cells showed significantly associated with positive bacterial culture. The most frequent bacteria isolated were Pseudomonas species 48(27.12%), in which Pseudomonas aeruginosa account for a higher percentage 46(25.98%) and one species (0.56%) of each P. stutzeri and P.florescence wasisolated followed by Acinetobacterspecies 44 (24.86%) in which Acinetobacterbaumanniiwas the commonest and accounts for a higher percentage 41 (23.16%) and one species(0.56%) of each of A. ursingi, A. hemolyticasandA.complexwere identified. On the other hand in the family of Enterobacteriaceae,the most common bacteria were Klebsiellapneumoniae44(24.86%), Enterobacter cloacae 18 (10.17%) and Escherichia species 11(6.21%). The susceptibility of bacterial isolates against 18 antibiotics from different classes of antibiotics was tested and it was found that most of the isolated species of non fermenter bacteria such as Acinetobacterand Pseudomonas species show multidrug resistant pattern and high resistance against most of the antibiotics commonly used. The most resistant antibiotics against non fermenter bacteria were Ticarcillin (81.82%) against Pseudomonas species and Ticarcillin, Tazobactam- Pipracillin and Cefoxitin (93.18%) against Acinetobacterspecies .The most resistant antibiotic against K. pneumonia andE.cloacaewere Cefoxitin(84.9%)and Amoxicillin Clavulanic acid (84.9%).The most resistant antibiotics against Escherichia specieswere Cefotaxime, Trimethoprim and Cefipime (90.91%) but the most effective antibiotic with a highsensitivity rate was Imipenem (90.91).Phenotypic tests were carried out for the detection of MBL enzyme for all studied isolates and it was found that Combined disk test was the most sensitive test giving the highest percentage (31.07%) followed by Double disk synergy test(28.8%), Modified Hodge test (20.9%) .Polymerase chain reaction assay was used for genotypic detection of MBL genes (blaIMP,blaVIM, ,blaNDM ) in all isolates and the results revealed that the gene blaIMPwas locatedin 33(18.64%),blaVIM,in19 (10.73%), 2(1.12%)forblaNDM Also these genes were detected in 25 stock cultures of Gram negative bacteria preserved in 25 °C since 2008 to 2010. blaIMP gene was detected in11(44%) , blaVIM in 12(48%) and 2(8%) for blaNDM, all these genes were detected in K. pneumonae,P. aeruginosa and A. baumanniiwith length amplified genes (230) bp for IMP and (390)bp for VIM and( 621)bp for NDM. Conclusions:These results indicate that most of the Meropenem resistant strains from infected burn wound strains in this study were producing MBL enzymes The presence of MBL genes among Meropenem sensitive strains indicates that there might be a hidden MBL gene among isolated strains which cannot be diagnosed by phenotypic tests leading to the dissemination of these genes in the hospital silently among patients even within normal health workers who act as carriers for MBL genes in future
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