Epidemiology Features of Acinetobacter baumannii Colonizing Respiratory Tracts of ICU Patients


  • Noor Al-Dabaibah
  • Nathir M. Obeidat
  • Asem A Shehabi


Background: A. baumannii is becoming a common opportunistic and nosocomialpathogen in ICUs worldwide. Few studies have investigated the epidemiology of A.baumannii isolates colonizing the respiratory tract of hospitalized patients in ICUs.Methods: A total of 93 patients admitted to various intensive care unites (ICUs)over a period of 10-month at the Jordan University Hospital (JUH) were investigatedfor colonizing their respiratory tract with A. baumannii. Risk factors for respiratorycolonization with A. baumannii were determined. All A. baumannii isolateswere examined for their antimicrobial susceptibility pattern, presence of specificβ-lactamase genes and common genotypes using enterobacterial repetitive intergenicconsensus sequences (ERICs) and PCR.Results: Two third of hospitalized patients (63/93; 67.7 %) have their respiratorytract colonized with A. baumannii, and significant risk factors associated withcolonization were longer ICU stay, use of mechanical ventilators and antibiotictreatment with carbapenems. All A. baumannii isolates were multidrug resistant(MRAB) and possessed blaOXA-51-like gene; in addition, 73% and 19% of theisolates harbored blaOXA-23-like and blaOXA-24-like genes, respectively. All isolateswere negative for MBL-encoding gene (blaIMP-1) and only two isolates (3%)harbored (blaVIM-2) gene. The genetic similarity of A. baumannii isolates usingERICs-PCR and constructed dendrogram showed 2 major genotype clusters ofgenetically related isolates.Conclusion: This study shows that few genotypes of MRAB are often colonizingthe respiratory tract of hospitalized patients in ICUs, and colonization was rarelyassociated with blood sepsis and mortality.