Colonization with OXA-23 and NDM positive clonally related carbapenem resistant acinetobacter baumannii’m ICU patients from Egypt

Carbapenem resistant Acinetobacter baumannii (CRAB) colonization is an important risk factor for CRAB infection especially in intensive care unit (ICU) patients. We aimed to evaluate the prevalence of colonization with CRAB in ICU patients, to characterize the molecular mechanisms involved in CRAB resistance and to examine clonal relatedness between the studied isolates. Thirty patients in the ICU were screened for CRAB colonization (February-October 2017. Rectal, nasal and axillary swabs were taken during the first 72 hours of hospitalization and at weekly intervals. Swabs were cultured on Acinetobacter CHROMagar. Identification and antimicrobial susceptibility testing (AST) were done using Vitek2 and verified by the presence of blaOXA-51-like. PCR was done for carbapenem resistance genes and genetic relatedness was studied using repetitive extragenic palindromic (REP) PCR. Eighteen CRAB isolates were recovered from 10 colonized patients (10/30; 33%). Four patients gave positive culture results in the first 72 hours of admission, while colonization was hospital acquired in six patients. All isolates were resistant to carbapenems, other β-lactam drugs, aminoglycosides and ciprofloxacin. BlaOXA-51-like was the main carbapenem resistance gene in all isolates (11/18; 61%) from Seven patients, followed by blaNDM-like (5/18; 27.8%) from four patients. REP-PCR delineated the 18 isolates into seven distinct patterns (A-G) in which A had 4 subtypes. CRAB colonization are increasingly common in the ICU, causing higher morbidity and mortality risks. The presence of blaOXA-51-like and blaNDM-like emphasizes the pervasiveness of these endemic enzymes. Well-established protocols for early detection of CRAB, proper infection-control measures and efficient surveillance systems are mandatory.