European Journal of Molecular & Clinical Medicine

Invasive infections due to Acinetobacter baumannii are among the leading
nosocomial infections in patients hospitalized in the intensive care unit (ICU). An increase in
multidrug-resistant has been observed in recent years. A hospital-based prospective study was
carried out on 287 laboratory-confirmed Acinetobacter species from various clinical samples
out of which 232 (81%) were found to be Acinetobacter baumannii and other species of
Acinetobacter were 55 (19%). Most of the isolates were obtained from pus samples (30.31%)
followed by Urine (25.43%), ET Tip (14.28%) ET Aspirate (12.19%) blood (4.18%). The
number of Isolates was more in IPD (91.99%) and less in OPD (8.01%). Among IPD
patients, the highest number of isolates were obtained from ICU (52.65%), surgery (21.97%),
and Obstetrics and gynecology (13.63%). Isolates showed the highest resistance towards
cephalosporins Ampicillin (89%) followed by Cefotaxime (87%), Ceftazidime (85%), and
ceftriaxone (84%). Among the carbapenem group, Meropenem was found more resistant in
comparison to Imipenem with a resistance rate of 61% and 56% respectively. Colistin was
found to be the most effective drug. Carbapenem resistance among other species of
Acinetobacter was 172 (61.82%) by the Modified carbapenem inactivation method (mCIM).
Out of 172 carbapenem-resistant isolates screened, 144 (83.72%) gave MHT positive that
confirms the production of carbapenemase by the isolates. A total of 140 (97.23%) out of
144 MHT positive isolates showed the presence of the target gene i.e., blaOXA-23.

Introduction: “Red alert” pathogen this is how Acinetobacterbaumannii identified nowdays in healthcare facilities, due to its extensive antibiotic resistance pattern. Multidrug-resistant A. baumannii infections are best treated with Carbapenems. The aim of the study is to estimate the numbers of blaoxaand ISAba1 producing strains among carbapenem-resistant A. baumannii clinical isolates. Method: identification of A. baumanniiwas carried out by Matrix-assisted laser desorption ionization–time of flight mass spectrometry, VITEK 2 compact was used to assess antimicrobial sensitivities and E test used to reconfirm susceptibility to imipenem, multiplex PCR for class D β lactamase genes detection. Mapping PCR carried out in order toestimate the presence of ISAba1 in relation to blaOXA-23 and blaOXA-51 genes. Results: Fourty eight A. baumanniistrains were isolated from different anatomical sites from surgical patients in Zagazig University hospital. Antibiogram showed that 81.3% (n=39) of the isolates were resistant to Imipenem, while 9 isolates were susceptible (18.7%). Of 39 resistant isolates to Imipenem, ISAba1 was detected in 35 isolates (89.7%). 34 isolates carried blaOXA-23 gene, all contained ISAba1/blaOXA-23 genes, and 20 contained ISAba1/blaOXA-51 genes. Resistant isolates to carbapenemsall had ISAba1 upstream of blaOXA-23 gene, WhileISAba1 upstream of blaOXA-51 found in both susceptible and resistant isolates. Conclusion: The ISAba1/blaOXA-23 genes were prevalent among the carbapenem-resistant A. baumannii isolates and may be responsible forcarbapenems resistance. The present study revealed that the existence of ISAba1/blaOXA-51 in A. baumannii isolates was not conclusive to carbapenems resistance