Molecular Characterization of Carbapenem-Resistant Acinetobacter baumannii Clinical Isolates from Egyptian Patients

Abstract

Acinetobacter baumannii (A. baumannii) represents a global threat owing to its ability to resist most of the currently available antimicrobial agents. Moreover, emergence of carbapenem resistant A. baumannii (CR-AB) isolates limits the available treatment options. Enzymatic degradation by variety of ß-lactamases, have been identified as the most common mechanism of carbapenem resistance in A. baumannii. The alarming increase in the prevalence of CR-AB necessitates continuous screening and molecular characterization to appreciate the problem. The present study was performed to assess the prevalence and characterize carbapenemases among 206 CR-AB isolated from various clinical specimens collected from different intensive care units at Kasr Al-Aini Hospital. All isolates were confirmed to be A. baumannii by detection of the blaOXA-51-like gene. Molecular screening of 13 common Ambler class bla carbapenemases genes in addition to insertion sequence (IS-1) upstream OXA-23 was performed by using four sets of multiplex PCR, followed by identification using gene sequencing technology. Among the investigated genes, the prevalence of blaOXA-23, and blaOXA-58 were 77.7%, and 1.9%, respectively. The ISAba1 was detected in 10% of the blaOXA-23 positive isolates. The prevalence of metallo-β-lactamases (MBLs) studied; blaNDM-1, blaSPM, blaVIM, blaSIM-1 were 11.7%, 6.3%, 0.5%, and 0.5% respectively. One of class A; bla KPC was detected in 10.7% of the investigated isolates. blaOXA-24/40, blaIMP, blaGES, blaVEB and blaGIM were not detected in any of the studied isolates. Moreover, 18.4% of the isolates have shown to harbor two or more of the screened bla genes. We concluded that the most prevalent type of ß-lactamases genes among CR-AB isolates collected from Egyptian patients were blaOXA-23 followed by blaNDM-1 and blaKPC.

Peer Review #1 of "Insights into mobile genetic elements and the role of conjugative plasmid in transferring aminoglycoside resistance in extensively drug-resistant Acinetobacter baumannii AB329 (v0.1)"

“…We detected the intrinsic resistance genes bla OXA-51 and bla ADC-25 as well as bla OXA-23 and bla TEM-1D in the genome of A. baumannii AB329. However, other beta-lactamase genes that were previously reported, such as bla PER-1 , bla NDM-1 , bla SPM , bla SIM , bla VIM , bla GIM , and bla IMP , were not detected (Leungtongkam et al, 2018a;Hassan et al, 2021;Kongthai et al, 2021). In addition, four classes of efflux pumps, including the MFS, RND, SMR, and MATE families, are associated with the antimicrobial resistance of A. baumannii (Abdi et al, 2020).…”

Molecular Characterization of Gene-Mediated Resistance and Susceptibility of ESKAPE Clinical Isolates to Cistus monspeliensis L. and Cistus salviifolius L. Extracts

“…e acquired carbapenem resistance in A. baumannii is often attributed to bla OXA-23 and bla OXA-24 , which are predominant in some Moroccan studies [42][43][44]. However, the weak prevalence of bla OXA-58 , bla VIM , and bla IMP reported by many studies [43,45], which were present in tested isolates, could be alarming since they could be easily transferred to other bacterial species. Furthermore, the P. aeruginosa harboring bla NDM found, to the best of our knowledge, for the first time poses a clinical challenge due to its potential transferability.…”