2.5.7 Acinetobacter.Varying frequencies of these carbapenemase genes in A. baumannii have been reported globally, with class D carbapenemase genes most often detected(Sabour et al.,2024)
 has been reported to show the presence of type AmpC chromosomal cephalosporinases, extended-spectrum B_lactamases, type D chromosomal (OXA-51), and plasmid (OXA-23, OXA-24, OXA-58, OXA143, and OXA 134) Carbapenemases, type A Carbapenemases (KPC and GES), and type B Carbapenemases (metallo-ss-lactamases), with the alteration of porins and efflux pumps(Requena_Cabello et al 2023)
 Acinetobacter baumanii Resistance to carbapenems is mainly mediated through acquired OXA-type carbapenem-hydrolyzing class D B lactamases [oxacillinases (OXAs)], encoded byblaoxA-23-like, blaoxA-40-like, blaoxA-58-like, blaoxA143-like, and blaoxA-235-like, Some variants of the intrinsic OXA-51-like carbapenemase confer carbapenem resistance when overexpressed via ISAbal.Freund, the presence of f-lactam antibiotic increased the cytoplasmic anhydromuropeptides which bind to AmpR and activatedAmpC while the absence of activating ligand-like peptidoglycan recycled product repressed AmpC expression, Previously, Ryuichi and coworkers determined the AmpC SS-lactamase expression level with or without AmpR and their results suggested that the resistance of CFE-1 (plasmid-encoded AmpC SS-lactamase) to cephalosporins is due to the substitution of Asp135Ala inAmpR of C. freundii )Tariq et al 2023).However, regional differences in the distribution of CREC CH?Ls have been observed, with KPC being predominant in North America, OXA-48 and VIM being predominant in Europe, and NDM being the most prevalent in China

A multinational surveillance study based on multi-locus sequence typing (MLST) revealed substantial clonal diversity of CREC, and ST114, ST93, ST90, and ST78 were potential high-risk clones globally widespread in 37 countries (Peirano et al., 2018).ECC strains are intrinsically resistant to cephalosporins due to the production of thechromosomalcephalosporinaseblaACT-16whereas the spread of acquired B-lactamases has been often documented, such as the class A extended-spectrum beta-lactamases (ESBLs) of the CTX-M and SHV families as well as carbapenemases, such as the VIM- and NDMtypes (class B), KPC-2 (class A) and OXA-48 (class).(Mavroidi et al 2023).In addition, overexpression of the ?-lactamase AmpC, the occurrence of extended-spectrum ?-lactamases (ESBLs), such as TEM, CTX-M, and SHV, membrane-associated mechanisms, such as outer membrane permeability, and the overexpression of efflux pumps have been demonstrated to contribute to carbapenem resistance in ECC.Cloacae, M. morganii, and C. freundii respectively.InC.