Carbapenem resistance in Acinetobacter baumannii: the molecular epidemic features of an emerging problem in health care facilities

Abstract

Acinetobacter baumannii is an opportunistic gram-negative pathogen with increasing relevance in a variety of nosocomial infections especially among intensive-care-unit (ICU) patients. Carbapenems have been widely used to treat serious multidrug-resistant A. baumannii infections; however, incidences of carbapenem-resistant A. baumannii are rising in several parts of the world and large and sustained outbreaks caused by such bacteria have been described. Carbapenem-resistant A. baumannii epidemics are sustained by clusters of highly similar strains that successfully spread among different cities and countries; their resistance phenotype is mainly due to the acquisition of carbapenem-hydrolyzing class D β-lactamase (CHDL) genes flanked by insertion sequence (IS) elements. Multi-facility outbreaks can be also sustained by inter-hospital transfer of colonized patients. Here, we review the global epidemiology of carbapenem-resistant A. baumannii, with the emphasis on the molecular epidemiology and genetic characterization of carbapenem resistance in epidemic strains.

Class 1 integrons in non-clonal multidrug-resistant Acinetobacter baumannii from Iran, description of the new bla IMP-55 allele in In1243

“…OXA-type b-lactamases are responsible for the most common type of carbapenem resistance via enzymatic degradation (Zarrilli et al, 2009). Although MBLs are not the predominant carbapenemases in A. baumannii, VIM, IMP, SIM and NDM metallo-b-lactamases have been found to contribute to the high-level resistance to carbapenems (Lin et al, 2014).…”

First Report of the blaOXA-23 Gene in a Clinical Isolates of Acinetobacter baumannii in Najaf Hospitals-Iraq

“…In the same manner, piperacillin-tazobactam, ampicillin-sulbactam and amikacin were the most active drug after carbapenem, study results similar to report from Iran, Feizabadi et al (2008) found that 42.1 and 38.2% of carbapenem resistant A. baumannii were susceptible to piperacillin-tazobactam and amikacin, respectively. These findings suggest the presence of another resistance mechanism that has not been previously investigated, such as extended spectrum β-lactamases, the modification of penicillin-binding proteins and the up-regulation of the efflux system (Zarrilli et al, 2009).…”

Comparison of Acinetobacter baumannii multidrugs resistant Isolates obtained from French and Tunisian hospitals

“…They showed multiple epidemic strains that persisted two years in some cases in the two hospitals study. The analysis of the molecular epidemiology and multidrug resistance of A. baumanni strains in the various parts of the world indicates a considerable degree of geographic diversity in the spread of various strains [23,24,25,26]. It's also demonstrated by multiple studies in Tunisia [20,21,27] and in France [28,29,30] that the multiresistance is common among A.baumannii giving nosocomial epidemics which were difficult to treat.…”