Molecular Epidemiology and Mechanisms of Carbapenem Resistance in Acinetobacter baumannii Endemic in New York City

Abstract

Multidrug-resistant Acinetobacter baumannii has emerged as a serious nosocomial pathogen in certain areas. In Brooklyn, New York, citywide surveillance revealed that approximately 2 of every 3 isolates were resistant to carbapenem antibiotics. Genetic fingerprinting revealed that 2 strains accounted for 82% of these resistant isolates. Compared with carbapenem-susceptible isolates, carbapenem-resistant isolates had reduced expression of 47-, 44-, and 37-kDa outer-membrane proteins. No specific carbapenemase was found; however, carbapenem-resistant isolates expressed greater levels of a class C cephalosporinase. Although expression of penicillin-binding proteins varied among strains, no consistent pattern appeared to account for carbapenem resistance. An efflux pump, present in several strains, did not appear to contribute to carbapenem resistance. Clonal spread of carbapenem-resistant A. baumannii has occurred in hospitals in Brooklyn. The preliminary findings for a small number of strains suggest that diminished production of outer-membrane porins, together with increased expression of a class C cephalosporinase, appear to be important factors leading to carbapenem resistance in this region.

Increasing Trend of Imipenem-Resistance Among Acinetobacter baumannii Isolated From Hospital Acquired Pneumonia in Northeast of Iran

“…In recent years, the increased use of antibiotics has led to the emergence of resistant strains (23). Antibiotic resistance to Acinetobacter baumannii may be acquired and intrinsic mechanisms, which these mechanisms include the enzyme, mutations in the gene target, the permeability of the outer membrane, and increase in expression of the efflux pumps (16,23). Today infection with multidrug-resistant (MDR), means that strains of Acinetobacter baumannii that are resistant to 3 current classes of antibiotics as well as strains of Acinetobacter baumannii in addition resistant to 3 common classes of antibiotics are resistant to imipenem as well and, are called extreme drug resistance (XDR) is increasing (24).…”

“…The imipenem resistance rate of A. baumannii from throughout the world in 2005 to 2009 reached resistance rates of more than 50% (15). The reports from Brooklyn, New York presented that almost 2 out of every 3 isolates were resistant to carbapenem antibiotics (16). In developing countries such as Iran, the incidence rate of carbapenem resistant A. baumannii (CNSAb) infections is a rising problem in hospitalized patients (17).…”

Ventilator-associated pneumonia in a tertiary care hospital in India: role of multi-drug resistant pathogens

“…MDR -Multi-drug resistant [25,26]. Similarly ESBL and AmpC β-lactamases were produced by a large proportion of the Enterobacteriaceae.…”

Prevalence of carbapenem resistance genes inAcinetobacter baumanniiisolated from clinical specimens obtained from an academic hospital in South Africa

“…This was a disturbing finding in that it showed that there are mechanisms of conferring resistance in A. baumannii other than the OXA and MBL genes. Such mechanisms may include diminished permeability of the cell membrane (3% as permeable as Escherichia coli), as described in a study by Quale et al 41 No further investigation into possible misidentification or determination of the antibiotic resistance mechanisms was conducted on these isolates. Thus, the possibility that the isolates were not true A. baumannii isolates cannot be excluded.…”