Characterization of carbapenem-resistant Acinetobacter baumannii isolates in a Chinese teaching hospital

Abstract

Carbapenem-resistant Acinetobacter baumannii (CRAB) presents a serious therapeutic and infection control challenge. In this study, we investigated the epidemiological and molecular differences of CRAB and the threatening factors for contributing to increased CRAB infections at a hospital in western China. A total of 110 clinical isolates of A. baumannii, collected in a recent 2-year period, were tested for carbapenem antibiotic susceptibility, followed by a molecular analysis of carbapenemase genes. Genetic relatedness of the isolates was characterized by multilocus sequence typing. Sixty-seven of the 110 isolates (60.9%) were resistant to carbapenems, 80.60% (54/67) of which carried the blaOXA-23 gene. Most of these CRAB isolates (77.62%) were classified as clone complex 92 (CC92), and sequence type (ST) 92 was the most prevalent STs, followed by ST195, ST136, ST843, and ST75. One CRAB isolate of ST195 harbored plasmid pAB52 from a Chinese patient without travel history. This plasmid contains toxin–antitoxin elements related to adaptation for growth, which might have emerged as a common vehicle indirectly mediating the spread of OXA-23 in CRAB. Thus, CC92 A. baumannii carrying OXA-23 is a major drug-resistant strain spreading in China. Our findings indicate that rational application of antibiotics is indispensable for minimizing widespread of drug resistance.

Characterization and molecular epidemiology of extensively prevalent nosocomial isolates of drug-resistant Acinetobacter spp

“…Epidemiological analysis of the 34 patients with carbapenem-resistant Acinetobacter spp indicated that 7 were ≥71 years old, 8 were between 61 and 70 years old, 5 were between 51 and 60 years old, 11 were between 21 and 50 years old, and 3 were ≤20 years old, with an average age of 47.6 years (SD = 21.31), ranging from 17-86 years, which was comparable to what was observed in other studies (48, 54, and 53.2 years; Wisplinghoff et al, 2000;Sunenshine et al, 2007;Godoy, 2012). In the patient sample, 20 were male (58.8%) and 14 were female (41.2%), supporting reports by Chang et al (2015) that males have a higher risk of infection than females. Analyzing the principal complaint related to patient admission, nine had hematological or solid neoplasms, eight had suffered trauma, five had neurological diseases, four had skin lesions (of which two were large burns), six had assorted clinical complaints (cardiac, respiratory, renal, digestive, metabolic), and two had been admitted due to post-surgery complications.…”

“…The genus Acinetobacter is widely distributed in nature (Baumann, 1968;Ferreira et al, 2011) and includes 37 different species (Peleg et al, 2008). Among these, Acinetobacter baumannii is the most clinically relevant species (Martins and Barth, 2013) and has emerged as a major problem in health institutions due to its ubiquity, difficult eradication (resistance to desiccation, chemical sanitizers, and ultraviolet) (Cherkaoui et al, 2015), and high tendency to acquire resistance to antibiotics (Peleg et al, 2008;Chang et al, 2015). This species is responsible for nosocomial infections, especially by cross transmission, and has a propensity to cause outbreaks (Khorsi et al, 2015).…”

“…Treating these infections has been a challenge, due to the resistance of these microorganisms to b-lactam antibiotics, which are highly-effective antimicrobial agents with low toxicity, that are widely used in the treatment of Gram-negative bacterial infections (Peleg et al, 2008;Chang et al, 2015).…”

“…Enzymes belonging to every class of b-lactamase from the Ambler molecular classification have been described in A. baumannii: class A, extended-Spectrum b-lactamases; class B, metallo-b-lactamases (MbL); class C, Acinetobacter-derived cephalosporinases, and class D, carbapenem-hydrolyzing class D b-lactamases (Hammoudi et al, 2015). Among these, the emergence of carbapenem resistance in A. baumannii has become a current global issue (Peleg et al, 2008;Chang et al, 2015). The molecular basis of carbapenem resistance is mainly due to the presence of Ambler class D oxacillinases, including the phylogenetic groups bla OXA-23 -like, bla OXA-40 -like, and bla OXA-58 -like oxacillinases, or to the overproduction of intrinsic enzymes of the group bla OXA-51 -like (Queenan and Bush, 2007;Abbott et al, 2013;), where the promoter sequences are associated with this gene, such as ISAba1 (de Sá Cavalcanti et al, 2013).…”

Distribution of Aminoglycoside Resistance Genes Among Acinetobacter Baumannii Strains Isolated From Burn Patients in Tehran, Iran

“…baumannii is an opportunistic pathogen primarily associated with nosocomial infections worldwide (17). In addition to causing broad range of infections (eg, pneumonia, urinary tract, bloodstream, and skin infections), this organism is responsible for 10% of all nosocomial infections.…”