Antimicrobial Resistance Determinants in Acinetobacter baumannii Isolates Taken from Military Treatment Facilities

Abstract

c Multidrug-resistant (MDR) Acinetobacter baumannii infections are of particular concern within medical treatment facilities, yet the gene assemblages that give rise to this phenotype remain poorly characterized. In this study, we tested 97 clinical A. baumannii isolates collected from military treatment facilities (MTFs) from 2003 to 2009 by using a molecular epidemiological approach that enabled for the simultaneous screening of 236 antimicrobial resistance genes. Overall, 80% of the isolates were found to be MDR, each strain harbored between one and 17 resistant determinants, and a total of 52 unique resistance determinants or gene families were detected which are known to confer resistance to ␤-lactam (e.g., bla GES-11 , bla TEM , bla OXA-58 ), aminoglycoside (e.g., aphA1, aacC1, armA), macrolide (msrA, msrB), tetracycline [e.g., tet(A), tet(B), tet(39)], phenicol (e.g., cmlA4, catA1, cat4), quaternary amine (qacE, qacE⌬1), streptothricin (sat2), sulfonamide (sul1, sul2), and diaminopyrimidine (dfrA1, dfrA7, dfrA19) antimicrobial compounds. Importantly, 91% of the isolates harbored bla OXA-51-like carbapenemase genes (including six new variants), 40% harbored the bla OXA-23 carbapenemase gene, and 89% contained a variety of aminoglycoside resistance determinants with up to six unique determinants identified per strain. Many of the resistance determinants were found in potentially mobile gene cassettes; 45% and 7% of the isolates contained class 1 and class 2 integrons, respectively. Combined, the results demonstrate a facile approach that supports a more complete understanding of the genetic underpinnings of antimicrobial resistance to better assess the load, transmission, and evolution of MDR in MTF-associated A. baumannii.

High prevalence of multidrug-resistance in Acinetobacter baumannii and dissemination of carbapenemase-encoding genes blaOXA-23-like, blaOXA-24-like and blaNDM-1 in Algiers hospitals

“…In agreement in our study, the prevalence of trimethoprim/sulfamethoxazole resistance in A. baumannii is high in many geographic regions [4] . Although acquired-dfr genes were previously reported within integron structures [4,49] , none of dfr gene clusters was detected in our strains. Trimethoprim resistance in Acinetobacter can be related to housekeeping dfr genes and to efflux systems [50,51].…”

“…Trimethoprim resistance in Acinetobacter can be related to housekeeping dfr genes and to efflux systems [50,51]. Sulfonamides resistance genes sul1 and sul2 genes were highly present in our strains, they are commonly described in Acinetobacter and are predictive of the presence of integrons [49,52] . tetB gene was highly prevalent among our tetracycline-resistant strains (76.54%) compared to tetA, as previously reported in Acinetobacter [53] , tetB also confers resistance to minocycline [2].…”

Magnesium alloy AZ91 exhibits antimicrobial properties in vitro but not in vivo

“…This bacterium was chosen, as it is a member of ESKAPE, a class of pathogens considered to be the most problematic due to growing multidrug resistance . Further, A. baumannii has become a significant cause of infections in military centers, and has been identified as a source of orthopedic device related infections …”

Antimicrobial Resistance Prediction in PATRIC and RAST

“…The traditional culture-based detection of AMR phenotypes has drawbacks because many organisms are fastidious growers or may be unculturable89. Molecular approaches, including the high-throughput detection of biomarkers, has improved dramatically over the years101112 but is often limited by the number of markers that can be detected and is constrained by our current knowledge of AMR resistance mechanisms, which are evolving rapidly1131415.…”