AUTHOR=Luo Ting L. , Rickard Alexander H. , Srinivasan Usha , Kaye Keith S. , Foxman Betsy 

TITLE=Association of blaOXA-23 and bap with the persistence of Acinetobacter baumannii within a major healthcare system

JOURNAL=Frontiers in Microbiology

VOLUME=6

YEAR=2015

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2015.00182

DOI=10.3389/fmicb.2015.00182

ISSN=1664-302X

ABSTRACT=<p><bold>Objectives:</bold><italic>Acinetobacter baumannii</italic> is an emerging opportunistic nosocomial pathogen. Two factors that may enhance persistence in healthcare settings are antimicrobial resistance and biofilm-forming ability. The aim of this work was to determine whether <italic>A. baumannii</italic> isolates that persist in healthcare settings (endemic), can be differentiated from sporadic isolates based upon their ability to resist antibiotics and their biofilm-forming capability.</p><p><bold>Methods:</bold> Two hundred and ninety <italic>A. baumannii</italic> isolates were isolated over 17 months in the Detroit Medical Center (DMC). The isolates were genotyped using repetitive extragenic palindromic-PCR (REP-PCR). REP-types appearing greater than 10 times during active surveillance were considered endemic. The <italic>in vitro</italic> biofilm-forming ability and antibiotic resistance profile of each isolate were evaluated. Isolates were tested for the presence of two genetic markers—one implicated in biofilm formation (<italic>bap</italic>) and the other in antibiotic resistance (<italic>bla<sub>OXA-23</sub>)</italic>.</p><p><bold>Results:</bold> Of the 290 isolates evaluated, 84% carried <italic>bap</italic> and 36% carried <italic>bla<sub>OXA-23</sub></italic>. Five unique REP-PCR banding-types were detected &gt;10 times (endemic) and constituted 58% of the 290 isolates. These five endemic REP-PCR types were 5.1 times more likely than sporadic isolates to carry both <italic>bap</italic> and <italic>bla<sub>OXA-23</sub></italic>. Furthermore, endemic isolates were resistant to 3 more antibiotic classes, on average, than sporadic isolates and four of the five endemic REP-PCR types formed denser biofilms <italic>in vitro</italic> than sporadic isolates.</p><p><bold>Conclusions:</bold> Endemic <italic>A. baumannii</italic> isolates are more likely than sporadic isolates to possess factors that increase virulence and enhance survival within a large healthcare system.</p>