Analysis of antibiotic resistance genes in multidrug-resistant Acinetobacter sp. isolates from military and civilian patients treated at the Walter Reed Army Medical Center.
Military medical facilities treating patients injured in Iraq and Afghanistan have identified a large number of multidrug-resistant (MDR) Acinetobacter baumannii isolates. In order to anticipate the impact of these pathogens on patient care, we analyzed the antibiotic resistance genes responsible for the MDR phenotype in Acinetobacter sp. isolates collected from patients at the Walter Reed Army Medical Center (WRAMC). Susceptibility testing, PCR amplification of the genetic determinants of resistance, and clonality were determined. Seventy-five unique patient isolates were included in this study: 53% were from bloodstream infections, 89% were resistant to at least three classes of antibiotics, and 15% were resistant to all nine antibiotics tested. Thirty-seven percent of the isolates were recovered from patients nosocomially infected or colonized at the WRAMC. Sixteen unique resistance genes or gene families and four mobile genetic elements were detected. In addition, this is the first report of bla(OXA-58)-like and bla(PER)-like genes in the U.S. MDR A. baumannii isolates with at least eight identified resistance determinants were recovered from 49 of the 75 patients. Molecular typing revealed multiple clones, with eight major clonal types being nosocomially acquired and with more than 60% of the isolates being related to three pan-European types. This report gives a "snapshot" of the complex genetic background responsible for antimicrobial resistance in Acinetobacter spp. from the WRAMC. Identifying genes associated with the MDR phenotype and defining patterns of transmission serve as a starting point for devising strategies to limit the clinical impact of these serious infections.
Hujer
Kristine M
KM
Research Service, Louis Stokes Cleveland Veterans Affairs Medical Center, Cleveland, Ohio 44106, USA.
Hujer
Andrea M
AM
Hulten
Edward A
EA
Bajaksouzian
Saralee
S
Adams
Jennifer M
JM
Donskey
Curtis J
CJ
Ecker
David J
DJ
Massire
Christian
C
Eshoo
Mark W
MW
Sampath
Rangarajan
R
Thomson
Jodi M
JM
Rather
Philip N
PN
Craft
David W
DW
Fishbain
Joel T
JT
Ewell
Allesa J
AJ
Jacobs
Michael R
MR
Paterson
David L
DL
Bonomo
Robert A
RA
D000150:Acinetobacter / Q000187:drug effects* / Q000235:genetics* / Q000302:isolation & purification; D000151:Acinetobacter Infections / Q000097:blood / Q000453:epidemiology / Q000382:microbiology / Q000635:transmission; D040981:Acinetobacter baumannii / Q000235:genetics / Q000302:isolation & purification; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016470:Bacteremia / Q000453:epidemiology / Q000382:microbiology; D003428:Cross Infection / Q000382:microbiology*; D024901:Drug Resistance, Multiple, Bacterial; D005798:Genes, Bacterial / Q000187:drug effects*; D006772:Hospitals, Military; D006801:Humans; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D008889:Military Personnel; D012189:Retrospective Studies; D014481:United States