Susceptibility of
            <i>Acinetobacter</i>
            Strains Isolated from Deployed U.S. Military Personnel

Hawley, Joshua S.; Murray, Clinton K.; Griffith, Matthew E.; McElmeel, M. Leticia; Fulcher, Letitia C.; Hospenthal, Duane R.; Jorgensen, James H.

doi:10.1128/aac.00858-06

Cited by 115 publications

(92 citation statements)

References 9 publications

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“…Admission-associated screening over the period of 2003-2009 has revealed that a wide range of patient isolates are resistant against most antimicrobials commonly used in the clinic and their ability to rapidly acquire additional resistance, such as described in the case of ABC isolates, which developed colistin resistance during the period of testing. 1,18 This trend was also confirmed in the present study-all tested isolates have to be considered MDR.…”

Section: Gentsupporting

confidence: 75%

In vitro characterization of multivalent adhesion molecule 7-based inhibition of multidrug-resistant bacteria isolated from wounded military personnel

et al. 2012

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Treatment of wounded military personnel at military medical centers is often complicated by colonization and infection of wounds with pathogenic bacteria. These include nosocomially transmitted, often multidrug-resistant pathogens such as Acinetobacter baumannii-calcoaceticus complex, Pseudomonas aeruginosa and extended spectrum b-lactamaseproducing Escherichia coli and Klebsiella pneumoniae. We analyzed the efficacy of multivalent adhesion molecule (MAM) 7-based anti-adhesion treatment of host cells against aforementioned pathogens in a tissue culture infection model. Herein, we observed that a correlation between two important hallmarks of virulence, attachment and cytotoxicity, could serve as a useful predictor for the success of MAM7-based inhibition against bacterial infections. Initially, we characterized 20 patient isolates (five from each pathogen mentioned above) in terms of genotypic diversity, antimicrobial susceptibility and important hallmarks of pathogenicity (biofilm formation, attachment to and cytotoxicity toward cultured host cells). All isolates displayed a high degree of genotypic diversity, which was also reflected by large strain-to-strain variability in terms of biofilm formation, attachment and cytotoxicity within each group of pathogen. Using non-pathogenic bacteria expressing MAM7 or latex beads coated with recombinant MAM7 for anti-adhesion treatment, we showed a decrease in cytotoxicity, indicating that MAM7 has potential as a prophylactic agent to attenuate infection by multidrug-resistant bacterial pathogens.

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Section: Gentsupporting

confidence: 75%

In vitro characterization of multivalent adhesion molecule 7-based inhibition of multidrug-resistant bacteria isolated from wounded military personnel

et al. 2012

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“…The finding of "cocarde" growth (increased growth near a disk surrounded by a zone of inhibition) has been reported with Serratia marcescens (11). The presence of "skip wells" with polymyxin MIC testing of P. aeruginosa (12) and A. baumannii (13) has also been reported. Heteroresistance, defined by population analysis profiles, has been described with isolates of A. baumannii, especially at concentrations of colistin surrounding the breakpoint of susceptibility (14).…”

mentioning

confidence: 84%

Irreproducible and Uninterpretable Polymyxin B MICs for Enterobacter cloacae and Enterobacter aerogenes

2013

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Carbapenem-resistant Enterobacter species are emerging nosocomial pathogens. As with most multidrug-resistant Gram-negative pathogens, the polymyxins are often the only therapeutic option. In this study involving clinical isolates of E. cloacae and E. aerogenes, susceptibility testing methods with polymyxin B were analyzed. All isolates underwent testing by the broth microdilution (in duplicate) and agar dilution (in duplicate) methods, and select isolates were examined by the Etest method. Selected isolates were also examined for heteroresistance by population analysis profiling. Using a susceptibility breakpoint of <2 g/ml, categorical agreement by all four dilution tests (two broth microdilution and two agar dilution) was achieved in only 76/114 (67%) of E. cloacae isolates (65 susceptible, 11 resistant). Thirty-eight (33%) had either conflicting or uninterpretable results (multiple skip wells, i.e., wells that exhibit no growth although growth does occur at higher concentrations). Of the 11 consistently resistant isolates, five had susceptible MICs as determined by Etest. Heteroresistant subpopulations were detected in eight of eight isolates tested, with greater percentages in isolates with uninterpretable MICs. For E. aerogenes, categorical agreement between the four dilution tests was obtained in 48/56 (86%), with conflicting and/or uninterpretable results in 8/56 (14%). For polymyxin susceptibility testing of Enterobacter species, close attention must be paid to the presence of multiple skip wells, leading to uninterpretable results. Susceptibility also should not be assumed based on the results of a single test. Until the clinical relevance of skip wells is defined, interpretation of polymyxin susceptibility tests for Enterobacter species should be undertaken with extreme caution.

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“…baumannii is now a multidrug-resistant opportunistic human pathogen that is frequently involved in outbreaks of nosocomial infections (10,18,22,42,46,50) and is an important cause of community-acquired pneumonia (2,4,8,21,53). In addition to its significance in infections in civilian settings, this bacterium has also been involved in wound infections among military personnel (12,15,41,55). Although nosocomial infections caused by A. baumannii have been reported worldwide (10,23,25,46,50) and throughout the United States (18,34), very little has been reported on the antibiotic susceptibility, genetic profiles, and molecular characteristics of hospital-acquired A. baumannii isolates in the Greater Los Angeles area.…”

Section: Discussionmentioning

confidence: 99%

“…Additionally, A. baumannii is increasingly recognized as an uncommon but increasingly important cause of community-acquired pneumonia, with a high mortality rate of 40% to 64% (2,4,8,21,53). In particular, increased incidences of A. baumannii infection have been reported among military personnel injured while deployed to Iraq and Afghanistan (12,15,41,55). Currently there are A. baumannii strains that are resistant to all major antibiotic classes normally used to treat infections with this organism, including ␤-lactams, aminoglycosides, fluoroquinolones, chloramphenicol, tetracycline, and rifampin (9,54).…”

mentioning

confidence: 99%

Phenotypic and Molecular Characterization ofAcinetobacter baumanniiClinical Isolates from Nosocomial Outbreaks in Los Angeles County, California

et al. 2008

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Multidrug-resistant Acinetobacter baumannii strains have increasingly resulted in nosocomial outbreaks worldwide, leaving limited options for treatment. To date, little has been reported on the antimicrobial susceptibilities and genomic profiles of A. baumannii strains from hospital outbreaks in the Greater Los Angeles area. In this study, we examined the susceptibilities and genetic profiles of 20 nonduplicate isolates of A. baumannii from nosocomial outbreaks in Los Angeles County (LAC) and determined their mechanisms of fluoroquinolone resistance. Antibiotic susceptibility testing indicated that the majority of these LAC isolates were not susceptible to 14 of the 17 antibiotics tested, with the exception of doxycycline, minocycline, and tigecycline. In particular, all isolates were found to be resistant to ciprofloxacin. Genomic DNA analysis revealed eight epidemiologically distinct groups among these 20 A. baumannii isolates, consistent with antibiotic susceptibility profiles. Sequencing analysis confirmed that concurrent GyrA and ParC amino acid substitutions in the "hot spots" of their respective quinolone resistance-determining regions were primarily responsible for the high-level ciprofloxacin resistance of these isolates. Antibiotic susceptibility testing using two efflux pump inhibitors suggested that the presence of efflux pumps was only a secondary contributor to ciprofloxacin resistance for some of the isolates. In summary, the present study has revealed good correlation between the antibiotic susceptibility profiles and genetic fingerprints of 20 clinical isolates from nosocomial outbreaks in Los Angeles County and has determined their mechanisms of fluoroquinolone resistance, providing an important foundation for continued surveillance and epidemiological analyses of emerging A. baumannii isolates in Los Angeles County hospitals.

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Susceptibility of Acinetobacter Strains Isolated from Deployed U.S. Military Personnel

Cited by 115 publications

References 9 publications

In vitro characterization of multivalent adhesion molecule 7-based inhibition of multidrug-resistant bacteria isolated from wounded military personnel

In vitro characterization of multivalent adhesion molecule 7-based inhibition of multidrug-resistant bacteria isolated from wounded military personnel

Irreproducible and Uninterpretable Polymyxin B MICs for Enterobacter cloacae and Enterobacter aerogenes

Phenotypic and Molecular Characterization ofAcinetobacter baumanniiClinical Isolates from Nosocomial Outbreaks in Los Angeles County, California

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