Genotypic Evolution of <i>Acinetobacter baumannii</i> Strains in an Outbreak Associated With War Trauma

Wortmann, Glenn; Weintrob, Amy; Barber, Melissa; Scott, Paul T.; Zoll, Scott T.; Eshoo, Mark W.; Sampath, Rangarajan; Ecker, David J.; Massire, Christian

doi:10.1086/588221

Cited by 23 publications

(25 citation statements)

References 7 publications

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“…In that study the investigators concluded that Rep-PCR was able to delineate S. pneumoniae with a discriminatory power equal to that of PFGE and suggested that it could be used as a stand-alone method for this species, with the only qualification that subtype groupings were more difficult to define by Rep-PCR. MLST with ESI-MS has been successfully used to type isolates of Streptococcus pyogenes, Acinetobacter baumannii, and Campylobacter species (8,9,13,21,38).…”

Section: Discussionmentioning

confidence: 99%

Occurrence, Distribution, and Origins of Streptococcus pneumoniae Serotype 6C, a Recently Recognized Serotype

et al. 2009

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The prevalence of Streptococcus pneumoniae serotype 6C, a recently recognized serotype that cross-reacts serologically with serotype 6A, was investigated. Isolates of serotype 6A in various collections were recovered, and serotype 6C was differentiated from 6A by multiplex PCR of DNA extracts by using appropriate primers. Antimicrobial susceptibility was performed by Clinical and Laboratory Standards Institute broth microdilution, and selected isolates were typed by pulsed-field gel electrophoresis, repetitive sequence-based PCR typing, and rapid multilocus sequence typing (MLST) by electrospray ionization mass spectrometry of PCR products. The sources of the isolates included blood (n ‫؍‬ 5), the lower respiratory tract (n ‫؍‬ 27), the sinus (n ‫؍‬ 5), the ear (n ‫؍‬ 2), and the nasopharynx (n ‫؍‬ 18); isolates were recovered from 49 children and 11 adults. Pediatric isolates were found in all six major U.S. geographic regions. Antimicrobial susceptibility showed that 22 isolates were nonsusceptible to penicillin, macrolides, and trimethoprim-sulfamethoxazole, 8 had other resistance patterns, and 30 were fully susceptible. The three typing methods used showed similar clusters of up to eight isolates per cluster. MLST showed five clusters related to serotype 6A, two clusters related to serotype 6B, one cluster related to serotype 3, and one cluster related to serotype 34. This study documents the occurrence, nationwide distribution, diversity, likely origins, and increasing incidence after 2001 of this recently recognized serotype. Serotype 6C warrants consideration for addition to future conjugate pneumococcal vaccines.The polysaccharide capsule is the major virulence determinant of Streptococcus pneumoniae, preventing phagocytosis. A total of 25 serotypes have one antigenic capsular determinant, while 21 serogroups have a common and one or more unique determinants. The number of known capsular serotypes, which totaled 90 in 1995 (16), increased to 91 in 2007 with the description of serotype 6C (34, 35). This new serotype crossreacts serologically with serotype 6A but is differentiated by a change in the wciN gene region of the capsular locus encoding for galactosyl transferase (32).A variety of capsular serotypes have been used to develop vaccines, and two such vaccines are currently available. The first is a 23-valent purified capsular polysaccharide vaccine (Pneumovax; Merck & Co, Whitehouse Station, NJ) containing 23 serotypes (1, 2, 3, 4, 5, 6B, 7F, 8, 9N, 9V, 10A, 11A, 12F, 14, 15B, 17F, 18C, 19F, 19A, 20, 22F, 23F, and 33F). The second is a 7-valent vaccine containing saccharides purified from capsular polysaccharides conjugated to a protein vector (PCV7) to provide immunity in children under 2 years of age (Prevnar; Wyeth Pharmaceuticals, Inc., Philadelphia, PA) and contains serotypes 4, 6B, 9V, 14, 18C, 19F, and 23F.In view of the inclusion of serotype 6B in PCV7 and the inability to differentiate serotypes 6A and 6C by serotyping, we recovered and reidentified isolates previously characterized as ser...

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Section: Discussionmentioning

confidence: 99%

Occurrence, Distribution, and Origins of Streptococcus pneumoniae Serotype 6C, a Recently Recognized Serotype

et al. 2009

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“…(8). PCR/ESI-MS has also been employed to track epidemics of A. baumannii associated with war trauma (31). In a multiclonal collection of Acinetobacter spp., PCR/ESI-MS analysis revealed that there was significant genetic diversity among clinical isolates (14).…”

Section: Discussionmentioning

confidence: 99%

“…Sites of infection include lung, bloodstream, urinary tract, and skin (20). In addition, A. baumannii has emerged as an important pathogen in injured United States military personnel stationed in Afghanistan and Iraq as they return to major military medical treatment facilities (14,(24)(25)(26)31). …”

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Rapid Determination of Quinolone Resistance in Acinetobacter spp

Hujer

Endimiani

et al. 2009

J Clin Microbiol

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In the treatment of serious bacterial infections, the rapid institution of appropriate antimicrobial chemotherapy may be lifesaving. Choosing the correct antibiotic or combination of antibiotics is becoming very important, as multidrug resistance is found in many pathogens. Using a collection of 75 well-characterized multidrug-resistant (MDR) Acinetobacter sp. isolates, we show that PCR followed by electrospray ionization mass spectrometry (PCR/ESI-MS) and base composition analysis of PCR amplification products can quickly and accurately identify quinolone resistance mediated by mutations in the quinolone resistance-determining regions of gyrA and parC, two essential housekeeping genes. Single point mutations detected by PCR/ESI-MS in parC (found in 55/75 of the isolates) and in gyrA (found in 66/75 of the isolates) correlated with susceptibility testing and sequencing. By targeting resistance determinants that are encoded by genes with highly conserved DNA sequences (e.g., gyrA and parC), we demonstrate that PCR/ESI-MS can provide critical information for resistance determinant identification and can inform therapeutic decision making in the treatment of Acinetobacter sp. infections.

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“…Comparative genomic analysis of a small number of clinical A. baumannii isolates previously revealed a poor correlation between genetic relatedness and patterns of antimicrobial susceptibility (1,17,35). Furthermore, a study involving wholegenome sequence analysis of six closely related clinical isolates revealed extensive divergence of the resistance genotype, with resistance genes associated with insertion sequences, plasmids, and a chromosomal resistance gene island all showing extensive variability, suggesting rapid evolution of drug resistance (2).…”

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Distribution of Intrinsic Plasmid Replicase Genes and Their Association with Carbapenem-Hydrolyzing Class D β-Lactamase Genes in European Clinical Isolates of Acinetobacter baumannii

Towner

Evans

Villa

et al. 2011

Antimicrob Agents Chemother

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Ninety-six genetically diverse multidrug-resistant clinical isolates of Acinetobacter baumannii from 25 hospitals in 17 European countries were screened by PCR for specific carbapenemase-hydrolyzing class D ␤-lactamase (CHDL) genes and by PCR-based replicon typing for the presence of 19 different plasmid replicase (rep) gene homology groups (GRs). Results were confirmed by DNA sequencing where necessary. All 96 isolates contained at least 1 (with a maximum of 4) of the 19 groups of rep genes. Groups detected were GR6 (repAci6; 93 isolates), GR2 (including repAci1 [67 isolates] and repAci2 [3 isolates]), GR16 (repApAB49; 12 isolates), GR12 (p2ABSDF0001; 10 isolates), GR3 (repAci3; 4 isolates), GR4 (repAci4; 3 isolates), GR10 (repAciX; 1 isolate), and GR14 (repp4AYE; 1 isolate). Variations in rep gene content were observed even among epidemiologically related isolates. Genes encoding OXA-58-like CHDLs (22 isolates) were associated with carriage of the repAci1, repAci3, repAci4, and repAciX genes, genes encoding OXA-40-like CHDLs (6 isolates) were associated with repAci2 and p2ABSDF0001, and genes encoding OXA-23-like CHDLs (8 isolates) were associated with repAci1. Most intrinsic Acinetobacter plasmids are non-self-transferable, but the almost ubiquitous repAci6 gene was strongly associated with a potential tra locus that could serve as a general system for plasmid mobilization and consequent horizontal transmission of plasmids and their associated antibiotic resistance genes among strains of A. baumannii.

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Genotypic Evolution of Acinetobacter baumannii Strains in an Outbreak Associated With War Trauma

Cited by 23 publications

References 7 publications

Occurrence, Distribution, and Origins of Streptococcus pneumoniae Serotype 6C, a Recently Recognized Serotype

Occurrence, Distribution, and Origins of Streptococcus pneumoniae Serotype 6C, a Recently Recognized Serotype

Rapid Determination of Quinolone Resistance in Acinetobacter spp

Distribution of Intrinsic Plasmid Replicase Genes and Their Association with Carbapenem-Hydrolyzing Class D β-Lactamase Genes in European Clinical Isolates of Acinetobacter baumannii

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