Abstract
To compare the two Acinetobacter baumannii multi-locus sequence typing (MLST) schemes and to assess their suitability to aid in outbreak analysis we investigated the molecular epidemiology of 99 Acinetobacter baumannii isolates representing outbreak-related and sporadic isolates from 24 hospitals in four different countries (Germany, Poland, Sweden, and Turkey). Pulsed-field gel electrophoresis (PFGE) was used as the reference method to determine the epidemiologic relatedness of isolates and compared to MLST using both the Oxford and Pasteur scheme. Rep-PCR was used to define international clonal lineages (IC). We identified 26 unique outbreak strains and 21 sporadic strains. The majority of outbreaks were associated with carbapenem-resistant A. baumannii harbouring oxacillinase OXA-23-like and corresponding to IC 2. Sequence types (STs) obtained from the Oxford scheme correlate well with PFGE patterns, while the STs of the Pasteur scheme are more in accordance with rep-PCR grouping, but neither one is mirroring completely the results of the comparator. On two occasions the Oxford scheme identified two different STs within a single outbreak where PFGE patterns had only one band difference. The CCs of both MLST schemes were able to define clonal clusters that were concordant with the ICs determined by rep-PCR. IC4 corresponds to the previously described CC15 Pasteur (= CC103 Oxford). It can be concluded that both MLST schemes are valuable tools for population-based studies. In addition, the higher discriminatory power of the Oxford scheme that compares with the resolution obtained with PFGE can often aid in outbreak analysis.
Highlights
Molecular epidemiological investigation of bacteria is one of the pillars that trigger the institution of targeted infection control measures, which are required to eliminate A. baumannii and to prevent further spread
Pulsed-field gel electrophoresis (PFGE) is suited for outbreak analysis and is well established for fine-scale typing in local epidemiological studies [7,8,17]
In the field of longitudinal epidemiological studies, the automated rep-PCR with its internet database and web-tools is an approved method that can be used for outbreak analysis but its discriminatory power is inferior to PFGE
Summary
Members of the Acinetobacter baumannii group, i.e. A. baumannii, A. nosocomialis, A. pittii, and A. seifertii are a frequent cause of nosocomial infections, in particular ventilator-associatedPLOS ONE | DOI:10.1371/journal.pone.0153014 April 12, 2016Comparison of Two MLST Schemes for Acinetobacter baumannii pneumonia, urinary tract, and bloodstream infections [1,2,3]. Members of the Acinetobacter baumannii group, i.e. A_baumannii, A. nosocomialis, A. pittii, and A. seifertii are a frequent cause of nosocomial infections, in particular ventilator-associated. Comparison of Two MLST Schemes for Acinetobacter baumannii pneumonia, urinary tract, and bloodstream infections [1,2,3]. Patients in high-dependency care are mostly affected, and increasing multi-drug resistance worldwide is a cause of growing concern [4,5]. A. baumannii is known to be the most frequent Acinetobacter species isolated from patients in the ICU setting and it is known for its resistance to adverse environmental conditions, longevity on inanimate surfaces and propensity for epidemic spread [6]. A. baumannii is causing outbreaks of hospital infections around the world that are notoriously difficult to control
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