Molecular epidemiology of clinical Acinetobacter baumannii and Acinetobacter genomic species 13TU isolates using a multilocus sequencing typing scheme

Abstract

To further expand the limited multilocus sequence typing (MLST) database for Acinetobacter baumannii, 53 clinical isolates from various outbreaks in Europe and the USA, collected between 1991 and 2004, plus the A. baumannii reference strain ATCC 19606(T) and 20 clinical Acinetobacter genomic species 13TU isolates from the same period, were analyzed using a new MLST scheme based on fragments of the gltA, gyrB, gdhB, recA, cpn60, gpi and rpoD genes. Data were compared with typing results generated using pulsed-field gel electrophoresis (PFGE) and randomly amplified polymorphic DNA (RAPD)-PCR. In total, 50 sequence types (STs) were distinguished among the A. baumannii isolates investigated, and the MLST data were in high concordance with the PFGE and RAPD-PCR results. Only five clonal complexes were identified by eBURST analysis, including the 21 STs listed in a previous study, suggesting high diversity among the A. baumannii isolates. With one exception, there was no relatedness among isolates from outbreaks in different countries (Europe) or regions (USA). No intercontinental spread was revealed. Acinetobacter genomic species 13TU isolates could also be analyzed using the A. baumannii MLST scheme (18 different STs) and could be distinguished from A. baumannii isolates according to characteristic sequences. It was concluded that the MLST scheme provides a high level of resolution and is a promising tool for studying the epidemiology of A. baumannii and Acinetobacter genomic species 13TU.

Significant spread of extensively drug-resistant Acinetobacter baumannii genotypes of clonal complex 92 among intensive care unit patients in a university hospital in southern Iran

“…In addition, we found a high prevalence (98 %) of the bla OXA-23 -like gene across different genotypes. These results are consistent with observations reported from various parts of the world, and they explain the high risk of failure of carbapenem treatment in A. baumannii infections [14,[29][30][31][32][33][34].…”

“…Our study shows that the various ST groups of A. baumannii comprise different MLVA types, as determined by the greater discriminatory power of the MLVA, which corroborates findings reported by other researchers [15,28,[30][31][32]. The majority of the six VNTR markers we used in the MLVA have also been applied in epidemiological investigations conducted in other Iranian hospitals [16,30], whereas no previous reports from Iran have included results obtained for Abaum_0017.…”

Characterization of Epidemiologically Unrelated Acinetobacter baumannii Isolates from Four Continents by Use of Multilocus Sequence Typing, Pulsed-Field Gel Electrophoresis, and Sequence-Based Typing of bla OXA-51-like Genes

“…The diversity of the isolates used in this study, compared with the limited diversity of the isolates in the A. baumannii database, meant that a considerable number of novel STs was expected. Indeed, 19 novel STs were detected, with this result being similar to that of Wisplinghoff et al (44). Together with some earlier preliminary supporting evidence (1,44), this indicates that A. baumannii is more diverse than originally thought, especially as A. baumannii tends to spread clonally during outbreaks (5, 34).…”

“…Multilocus sequence typing (MLST) schemes, which use several housekeeping genes, have already been used to type many pathogenic bacteria (15,17,20,40), including A. baumannii (1,31,44), and MLST is emerging as an alternative to PFGE. MLST is used mainly for global epidemiology studies, but it has also been used successfully for short-term investigation of an outbreak of meningococcal disease (11).…”

Genotyping methods for monitoring the epidemic evolution of A. baumannii strains

“…Although the ACB complex is considered to be an important nosocomial infectious agent, the clustering of A. nosocomialis and A. pittii together in an ACB complex is unsatisfactory because of the ambiguity in biological and pathological differences within the species. An ACB complex is often associated with nosocomial infections [9]; however, A. calcoaceticus is predominantly an environmental isolate [10]. Thus, precise identification of species in an ACB complex is essential to determine the pathology, epidemiology, and ecology within these species.…”