Molecular Characterization of Achromobacter Isolates from Cystic Fibrosis and Non-Cystic Fibrosis Patients in Madrid, Spain

Abstract

bMultilocus sequence typing and nrdA sequence analysis identified 6 different species or genogroups and 13 sequence types (STs) among 15 Achromobacter isolates from cystic fibrosis (CF) patients and 7 species or genogroups and 11 STs among 11 isolates from non-CF patients. Achromobacter xylosoxidans was the most frequently isolated species among CF patients.A chromobacter spp. are nonfermenting, Gram-negative rods that are widely distributed in nature, some of which are associated with opportunistic infection of humans (1). Because phenotypic methods for identification are inadequate, multilocus sequence typing (MLST) (2) and nrdA 765 DNA sequencing (3) have recently been developed to elucidate the taxonomy and epidemiology of Achromobacter isolates. In addition to seven previously named Achromobacter species, 14 new taxa have now been described, some of which are associated with infections in cystic fibrosis (CF) patients (2-5). The recent changes in the knowledge of the biodiversity of Achromobacter infections and the novel taxonomy mean that there are few published data on the clinical impact of different Achromobacter species. The aims of this study were to determine the prevalence and clinical importance of Achromobacter infection in CF patients in Spain and to understand the distribution of this genus among CF and non-CF patients.We undertook a retrospective study of all CF patients who were colonized or infected with Achromobacter and who were treated at the CF reference center of the Hospital Universitario 12 de Octubre (Madrid) between 2002 and 2012. Patients were considered chronically colonized if at least three positive cultures were obtained in 1 year and sporadically colonized if there were less than three positive cultures. Clinical records were reviewed to collect demographic, clinical, and microbiology data. Sputum samples were inoculated onto different culture media (Columbia 5% blood agar, MacConkey agar, mannitol-salt agar, chocolate agar, and Burkholderia cepacia selective agar [BCSA] medium). Phenotypic identification was performed using the Wider system (Francisco Soria-Melguizo, Spain) and API 20 NE (bioMérieux, Marcy l=Etoile, France). Antimicrobial susceptibility was determined by broth microdilution and the ε-test method and interpreted according to CLSI guidelines (6). Sequence analysis of 16S rRNA was used to confirm the phenotypic identification of Achromobacter spp., and MLST (2) and nrdA 765 DNA sequencing (3) were performed on all isolates. We tested for the presence of the bla OXA-114 -like gene by PCR for the identification of A. xylosoxidans (7). Taxonomic status was obtained by comparison of results to those in the GenBank (http://www.ncbi.nlm.nih.gov/BLAST) and MLST (http://pubmlst.org/achromobacter/) databases. Achromobacter isolates were also genotyped by pulsed-field gel electrophoresis (PFGE) (8). Univariate analysis was performed using the t test for continuous variables and the 2 or Fisher's exact test for categorical variables.Over the study period, 5.6% (14/250) of C...

Prevalence and species distribution of Achromobacter sp. cultured from cystic fibrosis patients attending the Aarhus centre in Denmark

“…A similar diversity was observed in the USA (14 different Achromobacter species and genogroups from 341 CF patients) [15], in Spain (six different species and genogroups from 14 CF patients) [16], in the UK (12 species and genogroups from 96 CF patients) [17] and in France (11 species and genogroups from 47 CF patients) [18]. In congruence with these studies, A. xylosoxidans was the Achromobacter sp.…”

Prevalence and Outcomes of Achromobacter Species Infections in Adults with Cystic Fibrosis: a North American Cohort Study

“…Studies have attributed persistent Achromobacter infections predominantly to A. xylosoxidans (2,11,12,18), with a few exceptions, including A. insuavis and A. dolens (5,6). We now know that this may represent a broader species distribution.…”

“…Two small single-center studies found that all patients were infected with unique Achromobacter strains (20,21). Conversely, several studies (both single and multicenter) have suggested that shared strains do exist (2,12,18,19,24,25,27,33,(43)(44)(45)(46)(47)(48), with common strains accounting for 5 to 50% of total Achromobacter infections. Additionally, chronic infection was most commonly due to persistence of the original infecting strain (14,19,45).…”

“…Species identification was determined by nrdA locus sequencing, one of the multilocus sequence typing (MLST) loci for Achromobacter spp. (18,54).…”

Detection of Achromobacter xylosoxidans in Hospital, Domestic, and Outdoor Environmental Samples and Comparison with Human Clinical Isolates

“…xylosoxidans is an important emerging pathogen among CF patients worldwide, commonly described as an environmental pathogen widely distributed in soils and waters (4,14,34,35). Nevertheless, this statement is not supported by any study in natural environments.…”