Genotyping of Environmental and Clinical Stenotrophomonas maltophilia Isolates and their Pathogenic Potential

Abstract

Stenotrophomonas maltophilia is a highly versatile species with useful biotechnological potential but also with pathogenic properties. In light of possible differences in virulence characteristics, knowledge about genomic subgroups is therefore desirable. Two different genotyping methods, rep-PCR fingerprinting and partial gyrB gene sequencing were used to elucidate S. maltophilia intraspecies diversity. Rep-PCR fingerprinting revealed the presence of 12 large subgroups, while gyrB gene sequencing distinguished 10 subgroups. For 8 of them, the same strain composition was shown with both typing methods. A subset of 59 isolates representative for the gyrB groups was further investigated with regards to their pathogenic properties in a virulence model using Dictyostelium discoideum and Acanthamoeba castellanii as host organisms. A clear tendency towards accumulation of virulent strains could be observed for one group with A. castellanii and for two groups with D. discoideum. Several virulent strains did not cluster in any of the genetic groups, while other groups displayed no virulence properties at all. The amoeba pathogenicity model proved suitable in showing differences in S. maltophilia virulence. However, the model is still not sufficient to completely elucidate virulence as critical for a human host, since several strains involved in human infections did not show any virulence against amoeba.

Quantitative analysis of volatile metabolites released in vitro by bacteria of the genus Stenotrophomonas for identification of breath biomarkers of respiratory infection in cystic fibrosis.

“…The clinical strains included in the present study belong to at least four of these genogroups (GGs) with GG6 containing most of them. All five environmental strains belong to either the strictly environmental species S. rhizophila (previous GG8) or GG9 [18][19][20]. …”

“…This species has been isolated from environmental sites only. Another distinct lineage, AFLP group 9 (MLST genogroup GG9 = 16S rRNA group E2), also seems to be a strictly environmental group [18][19][20]. In contrast, the AFLP group 6 (= MLST genogroup GG6) has repeatedly been shown to be prominent among clinical strains [16,17,37].…”

“…E2) and GG8 (S. rhizophila, syn. E1) branch at the base of Stenotrophomonas phylogenetic trees, and can therefore be considered ancestral lineages [18][19][20].…”

Requirement of the Pseudomonas aeruginosa CbrA Sensor Kinase for Full Virulence in a Murine Acute Lung Infection Model

“…Dictyostelium discoideum Ax2 was provided by M. Steinert (TU Branschweig) and routinely grown in HL-5 medium in cell culture flasks at 22.5°C (22). To analyze the virulence of the cbrA mutant using the amoeba host, the assay was performed according to a method described previously (23). Briefly, 50 l of overnight cultures grown in LB medium was mixed with 200 l PBS buffer and plated on M9 agar plates (6 g Na 2 HPO 4 , 3 g KH 2 PO 4 , 0.5 g NaCl, 1 g NH 4 Cl, 10 ml 100 mM MgSO 4 , 10 ml 10 mM CaCl 2 , 10 ml 40% glucose, and 15 g agar, per liter).…”

Multiple antibiotics resistant among environmental isolates of <i>Stenotrophomonas maltophilia</i>

“…Only confidence levels expressed as 'excellent identification' or 'very good identification' was considered in this study. All candidate isolates were confirmed by polymerase chain reaction with S. maltophilia-specific primers SM1f/SM4 as describe by Adamek et al (2011).…”