Phylogenetic Analysis ofStenotrophomonasspp. Isolates Contributes to the Identification of Nosocomial and Community-Acquired Infections

Abstract

Stenotrophomonas ssp. has a wide environmental distribution and is also found as an opportunistic pathogen, causing nosocomial or community-acquired infections. One species, S. maltophilia, presents multidrug resistance and has been associated with serious infections in pediatric and immunocompromised patients. Therefore, it is relevant to conduct resistance profile and phylogenetic studies in clinical isolates for identifying infection origins and isolates with augmented pathogenic potential. Here, multilocus sequence typing was performed for phylogenetic analysis of nosocomial isolates of Stenotrophomonas spp. and, environmental and clinical strains of S. maltophilia. Biochemical and multidrug resistance profiles of nosocomial and clinical strains were determined. The inferred phylogenetic profile showed high clonal variability, what correlates with the adaptability process of Stenotrophomonas to different habitats. Two clinical isolates subgroups of S. maltophilia sharing high phylogenetic homogeneity presented intergroup recombination, thus indicating the high permittivity to horizontal gene transfer, a mechanism involved in the acquisition of antibiotic resistance and expression of virulence factors. For most of the clinical strains, phylogenetic inference was made using only partial ppsA gene sequence. Therefore, the sequencing of just one specific fragment of this gene would allow, in many cases, determining whether the infection with S. maltophilia was nosocomial or community-acquired.

Are animals a source of Stenotrophomonas maltophilia in human infections? Contributions of a nationwide molecular study

“…In addition to the ST identification, the genogroups 2 and 6, the two most frequently encountered genogroups responsible for infections in humans, were comprised 26.4 and 13.2% of animal strains [8]. The presence of animal and human strains in the same genogroups suggest the possibility of (i) strain exchange between humans and animals or (ii) gene exchange through horizontal gene transfer between strains from the same genogroup, as reported by Cerezer et al for human and environmental strains [9]. Moreover, these genogroups included a large number of the strains responsible for respiratory tract infections in both human and animals [8].…”

“…We recently applied this last method to a large sample of human strains responsible for health care-associated infections, and we underlined the high prevalence of genogroup 6 and, more surprisingly, genogroup 2 [8]. Unfortunately, the various previously published studies did not include any strains originating from animals, even though Sm is responsible for colonization and infection in animals, particularly in horses [1,4,5,7,9,10]. A study of the genetic background of infectious strains from animals can help investigate their putative role as a reservoir for human infections.…”

An overview of various typing methods for clinical epidemiology of the emerging pathogen Stenotrophomonas maltophilia

“…In this view, MLST and phylogenetic analyses have been used for characterizing hospital and clinical strains of Stenotrophomonas spp. and for identifying community-and nosocomial-acquired origin of hospital infections (Cerezer et al, 2014). The inferred phylogenetic analysis by MLST clearly showed high clonal diversity, with the nosocomial isolates grouped separately from environmental strains (Cerezer et al, 2014).…”

“…and for identifying community-and nosocomial-acquired origin of hospital infections (Cerezer et al, 2014). The inferred phylogenetic analysis by MLST clearly showed high clonal diversity, with the nosocomial isolates grouped separately from environmental strains (Cerezer et al, 2014). Two subgroups of clinical isolates of S. maltophilia sharing high phylogenetic homogeneity presented intergroup recombination, thus indicating the high permittivity to horizontal gene transfer (Cerezer et al, 2014).…”

“…The inferred phylogenetic analysis by MLST clearly showed high clonal diversity, with the nosocomial isolates grouped separately from environmental strains (Cerezer et al, 2014). Two subgroups of clinical isolates of S. maltophilia sharing high phylogenetic homogeneity presented intergroup recombination, thus indicating the high permittivity to horizontal gene transfer (Cerezer et al, 2014). It was observed that, for most of the S. maltophilia clinical strains, the use of only ppsA partial gene sequence was sufficient to obtain a reliable phylogenetic inference (Cerezer et al, 2014).…”