The Toxin-Antitoxin Systems of the Opportunistic Pathogen Stenotrophomonas maltophilia of Environmental and Clinical Origin

Abstract

Stenotrophomonas maltophilia is a ubiquitous environmental bacterium that has recently emerged as a multidrug-resistant opportunistic pathogen causing bloodstream, respiratory, and urinary tract infections. The connection between the commensal environmental S. maltophilia and the opportunistic pathogen strains is still under investigation. Bacterial toxin–antitoxin (TA) systems have been previously associated with pathogenic traits, such as biofilm formation and resistance to antibiotics, which are important in clinical settings. The same species of the bacterium can possess various sets of TAs, possibly influencing their overall stress response. While the TA systems of other important opportunistic pathogens have been researched, nothing is known about the TA systems of S. maltophilia. Here, we report the identification and characterization of S. maltophilia type II TA systems and their prevalence in the isolates of clinical and environmental origins. We found 49 putative TA systems by bioinformatic analysis in S. maltophilia genomes. Despite their even spread in sequenced S. maltophilia genomes, we observed that relBE, hicAB, and previously undescribed COG3832-ArsR operons were present solely in clinical S. maltophilia isolates collected in Lithuania, while hipBA was more frequent in the environmental ones. The kill-rescue experiments in Escherichia coli proved higBA, hicAB, and relBE systems to be functional TA modules. Together with different TA profiles, the clinical S. maltophilia isolates exhibited stronger biofilm formation, increased antibiotic, and serum resistance compared to environmental isolates. Such tendencies suggest that certain TA systems could be used as indicators of virulence traits.

Inactivation of Opportunistic Pathogens Acinetobacter baumannii and Stenotrophomonas maltophilia by Antimicrobial Photodynamic Therapy

“…A. baumannii clinical isolate II-a [ 31 ] and S. maltophilia clinical isolate SM3 [ 32 ] were chosen for the aPDT approach study. In all experiments, A. baumannii was grown in Luria-Bertani (LB) and S. maltophilia was grown in Tryptone soya broth (TSB) medium; both isolates were grown at 37 °C.…”

Novel Antibiotic Resistance Genes Identified by Functional Gene Library Screening in Stenotrophomonas maltophilia and Chryseobacterium spp. Bacteria of Soil Origin

“…Six Stenotrophomonas maltophilia and eight Chryseobacterium spp. antibiotic-resistant isolates were used for genomic library construction; all bacteria were isolated from farming field soil in Lithuania during the year 2016 [ 17 , 65 ]. The isolates were designated as resistant if the MIC of antibiotic value matched EUCAST clinical breakpoints (v. 7.0, 2017, PK/PD (non-species related).…”

Toxin–Antitoxin Systems in Pathogenic Bacteria

“…Bleriot et al studied the molecular mechanisms associated with chlorhexidine (CHLX) adaptation in two clinical strains of Klebsiella pneumoniae by phenotypic and transcriptomic analyses and their association with a new PemK/PemI TA system [12]. Klimkaitè et al have found by bioinformatic analysis 49 putative TA systems in Stenotrophomonas maltophilia, and asked whether clinical and environmental isolates contain a different set of type II TA systems [13]. The authors observed that RelBE, HicAB, and the previously undescribed COG3832-ArsR operon were present solely in clinical S. maltophilia isolates collected in Lithuania, while HipBA was more frequent in the environmental ones.…”