-
Frontiers in Cellular and Infection... 2024The hemin acquisition system is composed of an outer membrane TonB-dependent transporter that internalizes hemin into the periplasm, periplasmic hemin-binding proteins...
INTRODUCTION
The hemin acquisition system is composed of an outer membrane TonB-dependent transporter that internalizes hemin into the periplasm, periplasmic hemin-binding proteins to shuttle hemin, an inner membrane transporter that transports hemin into the cytoplasm, and cytoplasmic heme oxygenase to release iron. Fur and HemP are two known regulators involved in the regulation of hemin acquisition. The hemin acquisition system of is poorly understood, with the exception of HemA as a TonB-dependent transporter for hemin uptake.
METHODS
Putative candidates responsible for hemin acquisition were selected via a homolog search and a whole-genome survey of . Operon verification was performed by reverse transcription-polymerase chain reaction. The involvement of candidate genes in hemin acquisition was assessed using an in-frame deletion mutant construct and iron utilization assays. The transcript levels of candidate genes were determined using quantitative polymerase chain reaction.
RESULTS
and operons were selected as candidates for hemin acquisition. Compared with the parental strain, and mutants displayed a defect in their ability to use hemin as the sole iron source for growth. However, hemin utilization by the and mutants was comparable to that of the parental strain. expression was repressed by Fur in iron-replete conditions and derepressed in iron-depleted conditions. HemP negatively regulated expression. Like , was repressed by Fur in iron-replete conditions; however, was moderately derepressed in response to iron-depleted stress and fully derepressed when hemin was present. Unlike and , the operon was constitutively expressed, regardless of the iron level or the presence of hemin, and Fur and HemP had no influence on its expression.
CONCLUSION
HemA, HemU, and TonB1 contribute to hemin acquisition in . Fur represses the expression of and in iron-replete conditions. expression is regulated by low iron levels, and HemP acts as a negative regulator of this regulatory circuit. expression is regulated by low iron and hemin levels in a -dependent manner.
Topics: Hemin; Stenotrophomonas maltophilia; Bacterial Proteins; Membrane Proteins; Iron
PubMed: 38596648
DOI: 10.3389/fcimb.2024.1380976 -
Journal of Medical Microbiology Nov 2014Infection is an important cause of morbidity and mortality among patients with end stage renal disease. Stenotrophomonas maltophilia is an unusual yet emerging pathogen... (Review)
Review
Infection is an important cause of morbidity and mortality among patients with end stage renal disease. Stenotrophomonas maltophilia is an unusual yet emerging pathogen in dialysis units. We performed a systematic PubMed/Medline and Scopus review of peer-reviewed English papers on S. maltophilia infections among patients undergoing chronic dialysis, with regard to vascular accesses, systemic infections and environment contaminations. Moreover, we suggest a treatment algorithm to preserve the patient and the permanent dialysis catheters.
Topics: Algorithms; Catheter-Related Infections; Communicable Diseases, Emerging; Gram-Negative Bacterial Infections; Humans; Renal Dialysis; Stenotrophomonas maltophilia
PubMed: 25102909
DOI: 10.1099/jmm.0.076513-0 -
Frontiers in Cellular and Infection... 2023complex (Smc) comprises opportunistic Gram-negative bacilli responsible for various nosocomial infections. Limited data exists concerning its evolutionary lineage,...
INTRODUCTION
complex (Smc) comprises opportunistic Gram-negative bacilli responsible for various nosocomial infections. Limited data exists concerning its evolutionary lineage, global prevalence and pathogenicity.
METHODS
We conducted an extensive genomic analysis on 734 Smc genomes, of which 90 were newly sequenced and isolated from different patients. The species composition and evolutionary relationships of Smc were examined using core protein sequence analysis. Pathogenicity evaluation was used by assays for swimming motility, biofilm formation and identification of virulence factors. The broth microdilution method was used to evaluate the drug resistance spectrum of clinical isolates.
RESULTS
Phylogenetic analyses delineated 24 species-level clades, dominated by (42.8%), (13.6%) and (9.9%). Geographically, strains were primarily distributed in Europe (34.2%), Asia (33.7%) and North America (24.0%), with intricate global distribution patterns. Meanwhile, 154 virulence-associated genes and 46 antimicrobial resistance genes within Smc were identified. These genes encoded span various functions, including motility, adherence, toxin, RND antibiotic efflux pumps, beta-lactamases and aminoglycoside-modifying enzymes. Moreover, significant variations were indicated in swimming motility and biofilm-forming capability across the different species, with exhibiting superior levels of both traits. Additionally, no statistically significant discrepancy was detected among Smc species to other antibiotics, despite the fact that all isolates were resistant to Ceftazidime and much higher than other species.
CONCLUSION
Our findings indicate the need to pay increased attention to other mainstream species of Smc besides in order to better manage Smc-related infections and tailor effective treatment strategies.
Topics: Humans; Virulence; Stenotrophomonas; Phylogeny; Stenotrophomonas maltophilia; Biological Evolution; Anti-Bacterial Agents
PubMed: 38268792
DOI: 10.3389/fcimb.2023.1325379 -
International Journal of Medical... 2018is a multi-drug resistant opportunistic pathogen that causes nosocomial infections in immunocompromised patients. This pathogen is difficult to treat owing to its...
is a multi-drug resistant opportunistic pathogen that causes nosocomial infections in immunocompromised patients. This pathogen is difficult to treat owing to its intrinsic multidrug resistance and ability to form antimicrobial-tolerant biofilms. In the present study, we aimed to assess the potential use of celastrol as a novel anti-biofilm and/or anti-virulence agent against . Results showed that celastrol at its sub-inhibitory doses decreased biofilm formation and disrupt the established biofilms produced by . Celastrol-induced decrease in biofilm formation was dose-dependent based on the results of the microtiter plate biofilm assays and confocal laser scanning microscopy. In addition, our data validated the anti-virulence efficacy of celastrol, wherein it significantly interfered with the production of protease and motility of . To support these phenotypic results, transcriptional analysis revealed that celastrol down-regulated the expression of biofilm- and virulence- associated genes (, , and ) in . Interestingly, celastrol significantly inhibited the expression of gene, which encodes the resistance-nodulation-division (RND)-type efflux pump, SmeYZ. Overall, our findings suggested that celastrol might be a promising bioactive agent for treatment of biofilm- and virulence-related infections caused by the multi-drug resistant .
Topics: Anti-Bacterial Agents; Bacterial Proteins; Biofilms; Cross Infection; Gene Expression Regulation, Bacterial; Humans; Pentacyclic Triterpenes; Stenotrophomonas maltophilia; Triterpenes; Virulence
PubMed: 29725253
DOI: 10.7150/ijms.23924 -
BMC Microbiology Sep 2020Stenotrophomonas maltophilia (S. maltophilia) is an important opportunistic pathogen that can be isolated in hospitals. With the abuse of broad spectrum antibiotics and...
BACKGROUND
Stenotrophomonas maltophilia (S. maltophilia) is an important opportunistic pathogen that can be isolated in hospitals. With the abuse of broad spectrum antibiotics and invasive surgical devices, the rate of S. maltophilia infection is increasing every year. This study was an epidemiological analysis of the clinical and molecular characteristics of S. maltophilia infection in a Chinese teaching hospital. The goal was to obtain a comprehensive understanding of the status of S. maltophilia infection to provide strong epidemiological data for the prevention and treatment of S. maltophilia infection.
RESULTS
A total of 93 isolates from Renji Hospital affiliated with the Shanghai Jiaotong University School of Medicine were included, in which 62 isolates were from male patients. In addition, 81 isolates were isolated from sputum samples. A total of 86 patients had underlying diseases. All patients received antibiotics. Multilocus sequence typing (MLST) analysis indicated that 61 different sequence types (STs) were found (including 45 novel STs), and MLST did not show significantly dominant STs. Pulsed field gel electrophoresis (PFGE) results showed that 93 isolates could be divided into 73 clusters, and they also showed weak genetic linkages between isolates. The resistant rates to trimethoprim/sulfamethoxazole (TMP/SMX) and levofloxacin were 9.7 and 4.3%, respectively, and all isolates were susceptible to minocycline. Four virulence gene's loci Stmpr1, Stmpr2, Smf-1, and Smlt3773 were positive in 79.6, 91.4, 94.6, and 52.7% of the isolates, respectively. Three biofilm genes rmlA, spgM, and rpfF were positive in 82.8, 92.5, and 64.5% of the isolates, respectively. Mean biofilm forming level of OD was 0.54 ± 0.49. We did not find any significant difference between different genders and different age-groups. We retrospectively analyzed data from patients in the intensive care unit (ICU) and the control group. The independent risk factors of those who were infected in the ICU included immunosuppression and the increased antibiotic usage.
CONCLUSIONS
Most of the patients had prior medical usage histories and baseline diseases. The positive rate of virulence genes was high, the drug resistance rate of S. maltophilia was low, and the biofilm formation ability was strong. The increased use of antibiotics was an independent risk factor for S. maltophilia infection, which should receive more attention. No obvious clonal transmissions were found in the same departments.
Topics: Adolescent; Adult; Aged; Aged, 80 and over; Anti-Bacterial Agents; Bacterial Typing Techniques; Biofilms; Case-Control Studies; China; Drug Resistance, Bacterial; Electrophoresis, Gel, Pulsed-Field; Female; Gene Expression; Genes, Bacterial; Gram-Negative Bacterial Infections; Hospitals, Teaching; Humans; Intensive Care Units; Levofloxacin; Male; Microbial Sensitivity Tests; Middle Aged; Minocycline; Molecular Epidemiology; Multilocus Sequence Typing; Opportunistic Infections; Retrospective Studies; Risk Factors; Stenotrophomonas maltophilia; Trimethoprim, Sulfamethoxazole Drug Combination
PubMed: 32993493
DOI: 10.1186/s12866-020-01985-3 -
BMC Research Notes Apr 2021The purpose of the present study was to investigate the antimicrobial susceptibility pattern, biofilm production, and the presence of biofilm genes among the S....
OBJECTIVE
The purpose of the present study was to investigate the antimicrobial susceptibility pattern, biofilm production, and the presence of biofilm genes among the S. maltophilia clinical isolates. A total of 85 clinical isolates of S. maltophilia were collected from patients referred to several hospitals. Susceptibility to antibiotics was investigated by disc diffusion method according to the guidelines of the Clinical and Laboratory Standards Institute (CLSI). By the crystal violet staining method, the capability of biofilm formation was examined. The genes associated with biofilm production were investigated by the PCR-sequencing techniques.
RESULTS
All isolates were resistant to doripenem, imipenem, and meropenem. Minocycline, trimethoprim/sulfamethoxazole and levofloxacin exhibited the highest susceptibility of 100%, 97.65%, and 95.29%, respectively. The results of crystal violet staining assay showed that all isolates (100%) form biofilm. Moreover, 24 (28.23%), 32 (37.65%), and 29 (34.12%) of isolates were categorized as weak, moderate, and strong biofilm producers, respectively. Biofilm genes including rpfF, spgM and rmlA had an overall prevalence of 89.41% (76/85), 100% (85/85) and 84.71% (72/85), respectively. Rational prescribing of antibiotics and implementation of infection control protocols are necessary to prevent further infection and development of antimicrobial resistance. Combination strategies based on the appropriate antibiotics along with anti-biofilm agents can also be selected to eliminate biofilm-associated infections.
Topics: Anti-Bacterial Agents; Biofilms; Drug Resistance, Microbial; Gram-Negative Bacterial Infections; Humans; Microbial Sensitivity Tests; Stenotrophomonas maltophilia
PubMed: 33879237
DOI: 10.1186/s13104-021-05567-y -
Frontiers in Cellular and Infection... 2020The complexity of biofilms constitutes a therapeutic challenge and the antimicrobial susceptibility of fungal-bacterial biofilms remains poorly studied. The filamentous...
The complexity of biofilms constitutes a therapeutic challenge and the antimicrobial susceptibility of fungal-bacterial biofilms remains poorly studied. The filamentous fungus (Af) and the Gram-negative bacillus (Sm) can form biofilms and can be co-isolated from the airways of cystic fibrosis (CF) patients. We previously developed an biofilm model which highlighted the antibiosis effect of Sm on Af, which was dependent on the bacterial fitness. The aim of the present study was to investigate the susceptibility of Af and Sm in mono- or polymicrobial biofilms to five antimicrobial agents alone and in two-drug combinations. Af and Sm clinical reference strains and two strains from CF sputa were tested through a planktonic and biofilm approaches. Af, Sm, or Af-Sm susceptibilities to amphotericin B (AMB), itraconazole (ITC), voriconazole (VRC), levofloxacin (LVX), and rifampicin (RFN) were evaluated by conventional planktonic techniques, crystal violet, XTT, qPCR, and viable plate count. Af planktonic cells and biofilms in formation were more susceptible to AMB, ITC, and VRC than Af mature biofilms. Af mature biofilms were susceptible to AMB, but not to ITC and VRC. Based on viable plate count, a lower concentration of LVX and RFN was required to reduce Sm cell numbers on biofilms in formation compared with mature biofilms. The antibiosis effect of Sm on Af growth was more pronounced for the association of CF strains that exhibited a higher fitness than the reference strains. In Af-Sm biofilms, the fungal susceptibility to AMB was increased compared with Af biofilms. In contrast, the bacterial susceptibility to LVX decreased in Af-Sm biofilms and was fungal biomass-dependent. The combination of AMB (64 μg/mL) with LVX or RFN (4 μg/mL) was efficient to impair Af and Sm growth in the polymicrobial biofilm. Sm increased the Af susceptibility to AMB, whereas Af protected Sm from LVX. Interactions between Af and Sm within biofilms modulate susceptibility to antimicrobial agents, opening the way to new antimicrobial strategies in CF patients.
Topics: Anti-Bacterial Agents; Antifungal Agents; Aspergillus fumigatus; Biofilms; Humans; Microbial Sensitivity Tests; Stenotrophomonas maltophilia
PubMed: 33123497
DOI: 10.3389/fcimb.2020.574028 -
Journal of Biomedical Science Apr 2022Stenotrophomonas maltophilia, a member of γ-proteobacteria, is a ubiquitous environmental bacterium that is recognized as an opportunistic nosocomial pathogen. FecABCD...
BACKGROUND
Stenotrophomonas maltophilia, a member of γ-proteobacteria, is a ubiquitous environmental bacterium that is recognized as an opportunistic nosocomial pathogen. FecABCD system contributes to ferric citrate acquisition in Escherichia coli. FeoABC system, consisting of an inner membrane transporter (FeoB) and two cytoplasmic proteins (FeoA and FeoC), is a well-known ferrous iron transporter system in γ-proteobacteria. As revealed by the sequenced genome, S. maltophilia appears to be equipped with several iron acquisition systems; however, the understanding of these systems is limited. In this study, we aimed to elucidate the ferric citrate acquisition system of S. maltophilia.
METHODS
Candidate genes searching and function validation are the strategy for elucidating the genes involved in ferric citrate acquisition. The candidate genes responsible for ferric citrate acquisition were firstly selected using FecABCD of E. coli as a reference, and then revealed by transcriptome analysis of S. maltophilia KJ with and without 2,2'-dipyridyl (DIP) treatment. Function validation was carried out by deletion mutant construction and ferric citrate utilization assay. The bacterial adenylate cyclase two-hybrid system was used to verify intra-membrane protein-protein interaction.
RESULTS
Smlt2858 and Smlt2356, the homologues of FecA and FecC/D of E. coli, were first considered; however, deletion mutant construction and functional validation ruled out their involvement in ferric citrate acquisition. FciA (Smlt1148), revealed by its upregulation in DIP-treated KJ cells, was the outer membrane receptor for ferric citrate uptake. The fciA gene is a member of the fciTABC operon, in which fciT, fciA, and fciC participated in ferric citrate acquisition. Uniquely, the Feo system of S. maltophilia is composed of a cytoplasmic protein FeoA, an inner membrane transporter FeoB, and a predicted inner membrane protein FeoI. The intra-membrane protein-protein interaction between FeoB and FeoI may extend the substrate profile of FeoB to ferric citrate. FeoABI system functioned as an inner membrane transporter of ferric citrate.
CONCLUSIONS
The FciTABC and FeoABI systems contribute to ferric citrate acquisition in S. maltophilia.
Topics: Bacterial Proteins; Escherichia coli; Escherichia coli Proteins; Ferric Compounds; Iron; Membrane Proteins; Membrane Transport Proteins; Receptors, Cell Surface; Stenotrophomonas maltophilia
PubMed: 35477574
DOI: 10.1186/s12929-022-00809-y -
Microbiology Spectrum Jun 2022Stenotrophomonas maltophilia, a nonfermenting Gram-negative rod, is frequently isolated from the environment and is emerging as a multidrug-resistant global...
Stenotrophomonas maltophilia, a nonfermenting Gram-negative rod, is frequently isolated from the environment and is emerging as a multidrug-resistant global opportunistic pathogen. S. maltophilia harbors eight RND-type efflux pumps that contribute to multidrug resistance and physiological functions. Among the eight efflux pumps, SmeYZ pump is constitutively highly expressed. In our previous study, we demonstrated that loss-of-function of the SmeYZ pump results in pleiotropic phenotypes, including abolished swimming motility, decreased secreted protease activity, and compromised tolerance to oxidative stress and antibiotics. In this study, we attempted to elucidate the underlying mechanisms responsible for -mediated pleiotropic phenotypes. RNA-seq transcriptome analysis and subsequent confirmation with qRT-PCR revealed that mutant experienced an iron starvation response because the genes involved in the synthesis and uptake of stenobactin, the sole siderophore of S. maltophilia, were significantly upregulated. We further verified that mutant had low intracellular iron levels via inductively coupled plasma mass spectrometry (ICP-MS). Also, KJΔYZ was more sensitive to 2,2'-dipyridyl (DIP), a ferrous iron chelator, in comparison with the wild type. The contribution of SmeYZ, SmeDEF, and SbiAB pumps to stenobactin secretion was suggested by qRT-PCR and further verified by Chrome Azurol S (CAS) activity, iron source utilization, and cell viability assays. We also demonstrated that loss-of-function of SmeYZ led to the compensatory upregulation of SbiAB and SmeDEF pumps for stenobactin secretion. The overexpression of the SbiAB pump resulted in a reduction in intracellular iron levels, which may be the key factor responsible for the -mediated pleiotropic phenotypes, except for antibiotic extrusion. Efflux pumps display high efficiency of drug extrusion, which underlies their roles in multidrug resistance. In addition, efflux pumps have physiological functions, and their expression is tightly regulated by various environmental and physiological signals. Functional redundancy of efflux pumps is commonly observed, and mutual regulation occurs among these functionally redundant pumps in a bacterium. Stenotrophomonas maltophilia is an opportunistic pathogen that shows intrinsic multi-drug resistance. In this study, we demonstrated that SmeYZ, SbiAB, and SmeDEF efflux pumps of S. maltophilia display functional redundancy in siderophore secretion. Inactivation of led to the upregulation of and . Unexpectedly, overexpression resulted in the reduction of intracellular iron levels, which led to pleiotropic defects in mutant. This study demonstrates a previously unidentified connection between efflux pumps, siderophore secretion, and intracellular iron levels in S. maltophilia.
Topics: Anti-Bacterial Agents; Bacterial Proteins; Homeostasis; Iron; Membrane Transport Proteins; Microbial Sensitivity Tests; Siderophores; Stenotrophomonas maltophilia
PubMed: 35647692
DOI: 10.1128/spectrum.02448-21 -
Frontiers in Cellular and Infection... 2023is a multidrug-resistant (MDR) opportunistic pathogen with high resistance to most clinically used antimicrobials. The dissemination of MDR and difficult treatment of...
BACKGROUND
is a multidrug-resistant (MDR) opportunistic pathogen with high resistance to most clinically used antimicrobials. The dissemination of MDR and difficult treatment of its infection in clinical settings are global issues.
METHODS
To provide more genetic information on and find a better treatment strategy, we isolated five , SMYN41-SMYN45, from a Chinese community that were subjected to antibiotic susceptibility testing, biofilm formation assay, and whole-genome sequencing. Whole-genome sequences were compared with other thirty-seven sequences.
RESULTS
The five strains had similar antibiotic resistance profiles and were resistant to β-lactams, aminoglycosides, and macrolides. They showed similar antimicrobial resistance (AMR) genes, including various efflux pumps, β-lactamase resistance genes (), aminoglycoside resistance genes [, ], and macrolide-resistant gene (). Genome sequencing analysis revealed that SMYN41-SMYN45 belonged to sequence type 925 (ST925), ST926, ST926, ST31, and ST928, respectively, and three new STs were identified (ST925, ST926, and ST928).
CONCLUSION
This study provides genetic information by comparing genome sequences of several isolates from a community of various origins, with the aim of optimizing empirical antibiotic medication and contributing to worldwide efforts to tackle antibiotic resistance.
Topics: Humans; Stenotrophomonas maltophilia; Anti-Bacterial Agents; Anti-Infective Agents; Drug Resistance, Microbial; Genomics; Gram-Negative Bacterial Infections; Microbial Sensitivity Tests
PubMed: 38089814
DOI: 10.3389/fcimb.2023.1266295