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Xanthomonas maltophilia [keywords]
- Exposure to extremely low-frequency magnetic field affects biofilm formation by cystic fibrosis pathogens. [JOURNAL ARTICLE]
- Future Microbiol 2014 Oct.:1303-1317.
SUMMARY Aims: To evaluate the in vitro effects of extremely low-frequency magnetic field (ELF-MF) on growth and biofilm formation by Staphylococcus aureus, Pseudomonas aeruginosa, Burkholderia cepacia and Stenotrophomonas maltophilia strains from cystic fibrosis patients. Materials & methods: The motion of selected ions (Fe, Ca, Cu, Zn, Mg, K, Na) was stimulated by the ion resonance effect, then influence on growth and biofilm formation/viability was assessed by spectrophotometry or viability count. Results: Generally, exposure to ELF-MF significantly increased bacterial growth and affected both biofilm formation and viability, although with differences with regard to ions and species considered. Conclusion: Exposure to ELF-MF represents a possible new approach for treatment of biofilm-associated cystic fibrosis lung infections.
- [Efficacy of tigecycline in treating severe infections of patients with hematological diseases.] [JOURNAL ARTICLE]
- Zhonghua Yi Xue Za Zhi 2014 Sep; 94(34):2669-2672.
To evaluate the efficacy and safety of tigecycline in treating secondary infections of patients with hematological diseases.A total of 85 cases of hematological patients with secondary infections were classified into empirical and targeted therapy groups. Empirical therapy group was composed of patients receiving tigecycline as an alternative due to ineffective anti-infection treatment for 3-5 days in the absence of microbiological evidence while those taking tigecycline based on microbiological evidence belonged to targeted therapy group. Dosage regimen of tigecycline: loading dose 100 mg, 50 mg every 12 hours as maintenance therapy for 2-4 weeks.Among them, except for 11 cases of bloodstream infections and 2 cases of fever for unknown reasons, the most common site for infection was lower respiratory tract. Among 45 isolated bacterial strains, Stenotrophomonas maltophilia (40%) was the most commonly seen while extended spectrum beta-lactamases (ESBLS)+ multidrug resistant gram negative bacilli 15.6%. Among 5 bacterial strains, there were 3 methicillin-resistant Staphylococcus aureus+golden staphylococci strains and 2 excrement enterococci. The total effective rate of tigecycline was 72.9%. And the bacterial clearance rates of acinetobacter baumannii, ESBLS+ gram-negative bacillus and stenotrophomonas maltophilia were 85%, 70% and 55% respectively. The effect of tigecycline was equivalent for two groups. Pneumonia patients obtained an effective rate of 71%, compared to those with bloodstream infections (54.5%). For patients whose absolute neutrophil counts were less than 0.2×10(9)/L, the effective rate decreased obviously (45% vs 81.5%, P = 0.003). Adverse reaction was mild due to mostly gastrointestinal symptoms.Tigecycline is a new treatment choice in treating secondary multidrug resistant infections of patients with hematological diseases. Empirical therapy of tigecycline may improve the therapeutic efficacy of patients non-responding favorably to conventional anti-infectives.
- Genome-Wide Identification of Genes Necessary for Biofilm Formation of Nosocomial Pathogen Stenotrophomonas maltophilia Reveals Orphan Response Regulator FsnR is a Critical Modulator. [JOURNAL ARTICLE]
- Appl Environ Microbiol 2014 Dec 5.
Stenotrophomonas maltophilia is a gram-negative, bacterial pathogen of increasing concern to human health. Most clinical isolates of S. maltophilia efficiently form biofilms on biotic and abiotic surfaces, making this bacterium resistant to a number of antibiotic treatments and hard to be eliminated. To date, very few studies have investigated the molecular and regulatory mechanisms responsible for S. maltophilia biofilm formation. Here we constructed a random transposon insertion mutant library of S. maltophilia ATCC 13637 and screened 14,028 clones. A total of 46 non-redundant genes were identified. Mutants of these genes exhibited marked changes in biofilm formation; suggesting multiple physiological pathways, including extracellular polysaccharide production, purine synthesis, transportation, peptide and lipid synthesis, were involved in bacterial cell aggregation. Of these genes, 20 putatively contributed to flagella biosynthesis, indicating a critical role for cell motility in S. maltophilia biofilm formation. Genetic and biochemical evidence demonstrated an orphan response regulator, FsnR, activated transcription of at least two flagella-associated operons by directly binding to their promoters. The regulatory protein plays a fundamental role in controlling flagella assembly, cell motility and biofilm formation. These results provide a genetic basis to systematically study biofilm formation of S. maltophilia.
- Characterization of a genomic island in Stenotrophomonas maltophilia that carries a novel floR gene variant. [JOURNAL ARTICLE]
- J Antimicrob Chemother 2014 Dec 4.
To characterize the chromosomally encoded novel floR gene variant floRv from Stenotrophomonas maltophilia of porcine origin and elucidate the gene order and content of the floRv-flanking regions in an MDR genomic island (GI).Whole genome sequencing was used to identify the unknown florfenicol resistance gene in S. maltophilia strain GZP-Sm1. The candidate gene was cloned into pMD19-T and Escherichia coli transformants carrying this vector were tested for phenicol MICs. Flanking sequences of the florfenicol resistance gene were identified by a de novo assembly and a primer walking strategy.GZP-Sm1 carried a floR gene variant, designated floRv. E. coli clones carrying this gene were resistant to chloramphenicol and florfenicol. The deduced 404 amino acid FloRv protein showed 84.1%-91.8% amino acid identity to various FloR proteins. The gene floRv was located in an MDR region within a 40 226 bp GI region. Six resistance genes, including floRv (phenicol resistance), tetR-tetA(A) (tetracycline resistance), strA/strB (streptomycin resistance), sul1 (sulphonamide resistance) and aadA2 (streptomycin/spectinomycin resistance), were located in this MDR region. PCR analysis revealed that the GI was not stable and could be excised from the chromosome as a circular intermediate.The floRv gene was identified in a porcine S. maltophilia isolate. Six resistance genes including floRv were located in a novel GI. As an opportunistic pathogen in animals and humans, S. maltophilia might act as a resistance gene reservoir in farm environments. Its contribution to the spread of resistance genes to other pathogens should be monitored.
- Susceptibility of Stenotrophomonas maltophilia Clinical Isolates to Antibiotics and Contact Lens Multipurpose Disinfecting Solutions. [JOURNAL ARTICLE]
- Invest Ophthalmol Vis Sci 2014 Dec 2.
Purpose:To determine the susceptibility of S. maltophilia to various antibiotics and contact lens multipurpose disinfecting solutions.
Methods:Forty S. maltophilia strains from contact lens cases, contact lenses, or eye swabs of contact lens wearers including from 27 asymptomatic wearers and 13 keratitis patients were examined for their susceptibility to different antibiotics using a disc diffusion assay, and to multipurpose disinfecting solutions using a broth microdilution method.
Results:Certain strains were resistant to aztreonum (15%), imipenem (93%), chroramphenicol (13%) and cefepime (8%). Two of those strains were multi-drug resistant. All strains were sensitive to trimethoprim-sulfamethoxazole, tigecycline, ceftazidime, and fluoroquinolones. Overall the MIC for all strains was significantly higher (p<0.05) for AQuify® (50% dilution) and OPTI-FREE® RepleniSH® (25%) than all other MPDS (3-14%; except RepleniSH vs. Menicare™ Soft (14%)). AQuify®, OPTI-FREE® RepleniSH® Menicare™ Soft had significantly higher minimum bactericidal concentrations (undiluted MPDS) than other disinfecting solutions (p <0.05).
Conclusions:The Australian ocular isolates of S. maltophilia remain susceptible to trimethoprim-sulfamethozole, tigecycline, and most of fluoroquinolones. However, the isolates showed resistance to certain multipurpose disinfecting solutions.
- Synergistic interactions in mixed-species biofilms of pathogenic bacteria from the respiratory tract. [Journal Article]
- Rev Soc Bras Med Trop 2014 Oct; 47(5):649-52.
Introduction Mixed-species biofilms are involved in a wide variety of infections. We studied the synergistic interactions during dual-species biofilm formation among isolates of Pseudomonas aeruginosa, Acinetobacter baumannii, and Stenotrophomonas maltophilia. Methods Isolates were cultured as single-species and all possible combinations of dual-species biofilms. Results The 61 A. baumannii biofilms increased by 26-fold when cultured with S. maltophilia isolates; 62 A. baumannii biofilms increased by 20-fold when cultured with S. maltophilia isolates; and 31 P. aeruginosa biofilms increased by 102-fold when cultured with S. maltophilia 106. Conclusions Synergy was observed between two isolates, including those that inherently lacked biofilm formation ability.
- Stenotrophomonas maltophilia and Vermamoeba vermiformis relationships: Bacterial multiplication and protection in amoebal-derived structures. [Journal Article]
- Res Microbiol 2014 Dec; 165(10):847-51.
Stenotrophomonas maltophilia, a bacteria involved in healthcare-associated infections, can be found in hospital water systems. Other microorganisms, such as Free Living amoebae (FLA), are also at times recovered in the same environment. Amongst these protozoa, many authors have reported the presence of Vermamoeba vermiformis. We show here that this amoeba enhances S. maltophilia growth and harbors the bacteria in amoebal-derived structures after 28 days in harsh conditions. These results highlight the fact that particular attention should be paid to the presence of FLA in hospital water systems, because of their potential implication in survival and growth of pathogenic bacterial species.
- Purification and characterization of novel organic solvent tolerant 98kDa alkaline protease from isolated Stenotrophomonas maltophilia strain SK. [JOURNAL ARTICLE]
- Protein Expr Purif 2014 Nov 21.
Ability of microorganisms to grow at alkaline pH makes them an attractive target for several industrial applications. Thus, search for new extremozyme producing microrganisms must be a continuous exercise. Hence, we isolated a potent alkaline protease producing bacteria from slaughter house soil. The morphological, biochemical and 16S rDNA gene sequencing studies revealed that the isolated bacteria is Stenotrophomonas maltophilia strain SK. Alkaline protease from S. maltophilia strain SK was purified by using ammonium sulphate precipitation and DEAE-cellulose ion exchange column chromatography. The purified enzyme was optimally active at pH 9.0 and temperature 40°C with broad substrate specificity. It was observed that the metal ions such as Ca(++), Mg(++) and Fe(+++) completely repressed the enzyme activity. The enzyme was stable in presence of various water miscible solvents like ethanol, methanol, isopropanol at 25% (v/v) concentration and less stable at 37.5% (v/v) concentration. These robust properties of enzyme might be applicable for various applications in detergent and pharmaceutical industries.
- Stenotrophomonas maltophilia with histopathological features mimicking cutaneous gamma/delta T-cell lymphoma. [JOURNAL ARTICLE]
- Int J Infect Dis 2014 Nov 13.:7-9.
We report a case of cutaneous Stenotrophomonas maltophilia infection which presented with clinical and histopathological findings that mimicked a gamma/delta (γδ) T-cell lymphoma. In this case, tissue culture of the biopsy specimen was key to determining the diagnosis and allowing appropriate treatment with oral trimethoprim-sulfamethoxazole and topical silvadene. A prompt complete resolution of lesions was observed following antibiotic treatment, with no recurrence of disease over the last 5 years, supporting an infectious rather than malignant etiology. In our patient, radiation therapy was indicated based on the misdiagnosis of γδ T-cell lymphoma, which was supported both clinically and histopathologically. However, tissue culture in this case avoided unnecessary radiation exposure and highlights the role of tissue culture in the evaluation of the biopsy of an undiagnosed cutaneous lesion.
- In vitro activity of potential old and new drugs against multidrug-resistant gram-negatives. [JOURNAL ARTICLE]
- J Infect Chemother 2014 Nov 13.
The aim of this study was to evaluate the in vitro susceptibility of MDR gram-negatives bacteria to old drugs such as polymyxin B, minocycline and fosfomycin and new drugs such as tigecycline.One hundred and fifty-three isolates from 4 Brazilian hospitals were evaluated. Forty-seven Acinetobacter baumannii resistant to carbapenens harboring adeB, blaOxA23, blaOxA51, blaOxA143 and blaIMP genes, 48 Stenotrophomonas maltophilia including isolates resistant to levofloxacin and/or trimethoprim-sulfamethoxazole harboring sul-1, sul-2 and qnrMR and 8 Serratia marcescens and 50 Klebsiella pneumoniae resistant to carbapenens harboring blaKPC-2 were tested to determine their minimum inhibitory concentrations (MICs) by microdilution to the following drugs: minocycline, ampicillin-sulbactam, tigecycline, and polymyxin B and by agar dilution to fosfomycin according with breakpoint criteria of CLSI and EUCAST (fosfomycin). In addition, EUCAST fosfomycin breakpoint for Pseudomonas spp. was applied for Acinetobacter spp and S. maltophilia, the FDA criteria for tigecycline was used for Acinetobacter spp and S. maltophilia and the Pseudomonas spp polymyxin B CLSI criterion was used for S. maltophilia.Tigecycline showed the best in vitro activity against the MDR gram-negative evaluated, followed by polymyxin B and fosfomycin. Polymyxin B resistance among K. pneumoniae was detected in 6 isolates, using the breakpoint of MIC > 8 ug/mL. Two of these isolates were resistant to tigecycline. Minocycline was tested only against S. maltophilia and A. baumannii and showed excellent activity against both.Fosfomycin seems to not be an option to treat infections due to the A. baumannii and S. maltophilia isolates according with EUCAST breakpoint, on the other hand, showed excellent activity against S. marcescens and K. pneumoniae.