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Xanthomonas maltophilia [keywords]
- Activity of the type I signal peptidase inhibitor MD3 against multidrug-resistant Gram-negative bacteria alone and in combination with colistin. [JOURNAL ARTICLE]
- J Antimicrob Chemother 2014 Aug 18.
Effective treatment of Gram-negative bacterial infections is increasingly challenging due to the spread of multidrug-resistant strains and a lack of new antimicrobials in development. Bacterial type I signal peptidases (SPases) represent a highly conserved and essential target for inhibition by novel compounds. SPases are required for the effective processing of membrane translocated proteins involved in core functions related to metabolism, virulence and resistance. In this study we assessed the biochemical and functional activity of a novel synthetic inhibitor (MD3) of SPases against a wide range of Gram-negative pathogens.The activity and specificity of MD3 for recombinant Pseudomonas aeruginosa SPase (LepB) and a genetically engineered LepB-regulatable strain were investigated. Antimicrobial activity of the compound alone and in combination with outer membrane-permeabilizing agents (sodium hexametaphosphate, colistin) was also determined against a collection of P. aeruginosa, Acinetobacter baumannii, Klebsiella pneumoniae and Stenotrophomonas maltophilia isolates.MD3 was found to inactivate the P. aeruginosa LepB protein (IC50 10 μM), resulting in antimicrobial effects potentiated in the presence of colistin. MD3 also demonstrated potent activity against wild-type and multidrug-resistant strains of A. baumannii and S. maltophilia with MICs ranging from 0.5 to 14 mg/L in the presence of subinhibitory concentrations of colistin.MD3 is a novel inhibitor of bacterial SPase in a range of non-fermentative Gram-negative bacteria. The antimicrobial activity is potentiated in combination with colistin and suggests that SPase inhibition warrants further exploration as a basis for future mono or combination therapies.
- Clinical characteristics and risk factors of infections caused by Stenotrophomonas maltophilia in a hospital in northwest China. [Journal Article]
- J Infect Dev Ctries 2014; 8(8):1000-5.
Stenotrophomonas maltophilia infections have recently increased in importance in China, particularly in intensive care units (ICUs). The aim of this study was to investigate the clinical characteristics and risk factors of S. maltophilia infection in ICU of a hospital in northwest China.The characteristics and outcomes of patients with any type of S. maltophilia infection at Shaanxi Provincial People's Hospital, Shaanxi, China, over a two-year period (from July 2011 to June 2013) were studied. S. maltophilia antimicrobial susceptibility was tested with the agar dilution method. The risk factors for all-cause in-hospital mortality were assessed with multivariate logistic regression.Forty patients (median age, 72 years; 77.5% males) with S. maltophilia infection were identified. The main type of infection was lower respiratory tract infection (97.5%); one patient had a bloodstream infection. A total of 97.5% patients were infected with two or more organisms at the same time. The main characteristics of the patients were prolonged use of mechanical ventilation, urethral catheter, and central venous catheter before the infections occurred. The case number of infection was not different in the four seasons. High in vitro sensitivity was observed to minocycline (91.2%), levofloxacin (85.3%), and trimethoprim-sulfamethoxazole (79.4%). Most patients received therapy with a combination of agents. The crude mortality was 50%. By multivariate analysis, low albumin content and hypotension were the independent prognostic factors for mortality.Appropriate antimicrobial treatment had no positive impact on mortality. The impacts of albumin supplements and increasing blood pressure on mortality require further clinical studies.
- Effects of the joint exposure of decabromodiphenyl ether and tetrabromobisphenol A on soil bacterial community structure. [JOURNAL ARTICLE]
- Environ Sci Pollut Res Int 2014 Aug 10.
Decabromodiphenyl ether (BDE209) and tetrabromobisphenol A (TBBPA) are the main contaminants at electronic waste (e-waste) recycling sites (EWRSs), and their potential toxicological effects have received extensive attention. However, the impact on soil microorganism of joint exposure to the two chemicals remains almost unknown. Therefore, indoor incubation tests were performed on control and contaminated soil samples to determine the response of soil bacterial community structure in the joint presence of BDE209 and TBBPA for the first time. The results have demonstrated that the soil bacterial diversity generally declined with increasing BDE209 and TBBPA concentrations and moderate and high doses of both chemicals can cause inhibitory effects. PCR-DGGE analysis indicated that the correlations between Shannon-Weaver index and contaminant concentrations could be well represented by a second-order polynomial model. The combined toxicity of the two chemicals was antagonistic during the first 14 days and then synergistic. Pectobacterium carotovorum, Sinorhizobium fredii HH103, and Stenotrophomonas maltophilia were highly tolerant to joint exposure during the entire incubation period. Moreover, some Staphylococcus strains were enriched after 90 days exposed to TBBPA or low concentrations of BDE209, indicating that they might degrade the two chemicals effectively. The results of these observations have provided some basic understanding of potential ecological effects of joint exposure to BDE209 and TBBPA on soil microorganism at EWRSs.
- Stenotrophomonas maltophilia: an emerging pathogen in dialysis units. [JOURNAL ARTICLE]
- J Med Microbiol 2014 Aug 7.
Abstract 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 Pub Med/Medline and Scopus review of peer-reviewed English papers on Stenotrophomonas 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.
- Identification of a Novel 6'-N-Aminoglycoside Acetyltransferase, AAC(6')-Iak, from a Multidrug-Resistant Clinical Isolate of Stenotrophomonas maltophilia. [JOURNAL ARTICLE]
- Antimicrob Agents Chemother 2014 Aug 4.
Stenotrophomonas maltophilia IOMTU250 has a novel 6'-N-aminoglycoside acetyltransferase encoding gene, aac(6')-Iak. The encoded protein, AAC(6')-Iak, consists of 153 amino acids and has 86.3% identity to AAC(6')-Iz. Escherichia coli transformed with a plasmid containing aac(6')-Iak exhibited decreased susceptibility to arbekacin, dibekacin, neomycin, netilmicin, sisomicin and tobramycin. Thin-layer chromatography showed that AAC(6')-Iak acetylated amikacin, arbekacin, dibekacin, isepamicin, kanamycin, neomycin, netilmicin, sisomicin and tobramycin.
- Characterization of Environmental CTX-M-15-Producing Stenotrophomonas maltophilia. [JOURNAL ARTICLE]
- Antimicrob Agents Chemother 2014 Aug 4.
Stenotrophomonas maltophilia is a widespread environmental microorganism (1) that has emerged as significant opportunistic pathogen (2) due to intrinsic resistance to almost all available antibiotics.…
- Recurrent Stenotrophomonas maltophilia Bacteremia after Iliac Crest Bone Graft Harvest. [Journal Article]
- Intern Med 2014; 53(15):1693-8.
We describe a rare case of recurrent Stenotrophomonas maltophilia bacteremia in a previously healthy 45-year-old man. The infection was caused by osteomyelitis at the site of an iliac crest bone graft harvest. A genetic analysis using enterobacterial repetitive intergenic consensus polymerase chain reaction (ERIC-PCR) revealed that the blood isolates and pathogens obtained from the surgical wound were identical. Initial treatment with levofloxacin and cefozopran was ineffective, but the patient's infection was successfully treated by long-term administration of latamoxef and trimethoprim-sulfamethoxazole. The present case suggests that attention should be given to the possibility of S. maltophilia infection in any situations.
- Comparisons between patients with trimethoprim-sulfamethoxazole-susceptible and trimethoprim-sulfamethoxazole-resistant Stenotrophomonas maltophilia monomicrobial bacteremia: A 10-year retrospective study. [JOURNAL ARTICLE]
- J Microbiol Immunol Infect 2014 Jul 28.
The impact of bacteremia due to the resistance of Stenotrophomonas maltophilia to trimethoprim-sulfamethoxazole (TMP-SXT) is uncertain. This study compared the clinical characteristics and outcomes of patients with TMP-SXT-susceptible (TSSSM) and TMP-SXT-resistant S. maltophilia (TSRSM) monomicrobial bacteremia.The medical records of adult patients with TSSSM and TSRSM monomicrobial bacteremia from January 2004 to December 2013 were reviewed and classified into two groups, namely, TSSSM and TSRSM.There were 184 patients with monomicrobial S. maltophilia bacteremia. The mean age was 68.3 years. Most patients were males (72.8%), had high Charlson Comorbidity Index scores, previously prescribed antimicrobial agents, and indwelling medical devices. The 14-day and in-hospital mortality rates were 23.9% and 47.2%, respectively. There were 128 patients (69.6%) with TSSSM and 56 (30.4%) with TSRSM. The incidence of TSSSM bacteremia increased during the study period. The TSSSM and TSRSM groups had similar demographic and clinical characteristics and no significant differences in 14-day and in-hospital mortality (24.2% vs. 23.2%, p = 0.833; 50.0% vs. 41.1%, p = 0.264, respectively). Patients with TSSSM bacteremia had an increased risk of septic shock (p = 0.044) and neutropenia (p = 0.028) at bacteremia onset. Logistic regression analysis indicated that acquisition of TMP-SXT resistance was an independent risk factor for prolonged hospitalization (p = 0.018) and catheter-related S. maltophilia bacteremia was inversely associated with prolonged hospitalization after bacteremia (p = 0.032).There were no significant differences in mortality for patients with TSSSM and TSRSM bacteremia, but patients with TSRSM bacteremia were associated with prolonged hospitalization after bacteremia onset.
- Antifungal activity of Stenotrophomonas maltophilia in Stomoxys calcitrans larvae. [Journal Article]
- Rev Bras Parasitol Vet 2014 Apr; 23(2):194-9.
The microbiota present in Stomoxys calcitrans larvae may assist their survival in contaminated environments through production of inhibitory substances. Bacteriological identification methods, the polymerase chain reaction (PCR) and scanning electron microscopy (SEM) were used to detect a bacterium naturally present in mucus and macerated S. calcitrans larvae. The antifungal activity was determined based on the results from disk diffusion tests on an artificial solid medium. The bacterium was identified as Stenotrophomonas maltophilia and presented antifungal activity against Beauveria bassiana sensu lato isolates CG 138, CG 228 and ESALQ 986. This result suggests that the larval microbiota is a factor that can compromise the use of B. bassiana s.l. fungus for biological control of S. calcitrans larvae.
- Diaryl-Substituted Azolylthioacetamides: Inhibitor Discovery of New Delhi Metallo-β-Lactamase-1 (NDM-1). [JOURNAL ARTICLE]
- ChemMedChem 2014 Jul 22.
The emergence and spread of antibiotic-resistant pathogens is a global public health problem. Metallo-β-lactamases (MβLs) such as New Delhi MβL-1 (NDM-1) are principle contributors to the emergence of resistance because of their ability to hydrolyze almost all known β-lactam antibiotics including penicillins, cephalosporins, and carbapenems. A clinical inhibitor of MBLs has not yet been found. In this study we developed eighteen new diaryl-substituted azolylthioacetamides and found all of them to be inhibitors of the MβL L1 from Stenotrophomonas maltophilia (Ki <2 μM), thirteen to be mixed inhibitors of NDM-1 (Ki <7 μM), and four to be broad-spectrum inhibitors of all four tested MβLs CcrA from Bacteroides fragilis, NDM-1 and ImiS from Aeromonas veronii, and L1 (Ki <52 μM), which are representative of the B1a, B1b, B2, and B3 subclasses, respectively. Docking studies revealed that the azolylthioacetamides, which have the broadest inhibitory activity, coordinate to the Zn(II) ion(s) preferentially via the triazole moiety, while other moieties interact mostly with the conserved active site residues Lys224 (CcrA, NDM-1, and ImiS) or Ser221 (L1).