OBJECTIVETo investigate the antimicrobial resistance of clinical isolates of Stenotrophomonas matophilia (SMA) and the mechanisms of their drug resistance.

METHODSDisc diffusion method (NCCLS) was used to detect the resistant patterns of 88 initial SMA isolates resistant to 12 antibiotics isolated from a local hospital in the past 4 years. PCR was used to detect the 7 aminoglycosides modifying enzymes genes (AME) against amikacin and gentamicin. Metal-beta-lactamases (MBLs) were screened by synergic method, and extended-spectrum beta-lactamases (ESBLs) were detected by double-disk synergy test.

RESULTSThe resistance rates of the SMA isolates were 0%-9.7% to minocycline, 12.5%-22.6% to ticarcillin-clavulanic acid, 12.5%-28.6% to levofloxacin, 18.8%-33.3% to doxycycline, 18.8%-40% to sulfamethoxazole compound, 50%-65.7% to ciprofloxacin, 50%-66.7% to cehazindme, 54.8%-66.7% to amikacin, 75%-100% to gentamicin, 81.3%-100% to piperacillin, 87.5%-100% to aztreonam and 93.5%-100% to imipenem. Aac(3)-I and ant(4')-II were not detected in these strains. The positive rates of the other 5 AME genes of aac(3)-II, ant(2'')-I, aac(6')-I, aac(3)-III, aac(3)-IV were 2.3%, 5.7%, 8%, 10%, and 10%, respectively. SMA strains producing ESBLs were found at the rate of 38.6%; 25% of the strains were MBL-producing, and 13.6% produced both ESBLs and MBLs.

CONCLUSIONMost of the SMAs we isolated are multidrug-resistant through various mechanisms. The choice of antibiotics should be made according to the susceptibility results.

Amikacin ; pharmacology ; Drug Resistance, Multiple, Bacterial ; Gentamicins ; pharmacology ; Humans ; Imipenem ; pharmacology ; Microbial Sensitivity Tests ; Stenotrophomonas maltophilia ; drug effects ; isolation & purification

We determined the antimicrobial susceptibility of 90 clinical isolates of Stenotrophomonas maltophilia collected in 2009 at a tertiary care hospital in Korea. Trimethoprim-sulfamethoxazole, minocycline, and levofloxacin were active against most of the isolates tested. Moxifloxacin and tigecycline were also active and hold promise as therapeutic options for S. maltophilia infections.
Anti-Infective Agents/*pharmacology ; Hospitals ; Korea ; Microbial Sensitivity Tests ; Minocycline/pharmacology ; Ofloxacin/pharmacology ; Stenotrophomonas maltophilia/*drug effects ; Trimethoprim-Sulfamethoxazole Combination/pharmacology

OBJECTIVETo investigate the antibiotic resistance and risky factors of nosocomial infections caused by Stenotrophomonas maltophilia, so as to help elucidate the difference of drug resistance between metallic beta-lactamase (MBL) producing and non-MBL producing strains.

METHODSStandard agar dilution method of NCCLS was employed in the isolation of 36 strains of Stenotrophomonas maltophilia from patients with nosocomial infection with respect to their in vitro antibiotic resistance to 18 kinds of antibiotics. MBL strains were identified by MBL-E test method.

RESULTSStenotrophomonas maltophilia in our hospital was mainly identified in the lower respiratory tract (88.9%), in which 88.2% (30/34) of the patients had serious original diseases, 50% of whom had received Imipenem/cilastatin sodium treatment. Thirty-six strains of Stenotrophomonas maltophilia were susceptible to new types of fluoquinolone antibiotics, i.e. Sparfloxacin, levofloxacin, gatifloxacin and doxycycline, with inhibitory rate ranging 97.2%, 94.4%, 91.7% to 83.3%, respectively. They could also be inhibited by SMZ/TMP and Ticarcillin/Lavulanic acid with inhibitory rate of 63.9% and 58.3%, respectively. There were 16 strains out of 36 of MBL bacteria with complete resistance to Imipenem/cilastatin sodium, but with higher susceptibility to aztreonam than those non-MBL producing strains.

CONCLUSIONThe nosocomial infection in our hospital caused by Stenotrophomonas maltophilia seemed to be related with severe primary disease and the use of Imipenem/cilastatin sodium. The newly developed fluoroquinolones possessed powerful antibacterial potency on Stenotrophomonas maltophilia found in nosocomial infection.

Antibiosis ; drug effects ; Cilastatin ; therapeutic use ; Cross Infection ; drug therapy ; microbiology ; Drug Resistance, Bacterial ; drug effects ; Fluoroquinolones ; therapeutic use ; Humans ; Imipenem ; therapeutic use ; Microbial Sensitivity Tests ; Risk Factors ; Stenotrophomonas maltophilia ; drug effects

Emerging resistance to trimethoprim/sulfamethoxazole (SXT) poses a serious threat to the treatment of Stenotrophomonas maltophilia infections. We determined the prevalence and molecular characteristics of acquired SXT resistance in recent clinical S. maltophilia isolates obtained from Korea. A total of 252 clinical isolates of S. maltophilia were collected from 10 university hospitals in Korea between 2009 and 2010. Antimicrobial susceptibility was determined by using the CLSI agar dilution method. The sul1, sul2, and sul3 genes, integrons, insertion sequence common region (ISCR) elements, and dfrA genes were detected using PCR. The presence of the sul1 gene and integrons was confirmed through sequence analysis. Among the 32 SXT-resistant isolates, sul1 was detected in 23 isolates (72%), all of which demonstrated high-level resistance (> or =64 mg/L) to SXT. The sul1 gene (varying in size and structure) was linked to class 1 integrons in 15 of the 23 isolates (65%) harboring this gene. None of the SXT-susceptible isolates or the SXT-resistant isolates with a minimum inhibitory concentration of 4 and 8 mg/L were positive for sul1. Moreover, the sul2, sul3, and dfrA genes or the ISCR elements were not detected. The sul1 gene may play an important role in the high-level SXT resistance observed in S. maltophilia.
Anti-Bacterial Agents/pharmacology ; Bacterial Proteins/*genetics ; Drug Resistance, Bacterial/genetics ; Gram-Negative Bacterial Infections/microbiology/pathology ; Humans ; Integrons/*genetics ; Microbial Sensitivity Tests ; Stenotrophomonas maltophilia/*drug effects/genetics/isolation & purification ; Trimethoprim, Sulfamethoxazole Drug Combination/*pharmacology

No abstract available.
Anti-Bacterial Agents/*pharmacology ; Bacterial Proteins/*genetics ; Carrier Proteins/*genetics ; Drug Resistance, Multiple, Bacterial/*genetics ; Humans ; Stenotrophomonas maltophilia/drug effects/*genetics/isolation & purification ; Transposases/*genetics ; Trimethoprim, Sulfamethoxazole Drug Combination/*pharmacology

BACKGROUND: Stenotrophomonas maltophilia is a gram-negative bacillus and a nosocomial pathogen in immunocompromised patients. Trimethoprim/sulfamethoxazole (TMP/SMX) is the drug of choice for treating S. maltophilia infection; however, resistance to TMP/SMX is increasing. In this study, we investigated the relationship between the incidence of TMP/SMX resistance and the presence of sul genes and mobile elements. METHODS: A total of 120 S. maltophilia isolates were collected from 3 university hospitals between April 2007 and April 2009. Antimicrobial susceptibilities were determined using the disk diffusion method. PCR and DNA sequencing were conducted for the detection of sul1, sul2, class 1 integron, and ISCR2 element. Repetitive extragenic palindromic sequence-based PCR (REP-PCR) was carried out to evaluate the genetic relatedness. RESULTS: The TMP/SMX-resistant (R) isolates harbored a significantly higher proportion of sul1 gene and class 1 integron than TMP/SMX-susceptible (S) isolates (P<0.001). Seventeen of 28 isolates with sul1 also had a class 1 integron, but none of the isolates without sul1 had a class 1 integron. The identified gene cassettes within class 1 integrons include aacA4, aadA1, aac6'-II, and qac. None of the 120 isolates carried sul2, glmM, or ISCR2 element. REP-PCR did not show any genetic relatedness among the isolates. CONCLUSIONS: In Korea, the resistance of S. maltophilia isolates to TMP/SMX is due to sul1 within a class 1 integron rather than to sul2. The class 1 integron also harbors multiple antibiotic resistance genes in addition to sul1, and therefore it could mediate multidrug resistance in S. maltophilia.
Anti-Bacterial Agents/*pharmacology ; Bacterial Proteins/genetics ; Carrier Proteins/genetics ; DNA, Bacterial/genetics ; Disk Diffusion Antimicrobial Tests ; Drug Resistance, Multiple, Bacterial/genetics ; Humans ; Integrons/genetics ; Polymerase Chain Reaction ; Stenotrophomonas maltophilia/*drug effects/*genetics/isolation &purification ; Trimethoprim-Sulfamethoxazole Combination/*pharmacology

PURPOSE: Fluoroquinolones, rapidly gaining prominence in treatment of Stenotrophomonas maltophilia (SMP), are noted for their potency and tolerability. However, SMP may rapidly acquire resistance to fluoroquinolones. We evaluated associations of clinical factors with acquisition of levofloxacin resistance (LFr) in SMP. MATERIALS AND METHODS: Our retrospective cohort study was based on patient data collected between January 2008 and June 2010. Through screening of 1275 patients, we identified 122 patients with data for SMP antibiotic susceptibility testing in > or =3 serial SMP isolates. RESULTS: We assigned the 122 patients to either the SS group (n=54) in which levofloxacin susceptibility was maintained or the SR group (n=31) in which susceptible SMP acquired resistance. In multivariate regression analysis, exposure to levofloxacin for more than 3 weeks [odds ratio (OR) 15.39, 95% confidential interval (CI) 3.08-76.93, p=0.001] and co-infection or co-colonization with Klebsiella pneumoniae resistant to levofloxacin (OR 4.85, 95% CI 1.16-20.24, p=0.030) were independently associated with LFr acquisition in SMP. CONCLUSION: Acquisition of LFr during serial sampling of SMP was related to the levofloxacin exposure.
Aged ; Anti-Bacterial Agents/*pharmacology/*therapeutic use ; Fluoroquinolones/pharmacology/therapeutic use ; Gram-Negative Bacterial Infections/drug therapy ; Humans ; Levofloxacin/*pharmacology/*therapeutic use ; Microbial Sensitivity Tests ; Middle Aged ; Retrospective Studies ; Stenotrophomonas maltophilia/drug effects/*pathogenicity

The aim of this study was to determine antimicrobial susceptibility of recent clinical Stenotrophomonas maltophilia isolates from Korea, and to compare the activity levels of several combinations of antimicrobials. A total of 206 non-duplicate clinical isolates of S. maltophilia was collected in 2010 from 11 university hospitals. Antimicrobial susceptibility testing was performed using the Clinical Laboratory Standards Institute agar dilution method. In vitro activity of antimicrobial combinations was tested using the checkerboard method. The susceptibility rates to trimethoprim-sulfamethoxazole and minocycline were 96% and 99%, respectively. The susceptibility rate to levofloxacin was 64%. All of four antimicrobial combinations showed synergy against many S. maltophilia isolates. A combination of trimethoprim-sulfamethoxazole plus ticarcillin-clavulanate was most synergistic among the combinations. None of the combinations showed antagonistic activity. Therefore, some of the combinations may be more useful than individual drugs in the treatment of S. maltophilia infection. Further clinical studies are warranted to validate our in vitro test results.
Anti-Infective Agents/*pharmacology ; Gram-Negative Bacterial Infections/microbiology ; Hospitals, University ; Humans ; Microbial Sensitivity Tests ; Minocycline/pharmacology ; Ofloxacin/pharmacology ; Republic of Korea ; Stenotrophomonas maltophilia/*drug effects/isolation & purification ; Trimethoprim-Sulfamethoxazole Combination/pharmacology

Stenotrophomonas maltophilia (previously named Xanthomonas maltophilia) is an aerobic, non-fermentive, Gram-negative bacillus that is wide spread in the environment. It was considered to be an organism with limited pathogenic potential, which was rarely capable of causing diseases in human other than those who were in debilitated or immunocompromised state. More recent studies have established that Stenotrophomonas maltophilia can behave as a true pathogen. Endocarditis due to this organism is rare, and only 24 cases of Stenotrophomonas maltophilia endocarditis have been reported in the medical literature. Most cases were associated with risk factors, including intravenous drug abuse, dental treatment, infected intravenous devices, and previous cardiac surgery. We present a case with two episodes of Stenotrophomonas maltophilia endocarditis after mitral valve prosthesis implantation, which was treated with antibiotics initially, and a combination of antibiotics and surgery later. To our knowledge, this is the first case of repetitive endocarditis due to Stenotrophomonas maltophilia.
Adult ; Anti-Bacterial Agents/*therapeutic use ; Bioprosthesis/adverse effects/*microbiology ; Endocarditis, Bacterial/*drug therapy/physiopathology ; Gentamicins/therapeutic use ; Gram-Negative Bacterial Infections/*drug therapy/physiopathology ; Heart Valve Prosthesis/adverse effects/*microbiology ; Humans ; Male ; Mitral Valve ; Recurrence ; Stenotrophomonas maltophilia/*drug effects ; Treatment Outcome ; Trimethoprim-Sulfamethoxazole Combination/*therapeutic use ; Vancomycin/therapeutic use

BACKGROUND: Stenotrophomonas maltophilia is a gram-negative bacillus that has become increasingly recognized as an important nosocomial pathogen, particularly in individuals with severe debilitation or immunosuppression. S. maltophilia is also characterized by its resistance to multiple antibiotics. S. maltophilia peritonitis in CAPD (continuous ambulatory peritoneal dialysis) patients is associated with a poor prognosis and loss of CAPD catheter. No report concerning this entity has been presented in Korea. Therefore, we describe and discuss five cases of the S. maltophilia infection associated with CAPD in three patients with peritonitis and two with exit-site infections. METHODS: We performed a retrospective search for episodes of S. maltophilia infections related to CAPD in our renal unit. The baseline levels of hemoglobin, albumin, cholesterol, BUN and creatinine were compared with age, sex and, if possible, the underlying disease-matched controls. RESULTS: All the patients with S. maltophilia peritonitis had diabetes mellitus as the underlying disease. The individual patients also had other significant combined morbidities, such as panhypopituitarism, COPD chronic obstructive pulmonary disease, cerebrovascular accident and myocardial infarction. The level of hemoglobin in these patients was significantly lower than in the controls, and the mean values of serum albumin, creatinine and BUN were also low. CONCLUSION: Immune dysfunction due to uremia, anemia, malnutrition, other comorbidities (e.g. diabetes mellitus), and also, an indwelling peritoneal catheter may be predisposing factors for the S. maltophilia infection in CAPD patients. Once the S. maltophilia infection is diagnosed in CAPD patient, the patient should be treated based on the understanding of this particular organism.
Adult ; Anti-Bacterial Agents/therapeutic use ; Biological Markers/blood ; Diabetes Complications/therapy ; Drug Resistance, Microbial ; Female ; Gram-Negative Bacterial Infections/blood/drug therapy/etiology/*microbiology ; Humans ; Korea ; Male ; Microbial Sensitivity Tests ; Middle Aged ; Peritoneal Dialysis, Continuous Ambulatory/*adverse effects ; Peritonitis/blood/drug therapy/etiology/*microbiology ; Retrospective Studies ; Risk Factors ; *Stenotrophomonas maltophilia ; Treatment Failure