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Find video protocols related to scientific articles indexed in Pubmed.
A multicentre hospital outbreak in Sweden caused by introduction of a vanB2 transposon into a stably maintained pRUM-plasmid in an Enterococcus faecium ST192 clone.
PLoS ONE
PUBLISHED: 08-25-2014
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The clonal dissemination of VanB-type vancomycin-resistant Enterococcus faecium (VREfm) strains in three Swedish hospitals between 2007 and 2011 prompted further analysis to reveal the possible origin and molecular characteristics of the outbreak strain. A representative subset of VREfm isolates (n?=?18) and vancomycin-susceptible E. faecium (VSEfm, n?=?2) reflecting the spread in time and location was approached by an array of methods including: selective whole genome sequencing (WGS; n?=?3), multi locus sequence typing (MLST), antimicrobial susceptibility testing, virulence gene profiling, identification of mobile genetic elements conferring glycopeptide resistance and their ability to support glycopeptide resistance transfer. In addition, a single VREfm strain with an unrelated PFGE pattern collected prior to the outbreak was examined by WGS. MLST revealed a predominance of ST192, belonging to a hospital adapted high-risk lineage harbouring several known virulence determinants (n?10). The VREfm outbreak strain was resistant to ampicillin, gentamicin, ciprofloxacin and vancomycin, and susceptible to teicoplanin. Consistently, a vanB2-subtype as part of Tn1549/Tn5382 with a unique genetic signature was identified in the VREfm outbreak strains. Moreover, Southern blot hybridisation analyses of PFGE separated S1 nuclease-restricted total DNAs and filter mating experiments showed that vanB2-Tn1549/Tn5382 was located in a 70-kb sized rep17/pRUM plasmid readily transferable between E. faecium. This plasmid contained an axe-txe toxin-antitoxin module associated with stable maintenance. The two clonally related VSEfm harboured a 40 kb rep17/pRUM plasmid absent of the 30 kb vanB2-Tn1549/Tn5382 gene complex. Otherwise, these two isolates were similar to the VREfm outbreak strain in virulence- and resistance profile. In conclusion, our observations support that the origin of the multicentre outbreak was caused by an introduction of vanB2-Tn1549/Tn5382 into a rep17/pRUM plasmid harboured in a pre-existing high-risk E. faecium ST192 clone. The subsequent dissemination of VREfm to other centres was primarily caused by clonal spread rather than plasmid transfer to pre-existing high-risk clones.
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Clinical evaluation of the FilmArray blood culture identification panel in identification of bacteria and yeasts from positive blood culture bottles.
J. Clin. Microbiol.
PUBLISHED: 10-02-2013
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The FilmArray platform (FA; BioFire, Salt Lake City, UT) is a closed diagnostic system allowing high-order multiplex PCR analysis with automated readout of results directly from positive blood cultures in 1 h. In the present study, we evaluated the clinical performance of the FilmArray blood culture identification (BCID) panel, which includes 19 bacteria, five yeasts, and three antibiotic resistance genes. In total, 206 blood culture bottles were included in the study. The FilmArray could identify microorganisms in 153/167 (91.6%) samples with monomicrobial growth. Thirteen of the 167 (7.8%) microorganisms were not covered by the FilmArray BCID panel. In 6/167 (3.6%) samples, the FilmArray detected an additional microorganism compared to blood culture. When polymicrobial growth was analyzed, the FilmArray could detect all target microorganisms in 17/24 (71%) samples. Twelve blood culture bottles that yielded a positive signal but showed no growth were also negative by FilmArray. In 3/206 (1.5%) bottles, the FilmArray results were invalid. The results of the FilmArray were reproducible, as demonstrated by the testing and retesting of five bottles in the same day and a longitudinal follow-up of five other blood cultures up to 4 weeks. The present study shows that the FilmArray is a rapid identification method with high performance in direct identification of bacteria and yeasts from positive blood culture bottles.
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The performance of 4 different supplements and 5 blood culture bottles types in detection of bacteria and Candida spp. in simulated sterile body fluid cultures.
Diagn. Microbiol. Infect. Dis.
PUBLISHED: 04-04-2013
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The purpose of this investigation was to evaluate the performance of 4 supplements: horse blood, fastidious organisms supplement (FOS), haemin isovitalex albumine (HIA), and brain heart infusion-haemin isovitalex albumine (BHI-HIA) and 5 blood culture bottles: Bactec Mycosis IC/F, Plus Aerobic/F, Peds Plus/F from the Bactec 9240 system, and BacT/Alert FA and BacT/Alert PF from the BacT/Alert 3D system, in detection of bacteria and Candida spp. in simulated sterile body fluids other than blood models. In total, 8 reference strains (Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pneumoniae, Neisseria meningitidis, Haemophilus influenzae, Listeria monocytogenes, Candida albicans, and Candida parapsilosis) and 11 clinical bacteria and yeast isolates (6 isolates from cerebrospinal fluid and 5 isolates from blood) were included in this study. Horse blood, FOS, and HIA were significantly better than no supplements (P < 0.0001, P < 0.0002, and P = 0.05, respectively) in detection of bacteria. Interestingly, there was no significant difference between BHI-HIA and bottles without any supplements. Sixty bottles analyzed of which 59 (98.33%) bottles with horse blood, 53 (88.33%) with FOS, 45 (75.00%) with HIA, and 43 (71.67%) with BHI-HIA signaled positive. The positivity rates with horse blood were significantly higher than with HIA and BHI-HIA (P < 0.0005 and P < 0.0001, respectively). Similarly, the blood culture bottles with horse blood had shorter time to detection (TTD) compared to bottles with FOS and HIA (P < 0.05 and P < 0.0001, respectively). When yeasts were analyzed, almost all (124/125) blood culture bottles with Candida spp. signaled positive even in the absence of supplements. Bactec Mycosis IC/F had significantly shorter TTD compared to Bactec Peds Plus/F, Bactec Plus Aerobic/F, BacT/Alert FA, and BacT/Alert PF bottles in detection of Candida spp. (P < 0.005, P < 0.05, P < 0.001, and P < 0.001, respectively). The present study showed that horse blood was the most effective supplement in growth of bacteria in the blood culture bottles that were analyzed in the study.
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Transport time for blood culture bottles: underlying factors and its consequences.
Diagn. Microbiol. Infect. Dis.
PUBLISHED: 02-21-2013
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In the present study we investigated transport times for blood cultures from three tertiary-care hospitals to Karolinska University Laboratory and identified predictors of long transport times. Concomitantly, consequences of delayed incubation on total detection time (TDT) were analyzed by in vitro sepsis models. A total of 909 blood cultures were studied. The median (interquartile range) transport time was 9 (3-15) h. The hospital accommodating the microbiology laboratory had the shortest transport time compared to the other two hospitals (P < 0.0001). Samples taken between 16:00-24:00 had longer transport times compared to samples taken between 8:00-16:00 and 24:00-08:00 (P < 0.0001). In vitro experiments showed that TDT was longer for samples pre-incubated at room temperature (RT) for 19 h compared to the ones pre-incubated for 2 h or 9.5 h (P < 0.0001). In conclusion, off-site location, time of sampling and number of transports per day were related to, and predictors of transport time.
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Identification of clinical Pasteurella isolates by MALDI-TOF -- a comparison with VITEK 2 and conventional microbiological methods.
Diagn. Microbiol. Infect. Dis.
PUBLISHED: 01-17-2013
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The aim of this study was to compare the performance of four methods that are widely used in the clinical microbiology laboratory for identification of Pasteurella species. The 4 methods evaluated were VITEK2, VITEK MS (BioMerieux), and Bruker Biotyper MS (Bruker) as well as traditional biochemical tests. Sequencing of the sodA gene was used as the reference method. Sixty-five isolates of Pasteurella spp. from 65 patients were analyzed. One Pasteurella multocida isolate from American Type Culture Collection (Manassas, VA, USA) was used as a reference. Traditional biochemical tests accurately identified 62/66 (94%) isolates. Both Bruker and Vitek matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) identified 59/66 (89%) strains, but VITEK2 could only identify 32/66 (48.5%) isolates correctly. The mean time to identification using biochemical tests was 20 hours; VITEK2 took 6 hours and MALDI-TOF approximately 10 minutes. In conclusion, MALDI-TOF is a quick method, which accurately identified most isolates of Pasteurella to the species level. Thus, MALDI-TOF constitutes a valuable diagnostic tool in the clinical laboratory.
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Neurosurgical gram-negative bacillary ventriculitis and meningitis: a retrospective study evaluating the efficacy of intraventricular gentamicin therapy in 31 consecutive cases.
Clin. Infect. Dis.
PUBLISHED: 05-02-2011
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Gram-negative bacillary (GNB) ventriculitis and meningitis are rare but serious complications after neurosurgery. Prospective studies on antibiotic treatment for these infections are lacking, and retrospective reports are sparse. At our hospital in Uppsala, Sweden, meropenem has been recommended as empirical therapy since 1996, with the addition of intraventricular gentamicin in cases that do not respond satisfactorily to treatment. In this study, we retrospectively compare the efficacy of combination treatment with intraventricular gentamicin to that of systemic antibiotics alone. In addition, we report our experience of meropenem for the treatment of GNB ventriculomeningitis.
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Screening for vancomycin-resistant enterococci: results of a survey in Stockholm.
APMIS
PUBLISHED: 05-19-2010
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Vancomycin-resistant enterococci (VRE) are emerging in Stockholm hospitals. To rapidly screen for VRE from stool and rectal swab samples, a detection assay combining broth enrichment and real-time PCR was set up. From September to December 2008, 6914 samples were screened for VRE using the broth-PCR combined assay. Of them, 5463 samples were reported as negative the day after sampling. Among the 6914 samples, 47 was screened as vanA probable and 44 of them were confirmed as VRE; 1314 samples was screened as vanB probable and 93 of them were confirmed as VRE. The 44 vanA-type VRE isolates, detected from 31 patients, were clustered into four genetic types by pulsed-field gel electrophoresis (PFGE). The same PFGE type was observed in multiple isolates recovered from the same patient with vanA VRE. The 93 vanB-type VRE isolates were detected from 60 patients, 59 of them harboring VRE with PFGE type 1. One patient with vanB VRE had two isolates of distinct PFGE types (types 1 and 5). PFGE type 1 and PFGE type 2 were predominant clones in vanB and vanA strains, respectively, represented by 98.3% (59/60) of patients with vanB VRE and 77.4% (24/31) of patients with vanA VRE.
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Multiplex and quantifiable detection of nucleic acid from pathogenic fungi using padlock probes, generic real time PCR and specific suspension array readout.
J. Microbiol. Methods
PUBLISHED: 05-21-2009
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A new concept for multiplex detection and quantification of microbes is here demonstrated on a range of infectious fungal species. Padlock probe methodology in conjunction with qPCR and Luminex technology was used for simultaneous detection of ten fungal species in one single experiment. By combining the multiplexing properties of padlock probes and Luminex detection with the well established quantitative characteristics of qPCR, quantitative microbe detection was done in 10-plex mode. A padlock probe is an oligonucleotide that via a ligation reaction forms circular DNA when hybridizing to specific target DNA. The region of the padlock probe that does not participate in target DNA hybridization contains generic primer sequences for amplification and a tag sequence for Luminex detection. This was the fundament for well performing multiplexing. Circularized padlock probes were initially amplified by rolling circle amplification (RCA), followed by a SybrGreen real time PCR which allowed an additive quantitative assessment of target DNA in the sample. Detection and quantification of amplified padlock probes were then done on color coded Luminex microspheres carrying anti-tag sequences. A novel technique, using labeled oligonucleotides to prevent reannealing of amplimers by covering the flanks of the address sequence, improved the signal to noise ratio in the detection step considerably. The method correctly detected fungi in a variety of clinical samples and offered quantitative information on fungal nucleic acid.
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Prevalence of qnr determinants among extended-spectrum beta-lactamase-positive Enterobacteriaceae clinical isolates in southern Stockholm, Sweden.
Int. J. Antimicrob. Agents
PUBLISHED: 03-06-2009
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Three hundred and nineteen extended-spectrum beta-lactamase-positive Enterobacteriaceae clinical isolates were screened for qnr genes. Twelve isolates were positive for qnr, including one qnrA1, two qnrB1, three qnrB2, one qnrB4, one qnrB6 and four qnrS1. No qnr-positive strains were identified among the isolates recovered before 2006. The first qnr-positive Escherichia coli was detected from a patient in 2006. qnr genes remained rare in E. coli (6/288; 2.1%), but appeared to be more prevalent in Klebsiella pneumoniae (4/25; 16%) and Enterobacter cloacae (2/3; 66.7%). All qnr-positive isolates were resistant to nalidixic acid while presenting varied susceptibilities to fluoroquinolones. Isolates harbouring qnrB4 or qnrB6 were highly resistant to all the fluoroquinolones tested. Their high-level resistance is associated with multiple chromosomal substitutions in gyrA and parC. Alterations at codons Ser-83 and Asp-87 in GyrA and at codons Ser-80 and Glu-84 in ParC were observed in these isolates.
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Clinical comparison of the Bactec Mycosis IC/F, BacT/Alert FA, and BacT/Alert FN blood culture vials for the detection of candidemia.
Diagn. Microbiol. Infect. Dis.
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The present study analyzed the performance of Bactec Mycosis IC/F, BacT/Alert FA, and BacT/Alert FN vials in detection and time to detection (TTD) of Candida spp. in 179 simultaneous blood cultures. The Mycosis IC/F, BacT/Alert FA, and BacT/Alert FN vials could detect Candida spp. in 144 (80.45%) of 179, 149 (83.24%) of 179, and 8 (4.47%) of 179 samples, respectively. With the presence of antifungal therapy, the numbers of positive vials were higher in BacT/Alert FA compared to Mycosis IC/F, 87/99 versus 73/99, respectively (P < 0.05). TTD (SD) for C. albicans was shorter in Mycosis IC/F than in BacT/Alert FA vials without antifungal therapy, 20.89 (9.33) versus 28.26 (9.77), respectively (P < 0.01). The detection of Candida spp., with concomitant bacteremia, was higher in Mycosis IC/F than in BacT/Alert FA vials, 28/30 and 19/30, respectively (P = 0.01). The present data show that the use of Bactec Mycosis IC/F together with BacT/Alert FA vials might improve the detection of Candida spp.
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JoVE Visualize is a tool created to match the last 5 years of PubMed publications to methods in JoVE's video library.

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