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Emmanuel Andre - One of the best experts on this subject based on the ideXlab platform.

  • ruptured aortic aneurysm due to mycobacterium bovis bcg with a delayed bacteriological diagnosis due to False Negative Result of the mpb 64 immunochromatographic assay
    BMC Research Notes, 2017
    Co-Authors: Joanna Simar, Leila Belkhir, Bertrand Tombal, Emmanuel Andre
    Abstract:

    Abstract Background Adjuvant therapy with bacillus Calmette–Guerin (BCG), a live attenuated strain of Mycobacterium bovis , has become the treatment of choice for low-risk superficial bladder carcinoma following transurethral resection of the bladder. Complications following vesical BCG instillations are uncommon but, in some cases, severe side-effects can occur such as sepsis or mycotic aneurysm. Besides usual laboratory techniques used for the diagnosis of Mycobacterium tuberculosis complex (MTBC) infections (smear microscopy and cultures), commercial immunochromatographic assays detecting MBP64, a 24 kDa M. tuberculosis complex-specific secretory protein, can rapidly distinguish MTBC and non-tuberculosis mycobacteria (NTM). MPB64 is found in M. tuberculosis , M. bovis and some but not all substrains of M.bovis BCG. Therefore, these immunochromatographic tests can lead to False Negative Results and delayed bacteriological diagnosis depending on the presence or absence of MPB64 protein in BCG substrains used for intravesical therapy. Case presentation We report the case of a 78-year-old male patient who was admitted to the hospital because of a 1-month history of unexplained fever, thrill, weight-loss and general malaise. His past medical history was marked by a non-muscle-invasive bladder carcinoma treated by transurethral resection followed by BCG instillations (Oncotice, Merck, USA). The patient was initially treated for a urinary tract infection but as fever persists after 72 h of antibiotherapy, urinary tract ultrasound was performed and revealed a large abdominal aortic aneurysm confirmed by computed tomography. Surgery was performed after multidisciplinary discussion. Direct smear of perioperative samples revealed acid-fast bacilli and both solid and liquid cultures were massively positive. Rapid identification of the positive mycobacterial culture was performed using an immunochromatographic assay based on the detection of the Mycobacterium tuberculosis MPB 64 antigen. The Result was Negative for Mycobacterium tuberculosis complex. After review of the medical record, a polymerase chain reaction (PCR) was performed and gave a positive Result for M. tuberculosis complex. Anti-tuberculosis therapy was started immediately and the patient evolved favorably. Conclusions Through this case, we showed how the utilisation of MPB64 immunochromatographic assays can provide misleading information due to the variable presence of this protein among the different BCG strains. This case further illustrates the utility of rapid TB complex-specific PCR assays which provide a more reliable identification of all MTBC species.

L Thomas - One of the best experts on this subject based on the ideXlab platform.

  • development of a real time staphylococcus aureus and mrsa sam pcr for routine blood culture
    Journal of Microbiological Methods, 2007
    Co-Authors: L Thomas, Heather F Gidding, Andrew N Ginn, Tom Olma, Jonathan R Iredell
    Abstract:

    Abstract The notification of “Gram-positive cocci, possibly staphylococcus” in a blood culture drawn from a seriously ill patient is responsible for a large amount of vancomycin prescribing in institutions where methicillin-resistant Staphylococcus aureus (MRSA) is an important cause of bacteraemia. A duplex real-time TaqMan polymerase chain reaction targeting the species-specific nuc gene, and the mecA gene encoding methicillin-resistance, was developed as a tool for rapid identification and detection of S. aureus and methicillin-resistance, and optimised for immediate as-needs testing. Three different DNA extraction methods achieved varying DNA quality, with PCR inhibition the main problem. Serial blood cultures ( n  = 120) identified as possible staphylococci on Gram stain from our clinical laboratory were examined. There was one False Negative Result for a methicillin-resistant Staphylococcus epidermidis , which was positive on repeat testing, and one False Negative Result due to DNA extraction failure for MRSA from peritoneal dialysate inoculated into blood culture medium. Sensitivity and specificity of 97% and 100%, respectively, were obtained for mecA ; and sensitivity and specificity of 98% and 100%, respectively, for nuc . Detection of slow-growing coagulase-Negative staphylococci as co-infecting strains may be reduced. The assay quickly and reliably identified S. aureus in mixed infection, and identified methicillin resistance in both S. epidermidis and S. aureus strains.

Seung Il Kim - One of the best experts on this subject based on the ideXlab platform.

  • risk factors for a False Negative Result of sentinel node biopsy in patients with clinically node Negative breast cancer
    Cancer Research and Treatment, 2017
    Co-Authors: Seung Ah Lee, Hak Min Lee, Hak Woo Lee, Ban Seok Yang, Jong Tae Park, Sung Gwe Ahn, Joon Jeong, Seung Il Kim
    Abstract:

    Purpose Although sentinel lymph node biopsy (SLNB) can accurately represent the axillary lymph node (ALN) status, the False-Negative rate (FNR) of SLNB is the main concern in the patients who receive SLNB alone instead of ALN dissection (ALND). Materials and Methods We analyzed 1,886 patientswho underwent ALND after Negative Results of SLNB,retrospectively. A logistic regression analysis was used to identify risk factors associated with a FalseNegative (FN) Result. Cox regression model was used to estimate the hazard ratio of factors affecting disease-free survival (DFS). Results Tumor located in the upper outer portion of the breast, lymphovascular invasion, suspicious node in imaging assessment and less than three sentinel lymph nodes (SLNs) were significant independent risk factors for FN in SLNB conferring an adjusted odds ratio of 2.10 (95% confidence interval [CI], 1.30 to 3.39), 2.69 (95% CI, 1.47 to 4.91), 2.59 (95% CI, 1.62 to 4.14), and 2.39 (95% CI, 1.45 to 3.95), respectively. The prognostic factors affecting DFS were tumor size larger than 2 cm (hazard ratio [HR], 1.86; 95% CI, 1.17 to 2.96) and FN of SLNB (HR, 2.51; 95% CI, 1.42 to 4.42) in SLN-Negative group (FN and true-Negative), but in ALN-positive group (FN and true-positive), FN of SLNB (HR, 0.64; 95% CI, 0.33 to 1.25) did not affect DFS. Conclusion In patients with risk factors for a FN such as suspicious node in imaging assessment, upper outer breast cancer, less than three harvested nodes, we need attention to find another metastatic focus in non-SLNs during the operation. It may contribute to provide an exact prognosis and optimizing adjuvant treatments.

I Olivotto - One of the best experts on this subject based on the ideXlab platform.

  • can we predict which women with a Negative sentinel lymph node biopsy are at high risk of a False Negative Result
    Cancer Research, 2009
    Co-Authors: Tanya Berrang, M Paquette, Ryan Woods, Caroline Speers, A Hayshi, L Lerch, C Walter, Sally L Smith, I Olivotto
    Abstract:

    Background: Standard of care for women with a positive sentinel lymph node biopsy (SLNB) is to have a completion axillary lymph node dissection (cALND). For women with a Negative SLNB, cALND is often not performed, accepting that a proportion will have a False Negative (FN) Result. FN rates are commonly reported based on surgeon experience. In the absence of cALND, information on FN rates will not be available, and other means of assessing the risk for FN SLNB is needed.Materials and Methods: Between May 1999 and December 2006, 1661 women with early-stage breast cancer that had undergone SLNB followed by cALND, were identified from our provincial database: 77 FN, 560 true positive (TP), and 1024 true Negative (TN). FN cases were matched 1:3 with TN cases by date of SLNB. Chi-square and Wilcoxon Rank-sum tests were used to screen variables and those with moderate association were identified and included in subsequent models. Logistic regression was used to develop a multivariable model to predict the probability of FN vs. TN status. ROC curves were used to estimate the optimal probability cut-off, at which sensitivity (SN) and specificity (SP) were maximized. The model9s performance was then assessed using a cross-validation technique.Results: Factors examined that did not significantly affect FN vs. TN status rate included: age, body mass index, previous breast surgery, histology, estrogen receptor status, margin status, tumor palpability, injection technique (peritumoral, periareolar), mapping agent used (yes/no), and SLNB done pre vs. post breast surgery (all p=NS). Factors identified that significantly affected FN vs. TN status (p 1). The final model contained 5 variables: T stage (1 vs. 2), tumor grade, number of SLN removed, tumor site, and LVI. ROC identified an optimal probability cut-point for this model of 0.217 (21.7% risk of FN) with a corresponding SN of 71% and SP of 70%. In the cross-validation, the model correctly classified 66% of cases (SN of 73%, SP of 64%) with an AUC of 0.76. With increasing FN risk, SN declined and SP increased such that at a FN risk of 30%, this model had a SN 56%, SP 77%, and accuracy 72%. Using this model a woman with a T1, lateral, grade 3, 1 SLN and LVI- had a predicted FN risk of 21.5%, increasing to 52.2% if she were LVI+.Discussion: For women with early breast cancer, a Negative SLNB Result has a significant impact on prognosis and recommendations for further systemic and radiation therapy, this model (T size, tumor grade, number of SLN removed, tumor site, and LVI) is the first that would offer a quantitative prediction of FN risk in this setting, which could influence further discussion and therapeutic decision making. Potential refinements of this model will be explored, incorporating 9lower-priority9 variables. Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 303.

Herman Nilssonehle - One of the best experts on this subject based on the ideXlab platform.

  • False Negative Result in the detection of an igm monoclonal protein by capillary zone electrophoresis
    Clinical Chemistry, 2004
    Co-Authors: Henrik Zetterberg, Herman Nilssonehle
    Abstract:

    Capillary zone electrophoresis (CZE) of serum proteins has developed into a rapid and sensitive analytical technique that is gaining impact in clinical laboratories because of its suitability for automation (1)(2). We report a case of plasmacytic lymphoma with an IgM monoclonal gammopathy that was difficult to detect by CZE. The patient was a previously healthy 49-year-old man who was referred because of palpable large (1.5-cm) lymph nodes bilateral in the submandibular region, in the neck, and in the axillae. Computed tomography scans revealed several large (1–1.5 cm) mediastinal and retroperitoneal lymph nodes. His blood hemoglobin concentration …