Application of molecular tools for the diagnosis of central nervous system infections

Routine Broad-Range Fungal Polymerase Chain Reaction With DNA Sequencing in Patients With Suspected Mycoses Does Not Add Value and Is Not Cost-Effective

Context.—

New molecular diagnostic tests regularly become available, and they may be assumed to be superior to traditional diagnostic studies. The added cost of these studies should be considered in conjunction with the value provided for patient care.

Objective.—

To assess the cost and diagnostic value of broad-range polymerase chain reaction (PCR) and DNA sequencing for the diagnosis of fungal infections compared with traditional studies.

Design.—

We reviewed the cost and clinical impact of broad-range fungal PCR/DNA sequencing for 65 specimens for which this test, a direct fungal examination, fungal culture, and a histopathologic assessment were performed.

Results.—

The sensitivity, specificity, and positive and negative predictive values for each of the assays studied were, respectively: histopathology (83.3%, 100%, 100%, and 98.3%); direct examination (66.7%, 100%, 100%, and 96.7%); fungal culture (83.3%, 100%, 100%, and 98.3%); and broad-range fungal PCR/DNA sequencing (83.3%, 95.0%, 62.5%, and 98.3%). The cost for broad-range fungal PCR/DNA sequencing was $32,500, compared with $8,591.70 for all traditional tests combined, for the 65 specimens included in this review.

Conclusions.—

Broad-range fungal PCR/DNA sequencing did not detect any infecting fungal pathogen that was not detected by at least 1 of the traditional methods, but 3 false-positives occurred. Broad-range fungal PCR/DNA sequencing is not a substitute for traditional laboratory studies and should be used judiciously to promote care affordability.

The safety and side effects of monoclonal antibodies

Monoclonal antibodies (mAbs) are now established as targeted therapies for malignancies, transplant rejection, autoimmune and infectious diseases, as well as a range of new indications. However, administration of mAbs carries the risk of immune reactions such as acute anaphylaxis, serum sickness and the generation of antibodies. In addition, there are numerous adverse effects of mAbs that are related to their specific targets, including infections and cancer, autoimmune disease, and organ-specific adverse events such as cardiotoxicity. In March 2006, a life-threatening cytokine release syndrome occurred during a first-in-human study with TGN1412 (a CD28-specific superagonist mAb), resulting in a range of recommendations to improve the safety of initial human clinical studies with mAbs. Here, we review some of the adverse effects encountered with mAb therapies, and discuss advances in preclinical testing and antibody technology aimed at minimizing the risk of these events.

Treatment of progressive multifocal leukoencephalopathy associated with natalizumab

We describe the clinical and therapeutic course of a 52-year-old patient with multiple sclerosis in whom progressive multifocal leukoencephalopathy (PML) developed after 12 months of therapy with natalizumab. The patient was hospitalized 2 months after the onset of neurologic and psychiatric symptoms and was treated with plasma exchange and immunoadsorption to eliminate natalizumab. After a brief improvement, he became critically ill with an apparent episode of immune reconstitution inflammatory syndrome. Steroid-pulse therapy led to stabilization of the patient's condition and clinically significant recovery. This case illustrates that prompt diagnosis and treatment may improve the outcome in patients with severe PML associated with natalizumab therapy.