An Update on the Laboratory Diagnosis of Neuromyelitis Optica Spectrum Disorders

Neuromyelitis optica spectrum disorder (NMOSD) is an autoimmune disorder of the central nervous system that is specifically associated with demyelination of spinal cord and optic nerves. The discovery of specific autoantibody markers such as aquaporin-4 IgG and myelin oligodendrocyte glycoprotein IgG has led to several methodologies being developed and validated. There have been numerous investigations of the clinical and radiological presentations used in the clinical diagnosis of NMOSD. However, although various laboratory diagnostic techniques have been standardized and validated, a gold-standard test has yet to be finalized due to uncertain sensitivities and specificities of the methodologies. For this review, the literature was surveyed to compile the standardized laboratory techniques utilized for the differential diagnosis of NMOSD. Enzyme-linked immunosorbent assays enable screening of NMOSD, but they are considered less sensitive than cell-based assays (CBAs), which were found to be highly sensitive and specific. However, CBAs are laborious and prone to batch variations in their results, since the expression levels of protein need to be maintained and monitored meticulously.Standardizing point-of-care devices and peptide-based assays would make it possible to improve the turnaround time and accessibility of the test, especially in resource-poor settings.

A study on the characterization of Propionibacterium acnes isolated from ocular clinical specimens.

Background & objectives: There are only a few reports available on characterization of Propionibacterium acnes isolated from various ocular clinical specimens. We undertook this study to evaluate the role of P. acnes in ocular infections and biofilm production, and also do the phylogenetic analysis of the bacilli. Methods: One hundred isolates of P. acnes collected prospectively from ocular clinical specimens at a tertiary care eye hospital between January 2010 and December 2011, were studied for their association with various ocular disease conditions. The isolates were also subjected to genotyping and phylogenetic analysis, and were also tested for their ability to produce biofilms. Results: Among preoperative conjunctival swabs, P. acnes was a probably significant pathogen in one case; a possibly significant pathogen in two cases. In other clinical conditions, 13 per cent isolates were probably significant pathogens and 38 per cent as possibly significant pathogens. The analysis of 16S rRNA gene revealed four different phylogenies whereas analysis of recA gene showed two phylogenies confirming that recA gene was more reliable than 16S rRNA with less sequence variation. Results of polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) had 100 per cent concordance with phylogenetic results. No association was seen between P. acnes subtypes and biofilm production. Interpretation & conclusions: RecA gene phylogenetic studies revealed two different phylogenies. RFLP technique was found to be cost-effective with high sensitivity and specificity in phylogenetic analysis. No association between P. acnes subtypes and pathogenetic ability was observed. Biofilm producing isolates showed increased antibiotic resistance compared with non-biofilm producing isolates.

Rapid Detection of Viable M. tuberculosis Directly from Sputum by Reverse Transcriptase PCR Targeting 85B Gene.

This study was carried out to standardize reverse transcriptase PCR (RTPCR) targeting 85B gene for the rapid detection of viable Mycobacterium tuberculosis (M tuberculosis) from sputum specimens. 100 sputum samples from clinically suspected tuberculosis patients were included in the study. The sputum samples were collected in sterile diethyl pyrocarbonate (DEPC) treated containers and transported in ice to the laboratory within 2 hours to prevent degradation of RNA. The following microbiological analysis was performed on the sputum specimens: Ziehl Neelsen staining, Mycobacterial culture by BACTEC TB 460 reader and RT-PCR targeting 85B gene. Out of the 100 sputum samples, 40 sputum samples were Ziehl Neelsen stain positive, 58 sputum samples were culture and RT-PCR positive and 42 were culture and RT-PCR were negative. Among direct smear positive specimens, 3 specimens did not grow in culture and was RT-PCR negative indicating the non-viability of the acid-fast bacilli seen in the direct smear. The results of RT-PCR and culture against control group and clinically diagnosed tuberculosis patients were statistically significant by Chi square test (P<0.001). RT-PCR targeting 85B gene of M tuberculosis standardized in our laboratory for is a rapid, reliable and sensitive technique to detect the viable M tuberculosis directly from sputum specimens.