Rapid alkaline methylene blue supravital staining for assessment of anterior segment infections

Purpose

To present the Löffler’s alkaline methylene blue technique of staining eye discharges in eyes with anterior segment infections.

Method

The Löffler’s alkaline methylene blue staining method is a simple staining technique that can be used to differentiate bacterial, viral, and fungal infections. It is a cationic dye that stains cells blue because the positively charged dye is attracted to negatively charged particles such as polyphosphates, DNAs, and RNAs. Specimens collected from patients by swabbing are smeared onto microscope slides and the methylene blue solution is dropped on the slide. The slide is covered with a glass cover slip and examined under a microscope. The entire time from the collection to the viewing is about 30 seconds.

Results

Histopathological images of the conjunctival epithelial cells and neutrophils in eye discharges were dyed blue and the nuclei were stained more intensely blue. Bacterial infections consisted mainly of neutrophils, and viral infections consisted mainly of lymphocytes.

Conclusions

Löffler’s alkaline methylene blue staining can be done in about 30 seconds for diagnosis. Even though this is a one color stain, it is possible to infer the cause of the infection by detection of the absence of bacteria and/or fungi in context of the differential distribution of neutrophils and lymphocytes.

An evaluation of synthetic and natural supravital stains for the cytological examination of dissociated cells in a microfluidic channel

OBJECTIVE

Advances in biotechnology will result in paradigm shifts in both oncology and diagnostics. In pathology, methods such as microfluidics are being explored as delivery tools so that processed cells can serve dual purposes: conventional cytology-based diagnostics and recovery of the same cells for molecular assays. This wet mount-based approach to diagnosis will require staining of these cells by supravital dyes. This study was undertaken to determine the optimal supravital stain for the examination of cells in the wet mount preparations present in microfluidic platforms.

METHODS

Cells were dissociated from portions of tissue similar in size to a traditional core biopsy. These tissue-free cells were separately examined with two synthetic dyes and two natural dyes at varying dilutions.

RESULTS

Different dilutions of the synthetic dyes toluidine blue and methylene blue resulted in varying degrees of staining, whereas different dilutions of the natural dyes resulted in fairly constant intensities of colour. These characteristics affected the visualization of cells in wet mount preparations: optimally titered synthetic dyes gave better nuclear detail and cytoplasmic contrast.

CONCLUSIONS

All four dyes stained the test cells, but to different degrees and intensities. In our assessment, optimally titered synthetic dyes were better suited to the wet mount approach of microfluidics when compared with natural dyes.