|Year : 2013 | Volume
| Issue : 1 | Page : 93-94
Iodine-glycerol as an alternative to lactophenol cotton blue for identification of fungal elements in clinical laboratory
R Vignesh1, CR Swathirajan1, S Solomon1, EM Shankar1, KG Murugavel1, I Paul1, G Waldrop1, SS Solomon2, P Balakrishnan1
1 Department of Infectious Diseases Laboratory, YRG Centre for AIDS Research and Education (YRG CARE), Chennai, India
2 Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, USA
|Date of Submission||05-Jul-2012|
|Date of Acceptance||08-Aug-2012|
|Date of Web Publication||15-Mar-2013|
Department of Infectious Diseases Laboratory, YRG Centre for AIDS Research and Education (YRG CARE), Chennai
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Vignesh R, Swathirajan C R, Solomon S, Shankar E M, Murugavel K G, Paul I, Waldrop G, Solomon S S, Balakrishnan P. Iodine-glycerol as an alternative to lactophenol cotton blue for identification of fungal elements in clinical laboratory. Indian J Med Microbiol 2013;31:93-4
|How to cite this URL:|
Vignesh R, Swathirajan C R, Solomon S, Shankar E M, Murugavel K G, Paul I, Waldrop G, Solomon S S, Balakrishnan P. Iodine-glycerol as an alternative to lactophenol cotton blue for identification of fungal elements in clinical laboratory. Indian J Med Microbiol [serial online] 2013 [cited 2020 May 29];31:93-4. Available from: http://www.ijmm.org/text.asp?2013/31/1/93/108752
Microscopic observation of wet mounts remains the most widely used method in clinical laboratories for identifying moulds based on their characteristic morphological features. The standard technique for the microscopic examination of fungal cultures is the lactophenol cotton blue (LPCB) slide tease method or the adhesive tape method.  LPCB is preferred universally for its usage as a fixative, stain and mounting medium.
However, according to material safety data sheets, exposure of phenol, one of the ingredients of LPCB, may be hazardous to laboratory personnel and to the environment.  Phenol, apart from being highly corrosive, is reported to possess tumorigenic and mutagenic properties and also known to be toxic to aquatic life.
Therefore, the need arises for an alternative safe, eco-friendly and equally functional fungal mount medium. Although iodine solution in combination with chloral hydrate (Melzer's solution) is currently being used in clinical mycology laboratories, it has never been used as a mounting medium for microscopic identification of fungi, heretofore.  Even still, chloral hydrate is known to be a hazardous substance. Hence, we examined the possibility of using iodine-glycerol as an alternative to LPCB and to evaluate its usefulness for wet mount preparations for microscopic observation and identification of certain clinical isolates of filamentous fungi.
Glycerol (0.25%) in iodine solution is a combination developed in our laboratory that is studied to provide longevity to iodine wet mounts.  Adhesive tape preparations of standard fungal cultures were made and were mounted using LPCB and iodine-glycerol simultaneously. The preparations were observed under the microscope comparing the visual clarity and staining characteristics.
Iodine-glycerol mounts were more transparent, allowing more light to pass through the specimen, and thereby revealing a clearer and more detailed view of the morphology of fungi than the LPCB mounts. The photomicrographs of iodine mount were of good quality and clarity, capturing finer details [Figure 1]. Lugol's iodine is reported to be a potent fungicide by interacting with thiol groups in enzymes and proteins and hence would possibly replace phenol, the killing agent of LPCB.  As the hygroscopic agent glycerol is incorporated as in LPCB, the iodine-glycerol mounts could also be used as semi-permanent preparations and therefore can be stored for longer duration until confirmation of fungal identification is available from mycology specialists. Further detailed investigations are needed to thoroughly evaluate if iodine-glycerol solution be possibly used as an alternative for LPCB for observing fungal mounts. Thus, we describe, herein, the fidelity of a simple and eco-friendly, iodine-glycerol method for the efficient preliminary identification of fungal elements.
|Figure 1: Semi-permanent wet mount preparation of fungal isolates using iodine-glycerol demonstrating (a) conidia of Alternaria alternata. (c) Flask-shaped phialides of Phialophora verrucosa, (d) Macroconidia of Microsporum canis. (b) and (e) conidiophores of Aspergillus fl avus under ×40 objective of binocular microscope (Leica|
DMLS, Wetzlar, Germany)
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| ~ References|| |
|1.||Rodriguez-Tudela JL, Aviles P. Improved adhesive method for microscopic examination of fungi in culture. J Clin Microbiol 1991;29:2604-5. |
|2.||IPCS. Phenol: Health and Safety Guide. Geneva: WHO; 1994. Available from: http://www.inchem.org/documents/hsg/hsg/hsg88_e.htm. [Last Accessed 2012 Jun 16]. |
|3.||B³aszkowski J, Renker C, Buscot F. Glomus drummondii and G. walkeri, two new species of arbuscular mycorrhizal fungi (Glomeromycota). Mycol Res 2006;110:555-66. |
|4.||Vignesh R, Sekar R, Shankar EM, Kumarasamy N, Murugavel KG, Irene P, et al. Wet mounting using iodine-glycerol provides a semi-permanent preparation for microscopic observation of faecal parasites. J Med Microbiol 2008;57:679-80. |
|5.||Russell AD. Similarities and differences in the responses of microorganisms to biocides. J Antimicrob Chemother 2003;52:750-63. |