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| Year : 1986 | Volume
: 32
| Issue : 1 | Page : 14-7 |
Characterization and antibiotic sensitivity patterns of yeast-like organisms.
Deshpande SD, Shetty CR, Murti PK
How to cite this article:
Deshpande S D, Shetty C R, Murti P K. Characterization and antibiotic sensitivity patterns of yeast-like organisms. J Postgrad Med 1986;32:14 |
How to cite this URL:
Deshpande S D, Shetty C R, Murti P K. Characterization and antibiotic sensitivity patterns of yeast-like organisms. J Postgrad Med [serial online] 1986 [cited 2023 Jun 5];32:14. Available from: https://www.jpgmonline.com/text.asp?1986/32/1/14/5373 |
Candida and other yeast-like organisms are known to be opportunistic pathogens. Candida often forms the normal flora of the skin, mouth, vagina and the intestine. It is known to infect patients with low body defence mechanisms and also those on broad spectrum antibiotics, corticosteriods and cytotoxic drugs. Diabetes mellitus and drug addiction are the other predisposing factors for candidiasis.[5],[8],[9],[11] This study was undertaken with a view to find out the distribution of different Candida species and other yeast-like organisms in our population and their antimicrobial susceptibilities.
One hundred and five yeast-like organisms were isolated from samples like sputum, cerebrospinal fluids, vaginal swabs and stool at the B.Y.L. Nair Charitable Hospital, Bombay. Various tests like growth pattern in Sabouraud's broth, germ tube formation, chlamydospore formation on corn meal agar, sugar fermentation and assimilation tests and urease production tests were performed on these isolates for identification and speciation.[9]
Antibiotic sensitivity tests were carried out by agar dilution method.[1],[3] The antimicrobial sensitivity test plates were prepared by incorporating the drugs, nystatin and hamycin in Sabouraud's dextrose agar. For nystatin, the concentrations chosen varied from 0.25 µg/ml to 16 µg/ ml and for hamycin, from 0.03 µg/ml to 4.0 µg/ml. Antibiotic plates were then divided into eight equal parts for eight different isolates and one standard loopful of inoculum was plated. Results were recorded after 48 hours of incubation at 37°C, taking the control plates into consideration.[1]
The incidence of different species of Candida amongst the 105 isolates is as shown in [Table 1] Some organisms showed variations from the classical reactions. Nineteen strains of C. tropicalis showed germ tube formation after incubating with plasma for 8 to 24 hours. Two strains of C. albicans did not show Chlamydospore formation on corn meal agar, whereas three strains of C. tropicalis showed chlamydospore formation on corn meal agar. Two strains of C. albicans and one strain of C. tropicalis did not show usual pattern of sugar assimilation. Only two strains gave variable results and could not be speciated.
In the present study 98 per cent of yeast-like organisms could be identified and speciated by using a battery of tests mentioned earlier. Taschdjian et al,[11] Dolan,[5] Huppert et al[8] and Dalal and Kelkar[4] using a combination of tests identified 76 per cent, 98.8 per cent, 96 per cent and 100 per cent of yeast-like organisms respectively.
Germ tube formation by C. albicans has received a great deal of attention, though in C. tropicalis, it has not been closely studied. In this work, all the 19 strains of C. tropicalis formed germ-tubes. Tierno and Milstoc[12] reported 4 strains and Martin[10] reported 26 strains of germ tube producing C. tropicalis. Martin further observed that they rapidly lost this ability during repeated sub-cultures.[10]
In this series 3 strains of C. tropicalis were found to produce chlamydospores on corn meal agar. Hasenclever[7] and Beheshti et al[2] reported 29 and 3 strains of C. tropicalis producing chlamydospores respectively.
In this work about 95 per cent of the isolates showed susceptibility to 8 µg/ml or less of nystatin and 88 per cent showed susceptibility to 1 µg/ml or less of hamycin. These results are comparable with those of Hamara and Pankienicz,[6] who found that all their isolates were inhibited by 6.4 µg/ml of nystatin. In a similar study by Athar and Swaroop,1 it was found that all the isolates were inhibited by 40 units/ml or less of nystatin and 0.64 µg/ml or less of hamycin on Sabouraud's dextrose agar.
From this study we conclude that germ tube and chlamydospore formation tests alone are not sufficient for characterisation of Candida species. Several tests are required for correct speciation of yeast like organisms. Further, at the point in time of this work, the M.I.C. values were within 8 µg/ml for nystatin and 1 µg/ml of hamycin.
We are grateful to M/s. Sarabhai Ltd. for the supply of nystatin and M/s. Hindustan Antibiotics for hamycin.
| 1. | Athar, M. A. and Swaroop, A.: The effect of agar media on the in vitro susceptibility of Candida species to polyene antibiotics. Ind. J. Med. Sci., 30: 147-155, 1976.  |
| 2. | Beheshti, F., Smith, A. G. and Krause, G. W.: Germ tube and chlamydospore by formation by Candida albicans on a new medium. J. Clin. Microbiol., 2: 345-348, 1975. |
| 3. | Clayton, Y.: Laboratory Methods in Antimicrobial Chemotherapy. Editors: D. S. Reeves and 1. Phillips et al. Churchill Livingstone, Edinburg and London. 1978, pp. 120-130. |
| 4. | Dalal, P. and Kelkar, S. S.: Candida species in human candidiasis Ind. J. Microbiol., 19: 26-28, 1979. |
| 5. | Dolan, C. T.: A practical approach to identification of yeast-like organisms. Amer. J. Clin. Pathol., 55: 580-590, 1971. |
| 6. | Hamara, L. K. and Panklenicz, I. J.: The susceptibility of Candida albicans to amphotericin-B, nystatin and 5-flurocytosine, Med. J. Aust., 22: 749-750, 1977. |
| 7. | Hasenelever, H. F.: The consistent formation of chlamydospores by Candida tropicalis. Sabouradia, 9: 164-166, 1971. |
| 8. | Huppert, M., Harper, G. and Sun, S. H. et al: Rapid methods for identification of yeasts. J. Clin. Microbiol., 2: 21-34, 1975. |
| 9. | Larone, D. H.: Medically Important Fungi-A Guide to Identification. Hoeber Medical Division of Harper and Row Publishers, New York, 1976, pp. 35-42. |
| 10. | Martin, M. V.: Germ tube formation by oral strains of Candida Tropicalis. J. Med. Microbiol., 12: 187-193, 1979. |
| 11. | Taschdjian, C. L., Burchall, J. J. and Kozinn, P. J.: Rapid identification of Candida albicans by filamentation of serum and serum substitutes. Amer. J. Dis. Childh., 99: 212-215, 1960. |
| 12. | Tierno, P. M. and Milstoc, M.: Germ tube positive Candida tropicalis. Amer. J. Clin. Pathol., 68: 294-295, 1977. |
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