Salar Zai ( Institute of Radiotherapy and Nuclear Medicine (IRNUM), Peshawar. )
Sher Mohammad Khan ( Institute of Radiotherapy and Nuclear Medicine (IRNUM), Peshawar. )
Jawad Gillani ( Institute of Radiotherapy and Nuclear Medicine (IRNUM), Peshawar. )
One hundred clinical specimens from hospitalized cancer patients were examined microscopically for evidence of yeast cells and cultured for Candida colonization. Candida cells were observed microscopically in both unstained and Gram-stained preparations and culture in 60% of specimens (JPMA 47:191, 1997.
More than 81 species of Candida are known, but Candidiasis is caused most commonly by Candida albicans1. Under normal conditions, members of Candida family are found in small numbers as a commensal of skin, mouth2, vagina, sputum, urine and stool and disease results only when a major change in normal flora or a disturbance of normal immune response occurs. Clinically, the disease may be acute, subacute, chronic or episodic. The infection may be localized to mouth, throat, skin, scalp, vagina3, fingers, nails, bronchi or become systemic as in septicemia, endocarditis and meningitis. Candidiasis can occur in all age groups but is most common in the new boms and the elderly. In healthy individuals, Candidiasis usually is a result of a damage in the epithelial barrier function. It occurs almost exclusively in debilitated patients whose normal defense mechanisms are impaired4. A patient with cancer may be immunocompromised because of the underlying malignancy or anticancer therapy. Specific malignancies may be associated with immune deficit that predisposes to infection with a particular pathogen. Therapy with corticosteroids or cytotoxic drugs and localized or widespread irradiation result infurther deterioration of the host defense mechanism. Cancer patients thus remainvulnerable to a wide variety of infections. The infectious complications may be life threatening and may limit the benefits of anticancer therapy. Control of infections is thus important to reduce morbidity and mortality in cancer patients5. This study was conducted to determinethe spectrum of Candidiasis in cancer patients.
Material and Methods
One hundred clinical specimens were obtained from hospitalized cancer patients to detect yeast cells and cultured for Candida. The specimens obtained for laboratoiy identification were urine, throat swab, blood, sputum, stool, pus and high vaginal swabs (HVS). A smear from each specimen and of deposit of centrifuged specimen of urine was prepared and examined microscopically as unstained and Gram~stained preparation for the presence of small, round to oval thin walled clusters of budding yeast cells (blastoconidia) and branching pseudohyphae. The specimens were inoculated onto Sabouraud’s dextrose agar and incubated at room temperature for 48 hours. Creamy, white, smooth, shiny colonies with a characteristic odour were ieganled as presumptive positive for Candida. Several colonies of the yeastwere emulsified into 0.5 ml of serumina testtube to give a slight opalescent suspension and incubated at 37°C for 3 hours. A drop of serum was then examined microscopically (one drop betweenthe slide and the cover slip) forthe presence of finger tubes. This test does not replace other tests, but is simple, quick and least expensive. A negative result excludes C. albicans and a positive result strongly indicates its presence. Although germ tube test is typical of C. albicans, it is not entirely specific. Some species of C. stellatoidea strain behave in the same way as do some strains of C. rugosa and C. utilis, butthese are rarely found inman. Inadditionto the germ tube test the strains were confirmed with the help of other physiological tests like urea hydrolysis, growth on cycloheximide at 37°C and fermentation reactions.
A total of 100 clinical specimens were obtained from hospitalized febrile cancer patients. Sixty patients were found positive for Candida both on microscopy and culture (Table).
All patients in this study had histologically confirmed cancers and were febrile at the time of hospitalization. Such patients are iinmunocompromised and are therefore, at high risk of acquiring a number of serious infections including Candidiasis, particularly when they present with fever. Malignancy itself can cause fever but 55 to 70% of fevers that occur in cancer patients are caused by infections especially in granulocytopenic patients6. The results of this study have confirmed the earlier findings6 that Candida albicans is the most common cause of Candidiasis, as 60% of the patients were found colonized with the yeast. Our results are also in line with those of Krammer et al7, who cultured C. albicans from the orophaiynx and stomach of more than 80% of patients on broad spectrum antibiotics. The cancer patients in this study were found to be colonized with C. albicans only. The incidence and cause of Candidiasis in cancer patients however, varies from study to study. Fourteen out of 25 patients were found to be colonized and infected by C. tropicalis in other studies8. Similarly C. krusei has been observed in cancer patients receiving fluconazole for antifungal prophylaxis9. Lack of immunity in cancer patients, the use of antibiotics, steroids, cytotoxic drugs and exposure to radiation may be responsible for such a high incidence of Candidiasis detected in this study. The reason for urinary Candidiasis may be prolonged catheterization alongwith the use of antibiotics. Candidiasis as high as 98% has been reported10 in 155 episodes of catheter-associated fungemia. The evidence of Candida colonization in these patients was correlated with invasive disease. A positive blood culture for Candida was highly correlated with invasive or disseminated infection in cancer patients. Undetected and untreated fungal infection can be rapidly fatal as a few patients have shown in this study. Early detection of Candidiasis is thus highly desirable to stop morbidity and mortality in cancer patients.
1. Wade, J.C. Epidemiology of Candida infections. In: Bodey, OP. eds. Candidiasis: Pathogenesis, Diagnosis and Treatment. Second ed, New York, Raven Press, 1993,p. 86.
2. Shelly, AS, and Roseff, SAM. Oral and esophageal candidiasis. Epidemiology ofCandida infections. In:Bodey,G.P. eds. Candidiasis: Pathogenesis, diagnosis and treatment. Second ed., New York, Raven Press, 1993, p. 185.
3. White, D. Effective management of vaginal thrush. Practitioner, 1995; 239:612-616.
4. Ellis, D.H. Clinical Mycology: The human opportunistic mycoses. New York, Pfizer Inc., 1994, pp. 17-38.
5. Rogers, T.R. Prevention of infection during neutropenia. Br. J. Haematol., 1991 ;79:544-549.
6. Pizzo, PA., Meyers, J., Freifeld, A.G. et at. Infections in the cancer patients. In: Devita, VT., Heliman, S. and Rosenberg, S.A. eds. Cancer principles and practices ofoncology. Philadelphia. J.B. Lippincott Company. 1993, pp. 2292-2337.
7. Kramer, B.S., Pizzo, P.A,, Robichand. K.J. et a!. Role of serial microbiologic surveillance and clinical evaluation in the management of cancer patients with fever and granulocytopenia. Am.J. Med., 1 982;72 :561-568.
8. Wingard, JR., Merz, W.G. and Saral, R. Candida tropicalis. A major pathogen in immunocompromised patients. Ann. Intern. Med., 1979;91 :539-543.
9. Wingard, JR., Merz, W.G. and Saral, R. Increase in candida krusei infection among patients with bone marrow transplantation and neutropenia treated prophylactically with fluconazole. N. Engl. J. Med., 199 1;325 : 1274-1 277.
10. Lecciones, J.A.,Lee, J.W, Navarro, E.E. at al. Vascular catheter-associated fungemia in patients with cancer. Clin. Infect. Dis., 1992;14:873-875.