| BACKGROUND: Cryptococcal meningitis (CM) is a kind of central nervous system fungous infectious disease, which seriously threatens the health of human for its poor prognosis and high mortality rate. In the past few years, several factors, including widespread use of immunosuppressant, broad-spectrum antibiotic, glucocorticoids, invasion examinations in intracalvarium, organ transplantation and AIDS prevalence result in a significant increase of CM incidence. Various symptoms, such as headache, fever, nausea and vomiting; meningeal irritation sign, pyramidal sign, psychiatric symptom, and epileptic seizure are the common clinical manifestations of CM. And the course of disease may be acute, subacute or chronicity. It's difficult to diagnose CM by clinical methods. Radiological examinations including computed tomography (CT) and magnetic resonance imaging (MRI) only help us to detect intracranial spaceoccupying lesion such as granuloma and perencephaly, hydrocephalus and hydrocephaly, all of which may have correlation with cryptococcus, Therefore, these methods are lack of specificity. X-ray examination of the chest shows hilar lymph nodes with patch or grain infiltration, lung cavitates or pleural effusion, which easily lead to misdiagnosis of tuberculose focus, pneumonia and lung spaceoccupying lesion. Nowadays, final diagnosis of CM mainly depends on the finding of pathogen in cerebrospinal fluid (CSF). Laboratory diagnosis methods using for CM's diagnosis include CSF India ink staining, alcian blue staining, PAS staining, fungus culture, ELISA, latex agglutination test, detection of monoclonal antibody, G ((1,3)-β-D-Polyglucosan) test, GM (galactomannan) test, and other molecular biology methods. However, these methods has obvious disadvantages such as low positive percentage, complex operative procedure, high cost , false positive and false negative, which cannot meet the clinical demands. Thus, it is imperative to explore an efficient method to diagnose the CM. May-Grunwald-Giemsa (MGG) staining has been widely used in abroad, and applied in our hospital since 1975 to detect the pathogens, including the cryptococcus. However, the specificity and validity of MGG staining in the diagnosis of CM is still fragmentary. OBJECTIVE: To evaluate the application of MGG staining in the diagnosis of CM and establish a new standard for final diagnosis of CM. METHOD: We retrospectively analyzed the clinical data and the diagnosis measurements of 37 cases of hospitalized CM patients from Jun. 1989 to Sept. 2008, among which 29 cases were male and 8 female, and 14 with underlying diseases. The average age was 28.7 ranging from 3 to 63 years. 21 cases had been misdiagnosed before hospitalization. CSF cells were collected by slide centrifugation method for cells counting and MGG staining. The pathogens with one or cluster, round or oval shape, diameter ranging from 5 to 15μm, non-nuclear and deep blue staining, and radial sentus were diagnosed to cryptococcus. Finally, we compared the positive percentage of cryptococcus by MGG staining with that of India ink staining. RESULTS: According to counting results of white blood cells in the CSF, 3 cases were normal while 34 were higher than normal values. Cytological classification of all patients'CSF cells showed that lymphocytes were mainly found in 27 cases, polymorphonuclear neutrophils in 5 and monocytes in the other 5 cases. Of all the cases, the CSF samples, in which the cryptococcus was detected by India ink staining, were 30 (81%), while those by MGG staining were 37 (100%).CONCLUSION: Positive percentage for diagnosis of CM by MGG staining was significantly higher than by India ink staining, a present gold standard for diagnosis of CM. MGG staining had such advantages as easy manipulation, high efficiency, low cost and time-consumption, and also enabled us to know the curative effects through observing dynamic changes of cytology. Thus, we suggest that MGG staining can be established as a new standard method for diagnosis of CM.
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