Comparison of three commercial cryptococcal latex kits for detection of cryptococcal antigen

Three commercial latex kits, IBL, MYCO-Immune, and IMMY, for the detection of cryptococcal antigen were compared in regard to sensitivity, specificity, and height of antigen titers. A total of 218 cerebrospinal fluid and 79 serum specimens from 239 patients were included. Twenty-two patients had culture-proven disseminated cryptococcosis. Both the IBL and MYCO-Immune kits had sensitivities of 100%, and the IMMY kit had sensitivities of 82.6 and 45.4% in CSF and serum specimens, respectively. There was one false-positive reaction in serum with the MYCO-Immune kit and one false-negative reaction on screen only with all three kits. Rheumatoid factor-containing sera were used to check the agglutination titers between matching anti-cryptococcal globulin reagents and normal globulin reagents. The finding that agglutination titer with anti-cryptococcal globulin reagents was fourfold higher than with normal globulin reagents in the MYCO-Immune kit is considered to be a cause for a false-positive reaction in serum.     

Magnetic resonance imaging study of cryptococcal neuroradiological lesions in HIV-negative cryptococcal meningitis

Magnetic resonance (MR) scanning has become an important diagnostic and management tool in cryptococcal meningitis (CM). However, there are only isolated case reports documenting neuroradiological findings in human immunodeficiency virus (HIV)-negative patients with CM and none has clearly addressed the relationship between cerebral lesions on magnetic resonance imaging (MRI) and prognosis. The MR brain images available from 114 HIV-negative patients with CM were retrospectively analysed. Patients were divided into Group I with one or more CM-related lesions and Group II without CM-related lesions. Initial clinical and biochemical markers and prognosis were collected and compared between the two groups. In the present study, the most common pattern of CM-related lesions by MRI was radiological meningitis, following by Virchow–Robin (VR) dilatation, hydrocephalus, intracerebral nodules and pseudocysts, which was different from previous studies reporting that the main MR findings of cerebral cryptococcosis in HIV-infected patients include dilated VR spaces, masses and pseudocysts. Compared to the patients without CM-related lesions, patients with CM-related lesions presented with a higher percentage of male patients, a higher frequency of altered mental status, a higher positive rate of Cryptococcus culture in cerebrospinal fluid (CSF) and a lower ratio of CSF glucose/blood glucose. Poor outcomes were more frequent in patients with presence of CM-related lesions compared to patients without CM-related lesions. In conclusion, the main pattern of cryptococcosis-related lesions on MR scanning differ between non-HIV- and HIV-positive patients with CM. The presence of CM-related lesions was significantly associated with predictors for poor outcome. Neuroimaging on MR scanning is a useful tool to evaluate the initial severity and prognosis of CM without HIV infection.     

Pseudooutbreak of cryptococcal meningitis.

A pseudooutbreak of cryptococcal meningitis was caused by the use of contaminated albumin solution used in the preparation of Papanicolaou-stained slides of cerebrospinal fluid. Organisms were seen in cytocentrifuge preparations, but not in India ink preparations of cerebrospinal fluid specimens. Cryptococcal antigen tests were positive and Cryptococcus neoformans was cultured from the albumin-treated cerebrospinal fluid specimens and from the albumin solution.     

False-negative cerebrospinal fluid cryptococcal latex agglutination tests for patients with culture-positive cryptococcal meningitis.

Three cases of false-negative cerebrospinal fluid latex agglutination test results for patients with culture-positive cryptococcal meningitis are reported. False-negative results occurred in settings of low cryptococcal antigen concentrations in cerebrospinal fluid and were dependent on the latex agglutination test kit used. Investigation of each case revealed that prozone phenomena or interference from bound antibody or protein could not account for the false-negative results.     

Binding of cryptococcal polysaccharide to Cryptococcus neoformans

Radioiodinated cryptococcal polysaccharide was used to study binding of the soluble polysaccharide to encapsulated and non-encapsulated cryptoccoci. Binding of polysaccharide to non-encapsulated cryptococci occurred rapidly over a 30-min period and was largely complete after 2 h. Bound, labeled polysaccharide was slowly eluted from Cryptococcus neoformans after the addition of unlabeled polysaccharide, indicating reversibility of binding. Non-encapsulated cryptococci bound polysaccharide in two ways. Specific binding to the yeast was saturable by ca. 82 ng of polysaccharide per 10(6) yeast cells. Nonspecific binding also occurred which was not saturable under the conditions used in our experiments. Phagocytosis of the non-encapsulated yeast strain was inhibited when the specific binding was ca. 50% saturated. Binding of polysaccharide to an encapsulated strain showed nonspecific, nonsaturable binding, but little specific binding occurred. Presumably the specific binding sites were saturated in the encapsulated strain. Polysaccharides obtained from a hypocapsular mutant (A61) and a normally encapsulated strain competed effectively with labeled serotype D polysaccharide for binding sites on non-encapsulated cryptococci and had identical phagocytosis-inhibiting properties. Similarly, polysaccharides from all four cryptococcal serotypes competed effectively with labeled serotype D polysaccharide for binding sites on the non-encapsulated strain, and all four polysaccharides inhibited phagocytosis of non-encapsulated Cryptococcus neoformans. Unmodified, de-O-acetylated, carboxyl-reduced, periodate-oxidized and reduced (polyalcohol), and Smith-degraded polysaccharides competed with labeled polysaccharide for binding sites on the cell. The unmodified, de-O-acetylated and carboxyl-reduced polysaccharides inhibited phagocytosis of non-encapsulated cells, but the polyalcohol and Smith product were unable to inhibit phagocytosis.     

Clinical manifestations and management of cryptococcal infection

Cryptococcus neoformans is an important fungal pathogen causing invasive infection, especially of the central nervous system in this era of the HIV/AIDS epidemic. The choice of treatment depends on site(s) of infection and the patient's immune status. Use of appropriate antifungal agents decreases mortality significantly, but requires continued therapy and long-term maintenance to prevent relapses. The use of liposomal amphotericin B (L Amp B) has overcome some of the difficulties usually found in this setting. The major advantage of these liposomal formulations are faster clearance of C. neoformans [cerebrospinal fluid (CSF) negative] and a reduction in amphotericin toxicity. The majority of clinical efficacy data related to L Amp B are derived from compassionate use studies and case series. Use of liposomal amphotericin has also shown to be a cost effective approach.     

Spontaneous cryptococcal peritonitis in cirrhotic patients

Spontaneous bacterial peritonitis is a common complication in patients with cirrhosis and ascites. However, spontaneous peritonitis caused by Cryptococcus neoformans is uncommon. Delayed diagnosis of cryptococcal peritonitis often results in death. We describe three cases of spontaneous cryptococcal peritonitis in patients with decompensated cirrhosis. One case had associated symptomatic human immunodeficiency virus infection. Clinical awareness of this entity may lead to the early diagnosis and proper treatment.     

Utility of clinical assessment,imaging, and cryptococcal antigen titer to predict AIDS-related complicated forms of cryptococcal meningitis

Background  

This study aimed to evaluate the prevalence and predictors of AIDS-related complicated cryptococcal meningitis. The outcome was complicated cryptococcal meningitis: prolonged (≥ 14 days) altered mental status, persistent (≥ 14 days) focal neurologic findings, cerebrospinal fluid (CSF) shunt placement or death. Predictor variable operating characteristics were estimated using receiver operating characteristic curve (ROC) analysis. Multivariate analysis identified independent predictors of the outcome.     

Detection of cryptococcal polysaccharide using counterimmunoelectrophoresis.

Counterimmunoelectrophoresis was used to detect Cryptococcus neoformans capsular polysaccharide in the body fluids of infected patients. Using rabbit anti-C. neoformans A15 globulin, counterimmunoelectrophoresis detected 1.25 microgram of purified cryptococcal polysaccharide per ml of cerebrospinal fluid (CSF) or urine and 2.5 microgram per ml of serum. When the body fluids were subjected to a hundredfold concentration prior to testing, as little as 25 ng of purified cryptococcal polysaccharide/ml CSF or urine and 80 ng/ml serum was detected. Among patients with cryptococcal meningitis, counterimmunoelectrophoresis detected polysaccharide in the CSF when the India-ink examination was negative. Using counterimmunoelectrophoresis, the concentrations of polysaccharide antigen in the body fluids of these patients could be estimated. Specificity of the rabbit anti-C. neoformans A15 globulin was evaluated. There was no crossreaction that detracted from its diagnostic usefulness. Rheumatoid factor was not a source of false-positive tests. Counterimmunoelectrophoresis is a useful technic for establishing a rapid, specific serologic diagnosis of cryptococcosis.     

Comparison of the PREMIER cryptococcal antigen enzyme immunoassay and the latex agglutination assay for detection of cryptococcal antigens.

A new enzyme immunoassay (EIA), PREMIER Cryptococcal Antigen, was compared with latex agglutination (LA) for the detection and quantitation of circulating capsular polysaccharide antigen from Cryptococcus neoformans. The clinical evaluation of PREMIER EIA as a screening assay, including 475 specimens with 120 LA and EIA positives, resulted in 99% sensitivity and 97% specificity. The clinical specimens included sera and cerebrospinal fluids as well as 10 rheumatoid factor-positive and 20 anti-nuclear antibody-positive serum samples. This monoclonal antibody-based assay detects serotypes A to D at 0.63, 0.63, 7.8, and 62 ng/ml, respectively. With three different known positive specimens, the assay was found to yield coefficients of variation of 2 to 12% for intra- and interassay comparisons of precision and reproducibility. The primary use for semiquantitative values derived with the LA or EIA is to follow the course of disease and monitor drug therapies. The present data suggest that the PREMIER EIA will be a valuable method for this purpose. We conclude that the PREMIER Cryptococcal Antigen EIA provides a rapid, convenient, and reliable antigen detection method for screening and semiquantitative determination of antigen levels.     

Effects of cyclosporine in experimental cryptococcal meningitis.

We studied the effects of cyclosporine on experimental cryptococcal meningitis. Like cortisone, cyclosporine depressed the highly effective defense mechanisms of normal rabbits against inoculated Cryptococcus neoformans, causing them to develop progressive, fatal cryptococcal meningitis. Unlike cortisone, which causes a striking reduction in leukocytes in cerebrospinal fluid, cyclosporine depressed mononuclear cell function rather than numbers. Interleukin 2, a primary target for the immunodepressive action of cyclosporine, appears to be of central importance in central nervous system defenses against cryptococci. The findings suggest that humans receiving cyclosporine are likely to suffer increased incidence of cryptococcal infection.     

Advantage of Fontana-Masson stain in capsule-deficient cryptococcal infection

We describe light and electron microscopic findings in three cases of pulmonary infection caused by capsule-deficient Cryptococcus neoformans (CDCN) and emphasize the value of the Fontana-Masson silver (FMS) stain in diagnosing cryptococcosis. Capsule-deficient C neoformans infections, including coccidioidomycosis, histoplasmosis, typical cryptococcosis, blastomycosis, candidiasis, and pneumocystosis were used as controls. Several stains including mucicarmine, alcian blue, and FMS were done on tissue sections from all of the above mentioned infections. It was found that while the FMS stain was positive only in the organisms of CDCN and typical C neoformans, the mucicarmine was positive only in typical C neoformans. The negativity of the mucicarmine in the organisms of CDCN reflected the absence of capsular material as demonstrated by ultrastructural study. Therefore, when fungal cultures are not available or are negative, and tissue mucicarmine is negative, the FMS stain is a valuable alternative for use on tissue sections. It may be used, along with routine fungal stains, when a yeast-forming fungal infection is suspected.