Evaluation of low cryptococcal antigen titer as determined by the lateral flow assay in serum and cerebrospinal fluid among HIV-negative patients: a retrospective diagnostic accuracy study

Evaluation of cryptococcal antigen testing using a novel chemiluminescence assay in two medical centers of China

Objective

This study aimed to assess the efficacy of innovative Chemiluminescence Immunoassay (CLIA) in testing Cryptococcal Antigen (CrAg) across two medical centers, employing the FDA-approved CrAg Lateral Flow Assay (LFA) by IMMY as a reference standard.

Methods

The study encompassed patients diagnosed with cryptococcosis at West China Hospital of Sichuan University (HX) between July 2022 and May 2023, and Suzhou Fifth People's Hospital (SZ) from September 2020 to September 2023. All specimens underwent simultaneous detection using the LFA (IMMY, Norman, USA) and CLIA (Chuanglan, Suzhou, China).

Results

A total of 628 patients were enrolled, revealing a remarkable 99.20% concordance between LFA and CLIA (623/628, 99.20%). The LFA exhibited a sensitivity of 96.83% (244/252) and specificity of 98.35% (179/182). Among the 42 patients with unaltered CrAg titers, the changes of Signal-to-Cut-Off ratio (ΔS/CO) results exhibited a noteworthy discrepancy, with 71.43% (30/42) demonstrating a decreasing trend in ΔS/CO of at least 10%.

Conclusions

The CLIA method demonstrated commendable specificity and sensitivity, exhibiting a high level of agreement with the FDA-approved LFA method. Additionally, CLIA demonstrated superior utility for treatment monitoring compared to LFA, offering continuous insight into the fluctuation of CrAg concentrations.

The significance of low titer serum cryptococcal antigen testing from 2017 to 2023 performed in a tertiary care center

Several false positive low serum cryptococcal antigen (SCrAg) reports by lateral flow assay (LFA) were identified in late 2016 at our tertiary care hospital. After the recall and correction of the problem in the reagent, we studied the significance of SCrAg LFA ≤ 1:10 from January 2017 to October 2023. Of 20 patients with 31 samples of SCrAg LFA ≤ 1:10, 14 patients (70%) were classified as true positives, four (20%) were indeterminate, and only two (10%) patients were false positives. If a new SCrAg LFA ≤ 1:10 is detected, it should be repeated, and additional workup should be pursued.

Cryptococcosis in wait-listed liver transplant candidates: Prevalence, manifestations, and risk factors

BACKGROUND

Liver cirrhosis compromises immunity against cryptococcosis, and liver transplant recipients tend to develop the disease earlier after transplantation, possibly due to unrecognized pretransplant infection. We assessed the prevalence and characteristics of cryptococcosis among liver transplant candidates and whether pre-transplant cryptococcal antigen (CrAg) can detect the disease before transplantation.

METHODS

We retrospectively included liver transplant candidates in a tertiary hospital during 2017-2022. Serum CrAg and pulmonary computed tomography were incorporated in routine transplant evaluation. Other investigations were done if indicated. Cryptococcosis was diagnosed by positive culture or CrAg. Risk factors for cryptococcosis were also assessed.

RESULTS

Of the 377 candidates with a median MELD-Na score of 18, 84.4% had hepatitis B virus (HBV) infection. Cryptococcosis was diagnosed in 10 (2.6%) candidates, by CrAg in 6, culture in 2, or both in 2. Only 3 had fever, and 3 were asymptomatic; 7 had pulmonary cryptococcosis. Of the 10 candidates with cryptococcosis, one underwent transplantation after 143-day antifungals. Of the 87 candidates undergoing liver transplantation, one (1.2%) recipient developed cryptococcosis 14 days post-transplant with negative CrAg three weeks before transplantation. HBsAg-positive chronic HBV infection with HBV DNA loads <2000 IU/mL was significantly associated with cryptococcosis (odds ratio 4.4, 95% confidence interval 1.2-16.5, p = 0.03) after the adjustment of MELD-Na score.

CONCLUSIONS

The prevalence of cryptococcosis was 2.6% among our liver transplant candidates and CrAg detected 80% of the cases. Disease presentation was mild and pulmonary disease predominated. HBsAg-positive chronic HBV infection with HBV DNA loads <2000 IU/mL was significantly associated with cryptococcosis.

Cryptococcal meningoencephalitis: Risk factors associated to death in a hospital in Northeastern Brazil

INTRODUCTION

Cryptococcosis is an opportunistic systemic mycosis caused by pathogenic encapsulated yeasts of the genus Cryptococcus. The objective of the present study was to evaluate the risk factors associated with death of patients diagnosed with meningitis due to Cryptococcus spp.

METHODS

This retrospective cohort study included patients admitted to the São José Hospital (SJH) with Cryptococcal Meningoencephalitis (CM) who were diagnosed between 2010 and 2018. Data collection was carried out by reviewing the patients' medical records. Death during hospitalization was considered the primary outcome.

RESULTS

From 2010 to 2018, 21,519 patients were admitted to the HSJ, 124 of whom were hospitalized due to CM. The CM incidence rate was 5.8 cases/103 hospitalizations. We included 112 patients in the study. Male patients were the most affected (82.1%), and the median age was 37 years [IQR: 29-45]. HIV coinfection occurred in 79.4% of the patients. Fever (65.2%) and headache (88.4%) were the most frequent symptoms. Greater cellularity in the CSF was the most related factor to CM in non-HIV individuals (p < 0.05). Death during hospitalization occurred in 28.6% (n = 32) of the patients. The independent risk factors associated with death during the hospitalization were women (p = 0.009), age > 35 years (p = 0.046), focal neurological deficits (p = 0.013), altered mental status (p = 0.018) and HIV infection (p = 0.040). The twelve-month survival was lower in HIV-positive patients (p < 0.05).

CONCLUSION

Early diagnosis, optimal treatment, and clinical follow-up strategies, especially in HIV patients, should be prioritized.

Diagnostic performance of the IMMY cryptococcal antigen lateral flow assay on serum and cerebrospinal fluid for diagnosis of cryptococcosis in HIV-negative patients: a systematic review

BACKGROUND

The incidence of cryptococcosis amongst HIV-negative persons is increasing. Whilst the excellent performance of the CrAg testing in people living with HIV is well described, the diagnostic performance of the CrAg LFA has not been systematically evaluated in HIV-negative cohorts on serum or cerebrospinal fluid.

METHODS

We performed a systematic review to characterise the diagnostic performance of IMMY CrAg® LFA in HIV-negative populations on serum and cerebrospinal fluid. A systematic electronic search was performed using Medline, Embase, Global Health, CENTRAL, WoS Science Citation Index, SCOPUS, Africa-Wide Information, LILACS and WHO Global Health Library. Studies were screened and data extracted from eligible studies by two independent reviewers. A fixed effect meta-analysis was used to estimate the diagnostic sensitivity and specificity.

RESULTS

Of 447 records assessed for eligibility, nine studies met our inclusion criteria, including 528 participants overall. Amongst eight studies that evaluated the diagnostic performance of the IMMY CrAg® LFA on serum, the pooled median sensitivity was 96% (95% Credible Interval (CrI) 68-100%) with a pooled specificity estimate of 96% (95%CrI 84-100%). Amongst six studies which evaluated the diagnostic performance of IMMY CrAg® LFA on CSF, the pooled median sensitivity was 99% (95%CrI 95-100%) with a pooled specificity median of 99% (95%CrI 95-100%).

CONCLUSIONS

This review demonstrates a high pooled sensitivity and specificity for the IMMY CrAg® LFA in HIV-negative populations, in keeping with findings in HIV-positive individuals. The review was limited by the small number of studies. Further studies using IMMY CrAg® LFA in HIV-negative populations would help to better determine the diagnostic value of this test.

Evaluation of a Cryptococcus Capsular Polysaccharide Detection FungiXpert LFA (Lateral Flow Assay) for the Rapid Diagnosis of Cryptococcosis

Cryptococcus is an opportunistic pathogenic fungus and is the major cause of fungal meningitis. The cryptococcal antigen (CrAg) lateral flow assay (LFA) is an immunochromatographic test system that has simplified diagnosis as a point-of-care test. In this study, we evaluated the diagnostic performance of Cryptococcal capsular polysaccharide detection FungiXpert (Genobio Pharmaceutical, Tianjin, China) using serum and cerebrospinal fluid (CSF) samples for the diagnosis of cryptococcosis and investigated the cross-reaction of the assays to pathogenic fungi and bacterium by comparing it to the U.S. Food and Drug Administration (US FDA)-approved IMMY CrAg LFA. Eighty CSF and 119 serum/plasma samples from 158 patients were retrospectively collected to test for qualitative or semi-quantitative detection of CrAg. Cross-reaction of the assays was tested using 28 fungi and 1 bacterium. Compared to IMMY CrAg LFA, the FungiXpert LFA demonstrated 99.1% sensitivity and 98.9% specificity in the qualitative test. In the 96 semi-quantitative CrAg assay results, 39 (40.6%) test titers of FungiXpert LFA were 1-2 dilutions higher than those of IMMY CrAg LFA. The Intraclass Correlation Coefficient of the Semi-quantitative results of CrAg titer tests via the two assays was 0.976. Similar to IMMY CrAg LFA, FungiXpert LFA showed cross-reactivity with Trichosporon asahii. Compared with the IMMY CrAg LFA, the FungiXpert LFA showed an equal, yet, excellent performance. However, it is important to note that these two assays have potential cross-reactivity to T. asahii when diagnosing patients. FungiXpert LFA is a rapid screening method for the effective and practical diagnosis and treatment of cryptococcosis.

Disseminated Cryptococcus in an immunocompetent patient due to prison yard pigeon exposure

Opportunistic infection by Cryptococcus is one of the most common occurrences in patients with Human Immunodeficiency Virus (HIV) disease or Acquired Immunodeficiency Syndrome (AIDS); however, it is a very rare discovery in the immunocompetent. This encapsulated, aerobic fungus can be found in bird droppings, the soil, or on trees, and breathing the spores can lead to pneumonia, meningitis, sepsis, skin lesions, or disseminate throughout the body. We discuss the unique presentation of an immunocompetent former inmate who was admitted to the hospital due to symptoms of dyspnea and fever. After a thorough history, physical exam, and diagnostic testing, the patient was diagnosed with disseminated cryptococcosis. The patient has since made a complete recovery and was discharged home after receiving careful medical management.

Clinical Predictors Impacting Cryptococcal Dissemination and Poor Outcome in Patients With Cirrhosis

Background

Cirrhosis is an end-stage liver disease and is reported as an independent risk factor for cryptococcosis. Information about cryptococcosis in patients with cirrhosis remains sparse.

Methods

Human immunodeficiency virus–uninfected patients with cryptococcosis and cirrhosis admitted to Huashan Hospital from July 2005 to June 2020 were reviewed. Efficacy and safety of antifungal treatments, clinical outcome, and prognostic factors of mortality were evaluated.

Results

A total of 49 cryptococcosis patients with cirrhosis were included. Sites of infection involved central nervous system (n = 38), lung (n = 21), bloodstream (n = 11), skin (n = 1), and bone (n = 1). Nine patients (18.4%) had pulmonary cryptococcosis alone. Viral hepatitis B infection (57.1%) was the most common cause of cirrhosis. Patients with decompensated cirrhosis (Child-Pugh class B and C) were more likely to have extrapulmonary cryptococcosis than those with compensated cirrhosis (90.7% vs 64.7%; P = .049). In patients with cryptococcal meningitis (CM), 7 were treated with amphotericin B with/without flucytosine, 5 with amphotericin B plus fluconazole with/without flucytosine, and 12 with fluconazole with/without flucytosine. Fluconazole (>400 mg/day) was well tolerated and only 1 patient had a mild adverse drug reaction. At 1-year follow-up, all patients treated with fluconazole with or without flucytosine survived, whereas the mortality rate was 14.3%–20.0% in the remaining groups. In addition, Child-Pugh class C cirrhosis (hazard ratio [HR], 7.555 [95% confidence interval {CI}, 1.393–40.971]) and time to diagnosis >120 days (HR, 18.619 [95% CI, 2.117–163.745]) were independent factors for 1-year mortality in patients with CM.

Conclusions

Severity of cirrhosis was associated with developing extrapulmonary cryptococcosis and mortality in CM. Early diagnosis and intervention of cryptococcosis are key for outcome.