Analytical and clinical validation of multiplex droplet digital PCR assay for detecting pathogenic fungal infection in lungs

Pulmonary invasive fungal infection in immunocompromised hosts is difficult to diagnose, and current tools for diagnosis or monitoring of response to antifungal treatments have inherent limitations. Droplet digital PCR (ddPCR) has emerged as a promising tool for pulmonary pathogen detection with high sensitivity. This study presents a novel ddPCR panel for rapid and sensitive identification of pulmonary fungal pathogens. First, a ddPCR method for detecting three fungal genera, including Pneumocystis, Aspergillus, and Cryptococcus, was established and evaluated. Then, the clinical validation performance of ddPCR was compared with that of qPCR using 170 specimens, and the 6 specimens with inconsistent results were further verified by metagenomics next-generation sequencing, which yielded results consistent with the ddPCR findings. Finally, the area under the ROC curve (AUC) was used to evaluate the efficiency of ddPCR. While the qPCR identified 16 (9.41%) cases of Aspergillus and 6 (3.53%) cases of Pneumocystis, ddPCR detected 20 (11.76%) Aspergillus cases and 8 (4.71%) Pneumocystis cases. The AUC for Aspergillus, Cryptococcus, and Pneumocystis was 0.974, 0.998, and 0.975, respectively. These findings demonstrated that the ddPCR assay is a highly sensitive method for identifying pathogens responsible for invasive fungal pulmonary infections, and is a promising tool for early diagnosis.      .

False-negative cerebral spinal fluid cryptococcal antigen lateral flow assay due to postzone phenomenon in a patient with disseminated cryptococcal disease: a case report

This report presents the case of false-negative cerebral spinal fluid (CSF) cryptococcal antigen (CrAg) lateral flow assay (LFA) in a HIV-positive 25-year-old male. The patient presented with headache, nausea and vomiting for 5 days and syncope for 1 day. An initial CSF CrAg LFA test was negative, but a 1:4 dilution of the CSF was weakly positive and a 1:8 dilution was positive. A serum cryptococcal antigen test was weakly positive. Cultures of blood and CSF were all positive for Cryptococcus neoformans. The explanation for the false-negative CSF CrAg LFA test is that the antigen concentration was too high causing the postzone phenomenon.

Comparative analysis of diagnostic methods for the detection of Cryptococcus neoformans meningitis

BACKGROUND

Cryptococcosis is a devastating opportunistic infection in immunocompromised individuals, primarily in people living with HIV/AIDS. This study evaluated a protocol for the early diagnosis of meningitis due to C. neoformans, utilizing established molecular techniques from serum and CSF samples.

METHODS

The 18S and 5.8S (rDNA-ITS) sequence-specific nested PCR assays were compared with direct India ink staining and the latex agglutination test for detection of C. neoformans in serum and cerebrospinal fluid (CSF) from 49 Brazilian suspected meningitis patients. Results were validated with samples obtained from 10 patients negative for cryptococcosis and HIV, and by analysis of standard C. neoformans strains.

PRINCIPAL FINDINGS

The 5.8S DNA-ITS PCR was more sensitive (89-100%) and specific (100%) than the 18S rDNA PCR and conventional tests (India ink staining and latex agglutination) for identification of C. neoformans. While the 18S PCR exhibited a sensitivity (72%) similar to that of the latex agglutination assay in serum samples, it was superior to the latex agglutination assay when testing CSF, with a sensitivity of 84%. However, the latex agglutination was superior to the 18SrDNA PCR in specificity in CSF (92%). The 5.8S DNA-ITS PCR yielded the highest levels of accuracy (96-100%) of any test for detection (serological and mycological) of C. neoformans in both serum and CSF.

CONCLUSION

Use of the nested 5.8S PCR was superior to other techniques for the diagnosis of cryptococcosis. The possibility of using serum, a non-invasively collected material, in a targeted 5.8S PCR analysis to identify Cryptococcus spp. is recommended, especially in immunosuppressed patients. Our results indicate that nested 5.8S PCR can increase the diagnostic capability of cryptococcosis, and we suggest its use to monitor patients in the future.

Clinical utility of cryptococcal antigen detection in transthoracic needle aspirate by lateral flow assay for diagnosing non-HIV pulmonary cryptococcosis: A multicenter retrospective study

Lateral flow immunoassay (LFA) detection of cryptococcal capsular polysaccharide antigen (CrAg) is reported to be the most rapid and convenient laboratory method for diagnosing cryptococcosis. Its clinical diagnostic use, however, is not well studied. We retrospectively analyzed the data from 97 patients with suspected pulmonary cryptococcosis (PC) at 2 tertiary care centers. CrAg in both serum and lung aspirate specimens were examined by LFA. We divided the patients who were diagnosed with PC into group I, patients positive for CrAg in both the serum and lung aspirate, and group II, patients positive for CrAg in the lung aspirate but not in the serum. We analyzed the differences in imaging distribution, morphological characteristics, and concomitant signs between the 2 groups. Of all 97 patients, 47 were diagnosed with PC. Lung aspirates were positive for CrAg in 46/47 patients with PC (sensitivity 97.9%, specificity 100%, positive predictive value = 100%, negative predictive value = 98%). There were no false positive results in the noncryptococcosis patients, revealing a diagnostic accuracy of 99%. Serum CrAg tests were positive in 36/47 patients with PC (sensitivity 76.6%, specificity 100%, accuracy 88.7%, positive predictive value = 100%, negative predictive value = 82%). Chest imaging data showed a statistically significant greater number of single lesions in group II than in group I (P < .05). More lesions accompanied by halo signs were showed in group I (P < .01), whereas more accompanied by pleural stretch signs were found in group II (P < .01). The LFA-positive rate of CrAg in lung aspirate samples was higher than that of the serum samples, especially in patients with single pulmonary lesion or in those accompanied by pleural stretch. The direct measurement of CrAg in lung aspirate is a rapid, useful alternative diagnostic method for PC confirmation.

Performance of the Colloidal Gold Immunochromatography of Cryptococcal Antigen on Bronchoalveolar Lavage Fluid for the Diagnosis of Pulmonary Cryptococcosis

Objective

This study aimed to investigate the efficacy of the colloidal gold immunochromatography method in the detection of Cryptococcus antigen in bronchoalveolar lavage fluid (BALF) for pulmonary cryptococcosis (PC) diagnosis.

Methods

A total of 111 patients with clinically suspected PC who were finally diagnosed with nonhuman immunodeficiency virus infection and hospitalized in the Ningbo First Hospital from March 2017 to December 2021 were retrospectively analyzed. All the confirmed cases were divided into two groups as follows: the PC group (33 cases) and the non-PC group (78 cases). All the patients were subjected to serum and BALF cryptococcal capsular polysaccharide antigen-lateral flow immunochromatographic assay (CrAg-LFA) and etiological culturing.

Results

In the PC group, serum CrAg-LFA was positive for 24 and negative for 9 cases, serum Cryptococcus culture was positive for 1 and negative for 32 cases, BALF CrAg-LFA was positive for 31 and negative for 2 cases, and BALF Cryptococcus culture was positive for 9 and negative for 24 cases. In the non-PC group, serum CrAg-LFA was positive for 1 and negative for 77 cases, serum culture was negative in all the cases, and both BALF CrAg-LFA and culture were negative in all the cases. The sensitivity, specificity, and accuracy of BALF CrAg-LFA for PC diagnosis were 93.9%, 100%, and 98.2%, respectively, whereas those of BALF culture were 27.3%, 100%, and 78.4%, respectively. The sensitivity and accuracy of BALF CrAg-LFA were higher than that of serum CrAg-LFA and BALF etiological culture with statistically significant differences (p < 0.05).

Conclusion

The diagnostic value of BALF CrAg-LFA for PC is superior to that of serum CrAg-LFA and BALF etiological culture.

Clinical epidemiology and high genetic diversity amongst Cryptococcus spp. isolates infecting people living with HIV in Kinshasa, Democratic Republic of Congo

Neuromeningeal cryptococcosis (NMC) is a life-threatening opportunistic infection in advanced HIV disease patients (AHDP). It is caused by Cryptococcus spp. complexes and mainly occurs in sub-Saharan Africa. In this study, we performed molecular characterization and antifungal susceptibility profiling of Cryptococcus isolates from AHDP in Kinshasa (DRC). Additionally, we investigated a possible association between NMC severity factors and the Cryptococcus neoformans (Cn) multilocus sequence typing (MLST) profiles. We characterized the isolates using PCR serotyping, MALDI-TOF MS, internal transcribed spacer (ITS) sequencing, and MLST. Susceptibility testing for the major antifungal drugs was performed according to the EUCAST guidelines. Parameters associated with NMC severity, such as hypoglycorrhachia (< 50 mg/dL), increased cerebral spinal fluid opening pressure (> 30 cm H₂O), and poor therapeutic outcome were compared with the Cn MLST sequences type (ST). Twenty-three out of 29 Cryptococcus isolates were identified as serotype A using PCR serotyping (79.3%; 95% IC: 65.5–93.1), while six (20.7%; 95% IC: 6.9–34.5) were not serotypable. The 29 isolates were identified by ITS sequencing as follows: Cryptococcus neoformans (23/29, 79.3%), Cutaneotrichosporon curvatus (previously called Cryptococcus curvatus) (5/29, 17.2%), and Papiliotrema laurentii (Cryptococcus laurentii) (1/29, 3.5%). Using the ISHAM MLST scheme, all Cn isolates were identified as molecular type VNI. These comprised seven different STs: ST93 (n = 15), ST5 (n = 2), ST53 (n = 1), ST31 (n = 1), ST4 (n = 1), ST69 (n = 1), and one novel ST that has not yet been reported from other parts of the world and was subsequently assigned as ST659 (n = 2). Of the included strains, only Papiliotrema laurentii was resistant to amphoterin B (1/29, 3.5%), 6.8% (2/29) were resistant to 5-flucytosine (the single Papiliotrema laurentii strain and one Cryptococcus neoformans isolate), and 13.8% (4/29) to fluconazole, including two of five (40%) Cutaneotrichosporon curvatus and two of 23 (8.7%) C. neoformans strains. We found a significative association between poor therapeutic outcome and a non-ST93 sequence type of causative strains (these concerned the less common sequence types: ST53, ST31, ST5, ST4, ST659, and ST69) (87.5% versus 40%, p = 0.02). Molecular analysis of Cryptococcus spp. isolates showed a wide species diversity and genetic heterogenicity of Cn within the VNI molecular type. Furthermore, it is worrying that among included strains we found resistances to several of the commonly used antifungals.

Transcriptional Profiles Elucidate Differential Host Responses to Infection with Cryptococcus neoformans and Cryptococcus gattii

Many aspects of the host response to invasive cryptococcal infections remain poorly understood. In order to explore the pathobiology of infection with common clinical strains, we infected BALB/cJ mice with Cryptococcus neoformans, Cryptococcus gattii, or sham control, and assayed host transcriptomic responses in peripheral blood. Infection with C. neoformans resulted in markedly greater fungal burden in the CNS than C. gattii, as well as slightly higher fungal burden in the lungs. A total of 389 genes were significantly differentially expressed in response to C. neoformans infection, which mainly clustered into pathways driving immune function, including complement activation and TH2-skewed immune responses. C. neoformans infection demonstrated dramatic up-regulation of complement-driven genes and greater up-regulation of alternatively activated macrophage activity than seen with C gattii. A 27-gene classifier was built, capable of distinguishing cryptococcal infection from animals with bacterial infection due to Staphylococcus aureus with 94% sensitivity and 89% specificity. Top genes from the murine classifiers were also differentially expressed in human PBMCs following infection, suggesting cross-species relevance of these findings. The host response, as manifested in transcriptional profiles, informs our understanding of the pathophysiology of cryptococcal infection and demonstrates promise for contributing to development of novel diagnostic approaches.

Cryptococcosis in the Democratic Republic of Congo from 1953 to 2021: a systematic review and meta-analysis

Cryptococcosis is a common opportunistic infection associated with HIV/AIDS. The present review systematically describes the clinical and biological aspects of cryptococcosis in the Democratic Republic of Congo (DRC) and estimates its 2020 burden in people living with HIV (PLHIV). Following PRISMA guidelines, we searched online databases for records of cryptococcosis/Cryptococcus spp. in the DRC. Meta-analysis was then performed to estimate summary statistics and the corresponding 95% confidence intervals (CI). A total of 30 studies were included. These included 1,018 cryptococcosis patients, including 80.8% with NMC and predominantly immunocompromised due to HIV/AIDS (97.6%). The NMC mean prevalence was estimated at 9.63% (95% CI: 5.99-14.07). More than one in two patients (52.7%) under treatment died. Monotherapy with fluconazole was the main treatment administered (80.6%). Furthermore, we estimate that about 9,265 (95% CI: 5,763-13,537) PLHIV had cryptococcosis in 2020, in DRC; of which about 4,883 (95% CI: 3,037-7,134) would have died in the same year. Among isolates in all included studies, 74 strains have been characterized. Of these, 82.4% concerned Cryptococcus neoformans sensu lato (s.l) (exclusively of serotype A and mostly of molecular types VNI and VNII) and 17.6% concerned Cryptotoccus gattii s.l (belonging to serotype B and molecular type VGI). Cryptococcosis remains common with an unacceptably high mortality rate. A large number of PLHIV affected by and dying from cryptococcosis in 2020 demonstrates its heavy burden among the Congolese PLHIV. To mitigate this burden, it is important to improve the quality and accessibility of care for all PLHIV.

Invasive Fungal Infections in Under-Five Diarrheal Children: Experience from an Urban Diarrheal Disease Hospital

Invasive fungal infections (IFIs) are opportunistic, especially in immunocompromised and hospitalized patients. Children with IFIs are more vulnerable to a fatal outcome. For early diagnosis and treatment, knowledge of the spectrum and frequency of IFIs among children is prerequisite. In this prospective observational study, we enrolled 168 children of 2–59 months old of either sex from March 2018 to December 2019 admitted to the Dhaka hospital, icddr,b. Study participants with suspected IFIs were with or without severe acute malnutrition (SAM) along with sepsis/pneumonia and fulfilled any of the following criteria: (i) failure to respond to injectable antibiotics, (ii) development of a late-onset hospital-acquired infection, (iii) needed ICU care for >7 days, (iv) took steroids/antibiotics for >2 weeks before hospitalization, and (v) developed thrush after taking injectable antibiotics. The comparison group included non-SAM (weight-for-length Z score ≥ −2) children with diarrhea and fever <3 days in the absence of co-morbidity. We performed real-time PCR, ELISA, and blood culture for the detection of fungal pathogen. Study group children with SAM, positive ELISA and PCR considered to have a IFIs. In the study group, 15/138 (10.87%) children had IFIs. Among IFIs, invasive candidiasis, aspergillosis, histoplasmosis detected in 6 (4.53%), 11 (7.97%), and 1 (0.72%) children, respectively, and (3/15 [2.17%]) children had both candidiasis and aspergillosis. Children with IFIs more often encountered septic shock (26.7% vs. 4.9%; p = 0.013) and had a higher death rate (46.7% vs. 8.9%; p < 0.001) than those without IFIs. IFIs were independently associated with female sex (OR = 3.48; 95% CI = 1.05, 11.55; p = 0.042) after adjusting for potential confounders. Our findings thus implicate that, malnourished children with septic shock require targeted screening for the early diagnosis and prompt management of IFIs that may help to reduce IFIs related deaths.

Evaluation of point of care serum cryptococcal antigen by lateral flow immunoassay for diagnosis of cryptococcosis and cryptococcal meningitis in HIV-positive patients

Background:

Cryptococcal meningitis (CM) is the initial acquired immunodeficiency syndrome (AIDS) defining illness in 2% of patients with CD4 levels <100/μL and a leading cause of mortality in AIDS in the developing world. It is the most common opportunistic infection of the central nervous system in AIDS in various Indian studies. Detection of serum cryptococcal antigen (SCRAG) is the most widely used diagnostic method for cryptococcosis. The presence of cerebrospinal fluid cryptococcal antigen (CSF CRAG) is diagnostic of CM. CRAG can be determined by latex agglutination (LAT), enzyme-linked immunosorbent assay and now, by lateral flow (LFA)immunoassay. LFA is a point of care test that rapidly detects CRAG.

Aims and Objectives:

This study compares LAT and LFA for the detection of serum CRAG and diagnosing CM.

Materials and methods:

Two hundred and ten patients of HIV/AIDS were submitted to SCRAG LFA by dipstick. A sample was also sent to laboratory for SCRAG by LAT. CSF examination was done for those who were positive for SCRAG LFA and those who had symptoms suggestive of meningitis. SCRAG by LFA was compared with SCRAG by LAT, CSF CRAG by LAT and LFA, CSF cryptococcal culture and CSF India ink examination for Cryptococcus.

Results:

Fifteen patients were found positive for SCRAG by LFA dipstick. All of them were also positive for SCRAG by LAT. Twelve of them had C. D4 count below below 100 cells/mm3. CSF CRAG was positive in all 12 SCRAG positive who were submitted to CSF examination.

Conclusion:

We found that serum detection of CRAG by LFA dipstick is as sensitive as CRAG detection in serum by LAT and CSF CRAG detection by LFA and LAT. It is thus a rapid test for diagnosing CM in HIV patients with low CD4 counts.

Identification and assessment of pulmonary Cryptococcus neoformans infection by blood serum surface-enhanced Raman spectroscopy

Cryptococcus neoformans (C. neoformans) is a causative agent for acute pulmonary infection, which can further develop to lethal meningoencephalitis if untreated. The meningoencephalitis infection can be prevented, if timely treatment on pulmonary cryptococcal infection can be implemented based on its early diagnosis and accurate assessment. In this study, blood serum surface-enhanced Raman spectroscopy (SERS) method was investigated on identification and assessment of pulmonary C. neoformans infection. The serum SERS measurements were collected from the mice infected with C. neoformans and the healthy mice, in which the infected mice were further divided into four subgroups according to the duration of infection. Based on those SRES measurements, biochemical differences were analyzed among those different groups to investigate the potential biomarkers for identifying and assessing the pulmonary C. neoformans infection. Furthermore, partial least square (PLS) analysis followed by linear discriminant analysis (LDA) model was employed to identify pulmonary cryptococcal infection and to assess the degrees of infection with the accuracies of 96.7% and 85.3%, respectively. Therefore, our study has demonstrated the great clinical potential of using serum SERS technique for an accurate identification and assessment of pulmonary cryptococcal infection.

Cryptococcal antigen among HIV1-infected individuals in north-central Nigeria

Background and Purpose

The potential for the invasion of the central nervous system by Cryptococcus species is underscored by the presence of this organism in the blood of immunocompromised individuals. Early adoption of sensitive methods for the diagnosis of Cryptococcus species will reduce the high morbidity and mortality associated with this disease. Regarding this, the aim of the present research was to detect cryptococcal antigen among HIV1- infected individuals in north-central Nigeria.

Materials and Methods

This prospective cross-sectional study was carried out on HIV-1 infected individuals accessing care at three health facilities in north-central Nigeria between November 2014 and March 2017. For the purpose of the study, blood samples were collected from 300 HIV1-infected individuals within the age group of 3-65 years. The CD4+ T-cell count was determined, and the samples were analyzed for cryptococcal antigenemia using the methods of lateral flow assay (LFA) and culture technique.

Results

Cryptococcus antigen was detected in 19.67% (59/300) of the patients, and only 25.4% (15/59) of the LFA-positive samples showed Cryptococcus species growth on Sabouraud dextrose agar after 3 days. Furthermore, fungal growth was observed in one of the specimens, which was LFA negative. Additionally, 30 of the 59 LFA-positive patients had cryptococcal antigen in their serum with a CD4+ T-cell count of < 150 cells/mm³.

Conclusion

As the findings of the present study indicated, infection with Cryptococcus species is a problem among HIV-infected patients in the region under study. Therefore, all HIV patients, especially those with a CD4+ T-cell count of < 150 cells/mm³, referring to the HAART clinics in Nigeria, should be screened for cryptococcal antigen.

Multilocus Sequence Typing of Clinical Isolates of Cryptococcus from India

Cryptococcosis is a life-threatening infection caused by Cryptococcus neoformans and C. gattii species complex. In the present study, to understand the molecular epidemiology of 208 clinical isolates of Cryptococcus from different parts of India, multilocus sequence typing (MLST) using ISHAM MLST consensus scheme for C. neoformans/C. gattii species complex was used. MLST analysis yielded a total of 10 Sequence Types (STs)-7 STs for C. neoformans and 3 for C. gattii species complex. The majority of isolates identified as C. neoformans belonged to molecular type VNI with predominant STs 31 and 93. Only 3 isolates of C. gattii species complex were obtained, belonging to ST58 and ST215 of VGI and ST69 of VGIV. Phylogenetic analysis revealed less diversity among the clinical Indian isolates compared to the global MLST database. No association between prevalent STs and HIV status, geographical origin or minimum inhibitory concentration (MIC) could be established.

Cryptococcus Infection in Captive Callitrichids in the United Kingdom

Cryptococcosis is widely reported in North America and Australia but considered rare in the UK. Disease is mainly caused by Cryptococcus neoformans and Cryptococcus gattii and affects animals and humans. Cases of cryptococcosis have been described in non-human primates, including a few in the Callitrichidae family. Six captive callitrichids from five zoological facilities in the UK were diagnosed with cryptococcosis on post-mortem examination over a 13-year period. Histological examination revealed intralesional yeast bodies consistent with Cryptococcus spp in lung, brain, lymph nodes, larynx, salivary gland and ears. C. neoformans was confirmed in two cases by culture and by culture and polymerase chain reaction (28S rRNA gene), respectively. This case series is the first report of Cryptococcus spp in captive callitrichids in the UK and reinforces the need to include this fungal disease in the differential diagnosis of sick callitrichids in zoo settings.

Diagnostic value of bronchoalveolar lavage fluid cryptococcal antigen-lateral flow immunochromatographic assay for pulmonary cryptococcosis in non-HIV patients

BACKGROUND

The aim of this study was to investigate the diagnostic value of cryptococcal antigen-lateral flow immunochromatographic assay (CrAg-LFA) in bronchoalveolar lavage fluid (BALF) of patients with pulmonary cryptococcosis (PC).

METHODS

A total of 308 patients were divided into the PC group (n = 72) and the non-PC group (n = 236). The clinical data, pathogen detection, radiological imaging, and the detection of the cryptococcal antigen in blood and BALF samples were analyzed.

RESULTS

The sensitivity, specificity, positive, and negative predicted values of CrAg-LFA in the serum were 75.0%, 99.6%, 98.2%, and 92.9%, respectively, while those in the BALF were 93.1%, 100.0%, 100.0%, and 97.9%, respectively. The sensitivity of the CrAg-LFA in BALF was significantly higher than that in the serum of the patients in the PC group (P < 0.05).

CONCLUSION

CrAg-LFA has a higher diagnostic value for PC when analyzing BALF samples compared to serum samples.

False-Negative Serum Cryptococcal Antigen Lateral Flow Immunoassay Result for a Patient with Disseminated Cryptococcal Disease

Cryptococcus neoformans (C. neoformans) is an opportunistic fungal pathogen to humans, which can be acquired from environmental sources. Its most important virulence factor is its polysaccharide capsule, which can be used for diagnostic tests that identify the cryptococcal antigen (CrAg). The CrAg lateral flow assay (LFA) is a dipstick immunochromatographic assay with high sensitivity and specificity; however, several false-negative cases have been reported. Here, we present a case of a false-negative serum CrAg LFA, in which the blood culture from a matched sample was positive for C. neoformans, thus demonstrating the postzone phenomenon.

Cryptococcal infections in children: retrospective study and review from Australia

Aim: Cryptococcosis causes significant morbidity and mortality worldwide, but pediatric data are limited. Methods: A retrospective literature review of Australian pediatric cryptococcosis and additional 10-year audit of cases from a large pediatric network. Results: 22 cases of cryptococcosis in children were identified via literature review: median age was 13.5 years (IQR 7.8-16 years), 18/22 (82%) had meningitis or central nervous system infection. Where outcome was reported, 11/18 (61%) died. Of six audit cases identified from 2008 to 2017, 5 (83%) had C. gattii disease and survived. One child with acute lymphoblastic leukemia and C. neoformans infection died. For survivors, persisting respiratory or neurological sequelae were reported in 4/6 cases (67%). Conclusion: Cryptococcosis is uncommon in Australian children, but is associated with substantial morbidity.

Pulmonary cryptococcosis: A review of pathobiology and clinical aspects

Pulmonary cryptococcosis is an important opportunistic invasive mycosis in immunocompromised patients, but it is also increasingly seen in immunocompetent patients. The main human pathogens are Cryptococcus neoformans and C. gattii, which have a worldwide distribution. In contrast to cryptococcal meningitis, pulmonary cryptococcosis is still underdiagnosed because of limitations in diagnostic tools. It can mimic lung cancer, pulmonary tuberculosis, bacterial pneumonia, and other pulmonary mycoses both clinically and radiologically. Pulmonary nodules are the most common radiological feature, but these are not specific to pulmonary cryptococcosis. The sensitivity of culture of respiratory samples for Cryptococcus is poor and a positive result may also reflect colonisation. Cryptococcal antigen (CrAg) with lateral flow device is a fast and sensitive test and widely used on serum and cerebrospinal fluid, but sera from patients with pulmonary cryptococcosis are rarely positive in the absence of disseminated disease. Detection of CrAg from respiratory specimens might assist the diagnosis of pulmonary cryptococcosis but there are very few data. Molecular detection techniques such as multiplex reverse transcription polymerase chain reaction (RT-PCR) could also provide better sensitivity but these still require validation for respiratory specimens. The first line of treatment for pulmonary cryptococcosis is fluconazole, or amphotericin B and flucytosine for those with central nervous system involvement. Pulmonary cryptococcosis worsens the prognosis of cryptococcal meningitis. In this review, we summarize the biological aspects of Cryptococcus and provide an update on the diagnosis and management of pulmonary cryptococcosis.

Deceptively asymptomatic cryptococcaemia in a renal transplant recipient: the lull before a storm

Cryptococcal infection constitutes around 3% of opportunistic infections in solid organ transplant recipients. Most common organ affected in renal transplant recipients (RTRs) is central nervous system and usually presents with chronic meningoencephalitis (CME). Ischaemic stroke as a consequence of cryptococcal meningoencephalitisis rare and possibly due to the involvement of intracranial vessel by exudates causing vasculitis-related thrombosis. In this context, we describe an unusual case of asymptomatic cryptococcaemia in an RTR, progressing on to acute ischaemic stroke secondary to acute CME with near complete neurological recovery following timely diagnosis, early and appropriate antifungal treatment. The index case attempts to re-emphasise the significance of mandatory screening required to exclude the possibility of dissemination of cryptococcaemia in RTRs besides highlighting the requirement of prolonged induction phase with combination therapy, particularly in presence of stroke.

Magnitude of Cryptococcal Antigenemia among HIV Infected Patients at a Referral Hospital, Northwest Ethiopia

Background

Cryptococcosis is one of the common opportunistic fungal infections among HIV infected patients living in Sub-Saharan Africa, including Ethiopia. The magnitude of the disease at Felege Hiwot Referral Hospital (FHRH) in particular and in Ethiopia at large is not well explored.

Methods

A retrospective document review and analysis was done on records of 137 HIV infected patients who visited FHRH ART clinic from 1 Sep to 30 Dec 2016 and had registered data on their sex, age, CD4 count and cryptococcal antigen screening result. The cryptoccocal antigen (CrAg) detection was done by the IMMY CrAg^® LFA (Cryptococcal Antigen Lateral Flow Assay) kit from patient serum as per the manufacturer's instruction. All data were entered, cleared, and analyzed using SPSS v20. Descriptive data analysis and cross tabulation were done to assess factors associated with cryptococcal antigenemia. Statistical significance was set at p-value less than or equal to 0.05.

Results

More than half of the participants, 54.7% (75/137), included in the study were females. The median age of the participants was 32.0 years (ranged: 8–52 years). The mean CD4 count was 51.8 with SD of 26.3 (range 3–98). All the patients were HIV stage IV. The proportion of positive cryptococal antigen from serum test was at 11.7% (95% CI: 7.3–18.1%). The IMMY CrAg^® LFA result was found statically associated with patient sex (p= 0.045). However, it was not associated with patient age group and the CD4 count (P>0.05)

Conclusions

This study provided baseline data on the magnitude of cryptococcal antigenemia among HIV positive patients that is not touched before in the studied area. The results of the study showed that this opportunistic fungal infection is an important health concern among HIV patients. Further studies with sound design employing adequate sample size should be considered.

Sensitivity of Cerebrospinal Fluid Cytology for the Diagnosis of Cryptococcal Infections: A 21-Year Single-Institution Retrospective Review

Objectives

Cryptococcal meningoencephalitis is the most common fungal infection of the central nervous system diagnosed by cerebrospinal fluid cytology (CSF) studies. Existing literature suggests that routine CSF cytomorphologic evaluations are exquisitely specific; however, less is known about their sensitivity.

Methods

An electronic record review of the cytopathology and microbiology files was conducted for the 21-year interval from January 1, 1995, through December 31, 2015.

Results

In 21 years, 12,584 CSF samples were processed in the laboratory. Of these, 24 (0.2%) were reported positive for cryptococcal organisms by light microscopy, and 129 CSF fungal cultures were positive for Cryptococcus species. All cotested specimens with positive cytology results were positive on culture (15 specimens, 100% specificity). Twenty-four samples with positive culture results were negative by CSF cytology (sensitivity 39%).

Conclusions

When culture is used as a gold standard, CSF cytology is 100% specific and 39% sensitive, with a positive predictive value of 100% and a negative predictive value of 99.8%.

CNS infections in patients with hematological disorders (including allogeneic stem-cell transplantation)-Guidelines of the Infectious Diseases Working Party (AGIHO) of the German Society of Hematology and Medical Oncology (DGHO)

Diagnosis of CNS infections remains a great challenge in patients with hematological disorders since symptoms might both be masked and be mimicked by other conditions such as metabolic disturbances or consequences from antineoplastic treatment. Thus, awareness of this complication is crucial and any suspicion of a CNS infection should lead to timely and adequate diagnostics and treatment to improve the outcome in this population.

Infections of the central nervous system (CNS) are infrequently diagnosed in immunocompetent patients, but they do occur in a significant proportion of patients with hematological disorders. In particular, patients undergoing allogeneic hematopoietic stem-cell transplantation carry a high risk for CNS infections of up to 15%. Fungi and Toxoplasma gondii are the predominant causative agents. The diagnosis of CNS infections is based on neuroimaging, cerebrospinal fluid examination and biopsy of suspicious lesions in selected patients. However, identification of CNS infections in immunocompromised patients could represent a major challenge since metabolic disturbances, side-effects of antineoplastic or immunosuppressive drugs and CNS involvement of the underlying hematological disorder may mimic symptoms of a CNS infection. The prognosis of CNS infections is generally poor in these patients, albeit the introduction of novel substances (e.g. voriconazole) has improved the outcome in distinct patient subgroups. This guideline has been developed by the Infectious Diseases Working Party (AGIHO) of the German Society of Hematology and Medical Oncology (DGHO) with the contribution of a panel of 14 experts certified in internal medicine, hematology/oncology, infectious diseases, intensive care, neurology and neuroradiology. Grades of recommendation and levels of evidence were categorized by using novel criteria, as recently published by the European Society of Clinical Microbiology and Infectious Diseases.

Comparison of Antigen Detection and Nested PCR in CSF Samples of HIV Positive and Negative Patients with Suspected Cryptococcal Meningitis in a Tertiary Care Hospital

INTRODUCTION

The cases of cryptococcal meningitis and other forms of cryptococcosis have increased in recent time and the present scenario of the condition with significant morbidity and mortality is actually posing a serious threat to the community, so an early and prompt diagnosis is necessary to prevent serious complications and thus improving the overall disease outcome.

AIM

Comparison of diagnostic efficacy of nested Polymerase Chain Reaction (PCR) with Latex Agglutination Test (LAT) in the Cerebro Spinal Fluid (CSF) samples of the cases of meningitis in HIV positive and negative cases.

MATERIALS AND METHODS

We have compared the diagnostic efficacy of Latex Agglutination Test (LAT) with nested Polymerase Chain Reaction (PCR) in 200 Cerebrospinal Fluid (CSF) samples, including 14 HIV positive also, in the cases of suspected cryptococcal meningitis. Nested PCR was done in all cases reporting positive by LAT and results were then compared with that of India ink and culture on Sabouraud Dextrose Agar (SDA), and the isolates were further identified by urease, nitrate and sugar assimilation tests.

RESULTS

Of the 200 cases, including 14 HIV positive, LAT was positive in 46 cases while 154 were negative. Out of these 46 LAT positive cases, nested PCR was positive in 40 cases only, while culture and India ink was positive in 38 and 33 cases respectively. Majority of the cases, 30 (65.2%) were between age group 21-50 years, while 2 (4.3%) in 0-20, and 14 (30.4%) in 51-80 years age group.

CONCLUSION

Although negative staining like India ink and nigrosin are most widely used techniques, but these suffer with subjective error. Rapid method like LAT is available but it always has the scope of false positive and negative results. In such cases nested PCR can help in establishing final diagnosis.

Evaluation of a new cryptococcal antigen lateral flow immunoassay in serum, cerebrospinal fluid and urine for the diagnosis of cryptococcosis: a meta-analysis and systematic review

BACKGROUND

A new lateral flow immunoassay (LFA) for the detection of cryptococcal antigen was developed.

OBJECTIVE

We aimed to systematically review all relevant studies to evaluate the diagnostic accuracy of the cryptococcal antigen LFA on serum, CSF and urine specimens.

METHODS

We searched public databases including PubMed, Web of Science, Elsevier Science Direct and Cochrane Library for the English-language literature published up to September 2014. We conducted meta-analyses of sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR) and diagnostic odds ratios (DOR) and SROC of LFA in serum and CSF, respectively. The sensitivity of LFA in urine was also analyzed. Subgroup analyses were carried out to analyze the potential heterogeneity.

RESULTS

12 studies were included in this study. The pooled sensitivity and specificity values of LFA in serum were 97.6% (95% CI, 95.6% to 98.9%) and 98.1% (95% CI, 97.4% to 98.6%), respectively. The average PLR of LFA in serum was 43.787 (95% CI, 22.60-84.81) and the NLR was 0.03 (95% CI, 0.01-0.09). The pooled DOR was 2180.30 (95% CI, 868.92-5471.00) and the AUC was 0.9968. The pooled sensitivity and specificity values of LFA in CSF were 98.9% (95% CI, 97.9% to 99.5%) and 98.9% (95% CI, 98.0% to 99.5%), respectively. The average PLR of LFA in serum was 48.83 (95% CI, 21.59-110.40) and the NLR was 0.02 (95% CI, 0.01-0.04). The pooled DOR was 2931.10 (95% CI, 1149.20-7475.90) and the AUC was 0.9974. The pooled sensitivity value of LFA in urine was 85.0% (95% CI, 78.7% to 90.1%).

CONCLUSIONS

The study demonstrates a very high accuracy of LFA in serum and CSF for the diagnosis of cryptococcosis in patients at risk. LFA in urine can be a promising sample screening tool for early diagnosis of cryptococcosis.

Cryptococcosis

Cryptococcosis is an infectious disease caused by the encapsulated fungi Cryptococcus neoformans and Cryptococcus gattii. Once a relatively uncommon cause of human disease, cryptococcal infection can develop in apparently immunocompetent hosts and has emerged as an important opportunistic infection in humans over the past several decades as immunocompromised populations expand in the setting of HIV/AIDS, organ transplantation, malignancies, and treatment for other conditions. Clinical manifestations are myriad but pulmonary and central nervous system (CNS) infections are the most common. Improvements in diagnostic testing and standardized approaches to antifungal therapy, when available, have made considerable impact in the management of this infection. While the widespread use of highly active antiretroviral therapy (HAART) has improved the outcome of cryptococcosis in many HIV-infected patients, cryptococcosis remains an entity of considerable morbidity and mortality in many parts of the world, and restoration of host immunity can present management challenges that require individualized management. As immunocompromised populations continue to expand, it is likely that cryptococcosis will remain an important opportunistic fungal infection of humans requiring ongoing investigation.

Cryptoccocal meningitis in Yaoundé (Cameroon) HIV infected patients: Diagnosis, frequency and Cryptococcus neoformans isolates susceptibility study to fluconazole

Cryptococcal meningitis is a mycosis encountered especially in patients with Acquired Immunodeficiency Syndrome and is fatal in the absence of treatment. Information on epidemiology, diagnosis and susceptibility profile to antifungal drugs, are scarce in Cameroon. Authors evaluated the diagnosis possibilities of the cryptococcal meningitis in Cameroon, and studied the antifungal susceptibility of isolated strains to fluconazole, used as first line treatment of the disease in Cameroon. Between December 2009 and July 2011, 146 cerebrospinal fluids obtained from HIV patients with suspicion of meningitis were analysed. The diagnosis procedure involved macroscopic and cyto-chemical analysis, India ink test, culture on Sabouraud chloramphenicol medium and antigen latex agglutination test. Antifungal susceptibility testing of isolated strains to fluconazole was done by the E-test(®) method. The diagnosis of cryptococcal meningitis gave 28.08% positive cases. Among these patients, 80% were at stages III and IV and 20% at stage I of the HIV infection, according to the WHO previous classification. Cyto-chemical analysis showed current findings in the case of cryptococcal meningitis. India ink test and latex agglutination test exhibited very high sensitivity and specificity (>94%). Fluconazole antifungal susceptibility testing gave MICs lower than 32μg/mL to 92.7% of isolated strains and MICs greater than this value to 7.3% of isolates. These results showed that cryptococcal meningitis remains a real problem among HIV infected patients in Yaoundé. The emergence of fluconazole reduced susceptibility strains is worrying. Nevertheless, efficacy of rapid detection tests is interesting because this will help in rapid diagnosis and treatment of patients.

Characterization of the antigenicity of Cpl1, a surface protein of Cryptococcus neoformans var. neoformans

Cryptococcus neoformans var. neoformans is an important fungal pathogen. The capsule is a well established virulence factor and a target site for diagnostic tests. The CPL1 gene is required for capsular formation and virulence. The protein product Cpl1 has been proposed to be a secreted protein, but the characteristics of this protein have not been reported. Here we sought to characterize Cpl1. Phylogenetic analysis showed that the Cpl1 of C. neoformans var. neoformans and the Cpl1 orthologs identified in C. neoformans var. grubii and C. gattii formed a distinct cluster among related fungi; while the putative ortholog found in Trichosporon asahii was distantly related to the Cryptococcus cluster. We expressed Cpl1 abundantly as a secreted His-tagged protein in Pichia pastoris. The protein was used to immunize guinea pigs and rabbits for high titer mono-specific polyclonal antibody that was shown to be highly specific against the cell wall of C. neoformans var. neoformans and did not cross react with C. gattii, T. asahii, Aspergillus spp., Candida spp. and Penicillium spp. Using the anti-Cpl1 antibody, we detected Cpl1 protein in the fresh culture supernatant of C. neoformans var. neoformans and we showed by immunostaining that the Cpl1 protein was located on the surface. The Cpl1 protein is a specific surface protein of C. neoformans var. neoformans.

Integrating Clinical Services for HIV, Tuberculosis, and Cryptococcal Disease in the Developing World

The success of antiretroviral therapy (ART) programs in the developing world is limited by the lack of adequate diagnostic tests to screen for life-threatening opportunistic infections such as tuberculosis (TB) and cryptococcal disease. Furthermore, there is an increasing need for implementation research in measuring the effectiveness of currently available rapid diagnostic tests. The recently developed lateral flow assays for both cryptococcal disease and TB have the potential to improve care and greatly reduce the time to initiation of ART among individuals who need it the most. However, we caution that the data on feasibility and effectiveness of these assays are limited and such research agendas must be prioritized.

Cost-effective diagnostic checklists for meningitis in resource-limited settings

BACKGROUND

Checklists can standardize patient care, reduce errors, and improve health outcomes. For meningitis in resource-limited settings, with high patient loads and limited financial resources, central nervous system diagnostic algorithms may be useful to guide diagnosis and treatment. However, the cost effectiveness of such algorithms is unknown.

METHODS

We used decision analysis methodology to evaluate the costs, diagnostic yield, and cost effectiveness of diagnostic strategies for adults with suspected meningitis in resource-limited settings with moderate/high HIV prevalence. We considered 3 strategies: (1) comprehensive "shotgun" approach of utilizing all routine tests; (2) "stepwise" strategy with tests performed in a specific order with additional tuberculosis (TB) diagnostics; (3) "minimalist" strategy of sequential ordering of high-yield tests only. Each strategy resulted in 1 of 4 meningitis diagnoses: bacterial (4%), cryptococcal (59%), TB (8%), or other (aseptic) meningitis (29%). In model development, we utilized prevalence data from 2 Ugandan sites and published data on test performance. We validated the strategies with data from Malawi, South Africa, and Zimbabwe.

RESULTS

The current comprehensive testing strategy resulted in 93.3% correct meningitis diagnoses costing $32.00 per patient. A stepwise strategy had 93.8% correct diagnoses costing an average of $9.72 per patient, and a minimalist strategy had 91.1% correct diagnoses costing an average of $6.17 per patient. The incremental cost-effectiveness ratio was $133 per additional correct diagnosis for the stepwise over minimalist strategy.

CONCLUSIONS

Through strategically choosing the order and type of testing coupled with disease prevalence rates, algorithms can deliver more care more efficiently. The algorithms presented herein are generalizable to East Africa and Southern Africa.

Fungal diagnostics: review of commercially available methods

Fungi and yeasts are critical causes of acute infection. As such, the detection and identification of these organisms are crucial in the diagnosis of affected patient populations. There is a vast array of commercial tests currently available for diagnostic purposes. These vary from traditional culture and biochemical methods to advanced multiparameter molecular tests. Recent technological advances have driven the development of rapid tests which are complementing and in some cases replacing the more traditional methods of detection. Irrespective of the method used the ultimate goal is timely detection of the infectious agent allowing appropriate treatment and improved outcome for the patient.

Rapid polymerase chain reaction diagnosis of white-nose syndrome in bats

A newly developed polymerase chain reaction (PCR)-based method to rapidly and specifically detect Geomyces destructans on the wings of infected bats from small quantities (1-2 mg) of tissue is described in the current study (methods for culturing and isolating G. destructans from bat skin are also described). The lower limits of detection for PCR were 5 fg of purified fungal DNA or 100 conidia per 2 mg of wing tissue. By using histology as the standard, the PCR had a diagnostic specificity of 100% and a diagnostic sensitivity of 96%, whereas the diagnostic sensitivity of culture techniques was only 54%. The accuracy and fast turnaround time of PCR provides field biologists with valuable information on infection status more rapidly than traditional methods, and the small amount of tissue required for the test would allow diagnosis of white-nose syndrome in live animals.