The frequency and diversity of lethal invasive fungal pathogens has moved beyond Aspergillus fumigatus to include a plethora of pathogens including the non-fumigatus species of Aspergillus, the Mucormycetes, Fusarium and Scedosporium species and a variety of melanised fungi. Identification by histopathology to genus or species level is limited and fungal cultures from tissue biopsy specimens are often negative.
A recent article by Salehi et al (2016) in a multicentre retrospective study in Iran, has evaluated a real-time qPCR assay which targets the internal spacer (ITS) region of ribosomal DNA (rDNA) to detect and identify genus and species of Aspergillus, the Mucormycetes, Fusarium and Scedosporium from FFPE tissue specimens in patients with histologically proven invasive fungal infections.
The qPCR assay evaluated showed an overall sensitivity of 64% for the identification of fungi from FFPE and highlighted that histopathological features of moulds may be easily confused in tissue sections:
- Fusarium oxysporum and Fusarium solani DNA was detected in five specimens but diagnosed as Aspergillus by histopathology
- Aspergillus flavus, Scedosporium apiospermum and Syncephalastrum were detected from samples classified as mucormycosis by histopathology
- Molecular results (R. oryzae and A flavus) correlated with only one of four tissue samples histologically suspected of having concomitant aspergillosis and mucormycosis; two with A. flavus only and one Mucor isolate
A key finding was the high sensitivity (94%) of the DNA extraction method utilised (automated EZ1 extraction instrument (Qiagen) in combination with a DNA tissue kit). This method gave an excellent yield compared to the 60-80% amplification success rates of other current methods. Direct identification by qPCR assays such as these demonstrate promise for a rapid, reliable adjunctive tool for the accurate identification of clinically relevant fungal pathogens. Sequence based analysis should also be possible, using a similar protocol.
Salehi et al 2016: J Clin Microbiol 54:2798–2803. doi:10.1128/JCM.01185-16
Guarner et al (2011) Histopathological Diagnosis of Fungal Infections in the 21st century.
E-learning course in direct microscopy for identifying fungal infections
Experts in Manchester have recently launched the first e-learning course in direct microscopy for identifying fungal infection, also teaching histological staining methods and interpretation of fungal elements. The course is accredited by the University of Manchester & will teach not only how to rapidly and accurately diagnose life-threatening fungal infections, but also how to set up direct microscopy in a diagnostic laboratory. It is available at www.microfungi.net. The first 50 students to complete this course will be offered free ESCMID membership for one year.
Over a million AIDS deaths preventable by 2020
Fungal infection causes around half of AIDS-related deaths, of which there were 1,100,000 in 2015 (UNAIDS fact sheet). An novel analysis: Modelling Reduction in AIDS deaths in conjunction with GAFFI (global action fund for fungal infections) suggests that the opportunity to save lives is being missed.
With improved access to antiretroviral therapy and a focus on diagnosing TB co-infection, deaths from AIDS have been falling. However, progress is slower than anticipated across the world. The UNAIDS aspirational target of zero AIDS deaths by 2015 was not met, however from UNAIDS numbers, there was a 41% reduction in lives lost (from 2010 at 1.76 m to 1.1 m in 2015).
Continued failure to focus efforts on advanced HIV infection and the 47% who have fungal infections means the current UNAIDS target of fewer than 500,000 annual deaths by 2020 will almost certainly be missed, as was the aspirational target of zero AIDS deaths by 2015. Retention in care is a major factor, but it is late presentation with overwhelming infection that is GAFFI’s primary concern.
GAFFI's projections reveal that by improving access to just 60% of those who need it, over 300,000 lives could be saved per year. By 2020 a total of over a million lives could have been saved, helping to meet the UNAIDS mortality reduction target reducing AIDS deaths to 500,000 per year.
South Africa & Rwanda are leading the world in screening for cryptococcal meningitis using a simple blood dipstick test. In South Africa, an estimated 250 000 patients living with HIV and with a CD4 count below 100 will be screened for the cryptococcal antigen annually. link
Micafungin is effective for candiduria
A recent shift in the epidemiology of candidiasis has been noted with an increase in the frequency of urinary tract infections (UTIs) caused by non-albicans Candida spp. commonly resistant to fluconazole. Echinocandins have fungicidal activity against Candida and penetrate well into the renal parenchyma. However, these agents achieve poor concentrations in the urine and are generally considered ineffective in the treatment of Candida UTIs.
A study of 33 hospitalized patients with candiduria or Candida UTI who received micafungin and had follow-up urine cultures were evaluated. The most commonly recovered species were C. albicans (n=13) and C. glabrata (n=10). Twenty-five patients (75%) had an indwelling urinary catheter. UTI was diagnosed in 16 (48%). Only 3 (10%) had concomitant Candida bloodstream infection. Micafungin was used for a mean duration of 6 days.
Gabardi and colleagues show that intravenous micafungin eradicates candiduria in 75% of patients, there is little else published on the use of echinocandins for candiduria.
More information, Article
Fungal Mycobiome is linked to Crohn's disease
Crohn’s disease (CD) is a relapsing inﬂammatory bowel disease that is driven by an abnormal immune response to gut microbial antigens, suggesting a complex interplay between host genetic factors and endogenous microbial communities. It is only recently that sequencing-based investigations of the gut microbial community have included the fungal community (mycobiome) confirming the importance of fungal component of the microbiome and conﬁrmed its involvement in Candida-host interplay in CD.
In a recently published article on CD patients and their healthy relatives (NCDR) vs a control group without CD or history of CD, signiﬁcant microbial interactions were identiﬁed and validated using single- and mixed-species bioﬁlms. The abundance of the fungus Candida tropicalis was signiﬁcantly higher in CD than in NCDR (p0.003) samples and positively correlated with levels of anti-Saccharomyces cerevisiae antibodies (ASCA). The abundance of C. tropicalis was positively correlated with S. marcescens and E.coli, suggesting that these organisms interact in the gut. CD and NCDR groups clustered together in the mycobiome but not in the bacteriome.
Biofilms comprising three species ie. C. tropicalis with S. marcescens and E. coli had a greater mass and thickness than those of single-and double-species bioﬁlms. Notably C. tropicalis bioﬁlms comprised blastospores, while double and triple species bioﬁlms were enriched in hyphae.
The results of this study indicate that the interplay between fungi and bacteria in the gut of Crohn’s disease patients may be very significant.
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LIFE would also appreciate your help to tell us if you have antifungal eyedrops in your country. GAFFI is seeking to map the availability of eyedrops globally.