Pre-analytical issues
There are many types of EIA used in microbiology and biochemistry. Depending on the format of the test, some have alternative names such as ELISA and CLIA (chemoluminescent immunoassay). Continue reading
| Organism | Microscopy | Culture and identification | Non-culture methods |
| General | Histopath PAS & silver stains etc.
K0H with Parker ink (skin scrapings/nails) |
SAB (Saborauds dextrose agar) medium +/- antibiotics +/- cycloheximide
For other media, see here. Blue thymol blue sticky tape preparation from cultures for examining hyphae and fruiting structures |
MALDI-TOF for ID
Invasive fungal disease: 1-3 Beta-D-Glucan assay (serum) – broad spectrum but not incl. Cryptococcus |
| Candida albicans and other similar species | Characteristic yeast shapes larger than bacteria; appear Gram positive | Colonies with ‘feet’ (C. albicans)
Chromogenic candida agar – usually sufficient for ID. Several types. Yeast sugar assimilation panels e.g. API , VITEK etc |
|
| C. neoformans
C. gattii |
India ink preparation for capsule (CSF)
NB. capsule production media dependent |
Presumptive: capsule+yeast= Cryptococcus (no other species has a capsule)
Urease positive Bird seed agar – pigmented colonies = Cryptococcus CGB medium- (L-Canavanine, glycine, 2 bromthymol blue agar) distinguishes C. gattii from C. neof. |
Crypto antigen lateral flow assay (serum/CSF)
IF serotyping of isolates- research only |
| Aspergillus species | Histopath – narrow septate hyphae; acute angle branching | Culture appearance- pigmentation
Species ID by sticky tape preparation |
Galactomannan EIA (serum, BAL)
Serum precipitins used in ABPA Dx
|
| Pneumocystis jirovecii(PJP) | Bronchial lavage / induced sputum – IF / silver / Giemsa stains | Usually a clinical diagnosis
No culturable
|
PCR more sensitive than IF |
Histopathologic Diagnosis of Fungal Infections in the 21st Century : excellent overview- invasive fungal infections are often recognised only by histopathologists post mortem! Also this slide set : https://www.slideshare.net/appyakshay/fungus-in-histopathology
Cryptococcal serum antigen screening for HIV positive patients– previous posting. This ICT has excellent sensitivity and specificity for crypto antigen detection.
India ink preparation Gram stain of Candida species
Guest posting: Associate Professor Anna Ralph, Director of Global and Tropical Health at Menzies School of Health Research, Darwin, Northern Territory, Australia.
News : UN General Assembly first ever High-Level Meeting on the fight against tuberculosis, September 28th 2018.
New(ish) WHO strategy and targets:
| SDGs | End TB Strategy | |
| Reduction in number of deaths vs 2015 | 90% | 95% |
| Reduction in TB incidence vs 2015 | 80% | 90% |
| TB-affected families facing catastrophic costs | 0% | 0% |
Guest posting: Dr Chris Ashhurst-Smith, Pathology North.
Part 3: Faeces culture plate reading. Video Felix Ferguson.
Guest posting: Dr Chris Ashhurst-Smith, Pathology North.
Here is part 2 about urine culture reading. Video by Felix Ferguson. Thank you Chris! Enjoy.
Guest posting: Dr Ian Marr, Microbiology Registrar, NSW Health Pathology.
Malaria diagnosis Marr August 2018 v2
Basic malaria microscopy – Part I: Learner’s guide. Second edition, February 2010 – World Health Organisation
Guest posting with permission from Laureate Professor Rodney Scott : these are his presentations provided to post-graduates in Nepal during his recent visit to inspect the new cytogenetics laboratory at the National Academy of Medical Sciences, Bir Hospital, Kathmandu. Most presentations have annotations.
BRCA1 and BRCA2 Structure:
Reference
