For a fungus, this thing attracts a lot of attention from the college. Question 9 from the second paper of 2014 asked for a substantial amount of detail regarding the diagnosis of aspergillosis, and Question 21 from the second paper of 2022 had required some discussion of the risk factors.
As with many of these, the Intensive Care Manual offers little help. Instead, one should turn to LITFL's CCC entry on this subject, which is precise and brief. However if one is not into brevity and precision, one can enjoy several hours submerged in the reference swamp listed below. Selected reading could be limited to the following exceptional articles:
Question 21 from the second paper of 2022 asked for the "risk factors for developing an invasive fungal infection in a critically ill patient", which then pivots into a discussion of Aspergillus. The impression this might give is that the college wanted the candidates to mainly discuss this specific pathogen, but the wording is deliberately more broad. This begs the question: what other invasive fungi did the college want us to know about?
Well. The excellent 2011 article by Muskett et al identifies Candida species as by far the most common pathogen. There are obviously several others, and the following list was compiled using a table from Shoham & Marwaha (2010):
The risk factors identified by Muskett et al (2011) were:
However these were the risk factors identified from the meta-analysis of a whole host of historical studies, and so represents a sort of pure distilled product from which you could manufacture a risk stratification tool or scoring system (as an example). CICM exams probably need something a bit more broad, and ideally with structure and categories (to aid memory deposition as well as to answer the examiner's comments from Question 21. A good example of such a list, with some distinctive categories, was found in an article on voriconazole by Zabalza et al (2013), and modified to suit the CICM answer:
One of the articles referenced by LITFL contains within it Table 2 (p.207) which lists the risk categories for invasive aspergillosis among ICU patients. In a contorted form, those data are displayed below:
Low risk |
Intermediate risk |
High risk |
|
|
|
It should be noted (from the same article) that merely being intubated places one at an increased risk of forming Aspergillus colonies in one's respiratory tract. This has the effect of causing positive test results, but no actual invasive disease.
An old 1977 article (from before PCRs and whatnot) and a new 2002 article describe the clinical picture. Their suggestions can be compiled into a table:
Pulmonary:
Extrapulmonary: immunocompromised host
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|
This answers Question 9 from the second paper of 2014.
Why the diagnosis is not straightforward:
The references which this author thought were the most authoritative were Hites et al (2016) for galactomannan and Marty & Koo (2009) for β-glucan.
Aspergillus galactomannan: blood
Aspergillus galactomannan: bronchoalveolar lavage
Aspergillus PCR on bronchoalveolar lavage specimens
Aspergillus hyphae identified
β-glucan antigen
LITFL link to an excellent Radiopedia page which has some lovely fungus balls. A definitive journal reference would have to be this 2001 article.
In brief, the radiological features are:
Open lung biopsy is not to be taken lightly. Furthermore, it is not always helpful. In one 2001 study the authors claim that they could histopathologically confirm invasive fungal infections only in 53.1% by open lung biopsy. Generally speaking these days people rely on laboratory data and radiology. The open biopsy remains at the hopeless end of the diagnostic algorithm flowcharts. Its only benefit is to spare the patient from a course of amphotericin therapy.
The Sanford Guide recommends the following:
Alternatives include
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Sherif, Rami, and Brahm H. Segal. "Pulmonary aspergillosis: clinical presentation, diagnostic tests, management and complications." Current opinion in pulmonary medicine 16.3 (2010): 242.
Meersseman, Wouter, et al. "Invasive aspergillosis in the intensive care unit."Clinical Infectious Diseases 45.2 (2007): 205-216.
Trof, R. J., et al. "Management of invasive pulmonary aspergillosis in non-neutropenic critically ill patients." Intensive care medicine 33.10 (2007): 1694-1703.
Mennink-Kersten, Monique ASH, J. Peter Donnelly, and Paul E. Verweij. "Detection of circulating galactomannan for the diagnosis and management of invasive aspergillosis." The Lancet infectious diseases 4.6 (2004): 349-357.
Musher, Benjamin, et al. "Aspergillus galactomannan enzyme immunoassay and quantitative PCR for diagnosis of invasive aspergillosis with bronchoalveolar lavage fluid." Journal of Clinical Microbiology 42.12 (2004): 5517-5522.
Pfeiffer, Christopher D., Jason P. Fine, and Nasia Safdar. "Diagnosis of invasive aspergillosis using a galactomannan assay: a meta-analysis." Clinical Infectious Diseases 42.10 (2006): 1417-1727.
Patmore, J. V., H. D. Goff, and S. Fernandes. "Cryo-gelation of galactomannans in ice cream model systems." Food Hydrocolloids 17.2 (2003): 161-169.
Wald, Anna, et al. "Epidemiology of Aspergillus infections in a large cohort of patients undergoing bone marrow transplantation." Journal of Infectious Diseases 175.6 (1997): 1459-1466.
Escuissato, Dante L., et al. "Pulmonary infections after bone marrow transplantation: high-resolution CT findings in 111 patients." American Journal of Roentgenology 185.3 (2005): 608-615.
Nucci, Marcio, et al. "Early diagnosis of invasive pulmonary aspergillosis in hematologic patients: an opportunity to improve the outcome." haematologica98.11 (2013): 1657-1660.
Acosta, J., et al. "A prospective comparison of galactomannan in bronchoalveolar lavage fluid for the diagnosis of pulmonary invasive aspergillosis in medical patients under intensive care: comparison with the diagnostic performance of galactomannan and of (1→ 3)–β–d‐glucan chromogenic assay in serum samples." Clinical Microbiology and Infection 17.7 (2011): 1053-1060.
Izumikawa, Koichi, et al. "Bronchoalveolar lavage galactomannan for the diagnosis of chronic pulmonary aspergillosis." Medical mycology 50.8 (2012): 811-817.
Boonsarngsuk, Viboon, et al. "False-positive serum and bronchoalveolar lavage Aspergillus galactomannan assays caused by different antibiotics."Scandinavian journal of infectious diseases 42.6-7 (2010): 461-468.
Digby, Justin, et al. "Serum glucan levels are not specific for presence of fungal infections in intensive care unit patients." Clinical and diagnostic laboratory immunology 10.5 (2003): 882-885.
Hage, Chadi A., et al. "Plasmalyte as a cause of false-positive results for Aspergillus galactomannan in bronchoalveolar lavage fluid." Journal of clinical microbiology 45.2 (2007): 676-677.
Buess, Michael, et al. "Aspergillus-PCR in bronchoalveolar lavage for detection of invasive pulmonary aspergillosis in immunocompromised patients." BMC infectious diseases 12.1 (2012): 237.
Heng, Siow-Chin, et al. "Clinical utility of Aspergillus galactomannan and PCR in bronchoalveolar lavage fluid for the diagnosis of invasive pulmonary aspergillosis in patients with haematological malignancies." Diagnostic microbiology and infectious disease 79.3 (2014): 322-327.
Franquet, Tomás, et al. "Spectrum of Pulmonary Aspergillosis: Histologic, Clinical, and Radiologic Findings 1." Radiographics 21.4 (2001): 825-837.
Kim, Kihyun, et al. "Importance of open lung biopsy in the diagnosis of invasive pulmonary aspergillosis in patients with hematologic malignancies." American journal of hematology 71.2 (2002): 75-79.
Blot, Stijn I., et al. "A clinical algorithm to diagnose invasive pulmonary aspergillosis in critically ill patients." American journal of respiratory and critical care medicine 186.1 (2012): 56-64.
Muskett, Hannah, et al. "Risk factors for invasive fungal disease in critically ill adult patients: a systematic review." Critical care 15.6 (2011): 1-15.
Shoham, Shmuel, and Shilpa Marwaha. "Invasive fungal infections in the ICU." Journal of intensive care medicine 25.2 (2010): 78-92.
Zabalza, Amaya, et al. "Voriconazole and its clinical potential in the prophylaxis of systemic fungal infection in patients with hematologic malignancies: a perspective review." Therapeutic Advances in Hematology 4.3 (2013): 217-230.
Hites, Maya, Eduardo Wilfrido Goicoechea Turcott, and Fabio Silvio Taccone. "The role of galactomannan testing to diagnose invasive pulmonary aspergillosis in critically ill patients." Annals of translational medicine 4.18 (2016).
Marty, Francisco M., and Sophia Koo. "Role of (1→ 3)-β-D-glucan in the diagnosis of invasive aspergillosis." Medical mycology 47.Supplement_1 (2009): S233-S240.