the management of critically ill patients with a suspected invasive fungal infection based on predefined clinical and microbiological criteria or the punctuation of a score may be a valid approach when the definitive diagnosis is feasible only in a small proportion of patients .
this is what vandewoude and colleagues propose with their retrospective analysis of all patients who had aspergillus spp .
fungal infections have increased in intensive care units ( icus ) over the past decades .
although less common than candidiasis , aspergillosis is more likely to result in a life - threatening infection .
thus , neutropenic patients , and those who receive long - lasting corticosteroid treatments , are at high risk for invasive aspergillosis .
this organism grows on a wide variety of organic material and the conidia are easily aerosolised .
although exposure is universal , invasive infection occurs almost entirely in immuno - suppressed individuals .
outbreaks have been described in bone marrow transplantation , solid organ transplant recipients and leukaemia patients in association with hospital construction and/or ventilation system contamination with aspergillus .
indeed , multiple organ failure and prolonged stays in the icu are associated with a complex decrease in immune functions , deactivation of macrophages and altered cellular response .
this is usually not feasible given the special circumstances of critically ill ventilated patients . likewise , screening the blood for galactomannan may be very valuable in neutropenic patients but its usefulness in icu patients is limited . before new antifungal agents were available , mortality of critically ill patients with invasive aspergillosis was nearly 100% .
currently , the therapeutic armoury has significantly improved with the introduction of new azoles ( i.e. , voriconazole ) and the echinocandins ( i.e. , caspofungin ) , a new class of drugs with a novel target .
many problems contribute to the lack of confident and timely diagnosis of invasive aspergillosis in critically ill patients . on one hand
, the early administration of antifungal agents may be life - saving , but clinicians must also bear in mind the problems and costs associated with needless treatments derived from the overinterpretation of the potential clinical significance of isolates of aspergillus spp . in respiratory samples .
propose a clinical algorithm based on the criteria defined by an international conference on the diagnosis of aspergillosis in immunocompromised patients . with this approach ,
approximately 50% of the patients were diagnosed with invasive aspergillosis and in the other 50% the isolation was considered colonization .
unfortunately , histology was available only in a small proportion of patients ( one - fourth of patients with presumed diagnosis of infection and one - tenth of the patients with the diagnosis of colonization ) . at first glance
, these results seem very hopeful , although positive and negative predictive values can not be calculated with these figures . the diagnostic accuracy of this algorithm can be improved .
many authors have documented that invasive aspergillosis can occur in certain types of ' non - immunocompromised ' critically ill patients .
three high risk groups stand out for invasive aspergillosis : chronic obstructive pulmonary disease , prolonged multiple dysfunction syndrome in the situation of immunoparalysis , and severe hepatic failure .
these underlying conditions are not included in the proposed criteria and they should be added to the list .
this may avoid the misclassification of these high risk patients if semiquantitative culture of bronchoalveolar lavage was not positive , a criterion not universally accepted .
moreover , a high resolution ct scan is nowadays mandatory and a normal portable chest x - ray may lead to an erroneous classification .
the significance of a positive respiratory culture for aspergillus spp . in a non - immunodepressed patient causes the clinician great uncertainty and doubt .
nowadays , the isolation of aspergillus spp . in a critically ill patient is not an exceptional curiosity .
definitions proposed by the european organisation for the research and treatment of cancer were not designed to guide clinical practice .
critical care physicians need a helpful instrument to decide in which circumstances antifungal therapy should be initiated early , given the high mortality of this infection but the availability of new and active agents .
obviously , this and other strategies need to be validated in large cohorts of critically ill patients before they can be recommended .
this is an urgent task because we do not expect to have at our disposal a precise microbiological test in the near future .
 the clinical relevance of recovering aspergillus species in intensive care unit patients is unknown . 
 diagnosis of invasive pulmonary aspergillosis is extremely difficult because there are no specific tests sensitive enough to detect it . 
 the rapidly fatal prognosis of this infection without treatment justifies early antifungal therapy . 
 a clinical algorithm may aid clinicians to manage critically ill patients from whose respiratory specimens aspergillus spp . 
 have been isolated . 
 this new tool needs to be validated in a large cohort of patients before it can be recommended . 
None
Abbreviations
Competing interests