This finding, in addition with the above-described data supporting biological plausibility, suggests that respiratory-tract Candida colonization may be associated with an increased risk of Pseudomonas infection. To date, however, respi-ratory-tract Candida colonization is not recognized as requiring preemptive antifungal treatment. Moreover, the strength of the Candida colonization-Pseudomonas VAP association may be underestimated: in experimental or clinical models of concomitant infection with C albicans and P aeruginosa, P aeruginosa suppressed the growth of C albicans in vitro and in vivo.
Our study has several limitations. First, we considered that retrieval of Candida from the respiratory tract indicated colonization rather than infection. This position is based on our clinical experience and on the literature. Furthermore, only a minority of our patients had evidence of invasive candidiasis or candidemia. Second, our finding that Candida colonization of the respiratory tract was associated with extrapulmonary and multiple-site Candida colonization may indicate a need for a preemptive treatment, as previously suggested.” other
However, although antifungal prophylaxis has been successful in critically ill patients at high risk for candidemia, no study has demonstrated benefits from preemptive antifungal therapy in critically ill patients with high Candida colonization index values. A recent before/after intervention study from Piarroux et al reported a reduced incidence of candidemia in critically ill surgical patents receiving preemptive antifungal therapy. However, no changes in ICU mortality rates could be observed. Third, although practices regarding the management of VAP and fungal infection and colonization were identical in the six participating ICUs, the study protocol did not include routine respiratory testing to look for Candida colonization, but only collection of bronchial specimens when VAP was suspected on clinical and biological grounds. Moreover, our patients might have had different number of cultures of respiratory specimen, a fact that may decrease the impact of the association reported. However, this means that our results reflect everyday practice and are easily applicable to critically ill patients receiving MV. Fourth, both Candida and Pseudomonas colonization might be consequences of previous antibiotic administration without significant association between these two pathogens. However, the lack of association with Staphylococcus pneumonia, another consequence of antibiotics use, indicates that an association between Candida and Pseudomonas remains plausible.
This study demonstrates an association between Candida colonization of the respiratory tract and subsequent Pseudomonas VAP. A causal relationship is biologically plausible. Further studies should strive to determine whether decolonization of the respiratory tract using local or systemic antifungal therapy reduces the incidence of Pseudomonas VAP.