Candida Colonization of the Respiratory Tract and Subsequent Pseudomonas Ventilator-Associated Pneumonia: Discussion

Candida Colonization of the Respiratory Tract and Subsequent Pseudomonas Ventilator-Associated Pneumonia: DiscussionIn ICU patients receiving MV, Candida, a normal inhabitant of the oral cavity and GI tract, spreads along the respiratory tract down to the alveoli, so that endobronchial specimen findings are positive but no clinical or pathologic evidence of pneumonia is detectable. In this situation, the positive specimens merely indicate colonization, and there is no evidence of invasive pulmonary candidiasis (true candidal pneumonia), a condition related to hematogenous dissemination of Candida with selective tropism for the bloodvessels and invasion of the lung parenchyma. The multicenter study reported here showed that Candida colonization of the respiratory tract was common, occurring in 25% of immunocompetent critically ill patients receiving MV. This is the first study that sought to identify diseases specifically related to Candida colonization of the respiratory tract. Although Candida colonization was not associated with increased mortality, longer durations were found for mean time receiving MV, mean time in the ICU, and mean time in the hospital. A finding from the present study is that in our selected patients, respiratory tract Candida colonization was associated with an increased risk for VAP and that this increase was explained by a greater risk of Pseudomonas VAP. canadian health&care mall

Interactions between bacteria and fungi have major environmental and medical consequences. Bacteria have been shown to induce morphologic changes in Candida, and Candida morphology and virulence are significantly affected by the presence of P aeruginosa. Pseudomonas produces a cell-cell signaling molecule (3-oxo-C12 homoserine lactone) capable of inhibiting Candida filamentation. Moreover, Spinelli et al showed that both Candida spp and P aeruginosa had the functional enzyme (2′-phosphotransferase) acting in concert with ligase to splice transfer RNA or other RNA molecules, a finding consistent with phylogenetic similarities between the two pathogens. In patients receiving MV, Pseudomonas forms a dense biofilm on Candida filaments, in agreement with the finding that Candida and Pseudomonas are among the most common pathogens retrieved from endotracheal tubes and from respiratory specimens in patients with VAP. In keeping with these data, our nested exposed/ unexposed analysis found that Candida colonization of the respiratory tract was associated with an increased risk of VAP. A finding from our study was that this association was more pronounced for Pseudomonas VAP (9% vs 4.8%, p = 0.049) than for other pathogens (Table 3).

Table 3—Characteristics of the Patients in the Second Nested Exposed/Unexposed Analysis With P aeruginosa VAP Episodes as Outcome Measure

Characteristics Respiratory Tract Candida Colonization (n = 211) No Respiratory Tract Candida Colonization (n = 394) p Valuef
Patient age, yrReasons for ICU admission 69 (55-76) 64 (50-74) 0.01
Acute respiratory failure 55 (26) 95 (24.1) 0.1
Shock 64 (30.3) 106 (26.9) 0.35
Coma 32 (15.2) 123 (31.2) < 0.0001
Infection at admission 113(53.6) 148 (37.5) < 0.0001
Direct admission 69 (32.7) 205 (52) < 0.0001
SAPS II score at admission (range) 45 (35-58.5) 48(36-61) 0.33
LOD score at admission (range) 5(3-7) 5(3-8) 0.11
MV within 48 h 175 (82.9) 350 (89) 0.57
Acute lung injury at admission! 156 (73.9) 257 (65.2) 0.22
ARDS at admission§ 93 (44.1) 160 (40.6) 0.37
Need for vasopressors 147 (69.6) 245 (62.2) 0.10
Antibiotics within 3 d after ICU admission 166 (78.6) 303 (76.9) 0.27
Occurrence of VAP 48 (22.7) 69 (17.5) 0.07
Occurrence of Pseudomonas VAP 19(9) 19 (4.8) 0.04
This entry was posted in Pulmonary Function and tagged Candida, mechanical ventilation, pneumonia, Pseudomonas, ventilator-associated pneumonia.