Malassezia furfur in the tracheal aspirate of ventilated neonates – a prospective, longitudinal study

Question: Systemic infections and death due to Malassezia furfur (Mf), a common skin yeast, have been reported in premature neonates. Central venous catheters (CVC) and parenteral lipids have been suggested as major risk factors for Mf infection resulting in pulmonary or systemic infection. The rate of colonization of CVCs with MF is second only to coagulase negative staphylococci. However, transbronchial infection of the lungs in ventilated infants might also be possible. Also, as Mf is an obligatory lipophilic yeast, it can only be detected in lipid-containing culture media or by Pappenheim staining. Thus, little is known about the incidence of Mf-infection or colonization in ventilated prematures and neonates.

The purpose of this study was to investigate the incidence of Mf in smears from tracheal aspirates of ventilated prematures and neonates.

Methods: After parental consent, tracheal aspirates (TA) from 26 ventilated neonates (10 males) were collected prospectively and longitudinally in a standardized fashion throughout the duration of mechanical ventilation (3x / week). TAs were centrifuged and pellets were smeared and stained according to Pappenheim method TA smears were coevaluated by an experienced microbiologist. Standard tracheal aspirate cultures were conducted in parallel. Additionally, clinical signs and symptoms for infections were recorded and if required laboratory investigations done.

Results: Patient characteristics were the following:

Gest Age [wks] Birthweight [g] Days on mech. ventilation

Median 28.5 962,5 7

Min 24 580 1

Max 36 2360 50

Of the 26 ventilated infants, thirteen infants were <28 weeks GA. Mf was detected in three extremely premature infants from this group (23%, GA: 23+2, 23+4 and 24+2 weeks; birth weights 580, 621 and 730g, respectively) at day 31, 10 and 21 after birth. The TA smears continued to be positive for Mf in all three patients for a further 13, 26 and 24 days, respectively. During the Mf positive period, all patients developed clinical and laboratory signs of pulmonary infection along with opacifications on X-ray despite adequate antibiotic treatment. All the three infants also had multiple risk factors associated with a systemic infection caused by Mf: central venous lines, intravenous lipids and multiple antibiotics.

Mf -colonization was also confirmed on light microscopy of TA-smears in all affected infants by an experienced microbiologist.

Conclusion: Pulmonary infections with Malassezia furfur in extremely premature infants are probably underestimated. In high-risk patients, the microbiology laboratory should be informed about the possibility of an infection with these organisms and search for the fungus in tracheal aspirate smears should be considered. To our knowledge, this is the first prospective study reporting M. furfur in tracheal aspirates of ventilated neonates. The significance of this finding, especially with regard to chronic lung disease needs to be evaluated.