Pneumocystis and Other Less Common Fungal Infections

Fungal infections, other than those caused by Candida species, rarely are considered in the differential diagnosis for an acutely ill newborn infant, because disorders of bacterial and viral etiology are vastly more common. Nevertheless, fungal infections do occur in neonates, especially in premature infants and those of very low birth weight (less than 1500g), and can cause serious and frequently fatal disease. The number of cases of invasive infection attributed to fungi among all patients in the United States quadrupled between 1990 and 2000. With advances in neonatal care, the epidemiology of fungal infections in the neonatal intensive care unit (NICU) has changed dramatically, with an estimated 10-fold increase in the past decade. As with any other infectious disease, the risk of fungal infection depends on the host and risk of exposure. The neonate has some risk of exposure to either Malassezia furfur or Pneumocystis jiroveci (previously Pneumocystis carinii , newly classified as a fungus on the basis of DNA sequence analysis), has a limited risk of exposure to Aspergillus species, and has an extremely low risk of exposure to other fungi—especially in the NICU setting. Therefore, it is not surprising that the most common fungal infection in neonates is candidiasis, followed by infections with P. jiroveci and M. furfur , whereas case reports or small series constitute the literature on aspergillosis and other fungal infections.