**3. Pathogenesis**

Pneumonia may be acquired by intrauterine (e.g. transplacental hematogenous, ascending from birth canal), intrapartum (e.g aspiration) or postnatal routes (e.g. hematogenous, environmental). The pathogens include mainly bacteria, followed by viruses and fungi which induce an inflammatory pulmonary condition (1,8). This may cause epithelial injury to the airways, leakage of proteinaceous fluid into the alveoli and interstitium, leading to surfactant deficiency or dysfunction. Data from a German study (9) suggest that respiratory insufficiency in pneumonia is most likely caused by inhibition of surface-tension-lowering properties of surfactant rather than by surfactant deficiency. Important predisposing factors in the evolution of pneumonia are immaturity, low birth weight, premature rupture of membranes, chorioamnionitis and factors associated with prolonged neonatal intensive care (2, 8).
