EDITOR, - Phillip E Hay and colleagues' report on abnormal bacterial colonisation of the genital tract and preterm labour.1 The association between infection and preterm labour has been widely reported, with the genital mycoplasmas (Ureaplasma urealyticum and Mycoplasma hominis) often being implicated.2 Many of the preterm infants need ventilation, and a considerable number develop chronic lung disease. In our unit in 1993 there were 84 survivors of <=30 weeks' gestation, of whom 41 developed chronic lung disease. The aetiology of this disease is multifactorial, with gestation and positive pressure ventilation being the most important determinants.

In a pilot study of the incidence of ureaplasma and mycoplasma infections the endotracheal secretions of all intubated neonates of <=30 weeks' gestation (n=63) were examined weekly from birth while the neonates remained intubated. Sixteen of the infants were positive for one or both organisms, with 11 yielding positive results on the first culture. Fifteen (94%) of these 16 infants with positive cultures went on to develop chronic lung disease whereas only 18 (38%) of the 47 infants for whom culture yielded negative results developed the disease (P<0.001). There were no significant differences between the two groups in gestation, birth weight, and duration of positive pressure ventilation.

These data agree with data from the United States. 3 It has been suggested not only that these organisms induce preterm labour but that their presence in the lungs causes a low grade inflammatory response, increasing the need for ventilation and hence increasing the degree of damage done by the ventilator, resulting in chronic lung disease. The presence of an inflammatory response in the development of chronic lung disease from the respiratory distress syndrome is well recognised,4and we have found an association between high levels of the cytokine interleukin-8 (as a marker of inflammatory …