In 2005 in the Eurotransplant region (Austria, Belgium, Germany, Luxemburg, The Netherlands and Slovenia) 444 lung transplantations were performed.

It is well known that infectious complications are the most common cause of morbidity and mortality at all time-points after lung transplantation. Infection rates among lung transplant recipients appear to be higher than those encountered in other solid organ transplant populations; for example, they may occur twice as frequently as in heart recipients.

The likelihood of developing a pulmonary infection is particularly high in the first half-year after transplantation, due to the augmented immunosuppression. In the later years, when bronchiolitis obliterans syndrome (BOS) develops, infectious complications are again more frequent. Pathologically, bronchiolitis obliterans (BO) is characterised by mononuclear cell infiltration, followed by the disturbance of the respiratory epithelium and progressive accumulation of fibroblasts and fibrous connective tissue in the airways. In patients with BOS, obliteration of the small airways, development of bronchiectasis and the enhanced immunosuppression, which is believed to slow down the obliterative process, are additional risk factors for infections. Death of BOS patients is usually related to respiratory failure due to recurrent respiratory tract infections or sepsis.

Epidemiology

Bacterial Pneumonia
Bacterial pneumonia is the most common infection in lung transplant recipients during the first post-operative months. The reported incidence range is 35-70%. Gram-negative organisms pre-dominate as the cause of these infections, and they can often be cultivated from the donor lung. Therefore, it is very important to know precisely the medical history of the donor (occult pre-transplant infection such as tuberculosis (TB) and duration of mechanical ventilation).

Before transplantation, bacteriological examination of the bronchial washings of the donor lung should be performed in all cases. After transplantation, the recipient’s own bacterial flora may become a source of infection. The native lung in single lung recipients and the trachea and the para-nasal sinuses in all transplant patients can serve as a good reservoir for various microorganisms such as gram-negative bacteria, methicillinresistant Staphylococcus aureus (MRSA), Candida, Aspergillus and non-tuberculous mycobacteria. This is especially true for patients with cystic fibrosis (CF), whose native airways and sinuses are chronically infected with virulent bacterial pathogens. Nonetheless, there is now evidence that CF patients have no excessive risk of post-operative infections. Some points with this unique patient population, however, have to be considered. First, CF patients should repeatedly undergo rigorous infection screening together with antibiotic sensitivity testing before transplantation. Furthermore, it is recommended to perform a sinus CT scan and, if necessary, sinus surgery before transplantation to improve the drainage of infected para-nasal sinuses. Colonisation with Burkholderia cepacia has been associated with high risk of severe post-operative infections and, consequently, with inferior survival rate. Therefore, many centres limit offering lung transplantation to CF patients with Burkholderia cepacia. In those CF patients colonised with other multi-resistant bacterial strains – Pseudomonas sp., Stenotrophomonas maltophilia – synergy test should be performed. If effective antibiotic combinations against these multi-resistant organisms cannot be assessed, the patient cannot be accepted for lung transplantation.