Simkania negevensis in bronchoalveolar lavage of lung transplant recipients: A possible association with acute rejection

BACKGROUND. Simkania negevensis is a novel organism closely related to chlamydiae. The organism has been associated with community acquired pneumonia and acute exacerbation of chronic obstructive pulmonary disease. The prevalence and pathogenic potential of S. negevensis is not known in lung transplant recipients. METHODS. In this multicenter study comparative analysis of bronchoalveolar lavage (BAL) in lung transplants (Tx) and kidney Tx, immunocompromised and nasopharyngeal (NP) washes of immunocompetent patients was done. The BAL specimens were tested by nested polymerase chain reaction (PCR) for C. pneumoniae and S. negevensis. Selected S. negevensis positive PCR cases were confirmed by culture. RESULTS. In the initial 41 BAL samples S. negevensis was detected in 97.5% (40/41) of lung transplant recipients as compared to 14.1% (1/7) in other organ transplant recipients (P<0.0001). In the sequential samples of 19 lung transplant recipients, 59% (24/41) had concomitant positive PCR and rejection as compared to 30% (3/10) who had negative PCR but had rejection (P=0.16). S. negevensis infection had hazard ratio of 3.29 (95% CI: 0.73-14.76; P=0.11) for developing acute rejection. CONCLUSION. S. negevensis is highly prevalent in liver Tx recipients and may be associated with acute rejection.