Infections Caused by Legionella micdadei and Legionella pneumophila among Renal Transplant Recipients

Abstract

In an analysis of legionellosis at Presbyterian-University Hospital in Pittsburgh [Pennsylvania, USA] during the 28 mo. after the original outbreak of pneumonia caused by L. micdadei, 101 consecutive renal-allograft recipients were studied. The prevalence of elevated titers of antibody to L. pneumophila or L. micdadei among the patients at the time of transplantation (21.6%) was not significantly different from that among kidney donors (13.4%; P > 0.025). Seroconversion occurred in 21 (23.6%) of 89 recipients during the 6 mo. after transplantation. Seven recipients who seroconverted were diagnosed as having legionella pneumonia, 8 had fever and pneumonitis attributed to other causes but compatible (on clinical grounds) with legionella infection, and 6 had no clinical evidence of infectious pneumonia. The interval from transplantation to onset of pneumonia was shorter for recipients with evidence of L. micdadei pneumonia than for patients with L. pneumophila pneumonia (P = 0.006); this finding suggested that the former disease occurred when the recipients were most immunocompromised. The original outbreak of L. micdadei pneumonia was found to have subsided 9 mo. after the last formally recognized case, but infections with L. pneumophila continued to occur thereafter.