SEROLOGICAL STUDY OF RESPONSES TO SELECTED PATHOGENS CAUSING RESPIRATORY-TRACT INFECTION IN THE INSTITUTIONALIZED ELDERLY

In a prospective 2-year study, serologial responses to selected pathog ens were analyzed in 224 episodes of fever attributable to respiratory tract infection (51.8%) or of unknown source (48.2%) in 131 residents of two long-term-care facilities. A serological response was identifi ed in 45 episodes (20.1%): Chlamydia pneumoniae (14 episodes), Haemoph ilus influenzae type b (1), influenzae virus type A (14), respiratory syneytial virus (RSV; 2), parainfluenza virus type 3 (7), C. pneumonia e and H. influenzae (3), C. pneumoniae and influenza virus type A (2), C. pneumoniae and RSV (1), and C. pneumoniae and parainfluenza virus type 3 (1). No serological responses to Chlamydia psittaci, Chlamydia trachomatis, parainfluenza virus types 1 and 2, influenza virus type B , or Mycoplasma pneumoniae were seen. Vaccination did not affect the d uration of fryer in those residents with serologically confirmed influ enza A. Serologically confirmed C. pneumoniae infection was detected i n 9.4% of all febrile episodes. Serological responses to a second agen t were detected in 33% of the patients with C. pneumoniae infections, and these dual infections were associated with an underlying malignanc y (P = .02). C. pneumoniae should be recognized as a potential pathoge n when choosing empirical antimicrobial therapy for respiratory tract infection in residents of long-term-care facilities.