Chlamydia Pneumoniae has been implicated as a cause of tonsillitis and
pharyngitis, but the incidence has varied from one to 19 per cent in
various studies. We investigated 51 patients admitted to University Co
llege Hospital, Galway, with severe tonsillitis. Throat swabs were exa
mined for evidence of Chlamydia pneumoniae using a direct monoclonal a
ntibody test. Blood was taken for serology from 45 patients. A further
specimen was taken at six weeks. A control group of 32 blood bank ser
a was used. Mean hospital stay was three days (one to eight). Five pat
ients (10 per cent) were monospot positive. Chlamydia pneumoniae was i
dentified by direct immunofluorescence on a tonsillar swab from one pa
tient who did not seroconvert. IgG antibody was identified in 13 cases
(29 per cent) and in seven of the control group (22 per cent). No ser
ological evidence of recent infection was found. Chlamydia pneumoniae
was not found to be a cause of severe acute tonsillitis in our study g
roup.