INFECTION WITH CHLAMYDIA-TRACHOMATIS LYMPHOGRANULOMA-VENEREUM SEROVARL1 IN HOMOSEXUAL MEN WITH PROCTITIS - MOLECULAR ANALYSIS OF AN UNUSUAL CASE CLUSTER

Among 767 rectal isolates of Chlamydia trachomatis obtained from men o ver the period 1981-1991, 7 were found to be a rare lymphogranuloma ve nereum serovar, L1. These isolates were from rectal specimens taken fr om five male patients in 1982-1983. Six of the seven isolates were ava ilable for DNA sequencing studies. All six of these isolates shared th e same DNA sequence in the major outer membrane protein (MOMP) gene va riable domains and had different MOMP sequences than did the prototype L1, L2, and L3 strains, suggesting a point source outbreak. All five patients infected with serovar L-1 were homosexual men who had symptom atic proctitis characterized by rectal pain, discharge, tenesmus, abno rmalities seen on anoscopy, and leukocytes seen on gram stains of rect al specimens. We conclude that an unrecognized point source outbreak o f the rare chlamydial L1 serovar occurred among homosexual men in Seat tle in 1982-1983, and that the clinical manifestations of L1 infection may be less severe than those of L2 infections.