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Tuesday, May 9, 2006
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Results of serologic tests for Chlamydia trachomatis in men presenting with suspected rectal lymphogranuloma venereum (LGV) – Massachusetts

Sylvie Ratelle, STD Division, Massachusetts Department of Public Health, State Laboratory Institute, 305 South Street, Boston, MA, USA, Thomas Bertrand, STD Director, Massachusetts Dept. of Health, Boston, MA, USA, William Dumas, Division of STD Prevention, Massachusetts Department of Public Health, Boston, MA, USA, Yuren Tang, STD Division, Bureau of Communicable Disease Control, Massachusetts Department of Public Health, State Lab Institute, 305 South Street, Room 561, Jamaica Plain, MA, USA, Linda Han, State Laboratory Institute, Massachusetts Department of Public Health, Boston, MA, USA, and Barbara Lambl, Department of Infectious Diseases, Boston Medical Center, Boston, MA, USA.


Background:
LGV has been identified in men who have sex with men (MSM) presenting with symptoms of proctitis. CDC genotyping of Chlamydia trachomatis (CT) isolated in the rectum can confirm cases of LGV. However, genotyping may not always be available. Serology could assist in diagnosis, but the interpretation of titers is challenging.

Objective:
To examine the distribution of serology titers among MSM with symptoms of proctitis who have positive rectal tests for LGV, positive rectal tests for CT (non LGV) and negative rectal tests for CT.

Method:
A prospective analysis of all cases of suspected rectal LGV reported to the Division of STD Prevention (DSTDP) with available rectal CT tests and serology (immunofluorescent assay) results.

Result:
Between January 1 and September 30, 2005, 35 cases of suspected rectal LGV were investigated by the DSTDP and 11 tested positive for CT by nucleic acid amplification tests (NAAT) (prevalence 31.4%). Nine of the 11 positive NAAT were sent to the CDC for genotyping and three were LGV types (all L2). Two of the LGV cases had serology results (1:1024 and 1:4096 - mean logarithm: 7.62). The serology titers for cases with negative CT results ranged from 1:16 to 1:1024 (mean logarithm: 4.97). The titers for cases with positive CT (not confirmed as LGV) ranged from 1:128 to 1:2048 (mean logarithm: 6.76).

Conclusion:
High serology titers can be found in men presenting with proctitis and testing negative for CT. However, preliminary data suggest that titers among confirmed LGV cases were higher when compared to non LGV CT and negative CT.

Implications:
Further analysis of serologic results with different technologies and a larger sample size is needed to better characterize titer distribution and spectrum of LGV disease.