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Chlamydia trachomatis serovars L1, L2, L3 cause lymphogranuloma venereum (LGV). An epidemic of proctitis due to L serovar infections (mostly L2b) has emerged primarily among men who have sex with men (MSM) in Europe.1 In the USA, limited availability of diagnostic testing for LGV hinders diagnosis and reporting to public health agencies. We hypothesised that LGV may be underdiagnosed in the USA.
We collected 1027 C trachomatis-positive specimens referred to our national, academic reference laboratory for routine C trachomatis testing by APTIMA Combo 2 (AC2, Hologic, Bedford, Massachusetts, USA) or culture. We used a modified Centers for Disease Control and Prevention (CDC) multiplex real-time PCR assay2 to detect L genovars. Specimens were collected between September 2011 and March 2012 and belonged to three cohorts (University of Utah IRB #7275): (A) consecutive specimens (gender ratio 1:1) from each of the four CDC sexually transmitted diseases surveillance regions3 (West n=200, Southeast n=200; Northeast n=195; Midwest n=198) positive for C trachomatis by AC2; (B) all specimens positive for C trachomatis and Neisseria gonorrhea by AC2 (dual positives) (n=196); (C) all specimens positive for C trachomatis by culture (n=37).
The median age was 21 years (range 13–72 years) and 49.7% were female. C trachomatis genotyping was successful in 859 (83.6%) specimens. L genovars were identified in two AC2-positive specimens and seven culture-positive specimens (1% total). No specimens were positive for L and non-L genovars. All nine L genovars-positive specimens were from men, six (67%) from rectal specimens, two from urethral specimens (22%) and one (11%) from an unknown source. Seven of the nine patients (78%) were from New York State, and one each from California and Wisconsin.
Partial ompA sequencing was successful for eight of the nine L genovar-positive specimens. Three specimens had ompA sequences identical to the L2b reference strain L2b/UCH-1/proctitis (GenBank accession number AM884177). Five specimens had one non-synonymous single nucleotide polymorphism, each, in the second hypervariable region; one (NY, GenBank accession KC534858) featured a L173F mutation (AM884177 numbering) and four (all NY) demonstrated a L173I mutation (KC534859). Both mutations were recently reported from patients in Spain (GQ413955, JX971936).4
We conclude that LGV is rare but present in men from diverse locations within the USA, including one state with no previous reports (Wisconsin). Identical ompA sequence variants in patients from Spain and New York State suggest transatlantic transmission of the L2b epidemic strain. Increased surveillance and availability of diagnostic tests capable of differentiating LGV strains are needed.
Acknowledgments
The authors thank Haley Elmer, Dave Davies, the molecular amplification and virology laboratories for technical assistance and the Department of Pathology and ARUP Institute for Clinical and Experimental Pathology for financial support.
Footnotes
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Contributors RS conceived the study. BAK and RS designed the study. All three authors acquired, analysed and interpreted the data. All three authors wrote the manuscript and approved the submitted version.
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Funding This work was supported by a grant from the University of Utah Department of Pathology.
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Competing interests None.
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Ethics approval University of Utah.
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Provenance and peer review Not commissioned; internally peer reviewed.