Pharyngeal chlamydia; temporary colonisation or persistent infection?
A prospective observational study

Modern nucleic acid amplification tests (NAAT) are far more sensitive to detect
infectious pathogens compared to older diagnostic cultivation methods. A few
copies of DNA can cause a positive test result, yet its relevance is not known.
Many pathogens can only infect specific bodily tissues and give rise to disease
(tissue trophism). Outside these tissues modern NAAT can (temporalily) detect
the precence of these organisms but the host immune system is capable to
eliminate the pathogens swift and efficient, thus preventing disease or further
transmission.
It is known that pharyngeal gonorrhea infections remain asymptomatic in 90% of
cases and are eliminated by the host within 3 weeks. Swift elimination of
gonorrhea from the pharynx is explained by low tissue tropism of the organism
for this location. Yet it is shown that screening for pharyngeal gonorrhea
infections is of relevance since they contribute to the transmission of
gonorrhea to partners via receptive oral sexual contact. (Linhart 2008) In this
project we will study the natural course of patients with a positive pharyngeal
swab for chlamydia.

What is the proportion of STI outpatient clinic visitors with a persistent
colonisation of chlamydia in the pharynx up until 3 weeks after the first
diagnosis based on a NAAT positive chlamydia pharyngeal swab.

Chlamydia persistence in the pharynx up until 3 weeks
Participants:
86 STD-clinic visitors consisting of 43 men who have sex with men (MSM) and 43
women who have sex with men (WSM)

Inclusion criteria:
oReceptive oral sex in the last 6 months (t-7)
- Pharyngeal swab (obtained on t-7 for the exclusion of a gonorrhea infection)
is chlamydia positive (based on the TMA Aptima Combo 2 assay NAAT, streeklab
GGD Amsterdam).

Exclusion criteria:
oAge under 18 years
-Other bacterial STD (gonorrhea, syphilis, lymphogranuloma venereum, chlamydia)
at t-7.
oafter the pharyngeal swab has been obtained the patient has been treated with
Ct sensitive antibiotics (rifampicin, tetracyclines, macrolides, sulfonamides,
quinolones, clindamycin, penicillins, cephalosporins).

Inclusion visit (t0);
-explaination of the study, sign informed consent and inclusion
-quationnaire e.g oral sexual contact.
osecond pharyngeal swab obtained for Ct determination (TMA Aptima Combo 2
assay)
ocontact tracing and treatment according to routine procedure.
- receptive oral sexual contact until the next visit is not allowed.
ò new appointment after 7 days

Second visit (t +7);
-questionnaire about oral sexual contact in the past week.
obtain a third pharyngeal swab for Ct determination (TMA Aptima Combo 2 assay)
-receptive oral sexual contact until the next visit is not allowed.
ò new appointment after 7 days

Third visit (to 14);
-questionnaire about oral sexual contact in the past week.
obtain a third pharyngeal swab for Ct determination (TMA Aptima Combo 2 assay)
-treat with azithromycin 1000 mg once

-Bacterial load determination in pharyngeal swabs at t = -7, t = 0, t = 7 and
t 14 (lab pathology VUMC)

end of the study

Apart from the routine diagnostic screening for STD's, 3 additional throat
swabs and a questionnaire on oral sexual contact are obtained. The associated
risk is nil