# Serological reactivity and bacterial genotypes in Chlamydia trachomatis urogenital infections in Guadeloupe, French West Indies

François-Xavier Weill, Simon Le Hello, Maïthé Clerc, Cédric Scribans, Bertille de Barbeyrac

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François-Xavier Weill, Simon Le Hello, Maïthé Clerc, Cédric Scribans, Bertille de Barbeyrac. Serological reactivity and bacterial genotypes in Chlamydia trachomatis urogenital infections in Guadeloupe, French West Indies. Sexually Transmitted Infections, 2010, 86 (2), pp.101-105. 10.1136/sti.2009.037036. pasteur-02019208

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Distributed under a Creative Commons Attribution 4.0 International License
Serological reactivity and bacterial genotypes in *Chlamydia trachomatis*
urogenital infections in Guadeloupe, French West Indies

3

4 François-Xavier Weill, MD, PhD¹,³*, Simon Le Hello, PharmD, MSc¹,³, Maithé Clerc²,

5 Cédric Scribans, MSc², and Bertille de Barbeyrac, PharmD, PhD¹²

6

7 ¹ Institut Pasteur de la Guadeloupe, Pointe à Pitre, France

8

9 ² CHU de Bordeaux, Laboratoire de Bactériologie, Centre National de Référence des
infections à *Chlamydia*, Bordeaux, France

11

12 ³ present address:

13 Institut Pasteur, Laboratoire des Bactéries Pathogènes Entériques, Paris, France.

14

15 Corresponding author

16 Laboratoire des Bactéries Pathogènes Entériques, Institut Pasteur, 28 rue du Docteur

17 Roux, 75724 Paris cedex 15, France. Tel: 33-(0)1 45 68 83 45. Fax: 33-(0)1 45 68 88 37.

18 E-mail: fxweill@pasteur.fr

19

20 SUMMARY

21

22 **Key-words:** *Chlamydia trachomatis*, epidemiology, serology, prevalence, genotyping,

23 Guadeloupe.
25

26 **KEY MESSAGES**

27

28 The prevalence of *Chlamydia trachomatis* urogenital infection was 16.9% in men and

29 9.8% in women in 2000 in Guadeloupe, French West Indies.

30

31 The distribution of *Chlamydia trachomatis* genotypes responsible for urogenital

32 infections in Guadeloupe, French West Indies, differed from that in mainland France.

33

34 The SERO-CT assay was unable to detect antibodies in the serum samples of patients

35 infected with *Chlamydia trachomatis* genotype Ia strains.

36

37 **STATEMENT**

38

39 The Corresponding Author has the right to grant on behalf of all authors and

40 does grant on behalf of all authors, an exclusive licence (or non exclusive

41 for government employees) on a worldwide basis to the BMJ Publishing Group Ltd

42 to permit this article (if accepted) to be published in STI and any other

43 BMJPGL products and sub-licences such use and exploit all subsidiary rights,

44 as set out in our licence http://sti.bmjjournals.com/ifora/licence.pdf).

45

46 **COMPETING INTEREST**

47 None declared.

48
49

# ABSTRACT

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51

**Objectives:** To determine the prevalence and genotypes of *Chlamydia trachomatis* urogenital infection in Guadeloupe, French West Indies. To compare *C. trachomatis* direct detection to serological testing.

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**Methods:** From March to November 2000, 971 consecutive patients (888 women and 83 men) who had been referred to clinical laboratory of the Institut Pasteur de la Guadeloupe for routine testing for genital infection, were recruited. Samples were subjected to a nucleic acid amplification assay (AMP CT, Gen-Probe). Genotypes were determined by *omp1* PCR-RFLP analysis. Serological testing was carried out with the commercially available peptide-based ELISA assay (SERO-CT IgG/IgA, Savyon/BMD).

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**Results:** Positive AMP CT test results were obtained for 102 (10.5%) of the 971 samples. The prevalence of infection was 16.9% in men and 9.8% in women. The most common genotypes were E (34.3%), F (23.9%), Da (13.4%), I (9%), and Ia (7.5%). No relationship was found between genogroups and age, sex or clinical symptoms. With AMP CT used as a reference, the sensitivity, specificity, positive, and negative predictive values of SERO-CT were 81.1%, 56%, 34.5% and 91.2 %, respectively, for IgG and 55.4%, 76.8%, 59.4 %, and 85.8 %, respectively, for IgA. IgG seroprevalence rates were very low (1/5, 20%) in patients infected with genotype Ia strains.

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**Conclusions:** The prevalence found in Guadeloupe did not differ not significantly from that which was found in mainland France. The genotypes Da, F, I, and Ia were more prevalent in Guadeloupe; however, the SERO-CT assay was unable to detect serum antibodies in 80% of the patients infected with genotype Ia strains.

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71

72
73 INTRODUCTION

74

75 *Chlamydia trachomatis* is considered to be the most common bacterial cause of
76 sexually transmitted infections (STIs) worldwide. It is currently classified into 19
77 different serovars on the basis of immunogenic epitope analysis of the major outer
78 membrane protein (MOMP). Serovars D to K, and related variants, Da, Ia, and Ga, are
79 generally found to be associated with urogenital infections. ¹,² Over the last two decades,
80 genotyping based on the *omp1* gene, encoding MOMP, has become a convenient
81 alternative to the laborious serotyping method. The single-copy *omp1* gene displays
82 extensive sequence variations in four regions (VS1-VS4), interspersed with five regions
83 of conserved sequence. The diversity of the DNA can be analyzed by restriction
84 fragment length (RFLP) analysis and/or by sequencing of the PCR-amplified *omp1*
85 gene. ¹⁻¹¹ Genotyping was originally carried out on cell cultures, but direct genotyping of
86 clinical specimens is now performed by sensitive nested PCR of the *omp1* gene.¹²
87 Phylogenetic analysis of *omp1* subdivides strains into three distinct genogroups : B
88 (serovars B, Ba, D, Da, E, L1 and L2), intermediate (serovars F, G, and Ga), and C
89 (serovars A, C, H, I, Ia, J, K, and L3). ¹,²

90 In Guadeloupe, French West Indies, there is no data in the literature concerning
91 *C. trachomatis* urogenital infection. In mainland France, commercially available PCR
92 methods have showed that the prevalence of such infection in symptomatic populations
93 was 8-10.2% in women and 16.4% in men (1994-1998). ¹³, ¹⁴ In the Caribbean region,
94 the prevalence ranges from 5.4% to 21% in asymptomatic women from Curaçao,
95 Barbados, and Trinidad, to 55% in STI clinic patients from Jamaica. ¹⁵⁻¹⁹ Despite the use
96 of different methods and populations, which made the results difficult to compare, these
97

studies provide useful data to national health authorities. A piece of valuable information
that has not yet been reported in the Caribbean region are the genotypes or serovars of
circulating *C. trachomatis* strains.

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We report here the first study on *C. trachomatis* urogenital infection in Guadeloupe. We established the prevalence of this infection by carrying out nucleic acid amplification tests (NAATs) on a population of 971 consecutive patients referred for routine testing for urogenital infection, and determined the genotypes by PCR-RFLP. We searched for relationships between genogroups and particular demographic, clinical, serological, and microbiological characteristics of the infected population.

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# MATERIALS AND METHODS

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## Study population

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Guadeloupe is an overseas French *département* covering 1705 km² and located in the Caribbean region. The archipelago had a total population of 422,000 inhabitants (1999 census data).

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The selected population consisted of 971 consecutive patients (888 women and 83 men), who were referred to the clinical laboratory of the *Institut Pasteur de la Guadeloupe*, Pointe à Pitre, Guadeloupe, by general practitioners, dermatologists or gynaecologists during the period from March to November 2000 for routine testing for urogenital infection. All the specimens were collected and all assays other than genotyping were carried out in the laboratory.

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Data, including demographic characteristics such as age and sex, clinical
symptoms and results of all microbiological investigations were recorded for two subsets of patients. The first subset was comprised of patients with a positive NAAT (n=102). The second subset comprised of those with an available serological test (n=333), was classified as follows: one CT+ group (n=74; median age: 24.6±7.4 years; range: 13-44) comprised of patients, 65 of which were women and 9 of which were men, with AMP CT-positive assays; and one CT- group (n=259; median age: 29.2±9.9 years; range: 14-70) comprised of 238 women and 21 men. Ethical approval was not required under local law for this study due to its retrospective design and use of data obtained through routine testing.

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### C. trachomatis nucleic acid detection

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C. trachomatis direct detection was performed with the Amplified Chlamydia trachomatis assay (AMP CT; Gen-Probe, San Diego, USA). This NAAT targets a specific 23S rRNA of C. trachomatis in a transcription-mediated amplification and hybridisation protection assay. Male urethral (n=72) and female endocervical (n=867) swabs or first-void urine specimens from men (n=11) or women (n=21) were collected and tested according to the manufacturer's instructions.

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### C. trachomatis antibody detection

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C. trachomatis antibody status was determined on 333 sera from 333 patients with the SERO-CT IgG/IgA test (Savyon/BMD, Marne-La-Vallée, France), according to
the manufacturer's instructions. This microtiter-based ELISA uses a mixture of species-specific peptides from the *C. trachomatis* MOMP for the detection of specific IgG and IgA antibody. Samples with index values (OD sample/OD negative control x 2) ≤ 1.1 were considered negative, whereas those with index values > 1.1 were considered positive.

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## Genotyping of *C. trachomatis*

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Of the 100 AMP CT-positive non-urine specimens, stored in a Gen-Probe transport tube at -70°C, 99 were transported frozen, overnight, to the French National Reference Centre for *C. trachomatis*. Samples were diluted 1/10 with lysis buffer and nested PCR analyses were performed by using primers NLO and NRO in the first step and PCTM3 and SERO2A in the second step, as described previously.⁵,⁶ The RFLP analysis of nested PCR products was carried out by using *AluI*, *HpaII-EcoRI-HinfI*, *CfoI*, *DdeI*, and *FokI*, as described previously.⁵,⁶

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## Statistical analysis

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Univariate comparisons were based on the Pearson's chi-squared statistic or two-tailed Fisher's exact tests for categorical variables, and on Student's t tests or analysis of variance for continuous variables. Analyses were performed with Stat software (Stata 7.0; Stata, College Station, USA). A p value of 0.05 was considered statistically significant.

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# RESULTS

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## C. trachomatis prevalence and characteristics of the infected population

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Positive results in the NAAT were obtained for 102 of the 971 samples (10.5%).

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The prevalence of *C. trachomatis* was 16.9% in men (15/83) and 9.8% (87/888) in women. The mean age of infected men and women was 29.4±6.9 years (range 20-44) and 24.4±7.2 years (range 13-44), respectively. Clinical symptoms were present in 89.3% (75/84) of infected women and in 92.9% (13/14) of infected men. The prevalence in women of co-infection with HIV, *Neisseria gonorrhoeae*, *Trichomonas vaginalis* and *Candida albicans* was 5.9% (5/84), 2.3% (2/87), 3.4% (3/87), 19.5% (17/87), and 5.7% (5/87), respectively. Bacterial vaginosis was seen in 58.6% (51/87) of the *C. trachomatis*-infected women. Infected men were co-infected with only one other agent, *N. gonorrhoeae*, in 3 of 14 (21.4%) patients.

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## Distribution of the C. trachomatis genotypes

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The *omp1* gene was successfully amplified in 67/99 (67.7%) non-urine positive samples. The distribution of the genotypes is shown in Table 1. The genotypes E (34.3%), F (23.9%), Da (13.4%), I (9%), and Ia (7.5%) were the most common. The genotypes were evenly distributed over the study period (data not shown). Due to the small number of non-E and non-F genotypes, the genotypes were grouped together into
191 the B, intermediate, and C genogroups for further analysis. ¹

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193 **Association of genogroups with demographic characteristics and clinical signs**

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195 Table 2 shows the association between demographic characteristics, clinical
196 signs, laboratory data and genogroup. No relationships were found between genogroup
197 and age, sex, clinical symptoms or other associated genital infections other than *N. gonorrhoeae* and the C genogroup (p =0.005). These co-infections (two caused by Ia
genotype strains and two by I genotype strains) occurred between July and September.
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200

201 **Relationships between chlamydial infection and serological data**

202

203 We evaluated the potential usefulness of serological testing, by analysing a
204 subpopulation of 333 patients with an available serological test result with the
205 commercially available peptide-based ELISA, SERO-CT IgG/IgA. A comparison of the
206 serological results with the results of the NAAT is shown in Table 3. The IgG and IgA
207 seroprevalence rates and the mean IgG and IgA ratios in the CT+ group were
208 significantly higher than those in the CT- group.
209

209 The sensitivity of SERO-CT for antibody detection (using the NAAT as the
210 reference) was 81.1% for IgG and 55.4% for IgA. The specificity of detection was 56%
211 for IgG and 76.8% for IgA. The specificity was higher (81.5%) for tests for the
212 simultaneous presence of IgG and IgA. Positive predictive values (PPV) were 34.5% for
213 IgG and 59.4% for IgA and negative predictive values (NPV) were 91.2% for IgG and
214 85.8% for IgA. IgG antibodies were found in 55.6% (35/63) of patients suffering from
215 lower abdominal pain. They were found in 81.2% (13/16) in such patients in the CT+
216 group and 46.8% (22/47) of such patients in the CT- group; whereas the occurrence of
217 abdominal pain was similar in the two groups: 22.2% (16/72) and 19.1% (47/246),
218 respectively.

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220 Relationships between genogroup and serological results

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222 Serological results were available for 46 of the 67 patients whose strains were
223 genotyped. Table 4 shows IgA and IgA seroprevalence rates as a function of genogroup.
224 Statistically significant higher IgG seroprevalence rates were found in patients infected
225 with genotypes of the intermediate (100%) and B (92.3%) genogroups than in those
226 infected with genotypes of the C genogroup (40%). Five of the 10 C genogroup strains
227 were of genotype I and the other five were of genotype Ia. IgG was detected in 60%
228 (3/5) of patients infected with strains of genotype I but in only 20% (1/5) of patients
229 infected with strains of genotype Ia.

230
231 DISCUSSION

232

233 We found the prevalence of *C. trachomatis* urogenital infection to be 10.7%
234 (10% in women and 18.1% in men) in our study population. This prevalence was lower
235 than those observed in symptomatic patients from the Caribbean region but did not differ
236 significantly from that of mainland France.

237 The failure rate (33%) for determination of genotypes by nested *omp1* PCR on
238 clinical samples in this study was higher than generally reported (< 20%). ¹⁰, ²⁰, ²¹ There
239 may be several reasons for this. It is more difficult to amplify the 1.2 kb *omp1* gene,
240 which is present as a single copy in the bacterium, than the smaller rRNAs present in
241 many thousands of copies. High failure rates are therefore likely for samples with small
242 numbers of micro-organisms or samples containing small number of infected cells. This
243 may account for the higher failure rate in men (50%) than in women (30.2%), due to
244 milder urethral scraping in men. Other hypothesis are the lack of a DNA extraction
245 procedure before PCR (Vanduynhoven et al. reported a nested PCR failure rate of
246 22.9%, which decreased to 4.9% following the use of DNA extraction methods) and the
247 quality of the DNA matrix stored in the Gen-Probe transport medium, which was
248 developed for the stabilisation of RNA molecules. ¹

249 This study is the first to describe the *C. trachomatis* genotypes circulating in
250 Guadeloupe and in the Caribbean region. The two most prevalent genotypes in
251 Guadeloupe, E and F, have also been reported to be the most prevalent around the
252 world.⁹, ¹¹, ²⁰, ²² However, the distribution of some other genotypes differed considerably
253 from that in mainland France: in particular, genotypes Da (13.4% vs 4.5%), F (23.8% vs
254 I (9% vs 3.5%) and Ia (7.4% vs 0.3%) were more prevalent, whereas genotypes
D (5.9% vs 11.2%), G (3% vs 11.8%), H (0% vs 5.1%), and K (0% vs 5.1%) were less prevalent.²³ Genotype Da infections have rarely been described since the first description of this serovar in 1991.²⁴ No Da genotypes were found among the 507 *omp1* sequences obtained for samples from a large US nationwide study conducted between 1995 and 1997.⁹ A genotyping study by PCR-RFLP (*CfoI*) in 2001 in Cameroon found a prevalence of the Da genotype of 8.6% (3/35), whereas in Senegal in 1996-1997, *omp1* sequencing revealed a prevalence of D/Da genotypes of 19% (4/21).⁶,¹¹ The D/Da strains belong to two distinct phylogenetic lineages.⁸ The Da strains from each lineage have a specific single nucleotide polymorphism (SNP) within *omp1* resulting in the loss of a *CfoI* restriction site and in amino acid substitution alanine to threonine at position 311/312 modifying the epitope recognised by the monoclonal antibodies used for the serotyping of group D strains.⁷,⁸ BLAST analysis can group *omp1* sequences into the appropriate lineage, but it is necessary to identify the SNP encoding the Ala311/312Thr substitution precisely for Da assignment. This may explain why it is more difficult to detect Da variants by *omp1* sequencing than by serotyping or PCR-RFLP, leading to possible underestimation. The PCR-RFLP profiles obtained with the Da and D strains from Guadeloupe were similar to those predicted from the *omp1* sequences of Da/TW-448 (first lineage), and D1 or D2 group (second lineage) strains, respectively.

The serovar variant Ia was described in 1991, following a study of 41 genital isolates isolated worldwide, in which Ia isolates were much more frequent than I isolates (41 vs 9).²⁴ In the United States, a high prevalence (14%) of genotype Ia was found during the 1995-1997 study.⁹ Other studies in the US found that infection with serovar Ia was significantly associated with being black.²⁵,²⁶ In a study carried out in 1994 in the Netherlands, male patients from Suriname were significantly more frequently
279 infected with genotype Ia strains than were men from the Netherlands, and women from 280 Suriname were more frequently infected with genogroup C strains than were women 281 from the Netherlands. ¹ In Africa, one study conducted in Senegal, found a genotype Ia 282 prevalence of 4.8% (1/21). ¹¹ In Asia, one studied reported a prevalence of genotype Ia 283 infection of 6.6% in pregnant women in Thailand, whereas another study reported a 284 significant increase in the prevalence of genotype I strains (Ia not differentiated from I) 285 in Japan between the mid 1990s (1/41, 2.1%) and 2003-2005 (10/81, 12.3%). ⁹, ²⁷ In 286 Guadeloupe, a large proportion of the population is Black and of African descent (about 287 80 %) and about 15% of the population is “Indian” and of Asian descent. That may 288 explain why genotypes I (9%) and Ia (7.5%) were well represented.

289 Serological results and direct evidence of infection have not been found to 290 correlate in many reports, even with an ELISA using specific *C. trachomatis* MOMP 291 peptides. ²⁸, ²⁹ This has been partially attributed to the antibody kinetics (i.e., the lag 292 period between being infected and the antibody response and the persistence of 293 antibodies after a resolved infection). Rabenau *et al*. reported a lower specificity (37.3%) 294 and a much lower PPV (< 20%) for IgG detection with SERO-CT than for detection 295 with NAAT. ²⁹ However, a high NPV (96.4%) was found to be useful for identifying 296 patients at high risk in whom *C. trachomatis* infection is unlikely to play a role. SERO- 297 CT was reported to outperform PCR for IgG detection in another study (specificity of 298 69% and PPV of 50%). ²⁸ We also found that this assay performed well for IgG and IgA 299 detection in comparison with AMP CT. Our results, however, could be affected by 300 patient selection bias as the analyses were done on a subpopulation selected based on the 301 basis on available serology. The requests for serology might indicate a higher risk of *C. trachomatis* infection, in particular upper genital tract infection or recurrent infections. 302
Indeed, the prevalence of this infection was found to be 21.5% (65/333) in the subpopulation vs 10.7% within the whole population. For optimal serological results, the selection or preparation of the microbial antigen is important. In a follow-up study, the SERO-CT gave false-negative results and the authors suggested that this test might not be suitable for all serovars.³⁰ We show here that SERO-CT detected no antibody response in 6/10 patients infected with strains of the C genogroup, particularly genotype Ia strains. However, further studies involving more cases are necessary to confirm this finding. The exact composition of the SERO-CT antigen mixture has not been made publicly available, but it seems likely than no Ia-derived peptide was included. Therefore, in seroepidemiological studies using such high-specificity ELISA-based assays, it is essential to establish, before beginning the study, that the ELISAs used are capable of detecting an antibody response in patients infected with the various circulating genotypes.

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## AUTHOR CONTRIBUTIONS

318

F-X.W. and B.D.B. designed the study; F-X.W. and S.L.H performed sampling and microbiological analysis; M.C. performed genotyping; C.S. performed statistical analysis; F-X.W. and B.D.B. analysed data; F-X.W., S.L.H, and B.D.B. wrote the manuscript.

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## WORD COUNT

325

Abstract (254), text (2567), number of figures (0) and tables (4)
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29. Rabenau HF, Kohler E, Peters M, et al. Low correlation of serology with detection of *Chlamydia trachomatis* by ligase chain reaction and antigen EIA. Infection 2000; 28:97-102.

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413

30. Clad A, Feidank HM, Kunze M, et al. Detection of seroconversion and persistence of *Chlamydia trachomatis* antibodies in five different serological tests. Eur J Clin Microbiol Infect Dis 2000; 19:932-937.

414

415

416

417

418
<table><thead><tr><th rowspan="2">Serovar</th><th rowspan="2"></th><th>Male</th><th>Female</th><th>Total</th></tr><tr><th>n</th><th>n (%)</th><th>n (%)</th></tr></thead><tbody><tr><td rowspan="4">B genogroup</td><td>D</td><td>0</td><td>4 (6.7)</td><td>4 (6)</td></tr><tr><td>Da</td><td>1</td><td>8 (13.4)</td><td>9 (13.4)</td></tr><tr><td>E</td><td>3</td><td>20 (33.3)</td><td>23 (34.3)</td></tr><tr><td>Subtotal</td><td>4</td><td>32 (53.4)</td><td>36 (53.7)</td></tr><tr><td rowspan="3">Intermediate genogroup</td><td>F</td><td>1</td><td>15 (25)</td><td>16 (23.9)</td></tr><tr><td>G</td><td>0</td><td>2 (3.3)</td><td>2 (3)</td></tr><tr><td>Subtotal</td><td>1</td><td>17 (28.3)</td><td>18 (26.9)</td></tr><tr><td rowspan="6">C genogroup</td><td>H</td><td>0</td><td>0</td><td>0</td></tr><tr><td>I</td><td>2</td><td>4 (6.7)</td><td>6 (9)</td></tr><tr><td>Ia</td><td>0</td><td>5 (8.3)</td><td>5 (7.5)</td></tr><tr><td>J</td><td>0</td><td>2 (3.3)</td><td>2 (3)</td></tr><tr><td>K</td><td>0</td><td>0</td><td>0</td></tr><tr><td>Subtotal</td><td>2</td><td>11 (18.3)</td><td>13 (19.4)</td></tr><tr><td colspan="2">Total</td><td>7</td><td>60 (100)</td><td>67 (100)</td></tr></tbody></table>

420

421

<caption>Table 1: Distribution of *C. trachomatis* genotypes in women and men, as determined by *omp1* nested PCR-based RFLP genotyping</caption>

422

423
<table><thead><tr><th></th><th></th><th>B genogroup</th><th>Intermediate<br>genogroup</th><th>C genogroup</th><th>P</th></tr><tr><th></th><th></th><th>(n=36)</th><th>(n=18)</th><th>(n=13)</th><th></th></tr><tr><th></th><th></th><th>n (%)</th><th>n</th><th>n</th><th></th></tr></thead><tbody><tr><td rowspan="2">Sex</td><td>Male</td><td>4 (11.1)</td><td>1</td><td>2</td><td rowspan="2">0.6**</td></tr><tr><td>Female</td><td>32 (88.9)</td><td>17</td><td>11</td></tr><tr><td rowspan="5">Age</td><td>&lt;=20</td><td>10 (27.8)</td><td>10</td><td>4</td><td rowspan="5">0.12**</td></tr><tr><td>[20-25]</td><td>13 (36.1)</td><td>3</td><td>6</td></tr><tr><td>[25-30]</td><td>5 (13.9)</td><td>4</td><td>3</td></tr><tr><td>&gt;30</td><td>8 (22.2)</td><td>1</td><td>0</td></tr><tr><td>Mean/Std.dev</td><td>25.1 ± 7.6</td><td>22.8 ± 6.3</td><td>22.1 ± 4.1</td></tr><tr><td rowspan="2">Clinical symptoms</td><td>Min-Max</td><td>15-44</td><td>16-42</td><td>13-30</td><td rowspan="2">0.28***</td></tr><tr><td>Absent</td><td>1 (2.9)</td><td>1</td><td>1</td></tr><tr><td></td><td>Present</td><td>33 (97.1)</td><td>17</td><td>12</td><td rowspan="2">0.76**</td></tr><tr><td rowspan="2">Pruritis</td><td>Absent</td><td>21 (63.6)</td><td>10</td><td>4</td><td rowspan="2">0.19*</td></tr><tr><td>Present</td><td>12 (36.4)</td><td>7</td><td>8</td></tr><tr><td rowspan="2">Pelvic pain</td><td>Absent</td><td>23 (69.7)</td><td>10</td><td>8</td><td rowspan="2">0.72**</td></tr><tr><td>Present</td><td>10 (30.3)</td><td>7</td><td>4</td></tr><tr><td rowspan="2">Discharge</td><td>Absent</td><td>6 (18.2)</td><td>2</td><td>2</td><td rowspan="2">0.9**</td></tr><tr><td>Present</td><td>27 (81.8)</td><td>15</td><td>10</td></tr><tr><td rowspan="2">Urethritis</td><td>Absent</td><td>30 (90.9)</td><td>16</td><td>10</td><td rowspan="2">0.72**</td></tr><tr><td>Present</td><td>3 (9.1)</td><td>1</td><td>2</td></tr><tr><td rowspan="2">Genital infections</td><td rowspan="2">N. gonorrhoeae</td><td>Absent</td><td>35 (97.2)</td><td>18</td><td>9</td><td rowspan="2">0.005**</td></tr><tr><td>Present</td><td>1 (2.8)</td><td>0</td><td>4</td></tr><tr><td rowspan="2">Vaginosis</td><td>Absent</td><td>18 (50.0)</td><td>10</td><td>5</td><td rowspan="2">0.64*</td></tr><tr><td>Present</td><td>18 (50.0)</td><td>8</td><td>8</td></tr><tr><td rowspan="2">T. vaginalis</td><td>Absent</td><td>34 (94.4)</td><td>18</td><td>12</td><td rowspan="2">0.58**</td></tr><tr><td>Present</td><td>2 (5.6)</td><td>0</td><td>1</td></tr><tr><td rowspan="2">Candida sp.</td><td>Absent</td><td>34 (94.4)</td><td>17</td><td>12</td><td rowspan="2">1**</td></tr><tr><td>Present</td><td>2 (5.6)</td><td>1</td><td>1</td></tr><tr><td rowspan="2">HIV</td><td>Absent</td><td>30 (88.2)</td><td>18</td><td>13</td><td rowspan="2">0.23**</td></tr><tr><td>Present</td><td>4 (11.8)</td><td>0</td><td>0</td></tr></tbody></table>

425 *Chi-squared test, ** Fisher's exact test, *** Analysis of variance test

<caption>426 Table 2: Clinical and laboratory data as a function of C. trachomatis genogroup</caption>
N (%) of

<table><thead><tr><th rowspan="2">Serological data</th><th colspan="3">Men</th><th colspan="3">Women</th></tr><tr><th>CT+<br>(n=9)</th><th>CT-<br>(n=21)</th><th>p</th><th>CT+<br>(n=65)</th><th>CT-<br>(n=238)</th><th>p</th></tr></thead><tbody><tr><td>IgA-negative</td><td>4</td><td>17</td><td>0.05*</td><td>29 (44.6)</td><td>182 (76.5)</td><td>&lt;0.0001*</td></tr><tr><td>IgA-positive</td><td>5</td><td>4</td><td></td><td>36 (55.4)</td><td>56 (23.5)</td><td></td></tr><tr><td>Mean IgA ratio</td><td>2.1±1.6</td><td>0.8±0.43</td><td>0.002***</td><td>1.6±1.4</td><td>1.0±1.1</td><td>0.0002***</td></tr><tr><td>Min-Max</td><td>0.5-5.32</td><td>0.39-2.13</td><td></td><td>0.27-8.02</td><td>0.14-12.34</td><td></td></tr><tr><td>IgG-negative</td><td>1</td><td>14</td><td>0.005*</td><td>13 (20.0)</td><td>131 (55.0)</td><td>&lt;0.0001*</td></tr><tr><td>IgG-positive</td><td>8</td><td>7</td><td></td><td>52 (80.0)</td><td>107 (45.0)</td><td></td></tr><tr><td>Mean IgG ratio</td><td>3.0±2.1</td><td>1.3±1.5</td><td>0.02***</td><td>4.5±3.1</td><td>2.0±2.2</td><td>&lt;0.0001***</td></tr><tr><td>Min-Max</td><td>0.7-7.56</td><td>0.38-5.48</td><td></td><td>0.41-11.6</td><td>0.22-11</td><td></td></tr><tr><td>IgA+/IgG+</td><td>5</td><td>3</td><td>0.02**</td><td>35 (53.8)</td><td>45 (18.9)</td><td>&lt;0.0001**</td></tr><tr><td>IgA-/IgG+</td><td>3</td><td>4</td><td></td><td>17 (26.2)</td><td>62 (26.0)</td><td></td></tr><tr><td>IgA-/IgG-</td><td>1</td><td>13</td><td></td><td>12 (18.5)</td><td>120 (50.4)</td><td></td></tr><tr><td>IgA+/IgG-</td><td>0</td><td>1</td><td></td><td>1 (1.5)</td><td>11 (26.1)</td><td></td></tr></tbody></table>

428 * Chi-squared test, ** Fisher's exact test, *** Student's t test

430 Table 3: Serological data in men and women as a function of positive and negative

431 results for C. trachomatis detection in the Gen-Probe AMP CT assay
<table><thead><tr><th rowspan="3">Serological data</th><th>B genogroup</th><th>Intermediate genogroup</th><th>C genogroup</th><th rowspan="3">P</th></tr><tr><th>(n=26)</th><th>(n=10)</th><th>(n=10)</th></tr><tr><th>n</th><th>n</th><th>n</th></tr></thead><tbody><tr><td>IgA-negative</td><td>10</td><td>3</td><td>7</td><td>0.15*</td></tr><tr><td>IgA-positive</td><td>16</td><td>7</td><td>3</td><td></td></tr><tr><td>Mean IgA ratio</td><td>1.44±0.93</td><td>1.6±0.74</td><td>1.87±2.47</td><td>0.70**</td></tr><tr><td>Min-Max</td><td>0.27-3.45</td><td>0.72-3.07</td><td>0.34-8.02</td><td></td></tr><tr><td>IgG-negative</td><td>2</td><td>0</td><td>6</td><td>0.001*</td></tr><tr><td>IgG-positive</td><td>24</td><td>10</td><td>4</td><td></td></tr><tr><td>Mean IgG ratio</td><td>5.5±2.9</td><td>6.5±3.8</td><td>2.3±2.6</td><td>0.008**</td></tr><tr><td>Min-Max</td><td>0.74-10.46</td><td>1.1-11.6</td><td>0.41-7.39</td><td></td></tr><tr><td>IgA+/IgG+</td><td>16</td><td>7</td><td>3</td><td>0.007*</td></tr><tr><td>IgA-/IgG+</td><td>8</td><td>3</td><td>1</td><td></td></tr><tr><td>IgA-/IgG-</td><td>2</td><td>0</td><td>6</td><td></td></tr></tbody></table>

434 * Fisher's exact test, ** Analysis of variance

435

<caption>436 Table 4: Serological data as a function of C. trachomatis genogroup</caption>

437