Prevalence of Chlamydia trachomatis: results from the first national population-based survey in France.

BACKGROUND: Few studies have estimated Chlamydia trachomatis (CT) prevalence in the general population, most prevalence studies being based on people already attending healthcare settings. OBJECTIVES: To estimate the prevalence of CT in France, assess the feasibility of home sampling without any face-to-face intervention and identify risk factors associated with CT infection using data from the Contexte de la Sexualité (CSF) survey on sexual behaviour; a national population-based survey, carried out by telephone in 2006. METHODS: A random subsample of sexually experienced people aged 18-44 (N=4957) were invited to participate in a CT home-sampling study (NatChla study). Participants' samples were tested for CT by PCR. Percentages were weighted for unequal selection probabilities and post-stratified based on French population census data. Independent risk factors were identified by logistic regression. RESULTS: CT prevalence in people aged 18-44 was estimated at 1.4% (95% CI 0.8% to 2.6%) for men, and 1.6% (95% CI 1.0% to 2.5%) for women. Increased rates were found in subjects aged 18-29: 2.5% (95% CI 1.2% to 5.0%) for men and 3.2% (95% CI 2.0% to 5.3%) for women. CT infection was associated, for both genders, with having their last sexual intercourse with a casual partner. Other risk factors were for men, having last intercourse with a new partner, living in the Paris area, and for women, multiple partners during the previous year, same sex partners and a low level of education. CONCLUSIONS: CT prevalence in France is similar to that in other developed countries. Home sampling proved feasible and useful to reach members of the population with limited access to traditional care.

French situation concerning the Swedish Chlamydia trachomatis variant.

In 2006, a plasmid deletion mutant of Chlamydia trachomatis was identified in Sweden that can not be detected with those commercial tests targeting the deleted area. In order to study the spread of this strain in France, a laboratory-based surveillance system was set up by the National Reference Centre for Chlamydiae and the Institut de Veille Sanitaire. Among 1,141 C. trachomatis-positive specimens from all over France, the new variant was only detected in one case. This case was a non-French resident consulting a sexually transmitted infections clinic. Although the new variant does not seem to be established in France as yet, surveillance based on the testing of C. trachomatis-positive samples from all over France continues.

Quality assessment of conjunctival specimens for detection of Chlamydia trachomatis by PCR in children with active trachoma.

One component of control programmes to eliminate trachoma is the treatment of Chlamydia trachomatis infection. A diagnosis of trachoma is based on clinical grounds, but the signs of active trachoma do not always correlate with the presence of C. trachomatis. During a therapeutic trial, the level of C. trachomatis infection in children with active trachoma in Guinea and Pakistan was assessed using a qualitative commercially available PCR that targeted the C. trachomatis plasmid. The influence of the quality of specimens on the efficiency of the PCR was investigated using two quantitative real-time PCRs targeting the specific omp1 gene of C. trachomatis and human chromosomal DNA, respectively. C. trachomatis was detected in c. 23% of children (aged 1-10 years) who presented with clinically active trachoma. Controls showed that PCR-related problems did not influence this detection rate. For 14% of the positive samples, C. trachomatis was detected in only one eye, with a significantly lower mean load of bacteria. These results suggest that epidemiological and therapeutic surveys should be conducted by sampling and testing both eyes. Moreover, the high variability of the cell load observed in the conjunctival swabs suggests that the effectiveness of swabbing may be questionable.

Increased expression of two multidrug transporter-like genes is associated with ethidium bromide and ciprofloxacin resistance in Mycoplasma hominis.

Two genes, md1 and md2, coding for multidrug resistance ATP-binding cassette transporters were identified in Mycoplasma hominis PG21. Expression of these two genes, quantified by quantitative competitive reverse transcription-PCR, was significantly increased in ethidium bromide-resistant strains of M. hominis compared to that in M. hominis PG21.

Mutations in 23S rRNA account for intrinsic resistance to macrolides in Mycoplasma hominis and Mycoplasma fermentans and for acquired resistance to macrolides in M. hominis.

The mechanisms of intrinsic resistance of Mycoplasma hominis to 14- and 15-membered macrolides were investigated in comparison with those of M. pneumoniae, which is naturally susceptible to macrolides. Radiolabeled erythromycin was not accumulated by M. hominis PG21, but addition of an ABC transporter inhibitor increased the level of erythromycin uptake more than two times, suggesting the existence of an active efflux process. The affinity of [(14)C]erythromycin to ribosomes isolated from M. hominis was dramatically reduced relative to that to ribosomes isolated from M. pneumoniae. The nucleotide sequences of 23S rRNA of both ribosomal operons rrnA and rrnB and ribosomal proteins L4 and L22 of M. hominis were obtained. Compared to the sequence of M. pneumoniae, M. hominis harbored a G2057A transition in its 23S rRNA sequence, as did M. fermentans, another mycoplasma that is erythromycin resistant. An additional C2610U change was also found in the sequence of M. hominis. Moreover, two M. hominis clinical isolates with acquired resistance to 16-membered macrolides were examined for mutations in domain II and domain V of 23S rRNA and in ribosomal proteins L4 and L22. Compared to the sequence of reference strain PG21, one isolate harbored a A2059G transition and a C2611U transition in one of the two rrn operons, while the other one was mutated only at position 2059, also on the same operon. No mutation was found in the two ribosomal protein sequences. Overall, the present study is an exhaustive characterization of the intrinsic resistance of M. hominis to 14- and 15-membered macrolides and the first description of mycoplasma clinical isolates resistant to macrolide, lincosamide, and streptogramin antibiotics harboring a mutation at position 2611 in the 23S rRNA.

Evidence of active efflux in resistance to ciprofloxacin and to ethidium bromide by Mycoplasma hominis.

The uptake of fluoroquinolones was characterized for the fluoroquinolone-susceptible strain PG21 of Mycoplasma hominis. Accumulation of fluoroquinolones appeared to occur by passive diffusion. Addition of arginine as the energizer significantly reduced the uptake of fluoroquinolones, suggesting the presence of an energy-dependent efflux process. Reserpine and orthovanadate, two multidrug pump inhibitors, increased significantly the ciprofloxacin (CIP) uptake. In contrast, such a strong effect was not observed for moxifloxacin and pefloxacin uptakes. Two ethidium bromide (EtBr)-resistant strains, selected in vitro, showed a resistance profile compatible with a multidrug-resistant phenotype, with increased MICs for the hydrophilic fluoroquinolones, CIP and norfloxacin, EtBr, and acriflavine. Taking the EtBr-resistant strain RB1La as a model, a significant decrease of the CIP and EtBr uptakes was observed compared to the reference strain PG21. In the presence of reserpine and orthovanadate, both inhibitors of ATP-dependent efflux pumps, the CIP uptake increased significantly, reaching approximately the same level as that of the susceptible strain. Similar results were obtained with EtBr uptake and efflux experiments. Our data suggest the presence of an active efflux system, possibly an ABC-type efflux pump, implicated in the resistance to CIP and unrelated compounds like EtBr in the human mycoplasma M. hominis.