Objectives: To test the effect of supplementing peer promotion of male condom use with clinic based counselling, measured in terms of STI prevalence and reported male condom use. Methods: 1000 female sex workers in Madagascar were randomised to two study arms: peer education supplemented by individual risk reduction counselling by a clinician (peer + clinic) versus condom promotion by peer educators only (peer only). STI testing was conducted at baseline and 6 months. Behavioural interviews were administered at baseline, 2, 4, and 6 months. Results: At baseline, women in the peer only arm had prevalences of 16.0%, 23.6%, and 12.1% for chlamydia, gonorrhoea, and trichomoniasis respectively, with an aggregate prevalence of 38.2%. Baseline STI prevalences for the peer + clinic arm were slightly lower and 34.1% in aggregate. At 6 months, aggregate STI prevalence increased in the peer only arm to 41.4%, whereas the aggregate prevalence diminished slightly to 32.1% in the peer + clinic arm. In logistic regression analyses, the estimated odds ratios (ORs) for chlamydia, gonorrhoea, trichomoniasis, and aggregate STI were 0.7 (95% confidence interval 0.4 to 1.0), 0.7 (0.5 to 1.0), 0.8 (0.6 to 1.2), and 0.7 (0.5 to 0.9) respectively, comparing the peer + clinic arm with the peer only arm. The logistic regression OR for reported condom use with clients in the past 30 days increased from 1.1 at 2 months to 1.8 at 6 months, comparing the peer + clinic arm with the peer only arm, and was 1.4 overall (1.1 to 1.8). Adjustment for baseline factors changed the regression results little. Conclusions: The impact of male condom promotion on behaviour can be heightened through more concentrated counselling on risk reduction. Persistently high STI prevalence despite increases in reported condom use by sex workers supports the need for multidimensional control programmes.

Recently, extracts of Dalbergia trichocarpa bark have been shown to disrupt P. aeruginosa PAO1 quorum sensing (QS) mechanisms, which are key regulators of virulence factor expression and implicated in biofilm formation. One of the active compounds has been isolated and identified as oleanolic aldehyde coumarate (OALC), a novel bioactive compound that inhibits the formation of P. aeruginosa PAO1 biofilm and its maintenance as well as the expression of the las and rhl QS systems. Consequently, the production of QS-controlled virulence factors including, rhamnolipids, pyocyanin, elastase and extracellular polysaccharides as well as twitching and swarming motilities is reduced. Native acylhomoserine lactones (AHLs) production is inhibited by OALC but exogenous supply of AHLs does not restore the production of virulence factors by OALC-treated cultures, indicating that OALC exerts its effect beyond AHLs synthesis in the QS pathways. Further experiments provided a significant inhibition of the global virulence factor activator gacA by OALC. OALC disorganizes established biofilm structure and improves the bactericidal activity of tobramycin against biofilm-encapsulated PAO1 cells. Finally, a significant reduction of Caenorhabditis elegans paralysis was recorded when the worms were infected with OALC-pre-treated P. aeruginosa. Taken together, these results show that triterpenoid coumarate esters are suitable chemical backbones to target P. aeruginosa virulence mechanisms.

Various species of the plant genus Dalbergia are traditionally used as medicine for sundry ailments and some of them have been shown recently to quench the virulence of Gram-positive and Gram-negative bacteria. Cell-to-cell communication mechanisms, quorum sensing (QS) in particular, are key regulators of virulence in many pathogenic bacteria. Screening n-hexane extracts of leaves, roots and bark of endemic Malagasy Dalbergia species for their capacity to antagonize QS mechanisms in Pseudomonas aeruginosa PAO1 showed that many reduced the expression of the QS-regulated genes lasB and rhlA. However, only the extract of Dalbergia trichocarpa bark (DTB) showed a significant reduction of QS gene expression without any effect on the aceA gene encoding a QS-independent isocitrate lyase. Further characterization of DTB impact on QS revealed that the QS systems las and rhl are inhibited and that swarming, twitching, biofilm formation and the production of pyocyanin, elastase and proteases are also hampered in the presence of the DTB extract. Importantly, compared with the known QS inhibitor naringenin, the DTB extract showed a stronger negative effect on twitching, biofilm formation and tobramycin resistance. Preliminary structural characterization of these potent biofilm disrupters suggests that they belong to the phytosterols. The strong inhibition of motility and biofilm formation suggests that the DTB extract contains agents disrupting biofilm architecture, which is an important observation in the context of the design of new drugs targeting biofilm-encapsulated pathogens.

Molecular methods that characterize the Neisseria gonorrhoeae porin protein Por are needed to study gonococcal pathogenesis in the natural host and to classify strains from direct clinical samples used with nucleic acid amplification-based tests. We have defined the capabilities of por variable region (VR) typing and determined suitable conditions to apply the method to direct clinical specimens. Nested PCR from spiked urine samples detected 1 to 10 copies of template DNA; freezing spiked whole urine greatly reduced the ability to amplify porB. In a laboratory model of mixed gonococcal infections, the por type of one strain could be determined in the presence of a 100-fold excess of another. por VR typing was used to examine clinical samples from women enrolled in studies conducted in Baltimore, Md., and Madagascar. por type was determined from 100% of paired cervical swab and wick samples from 20 culture-positive women from Baltimore; results for eight individuals (40%) suggested infection with more than one strain. In frozen urine samples from Madagascar, porB was amplified and typed from 60 of 126 samples from ligase chain reaction (LCR)-positive women and 3 samples from LCR-negative women. The por VR types of 13 samples (21%) suggested the presence of more than one gonococcal strain. Five por types, identified in >45% of women with typed samples, were common to both geographic areas. Molecular typing is an important adjunct to nucleic acid amplificationbased diagnostics. Methods that utilize direct clinical samples and can identify mixed infections may contribute significantly to studies of host immunity, gonococcal epidemiology, and pathogenesis.

No abstract