Evaluation of the microbiota-sparing properties of the anti-staphylococcal antibiotic afabicin.

BACKGROUND: Antibiotic use is associated with collateral damage to the healthy microbiota. Afabicin is a first-in-class prodrug inhibitor of the FabI enzyme that, when converted to the pharmacologically active agent afabicin desphosphono, demonstrates a staphylococcal-specific spectrum of activity. An expected benefit of highly targeted antibiotics such as afabicin is microbiome preservation. OBJECTIVES: To compare the effects of oral treatment with afabicin and standard-of-care antibiotics upon the murine gut microbiota, and to assess the effects of oral afabicin treatment on the human gut microbiota. METHODS: Gut microbiota effects of a 10 day oral course of afabicin treatment were monitored in mice and compared with clindamycin, linezolid and moxifloxacin at human-equivalent dose levels using 16S rDNA sequencing. Further, the gut microbiota of healthy volunteers was longitudinally assessed across 20 days of oral treatment with afabicin 240 mg twice daily. RESULTS: Afabicin treatment did not significantly alter gut microbiota diversity (Shannon H index) or richness (rarefied Chao1) in mice. Only limited changes to taxonomic abundances were observed in afabicin-treated animals. In contrast, clindamycin, linezolid and moxifloxacin each caused extensive dysbiosis in the murine model. In humans, afabicin treatment was not associated with alterations in Shannon H or rarefied Chao1 indices, nor relative taxonomic abundances, supporting the findings from the animal model. CONCLUSIONS: Oral treatment with afabicin is associated with preservation of the gut microbiota in mice and healthy subjects.

Psychological and behavioral interventions to reduce HIV risk: evidence from a randomized control trial among orphaned and vulnerable adolescents in South Africa.

Evidence-based approaches are needed to address the high levels of sexual risk behavior and associated HIV infection among orphaned and vulnerable adolescents. This study recruited adolescents from a support program for HIV-affected families and randomly assigned them by cluster to receive one of the following: (1) a structured group-based behavioral health intervention; (2) interpersonal psychotherapy group sessions; (3) both interventions; or (4) no new interventions. With 95% retention, 1014 adolescents were interviewed three times over a 22-month period. Intent-to-treat analyses, applying multivariate difference-in-difference probit regressions, were performed separately for boys and girls to assess intervention impacts on sexual risk behaviors. Exposure to a single intervention did not impact behaviors. Exposure to both interventions was associated with risk-reduction behaviors, but the outcomes varied by gender: boys reported fewer risky sexual partnerships (ß = -.48, p = .05) and girls reported more consistent condom (ß = 1.37, p = .02). There was no difference in the likelihood of sexual debut for either gender. Providing both psychological and behavioral interventions resulted in long-term changes in sexual behavior that were not present when either intervention was provided in isolation. Multifaceted approaches for reducing sexual risk behaviors among vulnerable adolescents hold significant promise for mitigating the HIV epidemic among this priority population.

Beneficial effects of probiotics in upper respiratory tract infections and their mechanical actions to antagonize pathogens.

Probiotics are live micro-organisms with beneficial effects on human health, which have the ability to counteract infections at different locations of the body. Clinical trials have shown that probiotics can be used as preventive and therapeutic agents in upper respiratory tract infections (URTIs) and otitis. Their mechanical properties allow them to aggregate and to compete with pathogens for nutrients, space and attachment to host cells. Consequently, they can directly antagonize pathogens and thus exert beneficial effects without directly affecting the metabolism of the host. An overview of the probiotics with such traits, tested up to date in clinical trials for the prevention or treatment of URTIs and otitis, is presented in this review. Their mechanical properties in the respiratory tract as well as at other locations are also cited. Species with interesting in vitro properties towards pharyngeal cells or against common respiratory pathogens have also been included. The potential safety risks of the cited species are then discussed. This review could be of help in the screening of probiotic strains with specific mechanical properties susceptible to have positive effects in clinical trials against URTIs.

Use of genotypic selection to detect P53 codon 273 CGT>CTT transversion: application to an occupationally exposed population.

CGT>CTT transversion in codon 273 of the P53 tumor-suppressor gene is one of the major mutations detected in human tumors. Within an epidemiological framework, we investigated the use of a genotypic selection method to measure this point mutation. The allele-specific polymerase chain reaction (AS-PCR) that was developed was able to detect 10 mutant copies of the gene among a total of 5 x 10(5) wild-type copies. We used this assay to detect CGT>CTT transversions in buccal cell DNA of production workers (n=76) from a viscose factory exposed to carbon disulfide (amongst other pollutants) and in the DNA of non-exposed office workers (n=67). The mutation appeared more frequently in the exposed than in the non-exposed worker who were smokers. The results of the study indicate that occupational exposure results in a significant increase in P53 CGT>CTT transversions and more especially identified occupational exposure in combination with smoking as a significant risk factor for the mutation. We conclude that AS-PCR of the P53 273rd codon transversions is a suitable technique for studying the effects of occupational exposure.