Genetic adaptation by Pseudomonas aeruginosa to the airways of cystic fibrosis patients.

In many human infections, hosts and pathogens coexist for years or decades. Important examples include HIV, herpes viruses, tuberculosis, leprosy, and malaria. With the exception of intensively studied viral infections such as HIV/AIDs, little is known about the extent to which the clonal expansion that occurs during long-term infection by pathogens involves important genetic adaptations. We report here a detailed, whole-genome analysis of one such infection, that of a cystic fibrosis (CF) patient by the opportunistic bacterial pathogen Pseudomonas aeruginosa. The bacteria underwent numerous genetic adaptations during 8 years of infection, as evidenced by a positive-selection signal across the genome and an overwhelming signal in specific genes, several of which are mutated during the course of most CF infections. Of particular interest is our finding that virulence factors that are required for the initiation of acute infections are often selected against during chronic infections. It is apparent that the genotypes of the P. aeruginosa strains present in advanced CF infections differ systematically from those of "wild-type" P. aeruginosa and that these differences may offer new opportunities for treatment of this chronic disease.

[Nature and sensitivity of bacteria superinfecting plantar ulcers caused by leprosy at the Marchoux Institute, Bamako, Mali]. / Nature et sensibilité des bactéries surinfectant les maux perforants plantaires d'origine lépreuse à l'Institut Marchoux, Bamako, Mali.

To determine potential usefulness of antimicrobial agents and to guide their prescription in the treatment of leprosy plantar ulcers, we conducted an in vitro study about germs' nature and sensitivity to antibiotics. We took samples of plantar ulcers secretion from 107 patients at Marchoux Institute. 92.5% of those ulcers were infected. These samples revealed 145 strains of micro-organisms among those, Staphylococcus aureus (70 strains) and genus Pseudomonas (41 strains) were the most frequent. These bacteria were resistant to several antibiotics currently used at Marchoux Institute (tetracycline, penicillin, cotrimoxazol and erythromicin). Antibiotics, efficient at 80% on tested strains, were expensive for patients. They cannot be recommended for the treatment of local infections. These results outline that the main treatment in plantar ulcers is based upon antiseptic solutions and keeping feet at rest. Antibiotherapy in case of extension of local infection would be based on the results of a previous study of sensitivity.