Clinical symptoms of impetigo and staphylococcal scalded skin syndrome may not only be expressed as the splitting of cell layers within the epidermis but are often accompanied by some localized inflammation. Toxin patterns of Staphylococcus aureus isolates originating from patients with impetigo and also from those with other primary and secondary skin infections in a retrospective isolate collection in France and a prospective isolate collection in French Guiana revealed a significant association (75% of the cases studied) of impetigo with production of at least one of the epidermolysins A and B and the bicomponent leucotoxin LukE-LukD (P < 0.001). However, most of the isolates were able to produce one of the nonubiquitous enterotoxins. Pulsed-field gel electrophoresis (PFGE) of genomic DNA hydrolyzed with SmaI showed a polymorphism of the two groups of isolates despite the fact that endemic clones were suspected in French Guiana and France. The combination of toxin patterns with PFGE fingerprinting may provide further discrimination among isolates defined in a given cluster or a given pulsotype and account for a specific virulence. The new association of toxins with a clinical syndrome may reveal principles of the pathological process.

In this study, we investigated the responses of cells acclimated to 300 µmol m s photon flux density to an increase (1000 µmol m s) or decrease (30 µmol m s) in photon flux densities. The light shift occurred abruptly after 5 days of growth and the acclimation to new conditions was followed during the next 6 days at the physiological and molecular levels. The molecular data reflect a rearrangement of carbon metabolism towards the production of phosphoenolpyruvic acid (PEP) and/or pyruvate. These intermediates were used differently by the cell as a function of the photon flux density: under low light, photosynthesis was depressed while respiration was increased. Under high light, lipids and proteins accumulated. Of great interest, under high light, the genes coding for the synthesis of aromatic amino acids and phenolic compounds were upregulated suggesting that the shikimate pathway was activated.This article is part of the themed issue 'The peculiar carbon metabolism in diatoms'.

Drug resistance in fecal bacteria was high in Wayampis Amerindians who did not take antibacterial agents and were not hospitalized for 1 year. In the Wayampis Amerindians, an isolated traditional community in French Guyana, antibacterial use was 0.64 treatments per person per year. Hospitalization rate was 6.1% per year. Antibacterial drug–resistant bacteria can spread in persons who are not taking antibacterial agents.

Nitrogen (N) and phosphorus (P) limitations induce triacylglycerol (TAG) accumulation and membrane lipid remodelling in the marine diatom Phaeodactylum tricornutum. However, a clear understanding of the metabolic reorientation is still lacking. Carbon partitioning is of great interest because this microalga produces various highly valuable molecules such as lipids and polyunsaturated fatty acids. This study compared growth, photosynthetic activity, biochemical and transcriptional responses of P. tricornutum throughout batch culture under N or P limitation. The integrated results show that the photosynthetic intensity was greatly reduced under N or P limitation. Under N limitation, the degradation and re-use of cellular N-containing compounds contributed to TAG accumulation, whilst P limitation favoured TAG accumulation due to the efficiency of carbon fixation, without massive degradation of essential compounds at cellular level. There was no difference in the partitioning of carbon to neutral lipids between N and P limitation. Substitution of phospholipids with betaine lipids appeared to be a P-specific acclimation strategy in P. tricornutum, which was largely regulated at the gene expression level. Betaine lipid synthesis was induced by P limitation. The lipid remodelling began once the medium became deficient in P. While the phospholipid biosynthesis pathway was not completely inhibited, a shift of lipid classes occurred immediately after their synthesis via phospholipid-recycling mechanisms.