Septicaemia models using Streptococcus pneumoniae and Listeria monocytogenes: understanding the role of complement properdin

Streptococcus pneumoniae and Listeria monocytogenes, pathogens which can cause severe infectious disease in human, were used to infect properdin-deficient and wildtype mice. The aim was to deduce a role for properdin, positive regulator of the alternative pathway of complement activation, by comparing and contrasting the immune response of the two genotypes in vivo. We show that properdin-deficient and wildtype mice mounted antipneumococcal serotype-specific IgM antibodies, which were protective. Properdin-deficient mice, however, had increased survival in the model of streptococcal pneumonia and sepsis. Low activity of the classical pathway of complement and modulation of FcγR2b expression appear to be pathogenically involved. In listeriosis, however, properdin-deficient mice had reduced survival and a dendritic cell population that was impaired in maturation and activity. In vitro analyses of splenocytes and bone marrow-derived myeloid cells support the view that the opposing outcomes of properdin-deficient and wildtype mice in these two infection models is likely to be due to a skewing of macrophage activity to an M2 phenotype in the properdin-deficient mice. The phenotypes observed thus appear to reflect the extent to which M2- or M1-polarised macrophages are involved in the immune responses to S. pneumoniae and L. monocytogenes. We conclude that properdin controls the strength of immune responses by affecting humoral as well as cellular phenotypes during acute bacterial infection and ensuing inflammation

[Microbiological and clinical diagnosis of acute endophthalmitis]

International audienceThe microbiological study identifies the bacterial spectrum after surgery, in acute, delayed-onset, or chronic endophthalmitis. DNA amplification of eubacterium-specific sequences in DNA extracted from ocular samples is a new tool for the etiological diagnosis of endophthalmitis. The most successful way to identify bacteria in endophthalmitis is the association of conventional cultures and panbacterial PCR on vitreous samples. Both techniques are complementary. The efficacy of these new molecular techniques should modify our future therapeutic strategies

Treatment of typhoid fever using ofloxacin. Clinical experience and determination of antibiotic diffusion into the mesenteric lymph nodes

Nine patients with typhoid fever were given ofloxacin in a daily dosage of 400 mg for ten days. All patients recovered with no relapses. No case of Salmonella typhi carriage was recorded. Diffusion of ofloxacin into mesenteric lymph nodes was studied in four patients. Mean concentration was 1.46 micrograms/g after four 200 mg doses. According to our results, ofloxacin could be considered as one of the alternatives for treating typhoid fever