Impact of galactomannan testing on the prevalence of invasive aspergillosis in patients with hematological malignancies.

Galactomannan (GM) is a polysaccharide component of the cell wall of Aspergillus spp. and is released into the host's circulation by growing hyphae. GM testing of patients with hematological malignancies has been rarely considered in recent epidemiologic studies of invasive mould infections (IMIs). The aim of the investigation was to analyze the impact of GM testing on the reported prevalence of IMI by comparing detection rates of IMI before and after the introduction of this diagnostic procedure. Prevalence of IMI was assessed by conducting a prospective single-centre study over seven months in 2010. Results obtained were then compared to those obtained with a representative collection of patients assessed by the same investigators at the same institution over seven months in 2007, i.e., prior to the introduction of GM testing. We found that, in general, detection rates of invasive aspergillosis (IA) and invasive mould infections increased significantly after the introduction of GM analysis. This study may therefore indicate that GM testing has a significant impact on the reported prevalence of IMI. Broad usage of such testing in patients with hematological malignancies may be able to produce a realistic picture of IMI rates when current diagnostic criteria are applied.

Rifaximin intake leads to emergence of rifampin-resistant staphylococci.

OBJECTIVES: Rifaximin is a poorly absorbed non-systemic antimicrobial agent used in various gastrointestinal disorders. Rifampin is pivotal for the treatment of staphylococcal foreign body infections and resistance develops rapidly during monotherapy. The close structural relation of rifaximin to rifampin may lead to cross-resistance. The aim of our study was to determine whether rifampin-resistance emerges in human skin staphylococci during or after oral intake of rifaximin. METHODS: Rifampin resistance of skin staphylococci in healthy volunteers during and after intake of rifaximin was determined by E-Test. RESULTS: Seven out of eleven volunteers developed rifampin-resistant staphylococci after intake of rifaximin. A total of eleven rifampin-resistant and three rifampin-intermediate staphylococcal isolates were found. Before or during intake no resistant isolate was detected. Shortly after discontinuation the rifampin-resistant strains were primarily isolated from the perianal skin, a few weeks later they were found more frequently on the skin of the hands and lower arms. CONCLUSION: Our data show that rifampin-resistant staphylococci emerge after intake of rifaximin. Since rifampin resistance is associated with treatment failure in staphylococcal foreign body infections, we conclude that rifaximin should be avoided in patients at risk for these infections.