Integrated MRSA-Management (IMM) with prolonged decolonization treatment after hospital discharge is effective: a single centre, non-randomised open-label trial.

BACKGROUND: Guidelines for the control of hospital-acquired MRSA include decolonization measures to end MRSA carrier status in colonized and infected patients. Successful decolonization typically requires up to 22 days of treatment, which is longer than the average hospital length of stay (LOS). Incomplete decolonization is therefore common, with long-term MRSA carriage as a consequence. To overcome this, we developed an integrated MRSA Management (IMM) by extending MRSA decolonization to the outpatient and domestic setting. The protocol makes use of polyhexanide-based products, in view of reported qac-mediated resistance to chlorhexidine in S. aureus and MRSA. METHODS: This is a prospective, single centre, controlled, non-randomized, open-label study to evaluate the efficiency of the IMM concept. The outcome of guideline-approved decolonization during hospital stay only (control group; n = 201) was compared to the outcome following IMM treatment whereby decolonization was continued after discharge in the domestic setting or in a long-term care facility (study group; n = 99). As a secondary outcome, the effect of MRSA-status of skin alterations was assessed. RESULTS: The overall decolonization rate was 47 % in the IMM patient group compared to 12 % in the control group (p < 0.01). The continued treatment after hospital discharge was as effective as treatment completed during hospitalization, with microbiologically-confirmed decolonization (patients with completed regimes only) obtained with 55 % for the IMM group and 43 % for the control group (p > 0.05). For patients with skin alterations (e.g. wounds and entry sites), decolonization success was 50 % if the skin alterations were MRSA-negative at baseline, compared to 22 % success for patients entering the study with MRSA-positive skin alterations (p < 0.01). CONCLUSIONS: The IMM strategy offers an MRSA decolonization protocol that is feasible in the domestic setting and is equally effective compared with inpatient decolonization treatment when hospital LOS is long enough to complete the treatment. Moreover, for patients with average LOS, decolonization rates obtained with IMM are significantly higher than for in-hospital treatment. IMM is a promising concept to improve decolonization rates of MRSA-carriers for patients who leave the hospital before decolonization is completed.

Biosynthesis of fungal melanins and their importance for human pathogenic fungi.

For more than 40 years fungi have been known to produce pigments known as melanins. Predominantly these have been dihydroxyphenylalanine (DOPA)-melanin and dihydroxynaphthalene (DHN)-melanin. The biochemical and genetical analysis of the biosynthesis pathways have led to the identification of the genes and corresponding enzymes of the pathways. Only recently have both these types of melanin been linked to virulence in some human pathogenic and phytopathogenic fungi. The absence of melanin in human pathogenic and phytopathogenic fungi often leads to a decrease in virulence. In phytopathogenic fungi such as Magnaporthe grisea and Colletotrichum lagenarium, besides other possible functions in pathogenicity, DHN-melanin plays an essential role in generating turgor for plant appressoria to penetrate plant leaves. While the function of melanin in human pathogenic fungi such as Cryptococcus neoformans, Wangiella dermatitidis, Sporothrix schenckii, and Aspergillus fumigatus is less well defined, its role in protecting fungal cells has clearly been shown. Specifically, the ability of both DOPA- and DHN-melanins to quench free radicals is thought to be an important factor in virulence. In addition, in several fungi the production of fungal virulence factors, such as melanin, has been linked to a cAMP-dependent signaling pathway. Many of the components involved in the signaling pathway have been identified.

PKSP-dependent reduction of phagolysosome fusion and intracellular kill of Aspergillus fumigatus conidia by human monocyte-derived macrophages.

Previously, we described the isolation of an Aspergillus fumigatus mutant producing non-pigmented conidia, as a result of a defective polyketide synthase gene, pksP (polyketide synthase involved in pigment biosynthesis). The virulence of the pksP mutant was attenuated in a murine animal infection model and its conidia showed enhanced susceptibility towards damage by monocytes in vitro. Because macrophage-mediated killing is critical for host resistance to aspergillosis, the interaction of both grey-green wild-type conidia and white pksP mutant conidia with human monocyte-derived macrophages (MDM) was studied with respect to intracellular processing of ingested conidia. After phagocytosis, the percentage of wild-type conidia residing in an acidic environment was approximately fivefold lower than that observed for non-pigmented pksP mutant conidia. The phagolysosome formation, as assessed by co-localization of LAMP-1 and cathepsin D with ingested conidia, was significantly lower for wild-type conidia compared with pksP mutant conidia. Furthermore, the intracellular kill of pksP mutant conidia was significantly higher than of wild-type conidia, which was markedly increased by chloroquine, a known enhancer of phagolysosome fusion. Taken together, these findings suggest that the presence of a functional pksP gene in A. fumigatus conidia is associated with an inhibition of phagolysosome fusion in human MDM. These data show for the first time that a fungus has the capability to inhibit the fusion of the phagosome with the lysosome. This finding might help explain the attenuated virulence of pksP mutant strains in a murine animal model and provides a conceptual frame to understand the virulence of A. fumigatus.

Complicated nosocomial pneumonia due to Legionella pneumophila in an immunocompromised child.

An immunocompromised child developed necrotizing pneumonia with BAL cultures growing Legionella pneumophila resistant to treatment, including erythromycin and rifampicin. Ciprofloxacin and clarithromycin reversed the clinical course; their use as first-line drugs is justifiable and a high index of suspicion for the occurrence of legionellosis is warranted.