Noncapsulated Klebsiella pneumoniae bearing mannose-containing O antigens is rapidly eradicated from mouse lung and triggers cytokine production by macrophages following opsonization with surfactant protein D

To better understand the relationship between the surface polysaccharides of pulmonary pathogens and components of the lung innate immune system, we employed selected serotypes of Klebsiella pneumoniae expressing distinct capsular polysaccharides and/or O antigen in a murine model of K. pneumoniae infection. In addition, we examined the effect of surfactant protein D (SP-D) on the cytokine response of human monocyte-derived macrophages to these serotypes in vitro. Noncapsulated mannose-containing O3 serotypes (K50/n and K55/n), which react efficiently with SP-D in vitro, triggered high levels of interleukin-1β (IL-1β) and IL-6 production. In vivo, they were more efficiently cleared from the lungs of mice but not from macrophage-depleted mice. They also were more efficiently internalized by alveolar macrophages in vivo. In contrast, galactose-containing O1 serotypes (K2/n and K21a/n), which interact poorly with SP-D, exhibited significantly lower cytokine production and less efficient pulmonary clearance and were ineffectively internalized by alveolar macrophages. These findings are consistent with in vitro results showing that production of IL-1β and IL-6 mRNA and IL-6 protein by human macrophages exposed to mannose-bearing Klebsiella O serotypes is significantly increased by SP-D. Thus, survival of inhaled bacteria in the lung depends partially on the lipopolysaccharide structure of the bacteria and their interactions with innate immunity components. We speculate that an imbalance of host SP-D and therefore cytokine levels may result in high susceptibility of the host to the pathogen

Rapid Emergence of Resistance to Linezolid during Linezolid Therapy of an Enterococcus faecium Infection

We report the emergence of linezolid resistance (MICs of 16 to 32 mg/liter) in clonally related vancomycin-susceptible and -resistant Enterococcus faecium isolates from an intensive care unit patient after 12 days of linezolid therapy. Only linezolid-susceptible isolates of the same clone were detected at 28 days after termination of linezolid therapy

Enhancing the Antifungal Activity of Griseofulvin by Incorporation a Green Biopolymer-Based Nanocomposite

Fungal biofilms have caused several medical problems, resulting in significant morbidity and mortality as well as poor response to antifungal drugs. The current study was designed to evaluate the enhancement of antifungal and anti-biofilm activity of Griseofulvin-loaded green nanocomposite-based biopolymers (Ge-Nco) of glycogen and gelatin against different strains of pathogenic Candida species. The prepared Ge-Nco was characterized using Fourier-transform infrared (FT-IR), X-ray diffraction pattern (XRD), scanning electron microscopy-energy dispersive X-ray (SEM-EDX) and transmission electron microscope (TEM). In addition, the morphology of the mature biofilm and the inhibition of biofilm was monitored and visualized using confocal laser scanning microscopy (CLSM). The minimal inhibitory concentrations (MIC) and (IC50) of Griseofulvin alone and the prepared Ge-Nco against three different strains of Candida sp. were determined according to Clinical and Laboratory Standards Institute (CLSI) method. The effects of Griseofulvin alone and Ge-Nco on the tested Candida sp. biofilm formation were determined by the crystal-violet staining protocol. The biofilm inhibition potential of Ge-Nco against the tested Candida sp. was detected and depicted under CLSM (2.5 D view). The findings depicted that Ge-Nco was prepared in nanometer size (10–23 nm). The observed minimum inhibitory concentration (MIC) of Griseofulvin alone and Ge-Nco against three different Candida sp. were found to be in range 49.9–99.8 μg/mL and 6.24–12.48 μg/mL, respectively. These results provide evidence for implementing efficient antivirulence approaches against three different Candida sp. that would be less likely to foster the emergence of resistance

Burkholderia Is Highly Resistant to Human Beta-Defensin 3

The bactericidal activity of the novel beta-defensin hBD-3 against 28 species and 55 strains of gram-positive cocci and gram-negative fermentative and nonfermentative rods was tested. All strains proved to be highly or intermediately susceptible to hBD-3 (minimal bactericidal concentration [MBC], ≤50 μg/ml), except for Burkholderia cepacia, for all 23 tested strains of which MBCs were >100 μg/ml