Investigation of nosocomial pneumocystis infections: usefulness of longitudinal screening of epidemic and post-epidemic pneumocystis genotypes

BACKGROUND: Twenty-five patients, of whom 22 were renal transplant recipients, developed Pneumocystis jirovecii infections at the nephrology department of Reims University Hospital (France) from September 2008 to October 2009, whereas only four sporadic cases had been diagnosed in this department over the 14 previous years. AIM: This outbreak was investigated by analysing patient encounters and P. jirovecii types. METHODS: A transmission map was drawn up. P. jirovecii typing at DHPS, ITS and mtLSU rRNA sequences was performed in the patients of the cluster (18 patients with Pneumocystis pneumonia (PCP) and seven colonized patients), 10 unlinked control patients (six PCP patients and four colonized patients), as well as 23 other patients diagnosed with P. jirovecii (nine PCP patients and 14 colonized patients) in the same department over a three-year post-epidemic period. FINDINGS: Eleven encounters between patients harbouring the same types were observed. Three PCP patients and one colonized patient were considered as possible index cases. The most frequent types in the cluster group and the control group were identical. However, their frequency was significantly higher in the first than in the second group (P < 0.01). Identical types were also identified in the post-epidemic group, suggesting a second outbreak due to the same strain, contemporary to a disruption in prevention measures. CONCLUSIONS: These results provide additional data on the role of both PCP and colonized patients as infectious sources. Longitudinal screening of P. jirovecii types in infected patients, including colonized patients, is required in the investigation of the fungus\u27s circulation within hospitals

Conformational changes of cytosolic loops of bovine rhodopsin during the transition to metarhodopsin-II: an investigation by Fourier transform infrared difference spectroscopy

In order to assign the structural changes of the protein, observed in the Fourier transform infrared (IT‐IR) difference spectra of the rhodopsin‐metarhodopsin‐II transition, to specific regions of the protein, rhodopsin was treated by proteases. Nonilluminated and bleached rhodopsin was treated with protease K and papain. Rhodopsin digested in the bleached state was subsequently regenerated with 11 ‐cis‐retinal. From these modified samples the rhodopsin‐metarhodopsin‐II FT‐IR difference spectra were measured. Comparing the difference spectra with that of unmodified rhodopsin, clear deviations in the amide‐I and amide‐II spectral range are observed. This indicates that in the unmodified pigment conformational changes of those parts of the cytosolic surface take place which are susceptible to the proteases. From the larger spectral changes obtained with samples digested in the bleached state it is concluded that the extent of modification is larger. The difference spectra of rhodopsin modified with 10 mM dithiothreitol support the existence of the 4th loop which also undergoes conformational changes. The spectral changes are interpreted in terms of a transition of an ordered structure of the loops in rhodopsin to a more random structure in metarhodopsin‐II. The results demonstrate that by combining FT‐IR spectroscopy with protein modification by specific proteases, conformational changes of the protein can be localized to specific regions