Attenuated antibody reaction for the primary antigen but not for the recall antigen of influenza vaccination in patients with non-Hodgkin B-cell lymphoma after the administration of rituximab-CHOP.

To assess the humoral response to the influenza vaccine in patients undergoing R-CHOP therapy (rituximab combined with cyclophosphamide, doxorubicin, vincristine, and predonisolone) for non-Hodgkin lymphoma (NHL), the anti-hemagglutinin (HA) titer in 7 NHL patients undergoing therapy was compared with those in 10 control group subjects in the 2005/2006 season. Four weeks after vaccination, the HA titers against the influenza type A H1N1 and type B antigens, the same antigens that had been used in the previous seasons, were elevated in all patients treated with R-CHOP. In contrast, there was no increase in the geometric mean titer for type A H3N2 antigen, which was newly included in 2005/2006 season, in the patients treated with R-CHOP, while there was a significant increase in the 10 control subjects (p = 0.014). This study showed that vaccination against influenza virus generated an appreciable humoral response to recall antigens in NHL patients treated with R-CHOP therapy, but not to the primary antigen.

A patient with acute myeloid leukemia who developed fatal pneumonia caused by carbapenem-resistant Bacillus cereus.

Bacillus cereus is known as a serious bacterial pathogen in neutropenic patients. B. cereus is often resistant to beta-lactams, including penicillins and cephalosporins. We report a case of fatal pneumonia caused by B. cereus in a patient with newly diagnosed acute myeloid leukemia (AML) during remission induction therapy. Cefepime was started for febrile neutropenia (FN) initially and was switched to panipem/betamipron, when fulminant pneumonia supervened. The isolated strain was resistant not only to cefepime but also to panipenem/betamipron. This is the first report of fulminant infection caused by carbapenem-resistant B. cereus in a neutropenic patient. B. cereus should be kept in mind as a target of empirical treatment when neutropenic patients develop pneumonia.

The iron-binding protein Dps confers hydrogen peroxide stress resistance to Campylobacter jejuni.

We identified and characterized the iron-binding protein Dps from Campylobacter jejuni. Electron microscopic analysis of this protein revealed a spherical structure of 8.5 nm in diameter, with an electron-dense core similar to those of other proteins of the Dps (DNA-binding protein from starved cells) family. Cloning and sequencing of the Dps-encoding gene (dps) revealed that a 450-bp open reading frame (ORF) encoded a protein of 150 amino acids with a calculated molecular mass of 17,332 Da. Amino acid sequence comparison indicated a high similarity between C. jejuni Dps and other Dps family proteins. In C. jejuni Dps, there are iron-binding motifs, as reported in other Dps family proteins. C. jejuni Dps bound up to 40 atoms of iron per monomer, whereas it did not appear to bind DNA. An isogenic dps-deficient mutant was more vulnerable to hydrogen peroxide than its parental strain, as judged by growth inhibition tests. The iron chelator Desferal restored the resistance of the Dps-deficient mutant to hydrogen peroxide, suggesting that this iron-binding protein prevented generation of hydroxyl radicals via the Fenton reaction. Dps was constitutively expressed during both exponential and stationary phase, and no induction was observed when the cells were exposed to H(2)O(2) or grown under iron-supplemented or iron-restricted conditions. On the basis of these data, we propose that this iron-binding protein in C. jejuni plays an important role in protection against hydrogen peroxide stress by sequestering intracellular free iron and is expressed constitutively to cope with the harmful effect of hydrogen peroxide stress on this microaerophilic organism without delay.