Levofloxacin to prevent bacterial infection in patients with cancer and neutropenia.

BACKGROUND: The prophylactic use of fluoroquinolones in patients with cancer and neutropenia is controversial and is not a recommended intervention. METHODS: We randomly assigned 760 consecutive adult patients with cancer in whom chemotherapy-induced neutropenia (<1000 neutrophils per cubic millimeter) was expected to occur for more than seven days to receive either oral levofloxacin (500 mg daily) or placebo from the start of chemotherapy until the resolution of neutropenia. Patients were stratified according to their underlying disease (acute leukemia vs. solid tumor or lymphoma). RESULTS: An intention-to-treat analysis showed that fever was present for the duration of neutropenia in 65 percent of patients who received levofloxacin prophylaxis, as compared with 85 percent of those receiving placebo (243 of 375 vs. 308 of 363; relative risk, 0.76; absolute difference in risk, -20 percent; 95 percent confidence interval, -26 to -14 percent; P=0.001). The levofloxacin group had a lower rate of microbiologically documented infections (absolute difference in risk, -17 percent; 95 percent confidence interval, -24 to -10 percent; P<0.001), bacteremias (difference in risk, -16 percent; 95 percent confidence interval, -22 to -9 percent; P<0.001), and single-agent gram-negative bacteremias (difference in risk, -7 percent; 95 percent confidence interval, -10 to -2 percent; P<0.01) than did the placebo group. Mortality and tolerability were similar in the two groups. The effects of prophylaxis were also similar between patients with acute leukemia and those with solid tumors or lymphoma. CONCLUSIONS: Prophylactic treatment with levofloxacin is an effective and well-tolerated way of preventing febrile episodes and other relevant infection-related outcomes in patients with cancer and profound and protracted neutropenia. The long-term effect of this intervention on microbial resistance in the community is not known

Protective Activity of the CnaBE3 Domain Conserved among Staphylococcus aureus Sdr Proteins

Staphylococcus aureus is an opportunistic pathogen, commensal of the human skin and nares, but also responsible for invasive nosocomial as well as community acquired infections. Staphylococcus aureus adheres to the host tissues by means of surface adhesins, such as SdrC, SdrD, and SdrE proteins. The Sdr family of proteins together with a functional A domain, contain respectively two, three or five repeated sequences called B motifs which comprise the CnaB domains. SdrD and SdrE proteins were reported to be protective in animal models against invasive diseases or lethal challenge with human clinical S. aureus isolates. In this study we identified a 126 amino acid sequence containing a CnaB domain, conserved among the three Sdr proteins. The three fragments defined here as CnaBC2, D5 and E3 domains even though belonging to phylogenetically distinct strains, displayed high sequence similarity. Based on the sequence conservation data, we selected the CnaBE3 domain for further analysis and characterization. Polyclonal antibodies raised against the recombinant CnaBE3 domain recognized SdrE, SdrC and SdrD proteins of different S. aureus lineages. Moreover, we demonstrated that the CnaBE3 domain was expressed in vivo during S. aureus infections, and that immunization of this domain alone significantly reduces the bacterial load in mice challenged with S. aureus. Furthermore, we show that the reduction of bacteria by CnaBE3 vaccination is due to functional antibodies. Finally, we demonstrated that the region of the SdrE protein containing the CnaBE3 domain was resistant to trypsin digestion, a characteristic often associated with the presence of an isopeptide bond

<i>Pneumocystis carinii</i> pneumonia in patients with malignant haematological diseases: 10 years' experience of infection in GIMEMA centres

Summary. A retrospective survey was conducted over a 10‐year period (1990–99) among 52 haematology divisions in order to evaluate the clinical and laboratory characteristics and outcome of patients with proven Pneumocystis carinii pneumonia (PCP) complicating haematological diseases. The study included 55 patients (18 with non‐Hodgkin's lymphoma, 10 with acute lymphoblastic leukaemia, eight with acute myeloid leukaemia, five with chronic myeloid leukaemia, four with chronic lymphocytic leukaemia, four with multiple myeloma, three with myelodysplastic syndrome, two with myelofibrosis and one with thalassemia) who developed PCP. Among these, 18 (33%) underwent stem cell transplantation; only two received an oral prophylaxis with trimethroprim/sulphamethoxazole. Twelve patients (22%) developed PCP despite protective isolation in a laminar airflow room. The most frequent symptoms were: fever (86%), dyspnoea (78%), non‐productive cough (71%), thoracic pain (14%) and chills (5%); a severe hypoxaemia was present in 39 patients (71%). Chest radiography or computerized tomography showed interstitial infiltrates in 34 patients (62%), alveolar infiltrates in 12 patients (22%), and alveolar–interstitial infiltrates in nine patients (16%). Bronchoalveolar lavage was diagnostic in 47/48 patients, induced sputum in 9/18 patients and lung biopsy in 3/8 patients. The diagnosis was made in two patients at autopsy. All patients except one started a specific treatment (52 patients trimethroprim/sulphamethoxazole, one pentamidine and one dapsone). Sixteen patients (29%) died of PCP within 30 d of diagnosis. Multivariate analysis showed that prolonged steroid treatment (P < 0·006) and a radiological picture of diffuse lung involvement (P < 0·003) were negative diagnostic factors

Antibodies against CnaBE3 and SdrE mediate opsonophagocytic killing of <i>S. aureus</i>.

<p>Sera of mice immunized either with CnaBE3 domain or with SdrE full length protein at dilution of 1:500, rabbit complement, human promyelocytic leukemia cells HL-60, and the <i>S. aureus</i> strain Newman were incubated for 1 h and plated on TSA for CFU counting. No bacterial killing was observed in the absence of serum, HL-60 cells, complement, or in presence of control serum (preimmune serum), showing the specificity of both CnaBE3 and SdrE antisera in mediating opsonophagocytic killing of the pathogen. Error bars represent standard deviation. Statistical analysis was performed by paired t test (*<i>p</i>≤0.05, ns means not significant). For calculation of the killing percentage see the material and method section.</p

CnaBE3 domain is recognized by sera of <i>S. aureus</i> infected patients.

<p>The immune reactivity of a panel of 30 human sera collected from <i>S. aureus</i> infected patients was tested against the CnaBE3 domain by ELISA assay. A panel of 46 sera collected from healthy donors was used as control. Anti-CnaBE3 IgG titers of sera collected from the patients were significantly higher than those of sera collected from healthy donors. Each dot represents a single serum, and geometric means are reported. Statistical analysis was performed with a Mann–Whitney U test. Values are expressed in lnAU (natural logarithm of Arbitrary Units), for the calculation method see the material and method section (*<i>p</i>≤0.05).</p

CnaBE3 domain sequence is highly conserved among phylogenetically distinct strains.

<p>A) The depicted phylogenetic tree was obtained using the Sequence Types (ST) of a panel of 59 epidemiologically relevant <i>S. aureus</i> strains. Clonal complexes 1, 5, 8 and 30 are highlighted. The eleven bacterial strains selected for conservation analysis are in bold. B) The percentages of amino acid sequence identity obtained from the comparison of Sdr proteins and the CnaBC2, D5 and E3 domain amino acid sequences of Newman strain to those of an epidemiologically relevant panel of <i>S. aureus</i> strains are reported. Dark gray color means that proteins are absent, whereas white color means present and conserved with an identity percentage ≥ 90, and light gray color means present but variable with an identity percentage ≥ 75 and ≤ 89, on at least 75% of the amino acid sequence.</p

Trypsin digestion of full length SdrE protein and sequence analysis of the 37 kDa resistant fragment.

<p>A) SDS-PAGE analysis of an overnight trypsin digestion of the full length SdrE protein dialyzed either in 1 mM CaCl₂ or in 1 mM EDTA. B) The C-terminal region of the full length SdrE protein is schematically depicted. The N-terminal sequence of the 37kDa resistant fragment obtained by Edman degradation (TPKYSLGDY) is shown, together with the peptides derived by trypsin digestion (black bars), and identified by analyzing the MALDI-TOF MS spectrum reported in panel C. “T” indicates trypsin autocatalytic fragment.</p

Anti-CnaBE3 domain antibodies recognize all the three Sdr full length proteins.

<p>Western blot analysis of bacterial cell wall extracts from NCTC8325, Newman, MSSA476, MW2, N315, Mu50, Mu3, USA300 FPR3757, MRSA252, TW20, and MN8 <i>S. aureus</i> strains blotted with anti-CnaBE3 domain antibodies. The Sdr proteins of each strain are highlighted.</p