Low prevalence of tissue detection of cefepime and daptomycin used as empirical treatment during revision for periprosthetic joint infections: results of a prospective multicenter study.

Data demonstrating that antibiotics administered intraoperatively in patients with surgical revision for periprosthetic joint infection achieve concentrations exceeding minimal inhibitory concentrations of the identified bacteria at the surgical site when the new implant is inserted are lacking. We prospectively included patients with periprosthetic joint infection operated with one- or two-stage replacement during which cefepime (2g)-daptomycin (10mg/kg) combination was administered intravenously as intraoperative empirical antibiotic treatment. Three biopsies (two bones and one synovial membrane) were taken from each patient just before the insertion of the new implant. Eighteen adults of median age 68 years were included. Knee was involved in 10 patients (55.6%) and surgery consisted in one-/two-stage replacement in 11/7 patients. A tourniquet was used during the intervention in the 10 patients with knee prosthesis. Among 54 tissue samples, cefepime and daptomycin were detected respectively in 35 (64.8%) and 21 (38.9%) cases (P=0.01). A total of 17 bacteria dominated by staphylococci (n=14) were identified in 10 patients; tissue inhibitory quotient calculated in 51 samples was >1 in 22 cases (43.1%) for cefepime and in 16 cases (31.4%) for daptomycin. The proportion of tissue samples with detectable antibiotic was significantly higher in hip versus knee prosthesis (P=0.03). The present study suggests that intraoperative empirical administration of cefepime-daptomycin combination during septic prosthetic joint replacement results in a high proportion of tissue samples in which at least one of the two antibiotics was not detected or at a low concentration despite satisfactory concomitant blood serum concentrations.

[Intraoperative exchange of the endotracheal tube using the Cook C-CAE airway exchange catheter]. / Changement peropératoire de sonde endotrachéale à l'aide du guide échangeur creux C-CAE (Cook).

The Cook airway exchange catheter is mainly used in ICU patients to exchange endotracheal tubes. We report three cases where this device was used during anaesthesia in patients with damaged tubes in critical circumstances (oropharyngeal bleeding, head and neck surgery). It allowed a fast and atraumatic exchange of the tubes.

The murine antibody response to lactate dehydrogenase-elevating virus.

Mice infected with lactate dehydrogenase-elevating virus (LDV) were found to produce high titres of IgG anti-LDV antibodies that remained elevated for more than 1 year. This response, which was T-dependent, showed a striking preponderance of IgG2a with, from one strain to another, variable proportions of IgG2b and IgG3 but always very little IgG1. The binding of these antibodies to viral protein blots showed a major reaction with VP3, the heterogeneous glycosylated material of the viral envelope. A minor reaction was also noted with VP1, the nucleocapsid protein, but no antibodies were detected against VP2, the non-glycosylated envelope protein of LDV. A similar preponderance of anti-VP3 antibodies was also observed in a large set of anti-LDV hybridomas. Analysis of VP3 with monoclonal antibodies suggested that, despite its heterogeneity, this material has a common polypeptide moiety that apparently carries two major epitopes.

In vivo suppression of T-dependent antibody responses by treatment with a monoclonal anti-L3T4 antibody.

Minute amounts of the anti-L3T4 antibody designated GK1.5 were found to deeply suppress in vivo antibody responses to T-dependent antigens. Primary responses to sheep erythrocytes were completely inhibited even when GK1.5 was administered up to 6 days before or 4 days after the antigen. Secondary responses to potent immunogens like sheep erythrocytes or keyhole limpet hemocyanin were also completely abolished by a single injection of GK1.5 just before the boost. This treatment had no effect on T-independent reactions such as the polyclonal activation of B lymphocytes with lipopolysaccharide or the anti-2,4,6-trinitrophenyl (TNP) response elicited by injection of TNP-Ficoll.

The complete amino acid sequence of diphtheria toxin fragment B. Correlation with its lipid-binding properties.

The complete amino acid sequence of fragment B from diphtheria toxin has been determined. The polypeptide chain was split with cyanogen bromide, o-iodosobenzoic acid, clostripain and trypsin; all amino acid sequence analyses were made by automated Edman degradation. Fragment B, which corresponds to the carboxy terminus of the toxin molecule, contains 342 amino acids and has an Mr of 37240. The proposed amino acid sequence fully confirms the structure recently deduced from the nucleotide sequence of the structural gene. The complete sequence is analyzed in relationship with the role of fragment B in the transfer of diphtheria toxin fragment A from the extracellular medium into the cell cytoplasm.

Partial purification of a membrane glycoprotein antigen by high-pressure size-exclusion chromatography without loss of antigenicity.

A high-pressure size exclusion chromatography system eluted with phosphate saline buffer containing 0.25% sodium deoxycholate has been developed that fractionates both soluble and membrane glycoproteins with good resolution and molecular weight versus elution time relationship. Using this system we fractionated membrane glycoproteins from a mutagenized mastocytoma cell that carries a strong transplantation antigen. After dialysis to remove the detergent, the fractions were tested for biological activity by an in vitro assay involving T-lymphocyte cell culture. Antigenic activity was found between 43 and 85 kdaltons. This demonstrates the efficiency of the system to resolve complex membrane protein samples without destroying their biological activity.

Primary structure of diphtheria toxin fragment B: structural similarities with lipid-binding domains.

Two different lipid-associating domains have been identified in the B fragment of diphtheria toxin using automated Edman degradation of its cyanogen bromide peptides, secondary structure prediction analysis, and comparisons with known phospholipid-interacting proteins. The first domain is located in the highly hydrophilic (polarity index [PI] = 61.0%) 9.00-dalton N-terminal region of fragment B. This region shows primary and predicted secondary structures dramatically similar to those found for the phospholipid headgroup-binding domains of human apolipoprotein A1 (surface lipid-associating domain). The second domain is located in the highly hydrophobic (PI = 32.4%) middle region of fragment B. Its structure resembles that found for the membranous domain of intrinsic membrane proteins (transverse lipid-associating domain). In contrast, the hydrophilic C-terminal 8,000-dalton region of fragment B (PI = 53.8%) does not show structural similarity with lipid-associating domains.

Isolation and characterization of the cyanogen bromide peptides from the B fragment of diphtheria toxin.

Homogeneous fragment B, obtained through nicking of diphtheria toxin with insoluble trypsin, was cleaved with cyanogen bromide in 70% formic acid. After citraconylation, the cleavage products were separated by gel filtration on Sephadex G--75 and purified by gel filtration, ion-exchange and thin-layer or paper chromatography. Six CNBr peptides were characterized, the composition of which account for the total amino acid content of fragment B. Their apparent molecular weights are: CB 1, 12 000; CB 2, 14 000; CB 3, 8000; CB 4a, 2400; CB 4b, 2200; CB 5, 2200. CB 4a is the NH2--terminal peptide; it contains the cysteine residue of the disulfide bridge linking fragment B to fragment A. CB 3 is the COOH--terminal peptide; it bears the disulfide bridge of fragment B. Characterization of two CNBr--derived overlapping peptides provided the positioning of CB 4b and CB 2 and allowed an alignment of the CNBr peptides of fragment B to be proposed.