Alain Ros

Ventilator temperature sensors: an unusual source of Pseudomonas cepacia in nosocomial infection

A prospective study was undertaken to determine the source of Pseudomonas cepacia colonization and infection that had affected ventilated patients in an Intensive Care Unit (ICU) for three years. Thirty-eight patients undergoing mechanical ventilation were enrolled during a six-week period. Samples were taken from patients, ventilator circuits and the environment for culture. P. cepacia was isolated from the condensate formed in the ventilator circuit and the source of the contamination was shown to be the temperature sensor. Ribotyping of the representative strains of P. cepacia performed with two endonucleases, EcoRI and PvuII, confirmed the homogeneity of the isolates from patients and ventilator circuits. A modification of the procedure for disinfection of the temperature sensors resulted in the eradication of P. cepacia from the ICU.

Reduction of Yersinia enterocolitica load in deliberately inoculated blood: the effects of blood prestorage temperature and WBC filtration

BACKGROUND: Yersinia enterocolitica is known to cause severe infections in patients who receive transfusions.

Differentiation of Pseudomonas aeruginosa strains by ribotyping : high discriminatory power by using a single restriction endonuclease

The genotypic diversity of 40 presumably epidemiologically unrelated strains of Pseudomonas aeruginosa belonging to nine different O-serotypes was analysed according to ribosomal DNA fingerprints. Ribotyping was performed with a digoxigenin-labelled DNA probe and four restriction endonucleases. Characteristic banding patterns of three to 12 bands were obtained with the different endonucleases. Among the 40 strains, eight, nine, 10 and 29 different ribotypes were differentiated with EcoRI, the combination EcoRI+HindIII, BamHI and PvuII, respectively. Poor correlations were noted between the results of serotyping and those of ribotyping. With the latter method, indices of discrimination were calculated for each enzyme from the data of the 40 unrelated strains: the values ranged from 0.678 for EcoRI to 0.979 for PvuII. Epidemiologically related samples were also tested; this enabled assessment of whether the method was able to cluster strains from a common origin with each of the enzymes tested. Ribotyping with PvuII endonuclease is proposed for screening large numbers of P. aeruginosa strains in epidemiological studies. Additional enzymes could be used to further increase the discrimination between isolates found to be indistinguishable with PvuII enzyme.

Characterization of Nosocomial Strains of Enterobacter aerogenes by Arbitrarily Primed-PCR Analysis and Ribotyping

OBJECTIVE To study the spread of strains of Enterobacter aerogenes in our hospital in 1992 and 1993 by using two genotypic markers, and to evaluate these methods for the epidemiological investigation of this species. DESIGN Ribotyping (using two endonucleases) and arbitrarily primed (AP)-PCR (using two different 10-mer primers) were applied to the epidemiological typing of clinical strains of E aerogenes isolated from hospitalized patients. SETTING AND PATIENTS The intensive care unit (ICU; 5 patients, 13 isolates), nephrology units (3 patients, 5 isolates), and surgery units (2 patients, 2 isolates) of the university hospital of Saint-Etienne (France). RESULTS Eight epidemiologically unrelated isolates, chosen as controls, exhibited distinct profiles, both by AP-PCR and ribotyping. Two clones of E aerogenes circulated in the ICU; both were isolated successively from samples of a single patient who stayed in the unit for almost 1 year. A third clone was recovered from patients of surgery units. A fourth clone was shown to have infected patients of nephrology units. CONCLUSIONS Ribotyping and AP-PCR appear to be reliable methods for typing E aerogenes strains implicated in nosocomial infection. The spread of independent clones of E aerogenes in different units of our hospital in 1992 and 1993 was demonstrated by both methods. This study emphasizes the need to choose the endonucleases or primers with care to obtain high discriminatory results in genotypic investigations.

Evaluation of the New Brilliance GBS Chromogenic Medium for Screening of Streptococcus agalactiae Vaginal Colonization in Pregnant Women

ABSTRACT Three commercial chromogenic agar media were evaluated for Streptococcus agalactiae screening in 200 vaginal swabs from pregnant women. The sensitivity and specificity were 94.3% and 100% for Granada medium (bioMérieux), 100% and 90.3% for Brilliance GBS medium (Thermo Fisher Scientific), and 100% and 98.8% for ChromID STRB medium (bioMérieux), respectively.

A 44,000 glycoprotein is involved in the attachment of echovirus-11 onto susceptible cells

Cellular receptors play an important role in viral pathogenesis. Until now little was known on echovirus (EV) receptor. Using detergent-treated KB cell extracts as immunogen, a mouse monoclonal antibody (Mab 143) was produced that selectively blocks the attachment of EV-11 to KB and other susceptible cells. By immunoblotting, Mab 143 detected a 44,000 protein on susceptible cell lines but not on cell lines from nonprimate origin. The receptor protein complex, purified from KB cell membranes by immunoaffinity using Mab 143 as ligand, was shown to contain a single glycoprotein with apparent molecular weight of 44,000 (gp44). The role of gp44 in the attachment of EV-11 onto KB cells was demonstrated by the ability (i) of affinity-purified gp44 to reduce the infectivity of EV-11 and (ii) of rabbit polyclonal antisera raised against gp44 to protect cells from the replication of various EV, as did Mab 143.

Evaluation of the new CE-IVD marked BD MAX Cdiff Assay for the detection of toxigenic Clostridium difficile harboring the tcdB gene from clinical stool samples

The evaluation of the fully automated BD MAX Cdiff assay on a panel of 100 stool samples characterized by the Xpert C. difficile assay reported a high concordance between the two molecular assays (kappa coefficient of 0.96), which makes this new assay suitable for routine detection of toxigenic Clostridium difficile.