Dynamics of fungal colonization in a new medical mycology laboratory.

OBJECTIVE OF THE STUDY: Study of the spatio-temporal fungal colonization in a new medical mycology laboratory. METHODS: A 17-month survey of airborne fungal contamination was conducted in a new medical mycology laboratory at a tertiary care university hospital. This survey was implemented at three different periods: before the new premises were occupied (period A), during the move into the new laboratory (period B) and after resumption of the mycological activities in these new premises (period C). RESULTS: During period A, the airborne fungal load ranged from 2.3 to 6 cfu/m(3). The most frequently recovered airborne fungi were Penicillium spp. (75 to 100%). During period B, a dramatic increase in Penicillium chrysogenum conidia was observed in the air of the new laboratory (40 to 160 cfu/m(3)). During period C, the fungal load ranged from 4.5 to 8.4 cfu/m(3). Penicillium was the most common genus identified in rooms of the laboratory where no filamentous fungi were handled, while Aspergillus was clearly the predominant genus (78%) in the room dedicated to the culture of filamentous fungi. CONCLUSIONS: We suggest that the specific fungal ecology in air of the room dedicated to the culture of filamentous fungi is due to the handling of a large number of medical strains of A. fumigatus.

In vitro combinations of five intravenous antibiotics with dalfopristin-quinupristin against Staphylococcus aureus in a 3-dimensional model.

We compared the in vitro activity of dalfopristin and quinupristin combined with five intravenous antibiotics in a 3-dimensional model. We tested six strains of Staphylococcus aureus selected with different patterns of resistance to methicillin and erythromycin. Dalfopristin and quinupristin displayed a very synergistic activity against all the strains with a mean 16- or 32-fold decrease of inhibitory concentrations in combination. That synergy was even better against erythromycin-resistant strains. In combination with tigecycline or fosfomycin, the antibacterial activity could be consistently enhanced with the same decrease of inhibitory concentrations. A synergy was also observed, less regularly and at a lower level, with rifampin, gentamicin or vancomycin. Combinations of dalfopristin and quinupristin with tigecycline or fosfomycin could be very interesting in clinical practice because the inhibitory effect could be achieved with very low concentrations of each component, even when erythromycin-resistant strains are concerned.

Prospective survey of indoor fungal contamination in hospital during a period of building construction.

An 18-month survey of indoor fungal contamination was conducted in one haematology unit during a period of construction work. Air was sampled with a portable Air System Impactor and surfaces with contact Sabouraud plates. During this survey the mean concentration of viable fungi in air was 4.2 cfu/m(3) and that for surfaces was 1.7 cfu/plate. At the beginning of construction work, there were increases in airborne fungal spores (from 3.0 to 9.8 cfu/m(3)) in the unit, but concentrations did not exceed 10 cfu/m(3) during the 18-month period. The most frequently recovered airborne fungi were Penicillium spp. (27-38%), Aspergillus spp. (25%) and Bjerkandera adusta, a basidiomycete identified with molecular tools (7-12%). Blastomycetes accounted for more than 50% of the fungal flora on surfaces. Investigating the impact of a new air-treatment system (mobile Plasmair units), there were significant reductions in fungal contamination for the Plasmer -treated rooms, and in these rooms we observed the same level of fungal load whether construction work was in progress or not.

Presumed pseudobacteremia outbreak resulting from contamination of proportional disinfectant dispenser.

Reported here are the microbiological and epidemiological details of a presumed outbreak of aerobic gram-negative bacilli infections affecting 19 hematological patients, which was traced to contaminated disinfectant. Over a 5-month period, the following organisms were isolated from the blood cultures of 19 neutropenic patients: Pseudomonas fluorescens (n = 13), Achromobacter xylosoxidans (n = 12), Comamonas testosteroni (n = 2) or Stenotrophomonas maltophilia (n = 1). The affected patients were all treated with an expensive regimen of broad-spectrum antibiotic therapy. The same bacteria were recovered from environmental samples as well as from the water pipes of an apparatus for dispensing disinfectant (didecyldimethylammonium chloride). Genotyping results indicated that many of the clinical strains were identical to strains isolated from the apparatus. It was eventually discovered that the night staff was in the habit of disinfecting the blood-culture bottles before use, thereby contaminating the bottles with bacteria contained in the disinfectant. Contamination of the apparatus resulted from faulty maintenance.

Reduced fungal contamination of the indoor environment with the Plasmair system (Airinspace).

Aspergillus spp. and other moulds cause life-threatening opportunistic infections in immunocompromised patients. Indoor contamination and construction work that liberate fungal spores are a major source of nosocomial aspergillosis. Dijon hospital is a tertiary care institution in northeast France undergoing construction work beside high-risk clinical units. To determine the impact of this activity, a surveillance programme was implemented one year before building work began in order to establish baseline levels of contamination. Air and surface fungal contamination in adult and paediatric haematology units were prospectively examined following use, or not, of a new air-treatment system with mobile Plasmair units (Airinspace). There were significant reductions in overall fungal contamination for the Plasmair treated rooms for air and surface samples in both clinical units. Plasmair treatment also significantly reduced A. fumigatus in the air. These data suggest that Plasmair units may provide an efficient method of reducing indoor fungal contamination in hospitals.

Canine distemper virus DNA vaccination induces humoral and cellular immunity and protects against a lethal intracerebral challenge.

We have studied the immune responses to the two glycoproteins of the Morbillivirus canine distemper virus (CDV) after DNA vaccination of BALB/c mice. The plasmids coding for both CDV hemagglutinin (H) and fusion protein (F) induce high levels of antibodies which persist for more than 6 months. Intramuscular inoculation of the CDV DNA induces a predominantly immunoglobulin G2a (IgG2a) response (Th1 response), whereas gene gun immunization with CDV H evokes exclusively an IgG1 response (Th2 response). In contrast, the CDV F gene elicited a mixed, IgG1 and IgG2a response. Mice vaccinated (by gene gun) with either the CDV H or F DNA showed a class I-restricted cytotoxic lymphocyte response. Immunized mice challenged intracerebrally with a lethal dose of a neurovirulent strain of CDV were protected. However, approximately 30% of the mice vaccinated with the CDV F DNA became obese in the first 2 months following the challenge. This was not correlated with the serum antibody levels.

Role of CD46 in measles virus infection in CD46 transgenic mice.

The susceptibility of CD46 (human membrane cofactor protein) transgenic mice to measles virus (MV) infection was investigated. Cell cultures (lung and kidney) established from transgenic and control mice showed that although both could be infected only those from the CD46+ mice gave fusion. A complete round of replication with the release of infectious virus was detected exclusively in the transgenic cell cultures whose permissiveness to MV was markedly less than that of Vero cells. The ability of MV to replicate in vivo in mice was studied using both vaccine and laboratory-adapted wild-type strains of virus. After intraperitoneal and intranasal inoculations of transgenic mice, virus replication could not be detected. In contrast intracerebral inoculation induced infection in both transgenic and nontransgenic mice. Our results from in vitro infection studies support the hypothesis that CD46 is a major host cell factor involved in the MV-induced fusion process and MV entry. The studies further indicate that MV tropism is not governed solely by the expression of the CD46 gene and that the high efficiency of the replicative cycles characteristic of fully permissive host cells requires additional factors, which are lacking in both transgenic and nontransgenic mice.

Measles virus DNA vaccination: antibody isotype is determined by the method of immunization and by the nature of both the antigen and the coimmunized antigen.

Plasmids encoding the measles virus hemagglutinin (HA) and nucleoprotein (NP) proteins inoculated into the skin of BALB/c mice by the gene gun method induced both humoral and cytotoxic lymphocyte class I-restricted immune responses. Although intramuscular immunization induces the immunoglobulin G2a (IgG2a) antibody isotype for both antigens, with gene gun immunization, the NP still generated mainly IgG2a and the major isotype induced by the HA was IgG1. Interestingly, gene gun coimmunization of HA and NP plasmids resulted in a dominant IgG1 HA response and the switching of antibodies generated against the NP to the IgG1 isotype.

Value of a ligase chain reaction assay for detection of ganciclovir resistance-related mutation 594 in UL97 gene of human cytomegalovirus.

Human cytomegalovirus (HCMV) isolates resistant to ganciclovir were found in patients undergoing therapy. Therefore, we have developed a new specific and sensitive method--a ligase chain reaction (LCR) assay--for detection of frequently encountered 594 mutated codon in ganciclovir (GCV) resistant virus. Previous studies characterized an alanine to valine change on codon 594 in resistant strains. A novel substitution in 594, alanine to glycine, is described which is also capable of conferring ganciclovir resistance. LCR products were analyzed on polyacrylamide gel- and the mutant was detected using a non radioactive method. The LCR product detection was then adapted to a microtitre plate format with a colorimetric detection. This method allowed the distinction of mutated GCV-resistant strains from sensitive strains with a high sensitivity, and the detection of a low percentage of mutated DNA in virus load. This assay could be useful in following the evolution of mutated DNA compared to viral infection.