European Journal of Clinical Microbiology最新文献

A monoclonal antibody specific for an epitope of a 50 kDa Plasmodium falciparum antigen was used in an enzyme immunoassay for detection of the corresponding exo-antigen in culture supernatant and in the sera of 31 patients suffering from acute malaria. The assay was specific for Plasmodium falciparum and did not appear to be strain restricted. A parasitaemia level below 0.001% could be detected.

Six Plasmodium falciparum/beta-galactosidase fusion proteins produced by a genomic DNA expression library, and two synthetic Plasmodium falciparum antigens were applied to ELISA and tested for their immunodiagnostic properties. Results were compared to reference methods, i.e. fluorescence antibody test with whole cell antigen and ELISA with detergent-soluble crude schizont antigen. Anti-Plasmodium falciparum antibodies could be detected by these molecular antigens to varying extents in human sera. Undesired reactivity to fusion proteins due to the high prevalence of antibodies to beta-galactosidase in human sera and undesired reactivity to one of the synthetic antigens (P12) frequently occurred. The antibodies responsible for the nonspecific reactivity could not be identified. It was concluded that the application of molecular Plasmodium falciparum antigens to ELISA represents a practicable approach to immunodiagnosis of malaria if the construction of epitopes that bind antibodies other than Plasmodium falciparum antibodies can be avoided.

The in vitro activity of pefloxacin, norfloxacin, ofloxacin and ciprofloxacin against 86 strains of mycobacteria was evaluated by broth dilution. While Mycobacterium avium, Mycobacterium scrofulaceum and Mycobacterium chelonae were resistant to all four antibacterials, the susceptibility of the other species, Mycobacterium tuberculosis, Mycobacterium kansasii, Mycobacterium xenopi and Mycobacterium fortuitum, depended on the antibiotic. Ofloxacin and ciprofloxacin (MIC90: 0.5 - 2 mg/l) were more active than pefloxacin and norfloxacin (MIC90: 2 - 16 mg/l).

In vitro experiments with frozen sections of human lung and kidney demonstrated that adhesion of Streptococcus pneumoniae Pn 629 Type 14 and Pseudomonas aeruginosa ATCC 27853 to human cells was mediated by bacterial lectins (adhesins) with N-acetyl-D-glucosamine/D-galactose or N-acetyl-neuraminic acid specificity. Blocking of the lectin binding sites on bacterial surfaces with competitive carbohydrates completely prevented the bacterial adherence, whereas non-specific carbohydrates (D-mannose, D-xylose) did not inhibit adherence.

An improved cell culture method for the recovery of Chlamydia trachomatis from clinical samples was evaluated. Freshly trypsinized HeLa 229 cells were infected in suspension culture and compared to a standard monolayer culture method. Among 1085 specimens evaluated, 84 were positive by both methods, 978 were negative by both methods, 2 were positive by the monolayer method only, and 21 were positive by the suspension method only. Inclusion counts were two-fold higher in the suspension culture method than in the monolayer method (p less than .001). It is concluded that freshly trypsinized HeLa 229 cells infected in suspension culture are more susceptible to infection with Chlamydia trachomatis than standard monolayer cells.

A simple, reproducible method for determining the antibiotic susceptibility of chlamydial isolates is described. Minimum inhibitory and lethal concentrations (MICs and MLCs) were determined for tetracycline and erythromycin titrated against a recent clinical isolate of Chlamydia trachomatis in McCoy cell cultures. A fluorescent antibody stain was found to be more sensitive than giemsa staining, generally giving two-fold higher values for both MICs and MLCs.

A six year retrospective survey of enterococcal urinary tract infections in hospital inpatients is reported. During the study period there was an increase in the proportion of significant cultures that yielded enterococci. These organisms were more frequently isolated from catheter specimens than midstream specimens of urine and from surgical than from medical wards.

Ciprofloxacin was found to be active against selected strains of methicillin-resistant as well as methicillin-susceptible Staphylococcus aureus and Staphylococcus epidermidis, having minimal inhibitory concentrations less than 0.8 micrograms/ml with inocula of approximately 10(4) CFU/ml. When killing kinetic studies were done with inocula of approximately 10(6) CFU/ml and various ciprofloxacin concentrations, the killing effect was low (less than 3 log10 in 6 h) and regrowth of the culture was seen after 24 h in at least one Staphylococcus aureus strain. After 48 h incubation, mutants with MICs eightfold that of the parental strain had grown to a number of approximately 10(10) CFU/ml.

In 1984 the European Study Group on Antibiotic Resistance (ESGAR) consecutively collected gram-negative bacilli and staphylococci blood isolates and performed susceptibility testing with 11 antibiotics using the microdilution method. In all 2,578 isolates were collected: 68% gram-negative bacilli and 32% staphylococci. The MICs of ampicillin and cefazoline for the susceptible gram-negative bacilli were 1-8 micrograms/ml; of piperacillin less than or equal to 0.5-4; of Sch 34343, cefotaxime, moxalactam, ceftazidime and aztreonam less than or equal to 0.5-2 micrograms/ml; of cefoxitin, cefuroxime and cefamandole less than or equal to 0.5-8 micrograms/ml. For susceptible staphylococci the MICs of cefazoline and cefuroxime were less than or equal to 0.5-1 micrograms/ml, and of cefoxitin, moxalactam, ceftazidime and cefotaxime, less than or equal to 0.5-32 micrograms/ml. The resistance levels varied between laboratories and countries, being lower in Northern Europe. In clinical protocols on patients with gram-negative septicemia from whom cefazoline-resistant strains were isolated, cefotaxime was the beta-lactam most commonly used (12%). In protocols on patients with staphylococcal septicemia from whom gentamicin-resistant or cefazoline-resistant strains were isolated, the most commonly used beta-lactam was cloxacillin (6%).

The influence of antibiotics on the frequency of colonization by Clostridium difficile and the presence of its cytotoxin in infants and older children was examined to determine its role in diarrheal disease. Cytotoxin was more closely associated with cases of diarrhea, both in infants and in children than the microorganism, although not significantly. The isolates were typed by means of sensitivity to bacteriophages and bacteriocins and their cytotoxigenic potential was also determined. Less than 30% of the colonized patients had toxigenic strains. A study of strain variability over a four-year period in the same hospital showed that two bacteriophage-bacteriocin types and non-toxigenic strains predominated. The common presence of non-toxigenic strains could explain in part the lack of correlation between isolation of Clostridium difficile and diarrhea. Most of the non-toxigenic strains showed moderate resistance to tetracycline, a property which might explain their ability to persist for long periods in the hospital.