Acta pathologica, microbiologica, et immunologica Scandinavica. Section B, Microbiology最新文献

The metabolism of xylitol in xylitol-sensitive strains (strains whose growth is inhibited by xylitol) and xylitol-resistant strains (growth not inhibited) of oral streptococci was compared. Both xylitol-sensitive and xylitol-resistant strains took up xylitol. In the sensitive cells, the xylitol was probably transported via a phosphotransferase system. This resulted in intracellular accumulation of xylitol-5-phosphate and xylulose-5-phosphate. These metabolites were not detected in the xylitol-resistant strains, which probably transported xylitol via a permease system. It appeared that the resistant strains were able to utilize xylitol as carbon and energy source in the absence of other carbohydrates.

Antigens for sensitization of sheep erythrocytes were released from C. fetus subsp. fetus and C. fetus subsp. venerealis suspensions by autoclaving in alkaline and neutral saline and by boiling in alkaline but not in neutral saline. Serotyping with rabbit antisera showed the same two serotypes of O-antigens, A and B, as shown by tube agglutination of heated bacteria. All C. fetus subsp. venerealis strains had the A antigen. The C. fetus subsp. fetus strains tested had either the A or B antigen. All ten human isolates tested were of the A type.

Antibodies against the Gc2 serotype determinant of gonococcal lipopolysaccharides (LPS) and antisera against strains of meningococci were tested by ELISA against the Gc2 LPS, and the antibodies examined for inhibition by bacteria of prototype strains of gonococci and meningococci. From one of the anti-meningococcal sera and anti-lactose (anti-lac) type of antibody was isolated. The results showed that antigenic sites belonging to the serotype, variable, and common sets of determinants as defined for gonococcal LPSs, may cross-react with meningococci. The anti-lac antibody combined with all of 34 strains of gonococci, with 41 out of 44 strains of meningococci tested, and with a Neisseria cinerea strain. The anti-lac showed no reactivity with any of a number of other Gram-negative cocci or bacilli examined. The results indicate that LPS from most strains of the pathogenic Neisseria species share a lactosyl moiety, presumably an inner core structure, of similar or identical configuration.

Twenty-four strains of Mobiluncus mulieris and 27 strains of Mobiluncus curtisii were tested with respect to 6 different biochemical characteristics: arginin-decarboxylase activity, beta-galactosidase activity, synergistic hemolysis with Staphylococcus aureus, hydrolysis of hippurate, migration through soft agar and reduction of nitrate. Antigens of the same strains, prepared by ultrasonication, were subjected to sodium dodecyl sulphate-polyacrylamide gel electrophoresis followed by immunoblotting using polyclonal rabbit antisera against two of the M. mulieris strains and five of the M. curtisii strains. Two different strongly reacting protein antigens could be detected in the M. mulieris strains. These strains could be separated into three groups based on the possession of either of the two antigens or both. In the M. curtisii strains, 10 strongly reacting protein antigens could be detected. Four strains possessed only one of these antigens, one did not possess any, while the remaining strains possessed different sets of 9 of them. Within each species common protein antigens were detected. No antigens were found which were shared by both species. The biochemical characteristics studied could not differentiate between the antigenic groups in any of the species. None of the antigenic subgroups of M. curtisii found in the present study was identical with any of the two subspecies (curtisii and holmesii) which have been proposed.

51 strains, including clinical isolates, type and reference strains of Mobiluncus, were studied as to phenotype and reactivity with a set of monoclonal antibodies to defined Mobiluncus antigens. Numerical analysis of phenotypic data and the reactivity with monoclonal antibodies showed that the bacteria are clustered to form the two main species, M. mulieris and M. curtisii, although some atypical variants occur. In indirect immunofluorescence assay, the unique antigens were fully exposed on the cell surface and could therefore be used as markers for specific microscopic identification of Mobiluncus in mixed vaginal samples from women attending an STD clinic. The monoclonal antibodies identified M. mulieris and M. curtisii, showing a high correlation with the detection of motile curved rods in wet smears and curved rods in Gram-stained preparations. 70% of the samples harbouring Mobiluncus as seen by direct identification with monoclonal antibodies were culture-positive when an elaborate dilution technique for culture was used.

We have characterized 20 Pseudomonas aeruginosa strains isolated from pneumonic mink lungs with regard to elastase production and serotype. P. aeruginosa PAO1, a well-characterized elastase-producing strain, and two elastase-deficient mutants of PAO1 were used for comparative purposes. Elastase activity was assayed on elastin agar and by using 14C-elastin coated microtiter plates. Elastase antigen was measured using a double antibody sandwich ELISA (enzyme-linked immunosorbent assay). Total proteolytic activity was determined on skim milk agar plates. The results from ELISA showed that all strains produced antigenically similar elastase, although the amounts produced varied considerably between strains. There was a good correlation regarding elastase assays between ELISA and 14C-elastin, elastin agar and total proteolytic activity on skim milk agar. No correlation was found between serotype and elastase activity. The results showed that the 14C-elastin assay is a simple and sensitive method of determining elastolytic activity of P. aeruginosa strains.

The emergence of ampicillin and chloramphenicol resistant Haemophilus influenzae type b in Denmark has created demands for alternative treatments of serious infections with H. influenzae. In this study 102 strains of H. influenzae recovered from cerebrospinal fluid (85) and blood (17) were tested for susceptibility to ampicillin, piperacillin, erythromycin, rifampicin, chloramphenicol, cefuroxime, cefotaxime, ceftazidime, ceftriaxone, moxalactam, aztreonam, and netilmicin by means of the agar dilution method. The majority (97%) was H. influenzae type b and of these strains 94% belonged to biotype I. Nine of the investigated strains were beta-lactamase producers. Ceftriaxone and cefotaxime were the most active agents (MIC90 less than or equal to 0.025 microliter/ml) followed by moxalactam and aztreonam (MIC90 = 0.1 microgram/ml). Except for ampicillin and piperacillin, the MIC was similar for beta-lactamase producers and non-producers. Several of the investigated antibiotics, especially some of the third generation cephalosporins, might constitute valid therapeutical alternatives to conventional drugs in the treatment of severe H. influenzae infections.

Genetic investigations of selected bovine and ovine strains of Pasteurella haemolytica sensu stricto (biogroup 1), P. haemolytica biogroups 2, 3, 5 and 9, P. testudinis and porcine isolates of so-called P. haemolytica, tentatively designated taxon 15, confirmed the existence of these phenotypically delineated taxa. Evidence was further obtained to indicate that P. haemolytica biogroups 1, 2, 3, 5 and 9 and P. testudinis constitute a new genus within the family Pasteurellaceae Pohl 1981, and that P. testudinis represents a "missing link" between so-called P. haemolytica biovars A and T. The proposed genus seems to contain several new species. Additional investigations are, however, indicated before final conclusions can be drawn. The authors desist from proposing genus and species names for the same reasons. Porcine strains provisionally named taxon 15 seem to constitute a separate group within the family Pasteurellaceae Pohl 1981, underlining the distinct degree of specificity members of this family show for host species.

Susceptibility of 553 blood culture isolates to gentamicin, tobramycin, amikacin, and netilmicin was determined by a routine disk diffusion method with semiconfluent growth (AB Biodisk, Solna, Sweden) and a microtiter-method (Sensititre). The disk diffusion test gave false sensitive results in 9.4-71% of the 9-39 aminoglycoside resistant strains studied. False resistant results occurred in 1.0-7.6% of measurements among the over 500 aminoglycoside sensitive strains. Because of the frequent error rate, the disk method with semiconfluent growth should be replaced with other methods in the determination of aminoglycoside resistance in bacteriological laboratories.