Acta microbiologica Academiae Scientiarum Hungaricae最新文献

A salmonella panama outbreak was observed in the months May through July, 1979, in the newborn and intensive wards of a paediatric hospital. The isolates proved to be multiresistant to antibiotics. To clarify the presumed R-plasmid nature of the multiresistance, the transfer of the resistance to five antibiotics, viz. ampicillin, chloramphenicol, streptomycin, kanamycin and tetracycline, was studied. Escherichia cole K12 Nalr, the strain used as recipient, acquired resistance simultaneously to four antibiotics, viz. ampicillin, chloramphenicol, streptomycin and kanamycin. The minimum inhibitory concentration for the transconjugants agreed well with that of the original S. panama strain. Resistant and multiresistant E. coli. strains not belonging to serogroups associated with infantile enteritis were isolated from the intestinal flora of several patients and symptomless carriers. Elimination of the transmissible multiresistance was observed in 0.15-1.1% of the strains.

Using strain SME-12 of Escherichia coli and its variants A and B showing large round, diffuse and compact-type colonial morphology, respectively, in soft-agar medium, their capsule showed that although these strains were similar in toxicity, the parent strain exhibited a large capsule, a large cell volume and a high mouse virulence. Variant A had no capsule, its cell volume was remarkably lower than that of the original strain, and was avirulent; variant B had no capsule and displayed the lowest cell volume and mouse virulence. With 193 fresh isolates of E. coli, the majority of colonies of 16, 152 and 25 strains were of large round, diffuse and compact types, respectively. Fifteen strains of pure growth type from each of the three groups were tested for mouse virulence. The majority of strains showing large round-type growth was virulent, diffuse-type strains displayed a low virulence, while no mouse was killed by compact-type strains.

Four hundred and seventy Klebsiella and 103 Enterobacter strains derived from urogenital infections, upper respiratory tract and wound infections were examined. (i) K. aerogenes was the most common among Klebsiella species, K. ozaenae and K. atlantae occurred frequently, K. pneumoniae, K. rhinoscleromatis, K. edwardsii and K. oxytoca were found rarely. The strains isolated from urine showed the most heterogeneous species distribution. Enterobacter species were in the order of frequency E. cloacae, E. liquefaciens, E. aerogenes. (ii) K. aerogenes strains belonged to 10, K. atlantae strains to 6 phage types; phage type II.A1 was the most frequent phage types. Typability varied between 23.7% and 48.0% with the different Klebsiella species, except K. edwardsii and K. oxytoca strains. None of the strains of these species were typable by phages. Among the Enterobacter species examined, only one E. liquefaciens strain was typable by phages. Strains of genus Enterobacter were lysed by the diagnostic phage C14 in 64%, no lysis was observed in the strains of genus Klebsiella. (iii) Multiple resistance was demonstrated in 36.6% of Klebsiella strains and in 16.5% of Enterobacter strains. The majority of the multiresistant strains was isolated from urine in both genera. Multiresistant strains belonged to the species K. aerogenes, E. cloacae and E. liquefaciens. Strains resistant to ampicillin were divided into 6 groups on the basis of cephaloridine and cephalothin resistance. The rate of multiresistant strains was higher among the Klebsiella and Enterobacter strains not typable by phages than in the typable ones.

While the plating efficiency of mycobacteriophage butyricum (By) on Mycobacterium smegmatis strain Rabinowitz (M.sm.R.) cells is less than 10(-8), it proved to be 5 X 10(-1) on the lysogenic Mycobacterium smegmatis strain Rabinowitz (M.sm.R. [V72]) cells. Bacteriophage By forms plaques on M.sm.R. cells at a very low frequency; it can, however, adsorb to these cells in the same degree as to its original host. The average burst size of Mycobacterium smegmatis strain butyricum (M.sm.b.) cells infected with mycobacteriophage By is 60, and that of M.sm.R. (V72) superinfected with bacteriophage By is only 6. A double lysognic strain was isolated from M.sm.R. (V72) cells surviving By phage infection.

Fine interhexonal connections were observed in high resolution electron micrographs of tight two-dimensional hexagonal crystalline arrays. Intrahexonal connections were found among the three polypeptides constituting the hexons. The length of the interhexonal connections was 2.73 mm, and their diameter 1.2 nm; that of the intrahexonal connections were 1.05 nm and 0.75 nm, respectively. The orientation of the hexons in a two-dimensional crystalline array corresponded to a corner to edge conjunction. One side of each of the three polypeptides, constituting a triangular hexon, corresponded to the sides of that hexon; their points of contact were the corners. A tentative diagram of the molecular arrangement of hexon polypeptides and of interhexonal connections was drawn up following analysis of the electron micrographs. It showed that parallel connections run to both ends of each polypeptide of a hexon, connected to one of the end parts of the two nearest polypeptides of the next hexon, as follows from the threefold symmetry. Thus, every hexon is joined to its six neighbours by six times two parallel connections. Two pairs of parallel connections enclose an angle of approximately 60 degrees.

Ovine fetuses were examined for immune responsiveness to ovine adenovirus (strain ORT/111) at 70-80 days of gestation. Nineteen days after experimental infection, all infected fetuses, along with their eventual non-infected twins, had neutralizing serum antibodies to the virus in the titre range of 1 : 32-1 : 128. The antibodies were identified electrophoretically as subclass IgG1 and IgG2. No other Ig-class was involved in the immune response. Infection of the fetuses accounted for antibody production in the maternal organism, too. Immunofluorescence tests detected a periarteriolar, diffuse or focal occurrence of IgG-positive cells in the fetal spleen, and in pulmonary, renal and cotyledon tissue samples. IgM-positive cells were found exclusively in the spleen, always in a low number and in diffuse distribution. No Ig-carrier cells were detected in the liver, thymus and lymph nodes. The blood contained both IgG and IgM-positive cells at a proportion of 6-7 and 1-2%, respectively. Spleen cell cultures stimulated in vitro with ovine adenovirus antigen showed an average 3HTdR incorporation rate of 22%.