Acta microbiologica Hungarica最新文献

The number of Salmonella enteritidis isolations started to rise in humans, eggs and egg products in 4 territories out of the examined 9 territories of Russia in 1986. The spread of S. enteritidis infections was connected with the consumption of hen's eggs as it was demonstrated by the analysis of the local outbreaks. Phage type of 1142 S. enteritidis strains isolated in Russia was determined using the Hungarian typing scheme. The strains were typable in 95.3% and 12 phage types were found. Phage type 1 was the most frequent (86.7%) among human strains and also among strains originated from hen and egg products. The examined 18226 human S. enteritidis strains isolated in Hungary between 1984 and 1989 belonged to 24 phage types and phage type 1 was predominant, the incidence of this type varying between 69.3% and 93.2%. The strains were sensitive to antibiotics, multiresistant strains were found in 1%. Plasmid content was examined of 138 strains; a 38 Md plasmid was carried by all of them and a 96 Md plasmid was harboured by 11 antibiotic-resistant strains. The tested strains produced enterobactin but no aerobactin.

We have previously demonstrated that acidic medium inhibits the replication of HIV-1. The present study was designed to examine the effects of other growth conditions and infection of fibroblasts by coculture with HIV infected lymphoid cells. Several lymphoblastoid cell lines normally grown in RPMI-1640 were grown in Eagle's MEM. These cells supported virus replication to higher titres than did RPMI-1640. Peak viral titres were achieved within 24-48 h after newly infected or chronically infected cells were placed in fresh medium. When virus was stored in liquid medium either frozen or at higher temperatures, virus titres were retained for several months while frozen but decreased upon storage at 4 degrees C or higher. If cells were passaged after trypsinization in Ca(++)-depleted medium, then a decreased susceptibility of cells for HIV-1 by 2 log10 at 24 h post infection was observed. Infectivity of cell-free and cell-associated HIV-1 was measured using syncytium formation, reverse transcriptase activity and p24 antigen. No fusion between HIV-1 infected CD4+ lymphoblasts and CD4- fibroblasts was observed but HIV-1 infected lymphoid cells, even in the absence of syncytium formation, exerted a strong toxic effect on fibroblasts. This study extends previous findings that medium acidity was inhibitory to virus replication and survival. Thus, conditions for study of HIV must be well controlled in buffered medium so that misleading results are not obtained regarding virus multiplication and possibly regarding transmission to and pathogenesis in CD4- cells.

A total of 121 Yersinia enterocolitica O3 isolates from patients with gastroenteritis and 37 Y. enterocolitica reference strains with different O antigens were tested for bacteriocine production and sensitivity. By using cross-streaking method strains belonging to serogroups of O5; O7,8; O7,13; O11; O11,23; O13,27; O17; O19,8 and O34 produced bacteriocin-like substances. None of the Y. enterocolitica O3 strains produced bacteriocin-like material and most of them were uniformly sensitive against the bacteriocin-like material produced by strains of serogroups O7,8; O7,13; O13,27 and O19,8. By sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) significant differences were demonstrated in the whole cell protein patterns of Y. enterocolitica reference strains belonging to different serogroups in the range of 33-47 kilodalton (kDa). Out of the ten examined bacteriocin-like material producer strains only one strain harboured a plasmid of about 60 megadalton (MDa).

The combined antiviral effects of some flavonoid compounds and acycloguanosine (acyclovir, Zovirax) were studied on the multiplication of herpes simplex virus types 1 and 2 in HEp-2 cells and on pseudorabies (Aujeszky) virus in chick embryo fibroblast cells by the yield reduction method. The flavonoids quercetin, quercitrin (quercetin-3-L-rhamnoside) and apigenin exhibit antiviral activity against these herpesviruses, and acyclovir is currently one of the most effective antiherpetic agents. In these studies, the simultaneous application of flavonoids with acyclovir resulted in an enhanced antiviral activity. A mathematical formula was used to interpret the drug interaction, resulting in FIC (fractional inhibitory concentration) indices. Meaning a synergic interaction, all combinations exhibited synergy, FIC values of 0.6-0.8 being commonly observed.

Enteroinvasive Escherichia coli exhibited a positive reaction in the mouse intestinal loop assay except for noninvasive mutant strains. These mean values of fluid weight per gut length of mouse loops inoculated with enteroinvasive E. coli were significantly higher than that given by brain heart infusion broth. Oedema and swelling in all positive loops, increased bacterial cell numbers within intestinal loops were observed.

Ten selected samples of amniotic fluid obtained through transabdominal amniocentesis from 10 pregnant women in their 17th-19th weeks of pregnancy were investigated for the survival of Neisseria gonorrhoeae in amniotic fluid. In 8 cases an antibacterial effect was observed with morphological changes comparable to the effect of benzylpenicillin. When N. gonorrhoeae was inoculated in amniotic fluid at 10(5)-10(7) cells/ml, it survived as an average 2 h longer than after inoculation of 10(2)-10(4) cells/ml. Electron microscopic pictures of gonococci taken after 2.6 and 24 h incubation in amniotic fluid correlated with the growth curves. Electron microscopically there were marked morphologic changes of N. gonorrhoeae, viz. vacuolar degeneration of their cytoplasm with a damage to the bacterial wall up to its complete destruction and lysis of the cell.

Antibodies to Legionella pneumophila were found by indirect immunofluorescence assay in 525 samples of human serum. The samples were obtained from 451 patients who were suspected of having an acute infectious illness, with mainly respiratory symptoms; 90 patients had antibodies to L. pneumophila (19.9%). The results suggest that the prevalence of L. pneumophila is greater than had previously been supposed.

A 4-kilobase congo red binding plasmid DNA fragment of pCAT 120 of Shigella dysenteriae 1 was transferred to an Escherichia coli K12 strain by transformation. Transformants were unable to grow in any liquid broth medium. Electron microscopic studies revealed that the transformants grown on tryptic soy agar were associated in clusters after cell division. Normal cell separation among the transformants in comparison with recipient E. coli K12 was only observed when the growth medium was supplemented with sterile culture filtrate of the recipient strain. An unknown factor(s) required for cell separation located on the chromosome was suppressed by a 4-kb congo red binding plasmid DNA (pCAT 120) fragment of S. dysenteriae 1.

A strain of Escherichia coli K-12 carrying the 140-Megadalton virulence plasmid of the enteroinvasive E. coli--J53(pSPl)--showed high virulence in the "mouse model", in chick embryos, but not in the Serény test. It expresses the outer membrane proteins thermoregulatedly, encoded also by the virulence plasmid. In orally infected streptomycin-pretreated mice this strain infects only the large bowel, shows adherence to the epithelial surface, but in its first step preferentially to the mucus excreted by the goblet cells. Epithelial penetration and intracellular multiplication occurs with a characteristic localization of bacteria in the depth of crypts. Consequence of the infection is degeneration of the epithelial surface, its denudation.

Two 1.7 Md plasmids of Staphylococcus epidermidis and three ones of Staphylococcus simulans determining inducible macrolide-lincosamide resistance are identical as judged by restriction endonuclease fingerprinting. These plasmids designated pEI2101, pEI9105, pE1107, pEI1108 and pEI6104, respectively, belong to the incompatibility group 12. Dot-blot hybridization by photobiotin-labelled gene probe developed from S. aureus erythromycin ribosomal methylase gene showed cross hybridization between methylase-coding reference plasmids and the tested ones. The examined plasmids proved to be no transmissible in mating experiments into S. aureus recipients.