Acta microbiologica Academiae Scientiarum Hungaricae最新文献

The number of patients admitted to hospital who harbour Pseudomonas aeruginosa, Proteus and Klebsiella, keeps rising. Of the factors predisposing to colonization, only diabetes and antibiotic therapy exert their effect equally in extrahospital and intrahospital environment. Malignant diseases, immune suppressive therapy and instrumental interventions play a predominant role in the hospital. In extrahospital environment, infancy and old age, poor general condition as well as in almost half of the cases, an inflammatory process caused by viruses or bacteria was found to create favourable conditions for the colonization of facultative pathogens. One of the main sources of the Gram-negative facultative pathogens studied was the faeces of enteric patients in the hospital. The frequency of P. aeruginosa, Klebsiella and Proteus positive cultures rose parallel in the faecal and non-faecal bacteriological samples in the period 1958 to 1977. The seasonal changes observed in the frequency of positive cultures revealed that the Gram-negative facultative pathogens had increased in number first in the enteral wards, spreading subsequently to the medical and paediatric wards, and finally they appeared in a high number in the surgical wards, originating from patients transferred there from the medical or paediatric wards.

In the presence of L-cysteine, all the 24 dermatophyton fungi under study grew poorly. None of the strains, except Trichophyton menatographytes var. quinckeanum, grew in the presence of 0.04 M L-cysteine. The strains growing on a medium containing L-cysteine showed morphological changes. The surface of the colonies lost its velvety appearance and became awnless or waxy. The strains grown in the presence of L-cysteine abundantly formed chlamydospores. The chains of chlamydospores may resemble yeast cell chains, but true budding forms were not found in cultures in vitro. If strains precultivated on L-cysteine-containing medium were injected intraperitoneally into mice budding forms appeared in the peritoneal fluid.

The role in the vesico-renal pathogenicity of Escherichia coli of mannose resistant fimbriae provisionally designated "119" has been studied in a suckling mouse model. Two to 3 days old mice were infected by route of the urinary bladder and the occurrence and character of the developing infection were investigated. (i) The fimbriated strain caused infection and inflammation of the bladder in almost 100%. In about 60% of the cases it lasted till the end of observations, the 35-37th day following inoculation. The washed, vortexed urinary bladder taken up in 5ml of saline contained a high number (10(6)-10(9)/ml) of bacteria, the urine was often cloudy, containing numerous leucocytes and epithelial cells packed with bacteria. The kidneys were soon involved and by the 23th ad 37th day gross changes were seen in about 25%. In 10%, a classical contracted kidney developed. (ii) The nonfimbriated derivate also caused acute or chronic urinary tract infection, but with a lower frequency and the number of bacteria was also lower by 3-4 log 10 exponents. The model seems to be promising for the study of bacterial infections of the urinary tract and perhaps also for elucidation of its immunological and therapeutic aspects.

A white sporulated stable mutant strain (strain No. 66/m) of a Streptomyces sp. belonging to the nigrescens group of the typical grey Streptomyces spp. has been isolated. On the basis of ISP *International Streptomyces Project) criteria strain No. 66/m would be considered a true member of the albus-group of Streptomyces (regarded by some workers as a well separated assemblage of species) all the more so because it fits into this alien group at least in such a degree as into that from which it has originated. Caution is necessary in using the aerial mycelium colour as a distinguishing diagnostic property for establishing large intraspecific groups, series, or even in separating species of Streptomyces.

Bacteriological examinations carried out in an infectious hospital revealed that the occurrence of Pseudomonas and Proteus grew 4-fold, and the rate of Klebsiella positive cultures 3.5-fold between 1958 and 1977. On the other hand, the occurrence of Staphylococcus aureus decreased to the half since 1961. The occurrence of Gram-negative facultative pathogens started to increase in the surgical wards in the fifties and the rise lasted until the mid-sixties. Pseudomonas aeruginosa was the most frequent among them. In contrast, Escherichia coli dominated and P. aeruginosa was the least frequent in the non-surgical wards. Here the Gram-negative facultative pathogens showed a more rapid increase and the incidence of P. aeruginosa and Proteus kept rising throughout the whole examination period. When Gram-negative facultative pathogens of hospital origin were colonizing, the proportion of sick persons versus symptomless carriers was significantly higher than in the case of extrahospital colonization on the basis of the records of 300 P. aeruginosa, 300 Proteus and 300 Klebsiella positive patients. This proportion changed parallel with the rate of the strains of hospital origin. The number of patients who acquired P. aeruginosa, Proteus or Klebsiella extrahospitally, kept continuously rising between 1958 and 1971. Thus, the advance of Gram-negative facultative pathogens is due not ony to nosocomial causes.

Stringent and relaxed Escherichia coli strains grown on minimal and on differently enriched media produced guanosine polyphosphates in the stationary phase of growth. On transition from the logarithmic to the stationary phase, stringent strains started to produce guanosine 5' triphosphate 3' diphosphate (pppGpp). and guanosine 5' diphosphate 3' diphosphate (ppGpp), while relaxes strains accumulated only ppGpp. When the stringent strain was cultivated on media enriched with Casamino Acids the leve of pppGpp decreased, while with yeast extract an almost twofold increase could be observed. The concentration of ppGpp increased with both nutrients as compared to that measured in minimal medium. Readdition of glucose to the stationary phase culture did not result in the slightest decrease of the nucleoside polyphosphate levels. In contrast, addition of a mixture of 20 L-amino acids or Casamino Acids or yeast extract to the medium caused an abrupt decrease in the guanosine polyphosphate levels. Qualitatively similar results were obtained with the relaxed strains except that the amounts of ppGpp were smaller than in the case of the stringent counterpart and the responses to the resupplementation were slower. Some possible mechanisms regarding the occurrence of guanosine polyphosphates in the stationary phase are discussed.

Treponema pallidum was discovered relatively late and was not cultured in vitro. Both the delineation of T. pallidum biology and the eradication of syphilis suggest the necessity of cultivation in vitro. An attempt has been made with an improved medium to cultivate pathogenic T. pallidum Budapest strain in vitro. Only in the first passage, evidence of in vitro multiplication of T. pallidum has been established by (i) macroscopic observation, (ii) darkfield examination, (iii) electron microscopic examination, (iv) optical densities, (v) tritium labelled thymidine incorporation, and (vi) the pathogenicity off the cultured organisms was evidenced by rabbit challenge. Explanation of the oxygen utilization of T. pallidum suspension is discussed. Unidentified formations were observed on electron micrographs from the 96 h cultures. They may belong to the multiplication forms of treponemes. Further experiments are needed for their identification and for expansion of the multiplication of T. pallidum beyond the first passage.