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

In order to investigate the course of Serratia marcescens endocarditis in groups of rabbits with and without an indwelling catheter, 130 rabbits were pretreated to produce left-sided endocarditis. Three clinical isolates of S. marcescens were used to infect the rabbits, i.e. CDC O13 (serum sensitive, proteolytic), SM 104 (serum resistant, proteolytic) and SM 55 (highly serum resistant, non-proteolytic). Ten rabbits with an indwelling catheter were challenged with CDC O13 and none of them died or showed evidence of endocarditis 28 days later. In groups of rabbits with indwelling catheters which were challenged with SM 104 or SM 55 there was a high incidence of endocarditis (19/20, 18/20, respectively), while groups without catheters inoculated with the same strains had a lower incidence (5/20, 15/20, respectively). In contrast to earlier observations with Streptococcus faecalis, the clinical and pathological data were not significantly influenced by the presence or absence of proteolytic capacity of the infecting strains. The results indicate that the ability of S. marcescens to establish endocarditis depends significantly on the degree of serum resistance of the strains. This difference was only demonstrable in experiments without an indwelling catheter during the infection period. The distrurbing influence of an indwelling catheter is discussed, and it is concluded that experimental models using indwelling catheters are inappropriate for studies on the pathophysiology of endocarditis.

A total of 412 strains of Yersinia enterocolitica and Y. enterocolitica-like bacteria were examined for their ability to interact with HeLa cell monolayers. Of 331 isolates from environmental sources in Scandinavia, only three strains biochemically classified as Y. pseudotuberculosis were invasive for HeLa cells. Invasiveness was also indicated for one strain (O-serogroup 2) from a disease goat. Another eight strains adhered firmly to the cell surface in great numbers. All of 22 strains belonging to O-serogroup 3 from human patients with gastroenteritis were invasive. Seven strains of O-serogroup 3 from small rodents and water were non-invasive. Among 33 reference strains representing Y. enterocolitica O-serogroup 1-34, invasiveness was indicated for strains with known pathogenicity (O-serogroup 1, 2, 3, 5-27, 8, 9). However, some strains belonging to O-serogroups with uncertain clinical significance were also invasive for HeLa cells. A close correlation between invasiveness and enterotoxin production was demonstrated for the 22 human clinical isolates belonging to O-serogroup 3.

Rabbit antisera against two strains of Campylobacter fetus ss. fetus (serotype A), two strains of C. fetus ss. intestinalis (serotypes A and B respectively), and eight stains of C. fetus ss. jejuni were used in serological studies of these strains with the use of co-agglutination (COA), line-rocket immunoelectrophoresis (L-RIE) and rocket-line immunoelectrophoresis (R-LIE). Whole bacterial cells, either heated at 56 degrees C. boiled or atuoclaved, were used in COA tests. Unheated sonicates were used in L-RIE, and sonicates, unheated, boiled or autoclaved, in R-LIE. The antigenic properties of C. fetus ss. fetus and C. fetus ss. intestinalis were distinctly different from those of the thermophilic C. fetus ss. jejuni strains as shown both by COA and L-RIE. Serotypes A and B of the two former species were also differentiated. In COA tests the C. fetus ss. jejui=ni organisms gave the strongest reactions with homologous antibodies, but several interstrain cross-reactions were seen. By absorption strain specific COA reagents were obtained. Several reactions of identity indicating cross-reactive antigens were also seen with L-RIE within the ss. jejuni group. These results generally agreed with those obtained by COA. With the use of unheated, boiled or autoclaved organisms or sonicates heat labile antigens were differentiated from heat stable ones with the use of COA and R-LIE. The apparent antigenic heterogeneity of Campylobacteria indicates the importance of their serological grouping, e.g. for clinical and epidemiological investigations. COA and immunoelectrophoresis techniques can be effectively applied for such studies.

Intraperitoneally (i.p.) injected interferon prolonged the survival time of mice inoculated intranasally (i.n.) with Sendai virus and reduced the mortality in mice inoculated i.n. with Haemophilus influenzae. Moderate concentrations of interferon were demonstrated in homogenized lungs of Sendai virus infected mice as long as the virus was present. Similar concentrations could be produced by i.p. injection of Sendai virus or interferon. Alveolar macrophages from mice treated i.p. with interferon or Sendai virus phagocytized more actively than control macropages. From the present and earlier data it is concluded that interferon may have a direct effect on the Sendai virus infection. The total effect of virus pneumonia is a reduction of the lung macrophage antimicrobial activity, and therefore the phagocytosis-modifying effect of interferon produced in the lungs is probably of minor importance for the outcome of the disease.

A study on the interaction of different sera and polymorphonuclear cells (PMN) with reference to the ABO blood group system on the phagocytosis of a radiolabelled strain of E. coli is reported. Using untreated sera, O cells were found to be the least sensitive and AB cells the most sensitive to reduction in phagocytic activity. No reduced phagocytic capability relative to the different sera used was observed when heat-inactivated sera were applied. Aspects of these results are discussed.

Insertion of a polyethylene catheter into the left ventricle of the heart was used for regular establishment of sterile endocarditis, and bacterial endocarditis was established by injection of approximately 10(8) Streptococcus faecalis into the blood stream at the same time as removal of the catheter which had been in place for 3 days. 100 out of 102 rabbits died spontaneously of bacterial endocarditis. Evidence is produced that the host-parasite interaction is influenced by the proteolytic property of S. faecalis in this experimental model. Two distinct types of clinical course are described: 1) A predominantly acute and damaging illness, characterized by a high level of bacteraemia, small amounts of soft, friable vegetations in the left side of the heart, high frequency of kidney infarcts and shorter survival time in rabbits infected with proteolytic strains. 2) A relatively subacute illness, characterized by a lower level of bacteraemia, large, hard, non-friable vegetations on the aortic valves, less pronounced destructive changes in the substance of valve leaflets, relatively lower frequency of kidney infarcts and longer survival time in rabbits infected with non-proteolytic strains. The results suggest that proteolytic strains of S. faecalis cause partial dissolution of the vegetations resulting in a more severe clinical picture.

The distribution of interferon in body fluids and tissues was studied in 18 rabbits infected experimentally with the agent of pleural effusion disease (PED). Circulating interferon of the classical type was demonstrable 12 h after inoculation, and a maximum response was attained 2-3 days later. Circulating interferon disappeared between 6 and 8 days after inoculation. Interferon titres of serum were closely correlated with the early phase of febrile response and probably also with the initial growth phase of the PED agent. The interferon titres of pleural fluid exceeded by far the titres of other body fluids and tissues. No interferon could be demonstrated in brain, liver and urine.

Binding of radiolabelled fibrinogen was measured to 197 strains of 16 different bacterial species. All streptococcal strains belonging to groups A, C, and G isolated from human sources were strongly positive. S. aureus strains showed low binding values. Occasional group B streptococci were positive. Reactive strains were also noted among group C streptococci of animal origin, Streptococcus zooepidemicus and Str. equii, and bovine beta-hemolytic group G streptococci. Bovine alpha-hemolytic group G strains as well as the remaining seven species of human origin were all negative. Inhibition experiments and correlation studies indicated that the streptococcal receptor for fibrinogen was different from immunoglobulin Fc binding reactivity. Comparisons with the newly discovered beta 2-microglobulin binding factor showed that trypsin concentrations which destroyed this receptor left the fibrinogen receptor intact. Although the two receptors correlate in strain population studies and show competition for binding the difference in trypsin sensitivity indicates that they represent two different structural entities. Both receptors might serve as basic markers for M-protein like surface components of Gram positive cocci.

beta-glucuronidase activity is an exclusive characteristic of E. Coli and some shigellae among Enterobacteriaceae and Vibrionaceae. An agar medium (PGUA agar) which permits the detection of bacteria with beta-glucuronidase activity in mixed cultures was evaluated as a primary culture medium for clinical samples of urine. The medium was selective for enterobacteria and yielded significantly higher recoveries than MacConkey agar. Based on the examination of 3,460 urine samples, it was found that the use of the PGUA agar has several advantages over conventional methods: 1) 94% of all E. coli cultures could be identified on the basis of their appearance on the primary plates; 2) The use of the PGUA method did not result in any misidentidications as compared to 1% of cultured misidentified by the conventional procedure; 3) Approximately one-half of the urine samples which contained E. coli as the sole organism could be reported following the reading of primary culture plates; 4) The application of the PGUA medium resulted in a 46% reduction in the cost of media employed and a 67% reduction in the time required for the processing of urine samples.