The virulence of clinical isolates of Acinetobacter calcoaceticus, Pseudomonas cepacia, and Pseudomonas maltophilia in urinary tract in mice was studied.In general, the virulence of these organisms in urinary tract of normal mice was relatively mild.The effect of anti-inflammatory and immunosuppressive drugs on pathogenicity of these organisms was studied in mice.The mice previously treated with betamethasone or prednisolone as anti-inflammatory drug, and with cyclophosphamide or azathiopurine as immunosuppressive drug, were more susceptible to these bacterial infections than were the non-treated ones.As for the capacity of bacterial attachment to the epithelial cells of the bladder, these organisms were generally shown to have low adhesion.Furthermore, the hemagglutination patterns were mannose-sensitive in human and guinea pig erythrocytes.
Pseudomonas aeruginosa and Escherichia coli were exposed to nocardicin A, and were subsequently observed with transmission and scanning electron microscopes. Although the nocardicin A-induced morphological alterations such as bulges and spheroplast formations were observed both in P. aeruginosa and E. coli, their positions on the cell surface were different in the two species.
The therapeutic efficacy of AC-1370, a new cephalosporin, was compared with that of cefoperazone in experimental infections in mice. For intraperitoneal infections caused by Escherichia coli and Klebsiella pneumoniae, the efficacy of AC-1370 was inferior to that of cefoperazone. On the other hand, AC-1370 was more potent than cefoperazone against pseudomonal infections. The MICs of AC-1370 against the test strains, however, were inferior or equivalent to those of cefoperazone. Serum and peritoneal exudate levels of AC-1370 in infected mice were more durable than those of cefoperazone. The relationship between AC-1370 and neutrophils was investigated. The efficacy of AC-1370 was more dependent on neutrophils than that of cefoperazone. AC-1370 did not enhance the neutrophil functions of migration and phagocytosis to any significant extent.
Pseudomonas aeruginosa and Escherichia coli were exposed to nocardicin A, and were subsequently observed with transmission and scanning electron microscopes. Although the nocardicin A-induced morphological alterations such as bulges and spheroplast formations were observed both in P. aeruginosa and E. coli, their positions on the cell surface were different in the two species.
The virulence of 40 clinical isolates of Acinetobacter calcoaceticus was studied by means of an experimental infection model in mice. The therapeutic efficacy of antibiotic treatment and the responses to nonspecific defense mechanisms were concurrently investigated. The LD50 value (cells/mouse) of A. calcoaceticus inoculated i. p. with mucin was>106 cells/mouse for. about 60% of the strains and ≤106 cells/mouse for the remaining 40%, with 15% of the latter strains being highly virulent (LD50: 103-105 cells/mouse). LD50 values derived by i. p. or i. v. inoculation without mucin were considerably lower than when mucin was concomitantly used. Tests on the therapeutic efficacy of antibiotics in the treatment of experimental i.p. infections revealed that tetracyclines, aminoglycosides and peptides, compounds which were highly active in vitro, were likewise very effective in vivo. The response to nonspecific defense mechanisms was investigated by testing the influence of serum and phagocytosis by polymorphonuclear neutrophils. Virulent strains were resistant to both effects.
We examined the effect of the slime isolated from Acinetobacter calcoaceticus on the functions of phagocytes.The slime showed high cytotoxicity to phagocytes of mouse, guinea pig and rabbit. The activity of NBT reduction, chemotactic activity and Phagocytic killing activity on Escherichia coli were suppressed by the addition of relatively small amounts of the slime to mouse leukocytes. It is suggested that the slime induced the enhancement of virulence of other species, because of suppression of the function of phagocytes.
The virulence of clinical isolates ofAcinetobactercal coaceticus subsp.anitratus was studied in mice, andin-vitro andin-vivo activities of several antimicrobial agents were evaluated Inm-vitro susceptibility testings, tetracyclines, aminoglycosides, and peptide were highly sensitive, and nunocycline and doxycycline were the most active of 21 antibiotics tested against 84 clinical isolates of Acin. calcoaceticus. Virulence tests for mice revealed that some strains exhibited high virulence with LD50 values between 103 and 10* viable cells/mouse. Against lethal and urinary tract infections produced by Acin. calcoaceticus Ac-54 strain in mice, minocycline, doxycycline, gentamicin, and dibekacin, which were highly active in vitro, were effective.
Acinetobacter calcoaceticus, which is unable to grow in the presence of glucose because it lacks hexokinase and gluconokinase activities, grows well in the presence of permeable intermediates of the tricarboxylic acid cycle. However, addition of glucose led to increased rates of growth with other carbon sources, although it is unable to grow in the presence of glucose as the sole carbon source. This species possesses pyrrolo-quinoline quinone-dependent glucose dehydrogenase on the outside of the membrane, and through coupling with this emzyme, ATP was synthesized in the presence of glucose. The newly biosynthesized ATP with the addition of glucose led to increases in the initial rate of the active transport system and the growth rate of the cells. The supplemental energy due to glucose oxidation may be obtained through a cytochrome-linked reaction with the glucose dehydrogenase.
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