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

The ultrastructure of Staphylococcus aureus grown on plates containing chlorpromazine (CPZ) in concentrations up to a bacteriostatic level (50 micrograms/ml) was studied. High concentrations of CPZ induced large mesosome-like structures and asymmetrical cell divisions in a considerable number of cells.

Staphylococcus aureus enterotoxins A, B, and C, were detected by means of a four-layer sandwich ELISA method. With toxin produced in broth supernatants, this ELISA method had a detection limit of 0.5 ng enterotoxin per ml. Conjoint with enterotoxin, S. aureus most often produces protein A. The protein A will interfere and produce false positive reactions in a sandwich ELISA, by binding nonspecifically the IgG in different layers, simulating the immunospecific toxin binding. With rabbit IgG coupled to Sepharose CL-4B gel, 99% of protein A could be removed from solutions, bringing the level under the interfering limit in the ELISA.

The production of enterotoxins by strains of Staphylococcus aureus of human and animal origin seems to be common. 104 out of 170 strains (61%) produced one or more of the A, B, and C enterotoxins. Strains from cow and milk often produced enterotoxin C, and enterotoxin A producing strains were mainly isolated from dogs. Human food poisoning seemed in our material to be induced by enterotoxin A producing strains.

Eighty-eight T-type 12 group A streptococcal strains were randomly selected from routine specimens in two epidemiologically unrelated districts. All of 26 M-type 12 strains lacked IgA and IgG Fc-receptors, whereas all 32 M-type 22 strains had IgG Fc-receptors and 20 of them also receptors for IgA Fc. The remaining strains were not further M-typed but 18 of these 30 strains exhibited receptors for IgG and 13 for IgA.

Herpes simplex virus (HSV) type 1 antigens were detected in infected human embryonic lung cells with the aid of specific antiserum and Staphylococcus aureus rich in protein A. When such staphylococci carrying specific anti-HSV IgG on their surface were interacted with various suspension of virus, a reduction in the initial virus titre of about 65% was obtained. However, no direct coagglutination was observed between cell-free supernatants of HSV or HSV-infected cells and sensitized staphylococci. When monolayers or suspended cells infected with the virus were treated with dilutions of specific anti-HSV antiserum followed by non-sensitized staphylococci (indirect method), an "aureola" of the bacteria was detected around the cells expressing the viral antigens. A similar picture was observed when infected cells were interacted directly with sensitized staphylococci. Viral antigens were detected already 12 hours post infection, well before the appearance of cytopathic effect. The sensitivity of the indirect method was found to be higher than that of the direct one and dependent on the multiplicity of infection and the serum dilution used. The method is proposed as a rapid means of identifying viral antigens in diagnostic and experimental virology.

Measurement of the IC50 of cis(Z)-clopenthixol and trans(E)-clopenthixol on 188 bacterial strains from human clinical specimens shows that the antibacterial activity of clopenthixol is exerted by both isomerical components and trans(E)-clopenthixol is the most active antibiotic of the two drugs against the sensitive strains. It is known that the trans(E)-clopenthixol isomere is without neuroleptic effect. The possibility of creating new antibiotics by e.g. steric alteration of neuroleptical agents is stressed. These drugs have different antibiotic patterns from those of classical antibiotics. It seems particularly promising that Pseudomonas aeruginosa is sensitive to these drugs.

The toxinogenicity of fifty coagulase-negative staphylococci isolated from various clinical syndromes was compared, using lysis of human erythrocytes, leakage of a radio-active marker from human embryonic lung fibroblasts by culture filtrates, and direct cytotoxicity of growing bacteria towards mouse skin fibroblasts in an agar overlay assay. Good correlation was obtained between those strains which elaborated greater than or equal to 16 HU/ml delta-toxin in culture, measurable also in terms of radioactive nucleotide leakage from tissue culture cells and those strains which caused a direct cytotoxicity effect in the colony overlay test. delta-toxin was implicated in the genesis of such cellular damage. Speciation of the coagulase-negative staphylococci revealed that isolates identified as S. epidermidis, S. saprophyticus and S. haemolyticus were most active in each of these tests. The colony overlay technique is suggested as being a potential screening assay for toxinogenic coagulase-negative staphylococci associated with clinical infections.