Induction of L-forms of Haemophilus influenzae in vitro.
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The induction of L-forms of Haemophilus influenzae by penicillin, amoxycillin and glycine has been studies in vitro on a nutrient-agar medium. The minimal inducing concentrations of the antibiotics were generally the same as their minimal inhibitory concentrations, but the addition of a sub-inducing concentration of glycine lowered the minimal inducing concentration of penicillin. Preliminary observations have shown that L-forms are induced by penicillin or amoxycillin on a medium in which mucoid sputum forms the sole source of nutrients, and that they remain viable for at least 48 h in the absence of added osmotic stabiliser. The minimal inducing concentration on "sputum agar" is within the range of concentrations measured in sputum from patients receiving amoxycillin therapy. The implications of these observations in relation to bactericidal therapy of haemophilus infections of the respiratory tract are discussed. (+info)
In vivo behavior of revertants from Stahylococcus aureus L-phase variants compared with the parent strain.
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The in vivo behavior of revertants of Staphylococcus aureus L-phase variants were studied in mice. The Giorgio strain of S. aureus was induced into L-phase variants by methicillin. After 13 serial passages in methicillin agar and six passages in antibiotic-free agar, reversion occurred. Six revertants, all phage untypable, coagulase negative, and mannitol negative, were inoculated intravenously into Swiss albino mice in comparison with the parent strain. Inoculation of 10(8) colony-forming units resulted in 38% mortality at 28 days for the Giorgio group and 0 to 2% for the revertants. The geometric mean titer of staphylococci in the kidneys was 3.5 x 10(5) for the Giorgio group and 0.5 x 10(0) to 1.0 x 10(2) for the revertants. Serial colony counts of blood, lungs, spleen, liver, and kidneys in mice inoculated with 10(7) colony-forming units showed faster clearance and failure of the revertant to colonize the kidneys. It is concluded that the in vivo behavior of the L-phase revertants was vastly different from that of the parent Giorgio strain. (+info)
Selective association of the chromosome with membrane in a stable L-form of Bacillus subtilis.
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A stalbe L-form (Sal-1) of Bacillus subtilis was found to have retained a markedly modified chromosome-membrane association when compared to intact cells. The membrane-deoxyribonucleic acid complex of the L-form was similar to that of its parental strain in quantity and stability. Genetic analysis of the L-form membrane-deoxyribonucleic acid complex revealed enrichment for markers close to the replication origin, but not for internal markers, indicating preferential attachment of the origin of chromosomal replication to the membrane. These results are in close agreement with those found for the parental bacterial form. In contrast, the replication termius region was not preferentially attached to the membrane of the L-form, even though it is enriched in the bacterial form. The association of the chromosome with the membrane at the replication terminus does not appear to be necessary for cell growth and separation, but because the L-form divides aberrantly, it may be one of the factors required for normal deoxyribonucleic acid segregation and septation. (+info)
Clinical and bacteriologic study of eighty-six patients with systemic lupus erythematosus complicated by infections.
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OBJECTIVE: To investigate the clinical and bacteriologic features of patients with systemic lupus erythematosus (SLE) complicated by bacterial and/or fungal infections. METHODS: Statistical analysis was made on basis of the clinical and bacteriologic data of 86 patients with SLE complicated by bacterial and/or fungal infections. RESULTS: One hundred and thirty-three episodes of infections occurred in 86 patients with SLE, in which 51.13% were nosocomial infections and 76.69% occurred in the blood system, respiratory tract, lungs and urinary tract. Gram-negative bacilli, gram-positive cocci, fungal and other bacterial infections accounted for 39.85%, 31.58%, 18.80% and 9.77%, respectively. In the bacterial infections, 18.52% were caused by L-form bacteria and more than 60% of the patients had no apparent toxic manifestations. The odds ratio (OR) of infection increased significantly in patients with damaged functions of the heart, lungs and kidneys, and in those who received high-dosage steroids. CONCLUSIONS: Patients with SLE tend to develop nosocomial infections with gram-negative bacilli which are the most common pathogens. The clinical manifestations of the infection are atypical. Careful inspection and monitoring, timely collecting the specimens for L-form bacterial culture can reduce misdiagnosis and missed diagnosis of the infection. (+info)
Ultrastructure of L-phase variants isolated from a culture of Mycobacterium phlei.
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Relatively stable L-phase colonies were isolated from old cultures of a selected clone of Mycobacterium phlei. The colonies grew at 52 degrees C and were composed of rod-shaped, oval or spherical cells. Large amoeba-like cells were occasionally present. These were usually limited by a double-layered membrane and devoid of normal cell-wall components such as bacteriophage receptors. The large amoeba-like bodies sometimes showed both outer and inner double-layered membranes, especially in pseudopodium-like cellular extensions. An unusual feature of rod-shaped cells was retention of the original shape despite the loss of their cell walls. Two types of walled cells occurred during successive transfers of L colonies. One was the true revertant which had characteristics in common with the wild-type M. phlei, such as growth at 52 degrees C and ultrastructural organisation. The other, designated as the "atypical-cell-wall variant", was characterised by growth at 52 degrees C, thick cell walls, and disordered septation. Wild-type M. phlei, L variants, revertants and atypical-cell-wall variants released mycobacteriophage particles. These bacteriophages were almost identical in respect to morphology, host range, and neutralisation by antiserum. The results obtained suggest strongly that all types of cells examined were derived from M. phlei. (+info)
Novel bacterial membrane surface display system using cell wall-less L-forms of Proteus mirabilis and Escherichia coli.
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We describe a novel membrane surface display system that allows the anchoring of foreign proteins in the cytoplasmic membrane (CM) of stable, cell wall-less L-form cells of Escherichia coli and Proteus mirabilis. The reporter protein, staphylokinase (Sak), was fused to transmembrane domains of integral membrane proteins from E. coli (lactose permease LacY, preprotein translocase SecY) and P. mirabilis (curved cell morphology protein CcmA). Both L-form strains overexpressed fusion proteins in amounts of 1 to 100 microg ml(-1), with higher expression for those with homologous anchor motifs. Various experimental approaches, e.g., cell fractionation, Percoll gradient purification, and solubilization of the CM, demonstrated that the fusion proteins are tightly bound to the CM and do not form aggregates. Trypsin digestion, as well as electron microscopy of immunogold-labeled replicas, confirmed that the protein was localized on the outside surface. The displayed Sak showed functional activity, indicating correct folding. This membrane surface display system features endotoxin-poor organisms and can provide a novel platform for numerous applications. (+info)
Failure to show mycoplasmas and cytopathogenic virus in rheumatoid arthritis.
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Synovial needle biopsies, joint aspirates, and joint tissue obtained at open operation from 41 cases of rheumatoid arthritis were inoculated onto PPLO media, L-form medium, and cell cultures for the isolation of mycoplasmas, L-form bacteria, and viruses. Medium suitable for the isolation of 'T' strain mycoplasmas was not employed. No mycoplasmas, L-form bacteria, or cytopathogenic viruses were shown. Similar specimens from nine patients diagnosed as having Reiter's disease were examined in a like manner and yielded only one Mycoplasma hominis type 1 isolate from a knee joint biopsy. It is concluded that known strains of mycoplasma and bacterial L-forms do not play a direct role in early and established cases of rheumatoid arthritis. Some of the cell cultures used in this study contained mycoplasma contaminants. Bacterial contaminants were also encountered in occasional batches of L-form medium. (+info)
Comparison of the binding of penicillin G to staphylococcal L-form and its parent strain membranes.
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The binding of penicillin G to a stable L-form from Staphylococcus aureus followed saturation-type kinetics with saturation achieved at 0.75 nmol/ml, the same as with its parent strain. (+info)