Showing papers in "Annales De L'institut Pasteur. Microbiologie in 1984"
TL;DR: The large plasmid group in Salmonella serotypes abortusovis, enteritidis, paratyphi C, newport and the virulence-associated plasmids in serotypes typhimurium and dublin constitute a single group of homology and represent a family of related plasmsids.
Abstract: Summary All studied isolates of Salmonella serotypes abortusovis (16 strains), enteritidis (30 strains), paratyphi C (29 strains), and 2 out of 10 isolates of serotype newport harboured large 54–76-Kb plasmids. No such plasmids were found in the following serotypes: agona, bovismorbificans, heidelberg, infantis, panama, paratyphi A, paratyphi B, saintpaul, senftenberg and typhi. These plasmids and the virulence-associated plasmids of Salmonella serotypes typhimurium and dublin were compared at the molecular level. Plasmids from the same serotype usually showed similar Hin dIII endonuclease patterns. Plasmids from different serotypes displayed markedly different cleavage patterns. Using the 3 H-labelled plasmid from serotype typhimurium strain C5 as a probe, nitrocellulose filter hybridization showed that all these plasmids shared homologous sequences distributed throughout the plasmid molecule. With the S1-nuclease method, all plasmids were 61 to 88% related to the virulence plasmid of serotype typhimurium strain C5. The large plasmids in Salmonella serotypes abortusovis, enteritidis, paratyphi C, newport and the virulence-associated plasmids in serotypes typhimurium and dublin thus constitute a single group of homology and represent a family of related plasmids. We suggest that this plasmid group may contribute to the pathogenic potential of host serotypes.
67 citations
TL;DR: From the presence of a membranous PG-containing cell wall, the GO appears to be a true bacterium of the Gram-negative type, and not a mycoplasma, and, therefore, characterization studies can be carried out directly on the organisms in situ.
Abstract: Summary Greening disease of citrus is characterized by the presence of procaryotic organisms in the sieve tubes of infected plants. These procaryotes have often been called mycoplasma-like. We have previously shown that the envelope of the organism was composed of two membranes, each with a triple-layered structure: an inner membrane (cytoplasmic membrane) and an outer membrane. Penicillin treatment of greening-affected plants results in remission of symptoms, suggesting the presence of a peptidoglycan (PG) layer in the envelope of the organism. However, when observed by conventional electron microscopy, no PG layer could be detected in the envelope of the greening organism (GO). Recently, we were able to transmit the GO from citrus to periwinkles by dodder. In periwinkles, GO multiply to high titres and, therefore, characterization studies can be carried out directly on the organisms in situ . Using papain treatment of GO in greening-infected periwinkles, we were able to visualize a PG-like layer in the envelope of the GO. This layer was removed by lysozyme treatment. In these respects, the structure of the GO envelope was nearly identical to that of E. coli , a Gram-negative bacterium, but was different from that of Staphylococcus aureus (a Gram-positive bacterium) treated in the same way. From the presence of a membranous PG-containing cell wall, the GO appears to be a true bacterium of the Gram-negative type, and not a mycoplasma.
54 citations
TL;DR: A collection of 31 strains received as Agrobacterium tumefaciens and A. radiobacter was subjected to detailed phenotypic and genomic studies, revealing the following points: regardless of their phytopathogenic effects, 3-ketolactose-producing A. tumefACiens and B. rubi strains group into one species.
Abstract: Summary A collection of 31 strains received as Agrobacterium tumefaciens and A. radiobacter was subjected to detailed phenotypic and genomic studies. These strains were recovered from plants, soil, water and clinical specimens. Type strains of A. tumefaciens, A. radiobacter, A. rhizogenes and A. rubi were also included. The strains were tested for their ability to use 169 organic compounds as sources of carbon and energy. In addition, 11 conventional characters were studied for each strain. Relatedness among the strains was assessed by determining the extent of reassociation in heterologous DNA preparations. S1 nuclease and diethylaminoethyl-cellulose filters were used to separate reassociated from non-reassociated nucleotide sequences, and to determine the thermal stability of related nucleotide sequences. The resultant data revealed the following points: 1) regardless of their phytopathogenic effects, 3-ketolactose-producing A. tumefaciens and A. radiobacter strains group into one species; this species contains 9 taxa which can be differentiated from each other by phenotypic and genomic characters; 2) clinical isolates did not induce tumours on plants and clustered in three taxa of this species; the clinical and ecological significance of these organisms is not known; 3) the present classification of the genus Agrobacterium is based on phytopathogenicity and does not reflect the phylogenetic relationships amongst these bacteria; as proposed previously by several workers, the genus Agrobacterium should be divided into 3 species on the basis of phenotypic and genomic characteristics. Different aspects of the classification and nomenclature of Agrobacterium are discussed.
40 citations
TL;DR: The results suggest the presence of only one or two sets (operons) of rRNA genes in the genome of Mollicutes, a number falling considerably below that of the eubacteria examined so far but resembling that found in archaebacteria.
Abstract: The small size of the mollicute genome considerably restricts the amount of genetic information available to the organisms. This is reflected in the relatively small number of cell proteins synthesized, the lack of many biosynthetic pathways and the marked dependence on exogenous nutrients for growth. The protein synthesizing machinery of mollicutes resembles that of eubacteria and is sensitive to the same antibiotics, except for rifampicin, to which RNA polymerases of mollicutes appear resistant. The mollicute ribosomes are built of 50 S and 30 S subunits and contain about 50 different proteins and 5 S, 16 S and 23 S rRNA, as in eubacteria. However, the 5 S rRNA in mollicutes appears shorter (107-112 nucleotides) than in eubacteria (116-120 nucleotides). We hybridized restriction endonuclease-digested DNA from a variety of Mycoplasma, Ureaplasma, Acholeplasma and Spiroplasma species with nick-translated probes consisting of defined portions of the rrnB rRNA operon of Escherichia coli and the rRNA operon of M. capricolum. The results suggest the presence of only one or two sets (operons) of rRNA genes in the genome of Mollicutes, a number falling considerably below that of the eubacteria examined so far but resembling that found in archaebacteria. Our data also indicate a marked nucleotide sequence homology along the rrnB rRNA operon of E. coli and the rRNA operons of the various mollicutes, indicating that the rRNA genes in mollicutes are linked in the classical prokaryotic fashion 16 S-23 S-5 S. Each mollicute appeared to possess, on its genome, different flanking sequences adjacent to the rRNA operon(s), resulting in species-specific hybridization patterns.(ABSTRACT TRUNCATED AT 250 WORDS)
40 citations
TL;DR: Mixed infections involving mycoplasmas, viruses and bacteria in chickens, turkeys, geese and ducks have been less well studied, but similar interactions seem to occur, and observations may give an indication as to the likely interactions between myccolytic virus, bacteria and viruses in other host species.
Abstract: Summary Mixed infections involving mycoplasmas, viruses and bacteria are well recognized in chickens. Synergism has been demonstrated between Mycoplasma gallisepticum and the viruses of Newcastle disease and infectious bronchitis and Escherichia coli, although the outcome of infection is influenced by many factors associated with the host and the organisms. Airsacculitis in broilers due to M. synoviae or M. gallinarum may be precipitated by concurrent respiratory virus infections including vaccine strains. Turkeys, geese and ducks have been less well studied, but similar interactions seem to occur. Such observations may give an indication as to the likely interactions between mycoplasmas, viruses and bacteria in other host species.
36 citations
TL;DR: The continuing occurrence of Tp-R-plasmid containing strains in the gut was associated with continuing antimicrobial Therapy; the strains generally disappeared after antimicrobial therapy was stopped.
Abstract: Summary Of 320 patients surveyed in a general hospital's medical wards during a 6-month period in 1981, 18 (5.6%) harboured enterobacteria which contained resistance plasmids conferring resistance to trimethoprim (Tp). At the beginning of the study period, Tp-containing therapy was not the first choice for treatment of infections caused by these bacteria and the incidence of plasmid-determined resistance was 10%. When Tp alone was used as the first choice of treatment of urinary tract infections and the use of this antimicrobial was correspondingly increased, the proportion of strains that contained Tp resistance plasmids (R-plasmids) decreased to 4%. Relatively more patients with Tp-resistant strains in the bowel had significant bacteriuria compared with those without Tp-resistant organisms. The continuing occurrence of Tp-R-plasmid containing strains in the gut was associated with continuing antimicrobial therapy; the strains generally disappeared after antimicrobial therapy was stopped.
35 citations
TL;DR: Characterization of the organisms and pathogenicity assays showed that the causal agent of the disease was a spiroplasma belonging to group IV, which was given to the reference strain B31 (ATCC 33834), one of the numerous similar isolate cultured from May-disease-affected bees.
Abstract: The haemolymph of honey-bees affected by a May disease-like disorder in southwestern France contained numerous spiroplasmas. Further characterization of the organisms and pathogenicity assays showed that the causal agent of the disease was a spiroplasma belonging to group IV. The name Spiroplasma apis was given to the reference strain B31 (ATCC 33834), one of the numerous similar isolates cultured from May-disease-affected bees. Spiroplasma isolates related to S. apis could be grown from the surface of flowers collected within the area visited by bees from the diseased hives. Several other strains belonging to group IV spiroplasmas were also isolated from the surface of flowers growing in southwestern France. In the same area, we also isolated, from pools of apparently healthy honey-bees and from the surface of a tulip tree flower, spiroplasma strains belonging to group I-2. One of these strains was shown to be pathogenic when introduced into adult bees by injection or food ingestion.
33 citations
TL;DR: Le gene celA qui code pour une endo-β-1,4-glucanase de Clostridium thermocellum a ete recemment clone chez Escherichia coli, la levure synthetise un materiel antigenique qui reagit avec un immunserum prepare contre l'endoglucanases de C. thermo cellum.
Abstract: Resume Le gene celA qui code pour une endo-β-1,4-glucanase de Clostridium thermocellum a ete recemment clone chez Escherichia coli. Lorsque ce gene est clone chez Saccharomyces cerevisiae, la levure synthetise un materiel antigenique qui reagit avec un immunserum prepare contre l'endoglucanase de C. thermocellum. L'activite specifique de l'endoglucanase dans la levure est egale a 28% de celle observee chez E. coli et a 11% de celle observee chez c. thermocellum. Cette activite est cytoplasmique. Son niveau est independant de l'orientation de celA dans le vecteur de clonage.
32 citations
TL;DR: Though the three proteins purified from S. citri strains are antigenically similar, they do not seem to share common epitopes with spiralin from the honey-bee spiroplasma B88 (serogroup I-2), a crossed immunoelectrophoretical comparison shows that all four spiralins are related.
Abstract: Summary Spiralins were purified by agarose-suspension electrophoresis after extraction with detergents from the membranes of the following spiroplasmas: Spiroplasma citri C 189, S. citri Maroc (R8A2), S. citri Scaph and the honey-bee spiroplasma B88. The four proteins (molecular mass ∼26,000 daltons, as determined by sodium dodecyl sulphate-pore gradient electrophoresis) showed very similar amino acid compositions characterized by the absence of methionine and tryptophan and a high polarity index (>49%). When compared with the amino acid composition of S. citri membrane, the four spiralins had little or no histidine, a low content of glycine, leucine, tyrosine, phenylalanine and arginine, and a high content of threonine, alanine and valine. Comparison of the amino acid compositions according to the criteria described by Cornish-Bowden ( Anal. Biochem. , 1980, 105 , 233–238) strongly suggests that all four spiralins are related. A crossed immunoelectrophoretical comparison, however, shows that though the three proteins purified from S. citri strains (serogroup I-1) are antigenically similar, they do not seem to share common epitopes with spiralin from the honey-bee spiroplasma B88 (serogroup I-2).
24 citations
TL;DR: A model is proposed to explain the mechanism of glutamate excretion triggering by surfactants and a distribution of complex lipids between the cell wall and the cell membrane is proposed.
Abstract: Summary Lipid alterations induced by surfactants to trigger glutamate excretion were investigated with an industrial strain of Corynebacterium glutamicum. The lipid composition of this strain was determined for cultures in a synthetic medium and in a complex medium. A distribution of complex lipids between the cell wall and the cell membrane is proposed. Depending on growth conditions, 70–85% of the cell fatty acids had saturated chains in cells grown with surfactants. In the synthetic medium up to 80% of the straight-chain fatty acids may have come from the acylated surfactant added to induce excretion. In industrial fermentation, the maximal excretion rate corresponded to the highest saturated fatty acid content of cells. It was shown by radioactive labelling in the synthetic medium that the addition of the acylated surfactant induced the degradation of more than 50% of the phospholipids. Some phospholipid synthesis occurred at that time using the surfactant (saturated) fatty acids, but the membrane did nor recover its previous phospholipid content. A model is proposed to explain the mechanism of glutamate excretion triggering by surfactants.
21 citations
TL;DR: DNA sequences corresponding to the entire pMH1 DNA have been found to be integrated in the high-molecular-weight-DNA molecules and perhaps the chromosomal DNA itself of two other S. citri strains.
Abstract: Summary Two plasmids, pMH1 with 7 kilobase pairs (Kbp) and pM41 with 8 Kbp, were purified from Spiroplasma citri strains MH and M4, respectively, and characterized by restriction mapping. Upon in vitro DNA recombination with plasmid pBR328 as a vector, pMH1 was cloned in Escherichia coli. Radioactive probes specific of the plasmids were used to investigate the occurrence of pMH1 and pM41 DNA sequences among various spiroplasmas. pM41 or a closely related plasmid was found in three other S. citri strains and also seems to be present as an 8-Kbp plasmid in three spiroplasmas not belonging to the S. citri species. Up to now, pMH1 had been found as a free 7-Kbp plasmid only in the S. citri strain MH. However, DNA sequences corresponding to the entire pMH1 DNA have been found to be integrated in the high-molecular-weight-DNA molecules and perhaps the chromosomal DNA itself of two other S. citri strains. DNA sequences hybridizable with pMH1 DNA have also been found to be integrated into high-molecular-weight-DNA molecules from several spiroplasma strains not belonging to the S. citri species.
TL;DR: Four restriction endonucleases were used to construct a physical map of the tetracycline-chloramphenicol resistance plasmid pIP401, which had been isolated from Clostridium perfringens.
Abstract: Summary Four restriction endonucleases were used to construct a physical map of the tetracycline-chloramphenicol resistance plasmid pIP401, which had been isolated from Clostridium perfringens. Twenty-seven restriction sites were placed within the 52-kb map, including 1 site for AvaI, 2 sites for KpnI, 10 sites for EcoRI and 14 sites for PstI. The loss of chloramphenicol resistance in the serived pIP406 plasmid was associated with a deletion of a 6.2-kb DNA segment located in a 10.55 EcoRI-PstI fragment. Two 1.4-kb inverted repeats were also characterized in both pIP401 and pIP406.
TL;DR: Although the 31P nuclear magnetic resonance spectra of the LPS differed in some respects, these differences did not seem to correlate with the disparity in sensitivity to gentamicin of the two organisms.
Abstract: Summary Comparative studies of a gentamicin-sensitive strain (P28–0) of Pseudomonas aeruginosa and a gentamicin-resistant mutant (P28–800) have been carried out. No aminoglycoside-modifying enzymes were detected in extracts of the mutant. Electron microscopy of thin sections and the loss of O-antigenicity suggested that resistance of the mutant to gentamicin was related to an alteration in the outer membrane. Analysis of the lipopolysaccharide (LPS) components of the cell walls revealed significant differences. The LPS from strain P28–0 was typical of wild-type P. aeruginosa strains of Habs serotype O6, with quinovosamine and aminogalacturonic acid as O-specific aminocomponents. The LPS from the resistant mutant lacked the O-specific polymer, but had a core oligosaccharide similar to that of the parent strain. Both LPS were rich in phosphorus, part of which was present in triphosphate residues. Although the 31P nuclear magnetic resonance spectra of the LPS differed in some respects, these differences did not seem to correlate with the disparity in sensitivity to gentamicin of the two organisms.
TL;DR: The growth of M. gallisepticum was monitored in regard to their capacity to haemagglutinate and the adhesin fraction was primarily composed of one polypeptide of about 75,000 molecular weight.
Abstract: The growth of M. gallisepticum was monitored in regard to their capacity to haemagglutinate. The maximal potential was with cells grown for about 22 h. M. gallisepticum, like M. pneumoniae, possess a Triton shell intracellular filamentous structure which is revealed by exposing the cells to a relatively low concentration of Triton-X100. The adhesin of M. gallisepticum was partially purified on sialoglycopeptide conjugated to Sepharose-4B. The adhesin fraction was primarily composed of one polypeptide of about 75,000 molecular weight.
TL;DR: It is verified that the branched-chain fatty acids found in diacyl phthiocerol and in the mycoside of M. leprae have the same configuration as in the analogous molecules isolated from M. tuberculosis or M. bovis.
Abstract: Summary The main lipids synthesized by Mycobacterium ulcerans are specific for the species. Three products were isolated by chromatography. Their structures were determined by means of spectrographic methods performed on the natural substances or on their split products. The most abundant products were phthiodiolone diphthioceranate and phenolphthiodiolone diphthioceranate. These structures have some analogies with those of phthiocerol dimycocerosate synthesized by M. tuberculosis and M. bovis, and with those of phenolphthiocerol mycocerosate synthesized by M. bovis. The reverse configuration of the polymethyl-branched-chain fatty acids isolated from the substances, according to their origin, remains to be pointed out. Little attention has generally been paid to the stereochemistry of such molecules. We verified that the branched-chain fatty acids found in diacyl phthiocerol and in the mycoside of M. leprae have the same configuration as in the analogous molecules isolated from M. tuberculosis or M. bovis, contrary to M. ulcerans. Another peculiarity of phenolphthiodiolone isolated from M. ulcerans is the occurrence of the phenol group in free form.
TL;DR: The GT-48 strain of Spiroplasma mirum was employed in an experimental brain infection in 1-day old suckling rats in order to define the localization and persistence of organisms in brain and spleen and to evaluate the responses of three distinct genetic lines of rats.
Abstract: Summary The GT-48 strain of Spiroplasma mirum was employed in an experimental brain infection in 1-day old suckling rats in order to define the localization and persistence of organisms in brain and spleen and to evaluate the responses of three distinct genetic lines of rats. Rat pups inoculated intracerebrally with 30–300 organisms exhibited peak infections at 15–20 days post-inoculation, while challenge levels of 3–30 organisms showed some persistent infections for as long as 60 days. The responses of three genetic lines of rats to the experimental spiroplasma infection did not differ significantly over a 60-day follow-up period. The acute-phase infection in suckling rats showed a rapidly developing and widespread dissemination of organisms to all major areas of the brain.
TL;DR: Extensive tests of the host ranges of the new insect mollicutes will be required before their suitability for biological control can be evaluated, and new information on the ecology of pathogenicity is provided.
Abstract: Summary Acholeplasmas, spiroplasmas and other non-helical sterol-requiring mycoplasmas of unknown phylogenetic affinity inhabit insects. Of these, only spiroplasmas are known to be pathogenic. Group I-2 spiroplasmas, or Spiroplasma apis, especially in combination with other organisms, reduce honey-bee longevity. Plant pathogenic mycoplasma-like organisms are often found intracellularly in insects. Spiroplasmas are found predominantly in the gut lumen or haemolymph (or both) of their insect hosts. Pathogenicity of mycoplasmas is usually altered by extended passage in unusual hosts, in only one of two alternate hosts, or in culture media. Enhancement of experimental pathogenicity may occur with extended cultural passages, but maintenance of natural pathogenicity must be accomplished by continuous exposure to the usual host. Recent data provide new information on the ecology of pathogenicity. Spiroplasmas from unique habitats also tend to be unique. Spiroplasmas isolated from flowers appear to be adapted to insect species that frequent floral surfaces. Group IV spiroplasmas have been isolated from members of 4 holometabolous insect orders (including Lepidoptera), all of which visit flowers. Social or predatory insects, or insects with an «aggregation phase in their life histories, also appear to be prone to spiroplasma infection. Some insect species which harbor spiroplasmas also carry infections of other mollicutes, some of which involve the haemolymph. Appearance of spiroplasmas in adult insects in nature is strongly affected by seasonality. Extensive tests of the host ranges of the new insect mollicutes will be required before their suitability for biological control can be evaluated.
TL;DR: The gene of Saccharomyces cerevisiae responsible for adenylate cyclase activity was cloned by complementation of a thermosensitive tsm0185 mutation in yeast and it was shown to complement the yeast cyr1 mutation.
Abstract: The gene of Saccharomyces cerevisiae responsible for adenylate cyclase activity was cloned by complementation of a thermosensitive tsm0185 mutation in yeast; it was also shown to complement the yeast cyr1 mutation. Preliminary results indicate the presence of a repeated sequence on the same genomic fragment.
TL;DR: Formation of toluene in growing cultures of Clostridium aerofoetidum strain WS was enhanced when the medium was supplemented with phenylacetic acid or with L-phenylalanine and L-methionine together.
Abstract: Summary Formation of toluene in growing cultures of Clostridium aerofoetidum strain WS was enhanced when the medium was supplemented with phenylacetic acid or with L-phenylalanine and L-methionine together. Evidence for the role of L-phenylalanine was shown by the detection of [2H2]-methyl[2,3,4,5,6-2H5]benzene («heptadeuterotoluene) in growing cultures with L-[2′,3′,4′,5′,6′-2H5]phenyl[2,3-2H3]alanine and L-methionine.
TL;DR: Morph and nutritionally, the bacteria described are clearly different from the 5 known species of the first morphological group whose cells have a diameter greater than 1 μm; they grew rapidly in media containing 0.4% yeast extract and 0.2% sodium acetate or benzoate.
Abstract: Summary The eleven strains studied were prototrophic and did not grow in media containing only 1% Bacto-peptone or Bacto-tryptone; they grew rapidly in media containing 0.4% yeast extract and 0.2% sodium acetate or benzoate. The maximal growth temperature ranged from 39 to 45°C. Six aliphatic acids, four aromatic acids and five phenols were used as sole carbon and energy sources by the 11 strains. Carbohydrates and amino acids (except for glycine)were not used as carbon and energy sources. Nitrate (but not nitrite) was used anaerobically as a respiratory electron acceptor. Nitrous oxide was used and reduced to N2 by only 3 strains. The mean guanine-plus-cytosine content of the DNA was 41.3±1.1 mol%. Morphologically and nutritionally, the bacteria described are clearly different from the 5 known species of the first morphological group whose cells have a diameter greater than 1 μm: Bacillus megaterium, B. cereus, B. cereus var. mycoides, B. macroides, B. badius, and B. fastidiosus. Strain B1 (=CCM 3364) is the holotype of Bacillus benzoevorans sp. nov.
TL;DR: The germ-free mouse associated with faecal microflora from a conventional animal seems to be a suitable model for determining in vivo the effect of low doses of antimicrobial drugs on drug resistance in lactose-fermenting enteric flora.
Abstract: Groups of germ-free mice kept in isolators and associated with faecal microflora from piglets were continuously given either water or a solution of one of the following: chlortetracycline (20 micrograms/ml), carbadox (50 micrograms/ml), olaquindox (50 micrograms/ml), bambermycin (flavomycin) (5 micrograms/ml) or mixtures of these drugs. The proportions of lactose-fermenting bacteria in their faeces which were resistant to chlortetracycline, carbadox or olaquindox were measured by a comparative plate-counting procedure. Compared to occurrence in control mice, the occurrence of antimicrobial drug-resistant bacteria was higher in mice receiving chlortetracycline (P less than 0.001) and lower in mice receiving bambermycins (P less than 0.005). In contrast, olaquindox and carbadox did not change the proportion of resistant coliforms in mice faeces. A control experiment was conducted with five groups of germ-free mice given the same flora and kept without drugs in separate isolators. No difference in the occurrence of resistant coliforms could be found between these groups. The germ-free mouse associated with faecal microflora from a conventional animal seems to be a suitable model for determining in vivo the effect of low doses of antimicrobial drugs on drug resistance in lactose-fermenting enteric flora.
TL;DR: The criteria which need to be fulfilled before regarding a microorganism as a cause of non-gonococcal urethritis (NGU) are considered in relation to Mycoplasma hominis, Ureaplasma urealyticum and M. genitalium.
Abstract: Summary The criteria which need to be fulfilled before regarding a microorganism as a cause of non-gonococcal urethritis (NGU) are considered in relation to Mycoplasma hominis, Ureaplasma urealyticum and M. genitalium . There is no evidence to support an aetiological role for M. hominis , but few appropriate investigations have been undertaken. The criteria have been met, for the most part, in the case of U. urealyticum , but further quantitative studies are required. The role of M. genitalium is unknown, but its biological and morphological features and ability to cause genital disease in animals suggest that it may be pathogenic for man. It is emphasized that the criteria for regarding a microorganism as a cause of NGU should also be used where feasible when investigating the infectious aetiology of other genitourinary conditions.
TL;DR: The susceptibility of 139 strains of Listeria towards eight antibiotics —penicillin, ampicillin, cephalotin, gentamicin, chloramphenicol, tetracycline, erythromycin and pefloxacin—was studied.
Abstract: Summary The susceptibility of 139 strains of Listeria towards eight antibiotics —penicillin, ampicillin, cephalotin, gentamicin, chloramphenicol, tetracycline, erythromycin and pefloxacin—was studied. All strains were susceptible to all antibiotics except pefloxacin. The lowest MIC (≤0.5 mg/l) were obtained with penicillin, ampicillin, gentamicin and erythromycin. For tetracycline, cephalotin and chloramphenicol, MIC ranged from 0.5 to 16 mg/l. The MIC of pefloraxin varied from 4 to 16 mg/l.
TL;DR: The reproducibility, specificity and discriminatory power of these phages suggest they may be a useful addition to previously recognized phages.
Abstract: Summary Coagulase-negative staphylococci, and in particular Staphylococcus epidermidis, are now being recognized as causing human infections with increasing frequency; the absence of an internationally accepted system of phage-typing for coagulase-negative staphylococci led us to isolate new phages. Fifty strains of S. epidermidis isolated from human infections were induced with mitomycin C: eight phages (41, 63, 118-II, 138, 245, 336, 392 and 550) were isolated. These phages were propagated on five different strains of S. epidermidis. Their lytic activity was studied on 561 strains. Phages 336, 392 and 550 had a different host-range and different propagative strains; they typed 93% of the strains susceptible to the 8 phages. The other phages had an activity similar to that of phage 336. Twenty-one per cent of non-epidemic strains were susceptible to at least one of the three phages. The reproducibility, specificity and discriminatory power of these phages suggest they may be a useful addition to previously recognized phages.
TL;DR: The contagious pleuropneumonia syndrome is easily reproduced in goats, using cultures and lung lesion homogeneizate given by endobronchial inoculation and by aerosol, and the same strains seem to be poorly pathogenic toward chick embryos inoculated in the yolk-sac.
Abstract: Summary The contagious pleuropneumonia syndrome is easily reproduced in goats, using cultures and lung lesion homogeneizate, given by endobronchial inoculation and by aerosol. The latter route causes hyperacure evolution, with septicaemia, multiple and disseminated lesions and death within three days following the onset of clinical signs. The same strains seem to be poorly pathogenic toward chick embryos inoculated in the yolk-sac. The nature of Mycoplasma capripneumoniae pathogenicity remains undetermined.
TL;DR: Perfusion culture of intact tracheas offers a distinct advantage over tracheal-ring explants for studies of pathogen attachment, and has been used to study the synthesis and secretion of mucous glycoprotein by the respiratory epithelium.
Abstract: Summary A comparison of various in vitro models of respiratory tissue is presented. Tracheal ring explant cultures can be readily infected with M. pneumoniae . A decrease in vigour and extent of ciliary beating becomes apparent 24–48 h after 60-min exposure to 10 7 cfu of mycoplasmas. Cytotoxicity can be substantiated with assays of dehydrogenase activity, ATP content and oxygen uptake. For studies of pathogen attachment, perfusion culture of intact tracheas offers a distinct advantage over tracheal-ring explants. A greater proportion of the pathogen uptake is mediated by specific receptor sites because artificial cut surfaces are eliminated. Such matrixembed/perfusion cultures have been used to assay the effectiveness of mycoplasma interactions with receptor site preparations. Triton X-100 effectively solubilizes glycoproteins which will bind with M. pneumoniae . Perfusion culture has also been used to study the synthesis and secretion of mucous glycoprotein by the respiratory epithelium.
TL;DR: The ultramicromethod of Uitendaal et al. is used to detect the presence of mycoplasmas in sera and in tissue culture medium, and the absence of adenosine phosphorylase activity seems to be the best guarantee that a serum is not contaminated by mycplasmas.
Abstract: Summary The importance of cell culture contamination by mycoplasmas is well recognized, but the means used to detect such contamination still need improvement. Most mycoplasmas possess an enzyme, adenosine phosphorylase, which is not found in cell lines. We used the ultramicromethod of Uitendaal et al. to detect the presence of mycoplasmas in sera and in tissue culture medium. The absence of adenosine phosphorylase activity seems to be the best guarantee that a serum is not contaminated by mycoplasmas. This test is also most efficient for the detection of mycoplasmas in tissue or cell cultures in vitro.
TL;DR: The insect cell lines Dm-1 (Drosophila melanogaster), AS-2 (Aceratagallia sanguinolenta) and AC-20 (Agallia constricta) were infected with spiroplasmas, mycoplasmas and Acholeplasma laidlawii and revealed the presence of non-helical forms inside the cells.
Abstract: Summary The insect cell lines Dm-1 (Drosophila melanogaster), AS-2 (Aceratagallia sanguinolenta) and AC-20 (Agallia constricta) were infected with spiroplasmas, mycoplasmas and Acholeplasma laidlawii. In Dm-1 cultures maintained at 25°C in M1A medium, all strains multiplied except M. hyorhinis and the uncultivable sex-ratio organism. Spiroplasma citri R8A2, S. floricola BNR-1 and OBMG, S. apis PPS-1 and the strains BC-3, corn stunt spiroplasma (CSS) and 267F produced cytopathogenic effects (CPE), whereas S. mirum SMCA, M. orale, M. arginini and A. laidlawii did not. Cytadsorption was found with the cultivable spiroplasmas and A. laidlawii. At 30°C. SMCA, M. orale, M. arginini and A. laidlawii killed the Dm-1 cultures. M. hyorhinis grew without any CPE. In AS-2 and AC-20 cultures grown at 28°C in LB medium, R8A2, B88, 277F, BNR-1 and PPS-1 multiplied and reached titres of 2×108 to 4×109 CFU/ml. They produced CPE leading to culture death. CSS did not grow. R8A2 reached higher titres in AS-2 cultures than in fresh LB medium. This stimulating factor was studied by means of conditioned medium. All 6 spiroplasmas cytadsorbed to AS-2 and AC-20 cells B88 and 277F adsorbed heavily, while the other 4 strains adsorbed only slightly. Fluorescent DNA staining with “Hoechst 33258” revealed the presence of non-helical forms inside the cells.
TL;DR: The severity of lung lesions induced by M. pulmonis membranes correlated with the degree of mitogenic responses of the different rat strains to this organism, and the mitogenic co-stimulation of both B and T lymphocytes in rat lungs was necessary to obtain maximal development of interstitial lymphocytic pneumonia.
Abstract: Summary The mitogenicity and pathogenicity of Mycoplasma pulmonis were compared in two rat strains. Both the mitogenic and the pathologic effects induced by M. pulmonis membranes were more severe in Lewis rats than in Hooded rats, and were dependent on the mitogen doses used. It was concluded that the severity of lung lesions induced by M. pulmonis membranes correlated with the degree of mitogenic responses of the different rat strains to this organism. The roles of T- and B-cell mitogens in induction of pneumonia were studied in Hooded rats treated intranasally with either the T-cell mitogen concanavalin A or with M. neurolyticum membranes which stimulate the B-cell populations, or with both concanavalin A and M. neurolyticum . Results clearly showed that the individual B- and T-cell mitogens affected the lungs of treated animals. Nevertheless, the mitogenic co-stimulation of both B and T lymphocytes in rat lungs was necessary to obtain maximal development of interstitial lymphocytic pneumonia.
TL;DR: The effect of bran ingestion on the flora of the human digestive tract was studied using two methods: quantitative enumeration of various microbial populations of the faecal flora, and a demonstration of the antagonistic effect exerted by the faepal flora against various potentially pathogenic bacteria of the environment.
Abstract: Summary The effect of bran ingestion on the flora of the human digestive tract was studied using two methods: quantitative enumeration of various microbial populations of the faecal flora, and a demonstration of the antagonistic effect exerted by the faecal flora against various potentially pathogenic bacteria of the environment. Since this latter study cannot be effected in human subjects, we used a model constituted by axenic mice inoculated with patients' flora. Faecal samples from 3 human donors receiving bran-containing diets were obtained prior to treatment and 30 days thereafter. These faecal samples were inoculated into exenic mice fed a diet with or without bran. The dominant floras of the human donors, before and after bran ingestion, were highly similar. The faecal floras of the gnotoxenic mice resembled those of the donors and no change resulting from the presence of bran in the diet could be observed. The drastic or permissive barrier effects exerted in the gnotoxenic mice by the human donors against Clostridium perfringens, Staphylococcus aureus, Candida albicans and Pseudomonas aeruginosa were not modified by the presence of bran in the diet. The large variability between animals in the barrier effect against Clostridium difficile masked any possible role of the bran. Study of the transit of Bacillus spores in the digestive tract of various mouse groups showed the existence of differences according to the origin of the inoculated floras, but not according to the presence or absence of bran in the diet.