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Volume 6,
Issue 2,
1973
Volume 6, Issue 2, 1973
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The Bactericidal Action of Immunoglobulin A
More LessSUMMARYBactericidal activity of serum IgA and secretory IgA in the presence of serum fractions deficient in several components of complement has been demonstrated. Two new serum factors independent of the complement system are postulated to explain the bactericidal action of IgA.
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In-Vitro Susceptibility of Mycobacterium Fortuitum and Related Strains to Cephalosporins
More LessSUMMARYThe sensitivity often strains of Mycobacterium fortuitum, 14 of M. abscessus, and 12 of M. borstelense to two cephalosporins was examined. M. fortuitum strains were resistant to cephalothin but sensitive to cephaloridine. The M. abscessus and M. borstelense strains were all highly resistant to cephalothin. All the M. abscessus strains and all but two strains of M. borstelense were resistant to cephaloridine. The use of cephaloridine resistance as a taxonomic aid is suggested. Cephaloridine may be useful in the treatment of infections with M. fortuitum.
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The Lipolytic Activity of Micrococcaceae from Human and Animal Sources
More LessSUMMARYGram-positive, catalase-positive cocci from man and animals were examined for lipolytic action in egg-yolk glucose broth and on various Tween compounds.
The reaction in egg-yolk glucose broth was given by some coagulase-positive staphylococci but not by any of the coagulase-negative strains. The cultures producing this reaction also attacked all the Tween compounds. In addition, nearly all egg-yolk negative, coagulase-positive staphylococci attacked Tween 20 and a number—particularly members of the 52, 52A, 80, 81 complex of phage-typing patterns—also attacked the longer-chained Tweens. The egg-yolk factor appeared to be antigenically distinct from the lipases that acted on Tween compounds, and from α-lysin.
Among the coagulase-negative cocci, the results showed broad differences between human and animal strains. Most of the human strains were staphylococci and were strongly lipolytic, whereas most of the strains from animals were micrococci and were feebly lipolytic.
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In-Vivo and In-Vitro Studies of the Effect of Specific Antitoxin on the Phagocytosis of Cells of Clostridium Botulinum Type A
J. B. Suzuki and N. GreczSUMMARYThe conversion of heat-resistant spores of Clostridium botulinum type A into germinated heat-sensitive cells in the peritoneal cavity of mice has been observed. This in-vivo germination of spores was depressed in mice passively immunised with type-A botulinal antitoxin. Studies, in which the release of free 45Ca in the urine of mice challenged with labelled Cl. botulinum spores provided an indicator of spore germination, showed that spore germination occurred normally at 8 hr in vivo. However, the rate of germination as determined from 45Ca excretion was substantially inhibited when antibody-treated spores were used as the challenge.
In in-vitro studies with guinea-pig leucocytes, spore germination was similarly assayed by monitoring the release of 45Ca from labelled spores. Spore germination in these leucocyte systems was also suppressed when the spores were first treated with Cl. botulinum type-A antitoxic serum, although phagocytic indices for antibody-treated spores and vegetative cells were increased. Release of type-A botulinal toxin was either completely prevented or substantially suppressed when Cl. botulinum spores and vegetative cells were treated with specific botulinal antibody and incubated with leucocytes.
These results demonstrate that combination of spores with type-specific antibody prompted phagocytic engulfment of antibody-coated spores, but strongly inhibited subsequent phagocytic digestion of engulfed spores.
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Studies on the Effect of Diphtheria Toxin on Protein Synthesis in Mice
More LessSUMMARYMice are several orders of magnitude more resistant to diphtheria toxin than are guinea-pigs and man. Resistance is, however, relative rather than absolute, because 2000 guinea-pig lethal doses cause death of mice within 36 hr. Mice subjected to this quantity of toxin subsequently received an injection of tritiated leucine during the latter stages of the toxaemia in order to assess de novo protein synthesis in vivo. All tissues from toxin-treated mice, with the exception of skeletal muscle and kidney, incorporated 3H-leucine to the same extent as did comparable tissues of normal animals, or to a greater extent. In view of the fact that the biochemical action of diphtheria toxin on more susceptible animals is known to result in a cessation of protein synthesis, the implications of the unexpected results are discussed in terms of species resistance to toxin and the pathophysiology of diphtheritic toxaemia.
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Further Observations on the Use of Organ Cultures in the Study of Acute Respiratorytract Infections
More LessSUMMARYSpecimens from 466 patients with acute respiratory-tract illnesses that failed to yield a causative agent by the standard methods of virus isolation were examined in organ cultures. Seventy-three viruses (15.7 per cent) were isolated. Most of them were rhinoviruses (81.0 per cent.) but seven coronaviruses, four of which were 229E-like, were also isolated. The majority of the rhinoviruses were detected in the initial organ-culture fluids, but several blind passages were needed for the organ-culture strains of coronaviruses. Although laborious, organ culture must remain an integral part of any detailed study of acute infections of the respiratory tract.
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A Rapid Slide-Agglutination Method for Typing Pneumococci by Means of Specific Antibody Adsorbed to Protein A-Containing Staphylococci
More LessSUMMARYA new slide-agglutination method was developed for the serological typing of pneumococci. Type-specific antibodies were bound to stabilised, protein-A containing staphylococci through theri Fc fragments. The combining sites of the antibodies remained available to the corresponding type-specific antigen; when pneumococci were mixed with a suspension of the stabilised staphylococci coated with homologous antibody, strong agglutination occurred rapidly. Eighty-nine pneumococcal strains were typed by this agglutination method. The results obtained were in complete agreement with those of typing by Neufeld’s capsule-“ swelling” method.
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Loss of Antibiotic Resistance in Staphylococcus Aureus in Vivo probably Resulting from Cloxacillin Therapy
More LessSUMMARYBetween Dec. 1971 and July 1972, a strain of Staphylococcus aureus was isolated on many occasions from the sputum of a patient suffering from fibrocystic disease. Early isolates of this strain all formed penicillinase and were resistant to fusidic acid, erythromycin, streptomycin and neomycin. On two occasions (31 May 1972 and 27 July 1972) about 30 per cent. of the colonies isolated from the patient were sensitive to one or more but not to all of these antibiotics, although they resembled the fully resistant strain in other properties. Loss of resistance to penicillin and to fusidic acid was always associated, as was loss of resistance to streptomycin and to neomycin; the latter two were often linked with loss either of erythromycin resistance or of δ-haemolysin production.
Because the patient was being treated with cloxacillin at the time of these isolations, and treatment of the strain with this antibiotic in vitro resulted in loss of resistance, it is inferred that the loss in vivo was probably due to cloxacillin therapy.
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Characterisation of a β-Lactamase Obtained from a Strain of Bacteroides Fragilis Resistant to β-Lactam Antibiotics
More LessSUMMARYThe minimum inhibitory concentration of six antibiotics for ten clinical isolates of Bacteroides fragilis was determined. One of the isolates, which was unusually resistant to ampicillin and cephaloridine, possessed an intracellular β-lactamase. This enzyme, which was more active against cephaloridine than against the penicillins, was characterised. No β-lactamase activity could be detected in any of the moderately resistant strains, or in whole-cell preparations, or culture filtrates. The production of β-lactamase was not induced in resistant or sensitive strains by growth in media containing ampicillin.
The above evidence supports the view that strains of B. fragilis that are highly resistant to β-lactam antibiotics owe this property to the presence of an intracellular β-lactamase.
Attempts to transfer antibiotic resistance from B. fragilis to Escherichia coli and vice versa, and from one strain of B. fragilis to another, were unsuccessful.
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Alimentary Mycotic Lesions in Cattle: A Histological and Cultural Study
More LessSUMMARYHistological examination of the small intestines and mesenteric lymph-nodes of 100 cattle slaughtered at an abattoir between 1 Jan. and 31 Aug. 1971 revealed granulomata containing “asteroid bodies” in 18 animals. Fungal hyphae were demonstrated in the asteroid bodies in 11 of these 18 cattle. Fungi were isolated from 18 out of 66 animals in which mesenteric nodes were examined by a reliable cultural method. The findings suggest that the intestine may be an important portal of entry in systemic fungal infections of cattle.
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A Taxonomic Scheme for Aerobic Diphtheroids from Human Skin
More LessSUMMARYMore than 1500 strains of aerobic cutaneous diphtheroids were characterised by morphological, biochemical, and nutritional tests. From the results of nine tests—lipophilic character, lipolytic ability, production of porphyrin, reduction of nitrate, and ability to decompose glucose, maltose, sucrose, fructose, and galactose—these strains could be divided into 15 groups: seven for the fluorescent strains and eight for the non-fluorescent strains. Distribution of the groups over the body surface varied, non-fluorescent group-I strains being particularly common in the nostrils.
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The Action of Streptolysin S on Mouseliver Mitochondria
More LessSUMMARYWe studied the action of streptolysin S on the respiration of mouse-liver mitochondria. Preparations of RNA-streptolysin S (RNA-SLS) impaired the succinic- and cytochrome-oxidase activity of these organelles. The ability to damage mitochondria could not be separated from the haemolytic activity of the toxin.
The presence of exogenous cytochrome C prevented impairment of these enzymatic activities by RNA-SLS and reversed the observable effects of the toxin on them. Thus it appeared that streptolysin S causes dislocation of the electron-transport between cytochrome C and oxygen. The ability of group-A streptococci to impair mitochondrial respiration may be of importance in the mechanism of pathogenicity.
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Fucidin-Resistant Staphylococci in Current Hospital Practice
More LessSUMMARYFifteen strains of S. aureus resistant to fucidin were isolated from 17 patients during the routine examination of clinical specimens in 1971 (1.4 per cent.). Over half of them were associated with sepsis, but only 40 per cent. were isolated from patients who had previously been treated with fucidin. In-vitro studies indicate that the strains have a stable basic level of resistance with the potential to increase this resistance to high levels on exposure to fucidin. The strains multiply as rapidly as fully sensitive strains, may be associated with persistent and relapsing sepsis and may persist in the carriage state for up to 21 mth.
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Prevalence of Cytomegalovirus Antibodies in the Population of Northern Greece
More LessSUMMARYA serological study has been carried out of the frequency of cytomegalovirus antibodies in urban and rural populations of Northern Greece. Complement-fixing antibodies were found in 62 per cent. of children aged 6 mth to 10 yr and in over 80 per cent. of adults.
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Effect of Co-Trimoxazole on Faecal Enterobacteria: No Emergence of Resistant Strains
More LessSUMMARYDuring treatment with co-trimoxazole, enterobacteria disappeared from the faeces of 12 of 14 patients investigated. Strains resistant to co-trimoxazole or trimethoprim were not isolated from any of the patients during the entire investigation.
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