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Volume 14,
Issue 1,
1981
Volume 14, Issue 1, 1981
- Short Articles
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Haemophili in Faeces
More LessSummary.By plating faeces on a selective medium, haemophili were isolated from 26% of 612 samples from patients of all ages and 12% of 525 samples from apparently healthy meatworkers. Most isolates were Haemophilus parainfluenzae. Only specimens received for laboratory investigation for pathogens were examined in this study; the faecal carriage of haemophili in healthy persons is not known.
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A rapid and simple method for distinguishing colonies of Proteus from those of Salmonella and Shigella
More LessSummary.A rapid and simple method is described by which colonies of Proteus can be distinguished from those of Salmonella and Shigella and other non-lactose-fermenting organisms growing on MacConkey’s agar or desoxycholate citrate agar. The method is based on the ability of Proteus to produce urease constitutively. The enzyme was detected by the degradation of urea by the inoculum, thereby creating an alkaline reaction on pH-indicator paper.
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Physiological diversity in clinical isolates of Pseudomonas aeruginosa
More LessSummary.The results of 91 characteristics selected from 165 tests performed on 127 clinical and other isolates of Pseudomonas aeruginosa were subjected to numerical analysis. Only one cluster, representing a single biotype of the species, was revealed at a similarity (S sm ) level of 95% and above. Ten melanogenic and six of the non-melanogenic isolates studied gave diverse atypical results in many of the tests; these strains appear to be aberrant forms of the species.
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Examination for influenza IgA and IgM antibodies in pregnancies associated with fetal neural-tube defects
More LessSummary.Early antenatal serum specimens were collected from 25 women who subsequently gave birth to infants with anencephaly or spina bifida. Fluorescent-antibody tests for influenza-specific IgA and IgM antibodies, although shown to be reliable for the detection of recent influenzal infection, failed to demonstrate such infection in any of these women. Early infection was detected in one of 50 control women who gave birth to a healthy infant. The results indicate that influenzal infection in pregnancy was not a major cause of neural-tube defects in Oxford during 1972–76, if a cause at all.
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Identification of leptospira serovars by restriction-endonuclease analysis Platexs XIII–XV
More LessSummary.Strains of Leptospira interrogans were examined by restriction-endonuclease analysis. Serovars hardjo and balcanica gave patterns that differed from each other, and from those of other members of the Hebdomadis serogroup and members of other serogroups. The method should be useful for the identification of leptospires and might throw light on problems of their classification.
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- Articles
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The IgM and IgG response to Bordetella pertussis vaccination and infection
More LessSummary.Ultracentrifugation was used to separate IgG from IgM in serum samples from children after pertussis vaccination or infection and the fractions were examined by indirect haemagglutination (IHA) and complement-fixation (CF) tests. IHA detected pertussis-specific IgM and IgG but CF detected only IgG which appeared to be of a different subclass from the IHA IgG. The IgM titres were higher after infection than after vaccination but the reverse tended to apply to the IgG titres. Little IgM or CF IgG was detected 5 months after a dose of vaccine, but the IHA IgG persisted longer. Vaccinated children who were subsequently infected showed IgM and CF IgG responses similar to those of unvaccinated, infected children but the IHA IgG titres reached much higher levels.
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Effect of the growth environment on cell-envelope components of Escherichia coli in relation to sensitivity to human serum
More LessSUMMARY.Three smooth strains of urinary Escherichia coli were grown in a chemostat under carbon-limited (C-lim) and magnesium-limited (Mg-lim) conditions over a range of dilution rates (D). Strain LP1674 was resistant to human serum under C-lim but became sensitive when grown under Mg-lim, the degree of sensitivity increasing as D increased. The transition to serum sensitivity was accompanied by loss of ability to produce extractable K1 antigen and a reduction in the amount of a 46k envelope polypeptide. C-lim cells of strain LP729 exhibited a delayed sensitive response to serum, the degree of lag in serum killing becoming less pronounced with increasing values of D; Mg-lim cells were more sensitive with little or no lag in serum killing. The degree of lag appeared to be directly related to the amount of the O side-chain sugar mannose associated with the lipopolysaccharide. C-lim and Mg-lim cultures of E. coli strain IP1395 were resistant to serum except when growing at near maximal rates. Although C-lim cultures contained more acidic polysaccharide than Mg-lim cells, transition to serum sensitivity did not appear to be related to exopolysaccharide production. Rapidly growing cells of strain LP1395 did, however, have lower lipopolysaccharide 0 side-chain sugar: core-sugar ratios than more slowly growing cells. With all three strains, changes in dilution rate and in the nature of the limiting nutrient were accompanied by changes in envelope protein composition.
This study demonstrates that many cell-surface changes occur in response to alterations in the growth environment and some of these may be correlated with changes in sensitivity to serum.
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Resistance transfer in mixed cultures of Staphylococcus aureus
More LessSummary.Transfer of resistance markers was regularly observed in mixed cultures of pairs of constructed strains of Staphylococcus aureus. This transfer was shown to be due to general transduction and required a lysogenic donor strain, carrying a transducing phage of serotype B and a transducible plasmid, and an acceptor strain without either strong restriction or an incompatible plasmid. Transfer was sometimes bidirectional when both strains carried a transducing phage. Unidirectional transfer occurred when the acceptor strain was immune. When the acceptor was sensitive to the donor phage, reversed transfer of a marker from the acceptor to the donor could take place.
The kinetics of transfer are governed by the rate of phage production, the rate of phage adsorption and the frequency of transduction. A mathematical model has been developed to describe the interplay of these factors. The numbers of transductants observed in mixed cultures agreed with those expected from the model.
Transfer was also observed in mixed cultures of constructed strains and wild-type strains. Transfer between wild-type strains is also possible, but was not observed in many combinations because of lack of transducing phage, strong restriction or other factors.
Transfer was also observed in local lesions in mice infected with two strains and in mixtures inoculated on to human skin.
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Sensitivity of staphylococci to fatty acids: novel inactivation of linolenic acid by serum
More LessSUMMARY.The inhibition of coagulase-negative staphylococci and Staphylococcus aureus of human or animal origin by most free fatty acids was similar, but coagulase-positive staphylococci were sensitive and coagulase-negative cultures were resistant to linolenic acid. Animal strains of S. aureus were more sensitive to linolenic acid than were human strains. These differences were reflected in the relative abilities of the three categories of strains to survive on human skin.
The antibacterial effects of 20 mg of linolenic acid were inactivated by 1 ml of serum in vitro. A test organism seeded on to skin also survived better if first suspended in serum. The mechanism of the interaction between serum and linolenic acid may be due to a detergent effect of the serum and could account for colonisation of diseased skin with S. aureus.
Cultures of S. aureus seeded on to human skin were rapidly killed after the skin has been covered with linolenic acid. The possibility of therapeutic use of linolenic acid as an antibacterial agent should be explored.
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The development of the bacterial flora in normal neonates
More LessSummary.The development of the bacterial flora of neonates during the first week of life was studied in 23 babies. Specimens of meconium or faeces were collected and swabs taken from the umbilicus and mouth on days 1, 2, 3 and 6. The bacteria present were isolated on a variety of plain and selective media. The predominant faecal organisms by the end of the first week were anaerobes. Bifidobacteria were isolated from all the neonates and bacteroides and clostridia were isolated from 78·3%. Bifidobacteria and bacteroides were present in large numbers; other species were isolated in smaller numbers. Enterococci were isolated from all neonates, enterobacteria from 82·6%, anaerobic cocci from 52·2%, and streptococci and staphylococci from 34·8% each.
Staphylococcus aureus was the predominant species isolated from the umbilicus; it was isolated from 21·7% of neonates on the first day rising to 87·0% by the sixth day and represented 49% of isolates from this site. S. albus, streptococci, enterococci and Escherichia coli were each isolated from a few neonates.
Viridans streptococci (31·4% of isolates) and Streptococcus salivarius (25·1%) were the commonest species recovered from the mouth. They were present from 8 h after birth; S. albus and Neisseria spp. were isolated later on the first day, and anaerobic species of Veillonella and Bifidobacterium appeared on the second day.
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Neuraminidase production by Bacteroidaceae
A. G. FRASER and R. BROWNSummary.The production of neuraminidase (EC 3.2.1.18) by 77 strains of Bacteroidaceae was investigated by techniques previously used to study neuraminidase production by clostridia. Conditions for culture and assay of Bacteroides fragilis neuraminidase were characterised. The enzyme is predominantly cell associated; it is not calcium dependent and the pH optimum for its production is c. 4.5.
Most neuraminidase-positive Bacteroides strains produced the enzyme well in the test media but a few strains failed to produce it consistently in one or other of the media. Because of these occasional variations, strains were grown and tested in at least two media before being defined as neuraminidase negative.
Within the B. fragilis group of species, B. fragilis, B. vulgatus, B. distasonis, B. ovatus, B. thetaiotaomicron and B. variabilis were neuraminidase positive while B. eggerthii, B. uniformis and B. splanchnicus were negative. Two subspecies of B. melaninogenicus (ss. melanino-genicus and ss. levii) were positive but the other (ss. intermedius) was negative. Strains of B. oralis and B. bivius produced the enzyme while B. ruminicola, B. disiens, B. asaccharolyticus and B. corrodens did not. The microaerophilic B. ochraceus were also positive. None of the Fusobacterium or Leptotrichia species tested produced neuraminidase.
Our results for neuraminidase production are consistent for all strains of each species examined and we suggest that tests for neuraminidase production would be a valuable addition to biochemical tests currently used in taxonomic studies of the Bacteroidaceae.
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Chlamydial serum IgG, IgA and local IgA antibodies in patients with genital-tract infections measured by solid-phase radioimmunoassay
P. TERHO and O. MEURMANSummary.A solid-phase radioimmunoassay (RIA) for IgG and IgA class antibodies to Chlamydia trachomatis was developed with C. trachomatis serotype L2 as antigen. The assay was sensitive, reproducible and correlated well with an immunofluorescence test (r = 0·85). Serum IgG antibodies were detected in 79% of Chlamydia isolation-positive versus 43% of isolation-negative male patients with urethritis, and serum IgA antibodies in 53% and 21%, respectively. Urethral IgA antibodies, measured from specimens taken for chlamydial isolation, could be detected in 94% and 38%, respectively. From 737 male urethral and 909 female cervical secretions screened for the presence of IgA antibodies, about half were isolation and IgA negative. Only 4% (6/151) of male and 5·4% (2/37) of female isolation-positive specimens were IgA negative. The determination of local IgA antibodies may be used as a screening test in chlamydial genital infections.
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Ovine systemic pasteurellosis caused by Pasteurella haemolytica biotype T
More LessSUMMARY.A detailed study was made of lambs aged 5–7 months naturally infected with Pasteurella haemolytica biotype T. In addition to the well known features of such infections, previously unreported necrotic lesions of the tonsil, oesophagus, pharynx and adjacent areas were consistently seen. Large numbers of P. haemolytica were present in the tonsil, oesophageal lesions, lung, liver and spleen, but few or none in other tissues. The evidence indicated that the disease was not a true septicaemia. It is postulated that P. haemolytica biotype T already present in the tonsils multiplies and invades the adjacent tissues of the upper alimentary tract; groups of organisms from this site enter the blood stream as emboli, most of which lodge in the capillary beds of the lung and liver; rapid multiplication of organisms in these tissues leads to death from the effects of endotoxin.
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Isolation of Bacillus licheniformis var. endoparasiticus from the blood of rheumatoid arthritis patients and normal subjects
More LessSummary.Sixty-five samples of blood from patients with rheumatoid arthritis and 94 from control subjects were examined by multiple culture and monthly subculture for periods of up to 33 months to detect the reversion stages of Bacillus licheniformis var. endoparasiticus (BLE), which exists as L-forms in blood.
Isolates of BLE were obtained more often from the blood of control subjects than from rheumatoid patients during the first 6 months of incubation, when there was clustering of positive cultures within samples. Thereafter, the isolation rate was similar for the two groups and positive cultures were distributed randomly between samples. Isolation of diphtheroid intermediate reversion stages (phases A and B) occurred mainly during the first year of incubation, but isolations of the fully reverted sporing bacillus (phase C) increased in frequency with incubation time, particularly from cultures with a high rate of desiccation during prolonged incubation. The proportion of different phases of BLE amongst the isolates and the distribution of the phases with incubation time were similar for the rheumatoid-arthritis patients and the normal subjects.
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Further studies of 35–40-nm virus-like particles associated with outbreaks of acute gastroenteritis
More LessSUMMARY.Virus-like particles similar in size and morphology to the Otofuke agent, which was detected first in an institutional outbreak of acute gastroenteritis at Otofuke, Hokkaido, Japan in 1978, were again observed in faeces from patients in four other outbreaks of acute gastroenteritis in Hokkaido.
In each of three outbreaks in which the faeces and paired sera of patients were available, apparent sero-responses against the particles obtained in corresponding outbreaks were confirmed. Serological analysis of the particles from five separate epidemics by immune elec-tronmicroscopy suggested that the particles from these epidemics may be related antigenically to one another.
Besides the above-mentioned particles measuring 35–40 nm in diameter, 15–20-nm “empty” particles were also found in the stool specimens obtained from two of the five epidemics. In addition, serological cross reactivity between these two kinds of particles was observed.
These findings provide further support for the aetiological role of the 35–40-nm particles (Otofuke agent-like particles) in acute gastroenteritis in older children and adults.
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Analysis of wall antigens of Aspergillus fumigatus by two-dimensional immunoelectrophoresis Plates VI–XII
More LessSummary.Water-soluble and surface-located antigens from Aspergillus fumigatus mycelium were analysed by two-dimensional electrophoresis (2D IEP) with selected sera. A complex pattern was seen when a water-soluble fraction reacted with hyperimmune sera. Significantly fewer precipitin peaks were seen when wall-located antigens were used in the 2D IEP system; this made possible the detection of a small number of recurring antigen-antibody interactions when sera from patients with aspergilloma or allergic bronchopulmonary aspergillosis were analysed. Many of these recurring precipitates were affected by lectins with specificity for α-D-glucose, α-D-mannose or N-acetyl-D-glucosamine. All the antigens were susceptible to hydrolysis by pronase, confirming the glycoprotein composition of many of these macromolecules.
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The pathogenicity of Bacteroides fragilis and related species estimated by intracutaneous infection in the guinea-pig
More LessSUMMARY.The pathogenicity of 42 strains of Bacteroides of human origin was estimated by intracutaneous injection of bacterial suspensions into guinea-pig skin. Comparisons of living and heat-killed suspensions revealed that B. fragilis strains maintained themselves and possibly multiplied in the skin, whereas the lesions induced by non-fra-gilis strains appeared to be due mainly to toxicity. Measurement of skin pathogenicity in terms of the number of viable organisms in the inoculum that produced a lesion 10 mm in diameter showed that B. fragilis was, on average, 17 times as pathogenic as non-fragilis strains.
Skin tests of pathogens may be of value in the analysis of virulence factors of Bacteroides and possibly of other anaerobic organisms.
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Antibody response to rubella ribonucleoprotein component after natural infection and after immunization
More LessSummary.Antibody to the ribonucleoprotein component of rubella virus occurs in only a proportion of patients with clinical rubella and is rarely present in individuals after administration of RA27/3 live attenuated virus vaccine.
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