-
Volume 19,
Issue 2,
1985
Volume 19, Issue 2, 1985
- Short Article
-
-
-
Effect of Microwave Energy on the Metabolism of Enterobacteriaceae
R. C. Spencer, S. Hafiz and C. CookSummaryThe effect of microwave irradiation on the metabolism of 94 strains of Enterobacteriaceae was studied. Sixteen substrates were used and the results obtained with microwave irradiation were compared with those given by conventional biochemical tests. There was good correlation between the methods but not sufficient to enable accurate identification of unknown species. However, microwave irradiation considerably increased the enzymatic activity of bacterial suspensions and the results obtained could form the basis for a rapid method of microbial identification
-
-
-
-
Methods for the Detection of Haemagglutinins in Aeromonas
More LessSummaryWhen grown in specified conditions and tested by a rocked-tile method, 40 of 41 isolates of two species of Aeromonas formed simultaneously at least two haemagglutinins among which were: (i) a mannose-sensitive haemagglutinin with strongest activity for guinea-pig or fowl red cells, formed by all of 31 isolates of A. hydrophila and 9 of 10 isolates of A. punctata ss. caviae; (ii) a haemagglutinin, sensitive to L-fucose or D-mannose, that reacted with human red cells and which was formed by all 41 isolates; and (iii) a mannose-resistant ‘tanned red cell’ haemagglutinin formed by 29 isolates of A. hydrophila and one isolate of A. punctata ss. caviae. Results emphasise that for the fullest possible identification of haemagglutinins produced by Aeromonas spp., strains should be cultured in a variety of conditions and tested with a wide range of red-cell species.
-
- Article
-
-
-
Antibiotic Resistance in Staphylococcus Aureus Isolated at an Australian Hospital between 1946 and 1981
More LessSummaryA total of 517 strains of Staphylococcus aureus isolated at a hospital in Melbourne, Australia between 1946 and 1981 was examined for resistance to a range of antimicrobial agents and for the presence of plasmid DNA. The use of mixed-culture transfer and restriction endonuclease analysis showed that the determinants for resistance to penicillin and to the heavy metals were carried by several related plasmids of (15–23) × 106 mol. wt, and that tetracycline resistance was encoded on a plasmid of 2·8 × 106 mol. wt in strains isolated before 1970. These phenotypes were chromosomally encoded in the majority of strains isolated thereafter. Resistance to chloramphenicol throughout the study period was plasmid-mediated. Of five aminoglycoside-resistance phenotypes, one was plasmid-mediated and three were chromosomally encoded. The remaining phenotype, specifying low-level gentamicin resistance, was found to be located on the chromosome of early isolates, but in later strains was borne by an 18 × 106 mol. wt plasmid which also encoded resistance to quaternary ammonium compounds.
-
-
-
-
A Morphological Study of Bacterial Colonisation of Intravenous Cannulae
More LessSummaryIn an investigation of bacterial colonisation of intravascular cannulae, 16 peripheral venous cannulae of the Venflon variety and 24 chronic haemodialysis cannulae were studied after removal from patients. Studies of colonisation included semi-quantitative microbiological culture and scanning electronmicrographic (SEM) observations. The microbiological findings indicated colonisation of the intravascular portion of the catheter in 4 of 16 Venflon cannulae and 18 of 26 haemodialysis cannulae, largely with skin commensal organisms. The results of the SEM studies were in broad agreement with the microbiological observations. Surface defects on the cannulae were shown to be associated with microbial colonisation which occurred either as isolated colonies or in association with a cellular fibrinous matrix. These observations are illustrated and discussed.
-
-
-
Effect of a Lysolecithin Analogue on Nonspecific Resistance to Infection of Mice
More LessSummaryThe effect of racemic 1-octadecyl-2-methoxy-sn-glycero-3 phosphorylcholine (ET-18-OCH3) on the nonspecific resistance of mice to infection with Salmonella typhimurium was investigated. Two S. typhimurium strains with different virulence were studied and no effect was observed in either case at concentrations of ET-18-OCH3 up to 100 μg/mouse. However, a concentration of 500 μg/mouse caused decreased resistance to S. typhimurium, correlating with a depression of carbon clearance. Treatment of macrophages with ET-18-OCH3 in vitro inhibited phagosome-lysosome fusion, but had no effect on zymosan-induced luminol-dependent chemiluminescence. The relationship between the adjuvant and nonspecific anti-infectious activity of ET-18-OCH3 and other compounds is discussed.
-
-
-
The Effects of pH on Colonic Bacteria Grown in Continuous Culture
More LessSummaryA model of the promixal colon was used to investigate the effects of pH on fermentation by colonic bacteria in vitro. Twelve continuous anaerobic cultures of human faecal bacteria were maintained at constant pH in a medium simulating ileostomy effluent. Five cultures were maintained at pH 7, five at pH 6, and two at pH 5. The pH of each of three further cultures was altered after they had reached steady state, either from 7 to 6 and then to 5, or from 5 to 6 to 7.
Both experimental designs showed that the pH exerted an important effect on bacterial metabolism without causing major changes in bacterial populations. Osmolality was lower in cultures run at a low pH. Total volatile fatty acid concentration was decreased at pH 5, and the production of propionic acid rather than acetic acid was favoured at pH 6. Changing the pH had no significant influence on the production of ammonia in these systems.
-
-
-
Comparison of Media with and Without ‘Panmede’ for the Isolation of Streptobacillus Moniliformis from Blood Cultures and Observations on the Inhibitory Effect of Sodium Polyanethol Sulphonate
More LessSummaryFastidious anaerobe broth and brain-heart infusion cysteine broth supplemented with ‘Panmede’ (a papain digest of ox liver) 2·5% supported the recovery of five Streptobacillus moniliformis strains from simulated blood cultures. Other media tested in parallel—brain heart infusion cysteine broth without ‘Panmede’ and Brewer’s thiogly-collate broth—were unreliable. Sodium polyanethol sulphonate (Liquoid) 0·05%, inhibited five isolates of S. moniliformis, including isolates from patients with Haverhill Fever. Occasionally, Liquoid 0·025% was also inhibitory and a heavy inoculum of one strain, NCTC11194, was completely inhibited by Liquoid 0·012% in simulated nutrient-broth blood cultures. These results suggest that the choice of media included in each blood-culture set is critical for the optimal isolation of S. moniliformis. Brain-heart infusion cysteine broth supplemented with ‘Panmede’, or commercially available fastidious anaerobe broth, without Liquoid, is recommended.
-
-
-
Clinical Comparison of Anaerobic Blood-Culture Media for Detecting Bacteraemia Due to Viridans Streptococci and Oral Anaerobes
More LessSummaryBrain heart infusion cysteine broth, with and without Panmede® (a papain digest of ox liver) and Fastidious Anaerobe Broth, with and without Liquoid, were compared by inoculating the broths with blood collected from each of 51 patients, 2 min after dental extraction. Bacteraemia caused by viridans streptococci or oral non-sporing anaerobes or both was detected in 39 patients (76%). Detection of bacteraemia caused by viridans streptococci and anaerobes was more rapidly achieved by the addition of Panmede to brain heart infusion broth. Significantly more cases of bacteraemia caused by viridans streptococci were detected by use of the Panmede-containing medium than by use of Fastidious Anaerobe Broth after incubation of the broths for only 1 day. Use of brain heart infusion cysteine broth with and without Panmede, and Fastidious Anaerobe Broth permitted detection of bacteraemia caused by viridans streptococci in 26, 11 and 22 patients respectively during incubation for 2 weeks. Bacteraemia caused by anaerobes was detected by use of these three media in 24, 13 and 23 patients respectively. The addition of Liquoid to Fastidious Anaerobe Broth had no significant effect on the detection of bacteraemia caused by viridans streptococci or anaerobes.
The Panmede-containing blood-culture medium should be a useful anaerobic broth in the investigation of patients with suspected endocarditis, because viridans streptococci are also rapidly detected.
-
-
-
Comparative Growth of Bacteroides Species in Various Anaerobic Culture Media
More LessSummaryThe growth of five species of Bacteroides in four anaerobic culture media was continuously monitored turbidimetrically. Interspecies differences were observed in the growth of Bacteroides spp. in the various media, but growth in Brain Heart Infusion broth supplemented with yeast extract, haemin and menadione, was consistently better than in Wilkins-Chalgren, Thioglycollate or Schaedler broths.
Microscopy of cultures grown overnight in Brain Heart Infusion broth showed that the bacteria exhibited normal morphology but most species grown in the other media displayed filamentation or chain formation. Four of the five species grown in Schaedler broth also exhibited spheroplast formation. This morphological change occurred in the stationary phase of growth, was reduced by inclusion of NaCl in the medium and was abolished in Schaedler broth prepared at double the recommended strength.
-
-
-
Colony Variants of Neisseria Meningitidis Strain 2996 (B: 2b: P1.2): Influence of Class-5 Outer Membrane Proteins and Lipopolysaccharides
More LessSummaryDifferent colonial morphologies were found among colonies of Neisseria meningitidis strain 2996 (B: 2b: P1.2). Examination of cultures, selected on the basis of colony transparency or opacity, revealed that both lipopolysaccharides (LPS) and class-5 outer membrane proteins (OMP) are associated with differences in colonial morphology. Among 13 variants, four LPS variants and two class-5 OMP variants were recognised. All variants were non-fimbriate. The LPS variations were confirmed by immunoprecipitation. In addition to these qualitative variations of LPS, meningococci synthesise LPS of different molecular size depending upon growth phase; larger LPS molecules were found after analysis of stationary-phase cultures than with exponential-phase cultures. These changes did not cause a change in serotyping characteristics. The recognition in this study of intra-strain heterogeneity of meningococcal LPS and class-5 OMPs is important for the understanding of meningococcal pathogenicity. This heterogeneity was also detected in simultaneous isolates from different sites of a patient.
-
-
-
Nasal Carriage of Staphylococcus Aureus in a Population of Healthy Nigerian Students
More LessSummaryThe nasal carrier-rate of Staphylococcus aureus in 548 Nigerians aged 9–32 years and attending various educational establishments was 56·4%. This rate decreased with increasing age. A significantly greater proportion of females (65·0%) than males (46·5%) were carriers, but the excess in females was apparent only in subjects aged >20 years. Mucoid strains of S. aureus, which gave a negative slide-coagulase reaction, were found in 21·5% of carriers aged 10–15 years, but were absent from members of other age-groups. A considerable proportion of all the strains tested were resistant to commonly used antibiotics.
-
-
-
Antimicrobial Resistance in Coagulase-Negative Staphylococci
More LessSummaryPatterns of resistance to antimicrobial agents were studied in 193 strains of coagulase-negative staphylococci isolated from hospital patients. Strains isolated from patients with malignant disease were significantly more often resistant to sulphonamide, trimethoprim, gentamicin and methicillin than were strains from other sources. Susceptibility to various β-lactam antibiotics and aminoglycosides was investigated in members of the two most frequent species: Staphylococcus epidermidis and S. haemolyticus. S. haemolyticus strains were not only more often resistant to methicillin than S. epidermidis strains (respectively 81% and 17%) but they were more highly resistant (mean MICs respectively 85 and 19 mg/L). Methicillin-resistant S. haemolyticus strains were highly resistant to nine other β-lactam antibiotics, whereas methicillin-resistant S. epidermidis strains showed both lower levels and a narrower spectrum of cross-resistance. Resistance to methicillin in members of both species was “heterogeneous”, i.e., only a minority of cells in a culture showed significant resistance. Almost all gentamicin-resistant strains were sensitive to netilmicin and amikacin; rifampicin, vancomycin and teicoplanin were also highly active in vitro.
-
-
-
In-Vitro Inhibition of Mycobacteria by Viridans Streptococci
More LessSummaryEleven strains of Mycobacterium tuberculosis and 13 other species of mycobacteria were examined for susceptibility to 26 strains of viridans streptococci. Susceptibility was detected by the simultaneous antagonism technique, but not by tests of deferred antagonism. It is concluded that in-vitro inhibition of mycobacterial growth by actively growing streptococci is due to a peroxide-mediated antagonism which is too variable to be of value for identification. However, a standard bactericidal test with hydrogen peroxide is worth investigation because this might provide a simple inexpensive aid for the identification of M. avium-intracellulare serotypes.
-
-
-
A Simple Adult-Mouse Test for Tissue Invasiveness in Yersinia Enterocolitica Strains of Low Experimental Virulence
More LessSummaryThe virulence of Yersinia enterocolitica depends on the presence of a 70-kilobase plasmid, called the Vwa plasmid. This situation is particularly favourable for studies of the mechanism of pathogenicity, but these are hindered by the lack of a suitable animal test to monitor the virulence of the human-pathogenic strains isolated outside the USA which belong to serogroups O:3, O:9 and O:5,27. We observed that, after oral administration to the mouse, the Vwa-positive strains of these serogroups produce a discrete systemic infection while the Vwa-negative strains do not. We present here a simple mouse-virulence test based on this observation.
-
-
-
Virulence of Bordetella Bronchiseptica in the Porcine Respiratory Tract
More LessSummaryThe virulence of Bordetella bronchiseptica in gnotobiotic piglets was studied by intranasal infection with 11 cultures derived from eight strains isolated from pigs (4), dogs (2), a human subject and a monkey. Six of the cultures contained organisms in phase I and five contained phenotypically different phase-III or -IV organisms. Of the phase-III and -IV cultures, four were derived from strains that had been isolated in phase I. Colonisation of the nasal cavity was investigated by counting bacteria in nasal swabs and washings. The toxigenicity of cell extracts from each strain and variant was determined by tests of lethality in mice or of cytopathogenicity in cell cultures. The results showed that two phase-I cultures from pigs colonised the nasal cavity and respiratory tract of gnotobiotic piglets better than did four phase-I cultures from other species. Phase-I organisms invariably produced capsules, fimbriae and mannose-resistant haemagglutination of guinea-pig erythrocytes. Four of five cultures in phases III and IV consisted of organisms that did not produce capsules, fimbriae or haemagglutination and colonised the nasal cavity poorly. Phase variation from I to III occurred in culture and in vivo, but variation from III to I occurred in vivo only and was accompanied by enhanced colonisation. Gnotobiotic piglets infected with porcine phase-I organisms exhibited atrophy of the nasal turbinate bones after 28 days; these organisms produced significantly more toxin than did bacteria in phase I from other species, or those in phases III and IV. It was concluded that the development of turbinate atrophy was associated with (1) the ability to produce heavy, persistent colonisation in the nasal cavity, and (2) the production of a heat-labile toxin. Only the two porcine phase-I cultures possessed both properties.
-
-
-
Unusual Cellular Fatty Acids and Distinctive Ultrastructure in a New Spiral Bacterium (Campylobacter Pyloridis) from the Human Gastric Mucosa
More LessSummarySpiral bacteria, named Campylobacter pyloridis, were obtained from endoscopic biopsies of the gastric antrum of 14 patients with active chronic gastritis. Methyl esters of their cellular fatty acids were prepared by acid-catalysed transmethylation of whole cells. Their major fatty acids were tetradecanoic acid (14:0) and cis-9, 10-methyleneoctadecanoic acid (19:0Δ), with a very small amount of hexadecanoic acid (16:0). This is markedly different from the fatty acids of other Campylobacter sp. whose major fatty acids are hexadecanoic, octadecenoic (18:1) and hexadecenoic acids (16:1). This is also different from other enterobacteria.
Thin-section electronmicroscopy of gastric mucosal biopsies, and negative staining of cultured C. pyloridis, revealed features that differ from those of other campylobacters so far studied. C. pyloridis has a smooth not a rugose surface and multiple unipolar flagella of the sheathed type, each with a terminal bulb. Flagellar sheaths were in continuity with the unit membrane of the outer cell wall.
The proposed species C. pyloridis does not belong among the spirochaetes and its DNA composition is incompatible with membership of the genera Spirillum or Vibrio but is compatible with Campylobacter. Thus C. pyloridis is either an atypical member of the genus Campylobacter, the limits of which may have to be redefined to accommodate the new species, or a representative of a new genus.
-
- Announcement
-
Volumes and issues
-
Volume 74 (2025)
-
Volume 73 (2024)
-
Volume 72 (2023 - 2024)
-
Volume 71 (2022)
-
Volume 70 (2021)
-
Volume 69 (2020)
-
Volume 68 (2019)
-
Volume 67 (2018)
-
Volume 66 (2017)
-
Volume 65 (2016)
-
Volume 64 (2015)
-
Volume 63 (2014)
-
Volume 62 (2013)
-
Volume 61 (2012)
-
Volume 60 (2011)
-
Volume 59 (2010)
-
Volume 58 (2009)
-
Volume 57 (2008)
-
Volume 56 (2007)
-
Volume 55 (2006)
-
Volume 54 (2005)
-
Volume 53 (2004)
-
Volume 52 (2003)
-
Volume 51 (2002)
-
Volume 50 (2001)
-
Volume 49 (2000)
-
Volume 48 (1999)
-
Volume 47 (1998)
-
Volume 46 (1997)
-
Volume 45 (1996)
-
Volume 44 (1996)
-
Volume 43 (1995)
-
Volume 42 (1995)
-
Volume 41 (1994)
-
Volume 40 (1994)
-
Volume 39 (1993)
-
Volume 38 (1993)
-
Volume 37 (1992)
-
Volume 36 (1992)
-
Volume 35 (1991)
-
Volume 34 (1991)
-
Volume 33 (1990)
-
Volume 32 (1990)
-
Volume 31 (1990)
-
Volume 30 (1989)
-
Volume 29 (1989)
-
Volume 28 (1989)
-
Volume 27 (1988)
-
Volume 26 (1988)
-
Volume 25 (1988)
-
Volume 24 (1987)
-
Volume 23 (1987)
-
Volume 22 (1986)
-
Volume 21 (1986)
-
Volume 20 (1985)
-
Volume 19 (1985)
-
Volume 18 (1984)
-
Volume 17 (1984)
-
Volume 16 (1983)
-
Volume 15 (1982)
-
Volume 14 (1981)
-
Volume 13 (1980)
-
Volume 12 (1979)
-
Volume 11 (1978)
-
Volume 10 (1977)
-
Volume 9 (1976)
-
Volume 8 (1975)
-
Volume 7 (1974)
-
Volume 6 (1973)
-
Volume 5 (1972)
-
Volume 4 (1971)
-
Volume 3 (1970)
-
Volume 2 (1969)
-
Volume 1 (1968)
Most Read This Month
