Browsing by Author "Timothy J. Coleman, Jaber S. Orwa, Mutwakil G. Ahmed"

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    An Approach to the Taxonomy of Gram-positive Anaerobic Cocci 1. Isolation and Identification
    (Sebha University, 2008) Timothy J. Coleman, Jaber S. Orwa, Mutwakil G. Ahmed
    The aim of this study was to collect and identify fresh isolates of Gram-positive anaerobic cocci (GPAC) from clinical materials as a basis for the study of taxonomy of GPAC. A total of 116 strains of GPAC, isolated from clinical materials collected from the Department of Microbiology, in St. Lukes Hospital, Guilford and St. Thomas Hospital, London, were investigated. The reference strains were obtained from the American Type Culture Collection (ATCC), Virginia Polytechnic Institute and State University (VPI) and the National Collection of Industrial Bacteria (NCIB). GPAC were identified on the basis of morphology, biochemical examination and the detection of the end products from the fermentation in peptone yeast extract glucose or chopped meat glucose media by means of Gas Liquid Chromatography (GLC). All of the strains studied were obligately anaerobic Gram-positive cocci (GPAC). They occurred in singles, pairs, tetrads, short or long chains. Peptone yeast extract without addition of carbohydrate supported their growth. The strains grew at 37ï‚°C. The G.L.C. profiles showed that all strains produced acetic acid and lactic acid. One hundred and three (89%) out of 116 isolates were considered to be different from each other at the species level. These were Peptostreptococcus (Pst.) anaerobius (26.7%), Peptococcus (Pc.) magnus (19%), Streptococcus (Str.) asaccharolyticus (6.9%), Peptostreptococcus (Pst.) micros (3.5%), Peptococcus (Pc.) asaccharolyticus (2.6%), Gaffkya (G.) anaerobia (1.7%), and Megosphaera (M.) elsdenni (0.9%). Thirteen (11.1%) out of 116 strains could not be speciated.
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    An Approach to the Taxonomy of Gram-positive Anaerobic Cocci. 2. Carbohydrate Fermentation
    (Sebha University, 2008) Timothy J. Coleman, Jaber S. Orwa, Mutwakil G. Ahmed
    An attempt was made to classify gram-positive anaerobic cocci (GPAC) on the basis of their production of fatty acids from the fermentation of mannose, galactose and rhamnose by the use of gas liquid chromatography (GLC). The only species that could be separated were Peptostreptococcus (Pst.) anaerobius and Megasphaera (M.) elsdenii. Unfortunately the other species were indistinguishable using information obtained from the GLC analysis.
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    An Approach to the Taxonomy of Gram-positive Anaerobic Cocci. 3. Antimicrobial Susceptibility Testing
    (Sebha University, 2008) Timothy J. Coleman, Jaber S. Orwa, Mutwakil G. Ahmed
    Antibiotics and dye susceptibility tests have been used by several investigators as selective agents or as presumptive procedures for the identification of anaerobes. In this study a total of 76 strains of Gram-positive anaerobic cocci (GPAC) were tested against five antibiotics (Oleandomycin, Vancomycin, Gentamycin, Tobramycin and Cephradine, and three dyes (Brilliant green, Crystal violet and Gentian violet), using agar plate dilution methods. Although the data of the susceptibility of GPAC to the tested antibiotics and dyes were of no use for the classification of these cocci, it could be concluded that Cephradine and Vancomycin are efficacious antibiotics against GPAC. However, Gentamycin and Tobramycin displayed an activity against Megosphaera (M.) elsdenii and Streptococcus (Str.) intermedius. In addition, Tobramycin was active against Gaffkya (G.) anaerobia, Peptococcus (Pc.) asaccharolyticus, Pc. prevotii and Pc. saccharolyticus, whilst all GPAC were resistant to Oleandomycin.
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    An Approach to the Taxonomy of Gram-positive Anaerobic Cocci. 4. The Cell Wall Composition
    (Sebha University, 2008) Timothy J. Coleman, Jaber S. Orwa, Mutwakil G. Ahmed
    The classification of Gram-positive anaerobic cocci (GPAC) has always been very unsatisfactory. Attempts to clarify the taxonomy of GPAC have involved several methods including the analysis of the composition of bacterial cell wall. In an attempt to obtain information on the cell walls of 24 strains of GPAC isolated from clinical materials at St. Lukes, Guilford, and St. Thomas Hospital, London, the amino acid and amino sugar composition was quantitatively determined by an amino acid analyzer, using the method of Park and Hancock. The present study has revealed that the evaluation of the cell wall components is an accurate and reproducible method for classification of GPAC. The investigation showed that there are major differences in the amino acid composition of the cell walls of the members of GPAC. On balance, the separation of most GPAC using this system in general is consistent with the principles of Holdman et al (1977) and added valid characteristics for certain organisms such as differentiation of the species of Pst. micros from Pc. magnus, and recognition of the species of Pc. variablis and Pc. anaerobius as a variant species of Pc. magnus. The most unexpected finding was the designated reference strains of Pc. asaccharolytius varied significantly in their cell wall components. Therefore, additional strains must be studied in order to clarify the characterization and hence the nomenclature of such organisms.
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    An Approach to the Taxonomy of Gram-positive Anaerobic Cocci. 5. The Metabolism of Amino Acid
    (Sebha University, 2009) Timothy J. Coleman, Jaber S. Orwa, Mutwakil G. Ahmed
    This study showed that the metabolism of amino acids was useful in differentiating between the species of Gram-positive anaerobic cocci (GPAC). The best results were obtained from those whose taxonomic positions or biochemical reactions were in doubt. These include Peptococcus ( Pc.) asaccharolyticus, Pc. aerogenes,, Pc. magnus, Pc. anaerobius, Pc. variabilis, Pc. niger and Peptostreptococcus (Pst. micros. For these species which are easily recognized by carbohydrate fermentation amino acid utilization was less discriminatory. It should be noted, however, that the most frequently isolated GPAC from clinical materials are those which have a high capacity to utilize amino acids. This study has revealed that the carbohydrate fermenters are less commonly encountered in clinical specimens. This indicates that the species which are more active against amino-acids are more commonly pathogenic, and this phenomenon should therefore be exploited to identify and classify the GPAC.
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    An Approach to the Taxonomy of Gram-positive Anaerobic Cocci. 6. The Metabolism of Amino Acids
    (Sebha University, 2009) Timothy J. Coleman, Jaber S. Orwa, Mutwakil G. Ahmed
    This study showed that the metabolism of amino acids was useful in differentiating between the species of Gram-positive anaerobic cocci (GPAC). The best results were obtained from these whose taxonomic position or biochemical reaction were in doubt. These include Peptococcus ( Pc.) asaccharolyticus, Pc. aerogenes,, Pc. magnus, Pc. anaerobius, Pc. variabilis, Pc. niger and Peptostreptococcus (Pst.) micros. For these species which are easily recognized by carbohydrate fermentation amino acid utilization was less discriminatory. It should be noted, however, that the most frequently isolated GPAC from clinical materials are those which have a high capacity to utilize amino acids. This study has shown this and that the carbohydrate fermenters are less commonly encountered in clinical specimens. This indicates that the species which are more active against amino-acids are more commonly pathogenic, and this phenomenon should therefore be exploited to identify and classify the GPAC.