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Biomedical subjects

G L French

Publications and source records attributed to G L French.

At least 91 records · Page 5Linked to original sources
PubMed1989

Rapid HPLC assay of fluoroquinolones in clinical specimens.

A simple isocratic HPLC procedure was developed for the analysis of seven quinolones and their metabolites in clinical specimens. It is likely that this system can be used for the assay of many other quinolone compounds, but not for nalidixic acid and the ciprofloxacin metabolite sulpho-ciprofloxacin which appear to be adsorbed in the column. Sample preparation takes approximately 20 min, and HPLC analysis is completed within 15 min with a simple solvent system eluted on a reversed phase column. The procedure is rapid, sensitive and specific, and is a modification of an assay for chloramphenicol and beta-lactam antibiotics. This method is therefore particularly useful for clinical laboratories, since a single HPLC system can be used for assays of chloramphenicol, beta-lactams and quinolones.

4-Quinolones↗
PubMed1989

Antimicrobial susceptibilities of halophilic vibrios.

Two hundred and forty-four clinical and environmental strains of nine species of halophilic vibrios isolated in Hong Kong were tested for their susceptibilities to 23 antimicrobial agents by an agar dilution method using unsupplemented Mueller-Hinton agar, an inoculum size of 10(5) cfu per spot and incubation for 18 h at 30 degrees C. Most strains were resistant to sulphamethoxazole, trimethoprim, penicillins and older cephalosporins, and most were susceptible to chloramphenicol, tetracycline, cotrimoxazole, the aminoglycosides, the newer cephalosporins, aztreonam, imipenem and the quinolones. However, there were significant differences between species, especially in their patterns of beta-lactam susceptibility.

Anti-Bacterial Agents↗
PubMed1989

A physiological classification of viridans streptococci by use of the API-20STREP system.

Physiological reactions of viridans streptococci were examined by the API-20STREP system and a selection of conventional tests. Cluster analysis of these results produced a classification similar to a taxonomic scheme based on that of Colman and Williams. The organisms could be divided into the six recognised species--Streptococcus mutans, S. bovis, S. mitior, S. sanguis, S. salivarius and S. milleri. Analysis confirmed that S. mitior and S. sanguis can be distinguished in the API-20STREP test by hydrolysis of arginine but not by dextran production. Although S. mutans, S. mitior and S. sanguis can be divided into two further subgroups, the taxonomic significance of this is unclear. With this means of classification, most organisms could be identified easily by a small number of tests. API-20STREP is convenient for performing physiological tests on viridans streptococci, but the information provided by the manufacturers in regard to identification and nomenclature is in need of revision.

Bacteriological Techniques↗
PubMed1989

Identification of viridans streptococci by pyrolysis-gas chromatography.

An isothermal method of pyrolysis-gas chromatography (Py-GC) was used for the identification of viridans streptococci. Pyrograms from 104 reference strains were subjected to a discriminant analysis to produce classification coefficients for the identification of 74 test organisms. Five groups representing recognised species were discriminated but Streptococcus milleri strains could not be distinguished from S. sanguis. If S. milleri and S. sanguis are regarded as a single pyrogroup, only three strains out of 74 were incorrectly identified by Py-GC. A multidimensional scaling analysis of the Py-GC data produced a similar species grouping, but this statistical method was less satisfactory for pyrogram data than discriminant analysis. While Py-GC was moderately successful for the identification of viridans streptococci, this study indicated that the technique has limited use in diagnostic medical microbiology because it is time-consuming and lacks flexibility.

Chromatography, Gas↗
PubMed1989

Vibrio parahaemolyticus and other halophilic vibrios associated with seafood in Hong Kong.

The summer prevalence of Vibrio parahaemolyticus and other halophilic vibrios in seafood from Hong Kong markets was investigated. Halophilic vibrios were isolated from all seven types of seafood examined, and comprised 9.1%, 8% and 6.1% of contaminating aerobic heterotrophic bacteria from mussels, clams and oysters respectively. Sucrose-positive vibrios were more common than sucrose-negative varieties. Vibrio alginolyticus was the most frequently isolated species, followed by V. parahaemolyticus, V. harveyi, V. fluvialis, V. vulnificus, V. pelagius, V. campbellii, V. spendidus and V. marinus. Mussels contained the highest concentration of V. parahaemolyticus (4.6 x 10(4)/g); oysters and clams contained 3.4 x 10(4)/g and 6.5 x 10(3)/g respectively. The ubiquity and relatively high concentrations of V. parahaemolyticus and other pathogenic vibrios in shellfish is a potential public health hazard in Hong Kong and other subtropical Asian countries.

Animals↗
PubMed1989

Vibrio vulnificus septicaemia presenting as spontaneous necrotising cellulitis in a woman with hepatic cirrhosis.

Vibrio vulnificus is a virulent marine organism commonly found in Hong Kong coastal waters which contaminates local sea-food. It may produce a primary septicaemia, often associated with secondary skin lesions, following ingestion of raw shell fish. We report a rapidly fatal case of primary V. vulnificus septicaemia in a 50-year-old housewife with post-hepatitic cirrhosis presenting as spontaneous necrotising cellulitis of the legs. V. vulnificus infection should be considered in patients with a history of liver disease with acute septicaemia and characteristic skin lesions.

Cellulitis↗
PubMed1988

Methicillin-resistant Staphylococcus aureus bacteraemia in Hong Kong.

In the first 22 months of operation at the Prince of Wales Hospital, 26 (46%) of 56 hospital-acquired Staphylococcus aureus bacteraemias were due to methicillin-resistant organisms (MRSA). There were 10 plasmid profiles amongst 24 of the MRSA strains analysed. MRSA bacteraemias were first seen in the hospital 1 year after opening when the isolation rate of MRSA from all sites had risen to about 1% of patient admissions. During the last 3 months of the study period, 17 out of 18 S. aureus bacteraemias were due to methicillin-resistant strains. Patients with MRSA bacteraemia were significantly more likely than those with methicillin-sensitive S. aureus bacteraemia to have had a severe underlying disease, a poor clinical prognosis, prolonged hospitalization, and prior antimicrobial therapy, especially with aminoglycosides. They also had a significantly longer hospital stay after infection, a significantly higher cost of antimicrobial therapy and a higher mortality rate. The lower mortality rate in MRSA patients treated with vancomycin (18%) compared with those treated with other antimicrobials (40%) confirms that, at present, vancomycin is the treatment of choice for invasive MRSA infections.

Cross Infection↗
PubMed1988

Thyroid abscess caused by Eikenella corrodens.

To our knowledge, this is only the fourth case recorded of thyroid abscess due to Eikenella corrodens and the first in which the causative organism has been isolated in pure culture from the site of infection. E. corrodens may be the cause of apparently sterile thyroid abscesses encountered in head and neck surgery and should be considered in their differential aetiology.

Abscess↗
PubMed1988

Susceptibility of Hong Kong isolates of methicillin-resistant Staphylococcus aureus to antimicrobial agents.

Two hundred and sixty-six non-replicate Hong Kong isolates of methicillin-resistant Staphylococcus aureus were tested for their susceptibility to various anti-staphylococcal agents. Multiple resistance was common. More than 95% of patient isolates were resistant to both gentamicin and tetracycline, 68% to erythromycin, 37% to chloramphenicol, 10% to trimethoprim, 5% to rifampicin and 2% to fusidic acid. No isolate was resistant to all these agents, but nineteen different patterns of resistance were identified. Selected gentamicin-resistant isolates were tested against other aminoglycosides, and were sensitive to amikacin and netilmicin. The pattern of aminoglycoside resistance indicated that all isolates produced the aminoglycoside-modifying enzymes APH-(2") and AAC-(6')-I. All isolates were sensitive to vancomycin and teicoplanin. A single strain was resistant to three of the five quinolones tested, but resistance to all the quinolones could be induced easily in vitro by exposure to increasing subinhibitory concentrations of norfloxacin in broth.

Anti-Bacterial Agents↗
PubMed1988

Susceptibilities of Hong Kong isolates of multiply resistant Shigella spp. to 25 antimicrobial agents, including ampicillin plus sulbactam and new 4-quinolones.

Seventy-two percent of 129 shigella isolates from two Hong Kong hospitals were Shigella flexneri. Twenty-six percent were S. sonnei, and there was only one isolate each of S. dysenteriae and S. boydii. Ninety-six percent of the isolates were resistant to two or more antibiotics, and up to 11 resistances were seen in a single isolate. Fifty-seven percent or more of these isolates were resistant to ampicillin, streptomycin, tetracycline, chloramphenicol, and sulfamethoxazole; and up to twenty-three percent were resistant to kanamycin, trimethoprim, trimethoprim-sulfamethoxazole, and gentamicin. All the isolates were susceptible to amikacin, nalidixic acid, and the newer 4-quinolone agents; and all but one were susceptible to the cephalosporins tested. Only three isolates remained resistant to ampicillin in the presence of sulbactam. Ampicillin plus sulbactam or the newer 4-quinolone agents may be alternatives for the treatment of severe infections caused by multiply resistant shigellas.

Ampicillin↗
PubMed1988

Analysis of antimicrobial susceptibility results using microcomputers.

A computer program has been developed on an IBM-PC-compatible microcomputer to analyze antimicrobial susceptibility results of large numbers of organisms tested against a variety of antimicrobial agents. For each species, the output includes the numbers, percentages, cumulative numbers, and cumulative percentages of organisms inhibited at different concentrations of each drug, the MICs for 50 and 90% of organisms tested, MIC ranges, and geometric mean MICs. The distributions of MICs are also plotted as histograms. The program was written in dBASE III command language, but a compiled version allows rapid program execution independently of the dBASE III package.

Microbial Sensitivity Tests↗
PubMed1988

Diagnosis of nasopharyngeal tuberculosis by detection of tuberculostearic acid in formalin fixed, paraffin wax embedded tissue biopsy specimens.

The use of gas chromatography and mass spectrometry with selected ion monitoring detected tuberculostearic acid (TBSA) in 10 of 12 formalin fixed, paraffin wax embedded nasopharyngeal and head and neck biopsy specimens from patients with confirmed tuberculosis and carcinoma, and in one of 50 control specimens (giving a sensitivity of 83% and a specificity of 98%). The two false negative cases had very small tissue fragments and the patient with a false positive result may have had pulmonary tuberculosis. Tuberculostearic acid (TBSA) was also detected in nine of 16 specimens from the head and neck region with non-caseating granulomas suspected, but not confirmed, to be tuberculosis. It is concluded that nasopharyngeal tuberculosis is relatively common in Hong Kong and should be considered when biopsy specimens show granulomas. The detection of TBSA in tissue biopsy specimens is a useful, rapid method for the diagnosis of tuberculosis and other mycobacterial infections, and can be conveniently performed within two days on formalin fixed and paraffin wax embedded material.

Granuloma↗
PubMed1988

Evaluation of the Microbact-24E bacterial identification system.

The Microbact 24E (MB24E) system is a commercial microsystem for the identification of common clinical isolates of Enterobacteriaceae and non-fermenting Gram negative bacilli, and consists of dehydrated substrates distributed in the wells of microtitre trays. This system was compared with the API20E for the identification of 386 bacterial isolates, which included 284 clinical and 102 environmental organisms. There was 97% and 91% agreement for the identification of clinical isolates of Enterobacteriaceae and other Gram negative bacilli, respectively. The identification of environmental isolates by both systems was less satisfactory. The API20E has a more extensive database than the MB24E and is thus more reliable for the identification of rare or unusual organisms, but the MB24E is cheaper, is easy and convenient to use, and is suitable for a routine microbiology laboratory.

Bacteriological Techniques↗
PubMed1988

Rickettsial infection presenting as culture-negative meningitis.

Meningitis is an unusual presentation of rickettsial infection. We report a patient who was confirmed by serology to have typhus fever (not scrub), but who presented with the typical findings of culture-negative bacterial meningitis. Neurological manifestations of different types of rickettsial infection are discussed.

Chloramphenicol↗