Search PubMed⌕ Search

Biomedical subjects

C A Ison

Publications and source records attributed to C A Ison.

At least 91 records · Page 5Linked to original sources
PubMed1988

The effect of media on antimicrobial susceptibility testing of Neisseria gonorrhoeae.

We have investigated the effect of four different media on the results of susceptibility tests for clinical and reference strains of Neisseria gonorrhoeae. Diagnostic Sensitivity Test (DST) agar supplemented with 5% lysed horse blood and 1% IsoVitaleX was regarded as the 'standard' and three other media were compared with it--DST plus 5% lysed blood, GC agar supplemented with 1% IsoVitaleX and Proteose agar plus 1% haemoglobin and 1% IsoVitaleX. We found no significant differences between the two DST media when testing penicillin, cefuroxime, tetracycline or erythromycin. Proteose agar compared well with the 'standard' for all antibiotics except erythromycin for which MICs were significantly increased. GC agar showed the poorest agreement with the 'standard' medium. Gonococci appeared more sensitive to tetracycline and less sensitive to erythromycin on this medium. The use of GC agar did not significantly affect susceptibilities to the beta-lactam agents tested, although MICs measured on GC agar did tend to be higher than on the 'standard' DST medium.

Anti-Bacterial Agents↗
PubMed1988

Evaluation of a fluorescent monoclonal antibody reagent for identification of cultured Neisseria gonorrhoeae.

We evaluated a new fluorescent monoclonal antibody reagent for confirmation of identity of Neisseria gonorrhoeae. The reagent correctly identified all 161 fresh clinical isolates of N. gonorrhoeae, which included 11 penicillinase producing strains (PPNG). The reagent also correctly identified 21 stored PPNG strains. No cross reactions were seen with 58 fresh clinical isolates of N. meningitidis, 12 stored strains of N. lactamica, or with strains of Gardnerella vaginalis, lactobacilli, Candida spp., Staphylococcus epidermidis or Enterobacteriaceae. Some cross reaction was noted with strains of S. aureus, probably related to cell-wall protein. A. However, this reagent was highly sensitive and specific for use against oxidase positive, gram-negative cocci isolated in London.

Antibodies, Monoclonal↗
PubMed1988

Susceptibility testing of Neisseria gonorrhoeae to penicillin and spectinomycin in a diagnostic laboratory.

Agar dilution breakpoint susceptibility testing using GC, DST, and proteose agars, was performed on consecutive clinical isolates of non-penicillinase producing Neisseria gonorrhoeae to examine the feasibility of using such a system in a diagnostic laboratory. The incidence and level of resistance to penicillin and spectinomycin was also assessed. On DST medium 93 of 200 (46.5%) of isolates were of intermediate resistance to penicillin (MIC 0.12-0.5 mg/l) and 21 of 200 (10.5%) were resistant to penicillin (MIC greater than or equal to 1.0 mg/l). Ninety two of 200 (46%) of isolates had an MIC to spectinomycin of 32 mg/l on DST agar. Isolates seemed to be more resistant when tested on the two other media. The methods used in this study could be applied in a routine diagnostic laboratory for immediate clinical benefit and long term epidemiological studies. To enable direct comparisons to be made between populations at different centres, however, methods for gonococcal susceptibility testing need to be standardised.

Culture Media↗
PubMed1987

The activity of the 4 quinolone Ro 23 6240 and the cephalosporins Ro 15 8074 and Ro 19 5247 against penicillin sensitive and resistant gonococci.

We have compared the in-vitro activity of the 4-quinolone Ro 23 6240 and the oral cephalosporins Ro 15 8074 and Ro 19 5247 with that of penicillin, spectinomycin, cefuroxime, ceftriaxone, ciprofloxacin, ofloxacin and norfloxacin against 60 strains of Neisseria gonorrhoeae. MICs 90 against penicillinase producing N. gonorrhoeae (PPNG) and chromosomally-mediated resistant N. gonorrhoeae (CMRNG) respectively were: spectinomycin 16 and 16 mg/l, cefuroxime 0.12 and 1.0 mg/l, ceftriaxone 0.008 and 0.03 mg/l, Ro 15 8074 0.015 and 0.12 mg/l, Ro 19 5247 0.015 and 0.12 mg/l, Ro 23 6240 0.06 and 0.06 mg/l, ciprofloxacin 0.008 and 0.015 mg/l, ofloxacin 0.03 and 0.06 mg/l, norfloxacin 0.06 and 0.12 mg/l. The spectinomycin resistant and spectinomycin-sensitive strains did not differ. All three new agents show good activity against gonococci and warrant further clinical investigation. Ro 23 6240 in common with the other 4-quinolones appears to be as active against gonococcal strains exhibiting non-enzymic chromosomal resistance to penicillin as against PPNG and penicillin-sensitive isolates.

Anti-Bacterial Agents↗
PubMed1987

Neisseria gonorrhoeae: a versatile pathogen.

Neisseria gonorrhoeae is one of the most important causes of sexually transmitted disease. We do not fully understand the pathogenesis of infection with this organism, although recent improvements in immunological and molecular techniques have brought us closer to an answer. These techniques are now also being used to detect and identify N gonorrhoeae and to analyse the epidemiology of gonorrhoea. Plasmid and chromosomal mediated antibiotic resistance increases the difficulty of controlling gonorrhoea. Resistant strains occur all over the world and new patterns of resistance are still emerging. A better understanding of gonococcal pathogenicity is necessary for the development of an effective vaccine. Despite work on pili and outer membrane proteins no vaccine yet exists. The control of gonorrhoea still depends on diagnosis, treatment, and epidemiological control, facilities that are not widely available in many of those parts of the world where gonorrhoea is a major problem.

Drug Resistance, Microbial↗
PubMed1987

New microbial and host factors in disseminated gonococcal infection: case report.

Disseminated gonococcal infection was diagnosed in an immunocompromised patient who presented with oliogoarthropathy and tenosynovitis. The gonococcal isolate was prototrophic, showed intermediate resistance to penicillin, and belonged to serogroup WII/III. An isolate from the patient's sexual contact showed similar characteristics. The patient had a Saccharomyces opsonin defect, which is associated with childhood infections and has not been reported previously in association with disseminated gonococcal infection. The pathogenetic importance of the unusual isolate and the underlying host defence defect is considered.

Adolescent↗
PubMed1987

Development and evaluation of scheme for serotyping Gardnerella vaginalis.

Antibodies to Gardnerella vaginalis were raised in rabbits. Nine antisera that reacted with their immunising strains, but not with the remaining eight strains, were used to develop a serotyping scheme. A dot blotting technique was used, and complexes of antigen and antibody were visualised using anti-rabbit immunoglobulin linked to alkaline phosphatase. Of 91 clinical isolates used to evaluate the scheme, 79 (87%) were typable and 52 (57%) reacted with only a single antiserum. The antigens expressed were stable during growth on different media and on subculture. The specificity of the antibody was shown to be directed against different immunodominant proteins and possibly a carbohydrate.

Antibody Specificity↗
PubMed1987

Chromosomal resistance of gonococci to antibiotics.

Three hundred and twenty nine strains of non-penicillinase-producing Neisseria gonorrhoeae (non-PPNG) isolated from men and women were tested for their susceptibility to a range of antibiotics, and were also auxotyped and serogrouped. Nearly 6% (18) of 312 strains tested were resistant to 1 mg/l or more penicillin (compared with 4.4% of PPNG strains isolated in 1981). Many (198, 64%) strains showed intermediate resistance to penicillin (0.12-0.5 mg/l). Nearly 5% (15) of 312 strains tested were resistant to 0.5 mg/l or more cefuroxime, and there was a high degree of cross resistance between these two antibiotics. High levels of resistance to erythromycin and tetracycline were also found, and there was also appreciable cross resistance between these antibiotics and the beta lactam drugs. Resistance to spectinomycin was rare, and there was no cross resistance between spectinomycin and other agents tested. Levels of resistance between strains isolated from different anatomical sites did not differ, except that resistance to erythromycin was greater in rectal isolates. Four main auxotypes were detected. Strains requiring arginine, hypoxanthine, and uracil (AHU-) were more prevalent from the cervix. We have shown that there is an association between auxotype, serogroup, and level of sensitivity to penicillin, cefuroxime, and tetracycline.

Anti-Bacterial Agents↗
PubMed1986

Homology of cryptic plasmid of Neisseria gonorrhoeae with plasmids from Neisseria meningitidis and Neisseria lactamica.

DNA probe hybridisation was used to examine the relation between the cryptic plasmid from Neisseria gonorrhoeae and plasmids carried by pharyngeal isolates of Neisseria meningitidis and Neisseria lactamica. The complete gonococcal cryptic plasmid and HinfI derived digestion fragments subcloned into Escherichia coli were used to probe Southern blots of plasmid extracts. Homology was found to a plasmid of approximate molecular weight 4.5 kilobase pairs (Kb) but not to plasmids of less than 3.2 Kb or 6.5 Kb. Eleven of 16 strains of N meningitidis and two of six strains of N lactamica carried plasmids that showed strong hybridisation with the 4.2 Kb gonococcal plasmid. Hybridisation of plasmids from non-gonococcal species of neisseria with the gonococcal cryptic plasmid indicates that caution should be taken when using the cryptic plasmid as a diagnostic probe for gonorrhoea.

DNA, Bacterial↗
PubMed1986

Penicillinase producing gonococci: a spent force?

Though the incidence of gonorrhoea caused by penicillinase producing Neisseria gonorrhoeae (PPNG) strains at St Mary's Hospital rose rapidly from 1980 to reach 6.2% in 1982, it declined in 1983 (8.6%) and in 1984 (6.5%), a trend that has continued in 1985. The use of penicillinase stable antibiotics or more effective contact tracing are unlikely to be responsible for this recent decline. We have always isolated very few PPNG strains from homosexual men, and the possible effects of the acquired immune deficiency syndrome (AIDS) on sexual behaviour in this group is therefore unlikely to be relevant. We have seen a steady increase in the proportion of PPNG strains carrying the 4.4 megadalton penicillinase plasmid (67% of PPNG strains in 1984). Strains carrying both the 4.4 megadalton plasmid and the 24.5 megadalton conjugal plasmid were very common in 1982, but since then have declined in importance. PPNG strains carrying the 3.2 megadalton plasmid have become less common, and the presence of the 24.5 megadalton plasmid in these strains has not apparently led to their wider dissemination in the community. Whereas the basic pattern of PPNG auxotypes has changed little, since 1982 we have isolated an increasing number of mixed auxotypes with nutritional requirements other than just proline. PPNG strains carrying the 4.4 megadalton plasmid seem to be more resistant to erythromycin, tetracycline, and streptomycin than those carrying the 3.2 megadalton plasmid. Spectinomycin resistance has only occurred in strains carrying the 4.4 megadalton plasmid.

Gonorrhea↗
PubMed1986

The specificity of serum and local antibodies in female gonorrhoea.

Immunoblotting has been used to compare the specificity of serum and local IgG and IgA antibodies in 13 women with gonorrhoea and in 13 controls. The technique allowed the simultaneous detection of antibodies to the major outer membrane proteins I, II, and III, pili and lipopolysaccharide; antibodies to another antigen which is probably a 'carbohydrate' were also detected. Serum and local IgG and IgA were found to be produced to several antigens during gonococcal infections, although the quantity of antibody was greater in serum. There was little change in the specificity of serum antibodies whereas the local response to LPS and pili increased over the two week study period. Serum antibody to LPS was more often IgG than IgA. Sera contained antibodies to 'carbohydrate', pili and lipopolysaccharide (LPS) whilst the local response was largely to the latter two antigens. Antibody to the outer membrane proteins was rarely detected. Control sera, but not vaginal washings, contained IgG and IgA to the major antigens but the staining of the immunoblots was less intense than those from patient's sera suggesting quantitative differences.

Adolescent↗
PubMed1985

Evaluation of a direct immunofluorescence test for diagnosing gonorrhoea.

A new direct immunofluorescence reagent (Syva and Genetic Systems Inc) was evaluated for its ability to detect Neisseria gonorrhoeae in specimens from populations with a high prevalence of the infection. Gonorrhoea was diagnosed by culture in 45 of 105 (43%) urethral specimens from men and 17 of 90 (28%) urethral and 25 of 60 (42%) cervical specimens from women. In men the immunofluorescence test had a sensitivity of 84.4% and a specificity of 100%; Gram staining gave values of 94% and 100%, respectively. The sensitivity of the immunofluorescence test could be increased to 89% by testing duplicate smears. In women the immunofluorescence test had a sensitivity of 65% and a specificity of 98% for urethral samples and values of 72% and 94%, respectively for cervical samples. At both sites the sensitivity of the Gram stain was 40% and the specificity 100%. The testing of duplicate immunofluorescence smears increased the sensitivity to 76% for urethral and 88% for cervical samples.

Cervix Uteri↗