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Biomedical subjects

C A Ison

Publications and source records attributed to C A Ison.

At least 109 records · Page 6Linked to original sources
PubMed1985

Carriage of Gardnerella vaginalis and anaerobes in semen.

Gardnerella vaginalis was isolated from 22 (38%) of 58 semen samples obtained from men attending an infertility clinic. Counts ranged from 1.2 X 10(3) to greater than 10(7) colony forming units (cfu)/ml. There was no association between the isolation of G vaginalis and the sperm count. Twenty (34.4%) samples contained non-sporing anaerobes and nine (15.5%) both anaerobes and G vaginalis. The infective dose of G vaginalis is not known, but semen could act as a medium for its sexual transmission.

Bacteria, Anaerobic↗
PubMed1985

Testing sensitivity of Neisseria gonorrhoeae to spectinomycin.

A concentration of 16 mg/l spectinomycin incorporated in agar gave the best discrimination between Neisseria gonorrhoeae sensitive and resistant to spectinomycin. This method was compared with spectinomycin sensitivity testing with 25 micrograms or 100 micrograms discs. Both methods agreed fully for 197 spectinomycin sensitive and three spectinomycin resistant gonococci. The agar incorporation "breakpoint" concentration technique failed to detect a small spectinomycin resistant population in a fourth isolate, which was detected by disc testing. It may be possible to predict the emergence of spectinomycin resistance among strains of N gonorrhoeae.

Microbial Sensitivity Tests↗
PubMed1984

Spectinomycin as initial treatment for gonorrhoea.

The prevalence of penicillinase producing Neisseria gonorrhoeae at this hospital increased exponentially from less than 0.5% in 1978 to 6.5% of all isolates in 1982. In January 1983 first line treatment for uncomplicated heterosexual anogenital gonorrhoea was therefore changed from ampicillin and probenecid to spectinomycin. This subsequently cured 95% of cases seen at the Praed Street Clinic. Although there was an initial fall in the monthly isolation rate of penicillinase producing N gonorrhoeae after the introduction of spectinomycin, this was not maintained. The exponential increase in the prevalence of the strain did slow in 1983, rising to only 8.7%. This, however, may have reflected a general decline in the rate of increase of penicillinase producing N gonorrhoeae throughout Britain. The failure to influence the prevalence of penicillinase producing N gonorrhoeae to any great degree may have been due in part to spectinomycin resistance in both penicillinase producing and non-penicillinase-producing N gonorrhoeae. All of the isolates appeared identical, apart from the presence of the 4.4 megadalton plasmid in penicillinase producing N gonorrhoeae, but they could not be linked epidemiologically. Changing treatment in only one of the many venereal diseases clinics in London, where patients have open access to all such clinics, is unlikely to affect the prevalence of penicillinase producing N gonorrhoeae. This has probably been more important than spectinomycin resistance in limiting the effectiveness of spectinomycin in reducing the prevalence of the strain.

Adolescent↗
PubMed1984

Plasmids in throat and genital isolates of meningococci.

Plasmids 1.6, 2.8, or greater than 40 megadaltons in size were found in one urethral and nine throat strains of meningococci. Throat meningococci are known to be heterogeneous in their aminopeptidase profiles. Their unexpected content of plasmids is further evidence of their difference from classic systemic strains. Although the 2.8 megadalton plasmid has some resemblance to the well known 2.6 megadalton gonococcal plasmid, restriction enzyme studies gave no evidence of identity. Possible sources of the plasmids are discussed.

Aminopeptidases↗
PubMed1984

Studies on the mechanism of adhesion of Gardnerella vaginalis to human erythrocytes.

A quantitative method using radiolabelled bacteria was used to examine the adherence of Gardnerella vaginalis to human erythrocytes. Adherence was mannose resistant, but inhibited by D-galactose and D-galactosamine. It was independent of temperature, but reduced at pH 3. There was considerable variation in the adherence of different isolates of G. vaginalis to human erythrocytes.

Erythrocytes↗
PubMed1984

Vaginal colonization of pig-tailed macaques by Gardnerella vaginalis.

Ten pig-tailed macaques inoculated intravaginally with Gardnerella vaginalis organisms were colonized for 11-39 days. In contrast, 4 tamarins and 3 chimpanzees inoculated similarly failed to become colonized. Examination of Gram-stained vaginal smears obtained from infected pig-tailed macaques failed to demonstrate clue cells, a feature which is pathognomonic of non-specific vaginitis in humans. Additionally, the pH value, the levels of non-volatile fatty acids and the anaerobic flora of the macaque vagina differed from these aspects of the human vagina. While these differences indicate that gardnerella-infected macaques are unsuitable as a model of gardnerella-associated vaginitis in humans, such animals may prove useful for studying selected aspects of the biology of G. vaginalis such as the adhesion and interaction of the bacteria with the vaginal mucosa.

Animals↗
PubMed1984

A study of the susceptibility of three species of primate to vaginal colonization with Gardnerella vaginalis.

In an attempt to develop an animal model of Gardnerella-associated vaginitis, several strains of Gardnerella vaginalis were inoculated into the lower genital tract of female pig-tailed macaques, tamarins and chimpanzees. G. vaginalis was not recovered from either tamarins or chimpanzees, but was recovered from each of 1O pig-tailed macaques inoculated with either of two freshly isolated Gardnerella strains, colonization persisting for 11-39 days. Examination of Gram-stained vaginal smears obtained from infected pig-tailed macaques failed to demonstrate clue cells, a feature which is pathognomonic of Gardnerella-associated vaginitis in humans. Other features characteristic of non-specific vaginitis, namely an increase in vaginal pH, and an increase in the ratio of succinate to lactate (S/L ratio) in vaginal fluid were not found. However, the physiology of the macaque vagina was found to be different from that of the human, the vaginal pH and S/L ratio of uninfected macaques both being higher than that seen in humans. The physiological differences between the macaque and human vagina may be due, in part, to a difference in their anaerobic vaginal flora. While these inter-species differences in vaginal physiology and microbiology limit the relevance of the pig-tailed macaque as a model of Gardnerella-associated vaginitis, the ease with which macaques are colonized with G. vaginalis may prove useful in studying bacterial adhesion and local immunity.

Animals↗
PubMed1983

Spectinomycin resistant gonococci.

A study was conducted examining the properties of 10 clinical isolates of spectinomycin resistant gonococci from patients attending clinics at St Mary's and St Thomas's Hospitals, London. All of the isolates produced beta-lactamase and contained plasmids of 2.6, 4.4, and 24.5 megadaltons and required proline for growth. None produced aminoglycoside modifying enzymes. Resistance to spectinomycin was transferred from some of the isolates by transformation but at a much lower frequency than resistance to streptomycin. The isolates from St Mary's Hospital were detected after therapy with spectinomycin, whereas those from St Thomas's Hospital were not. Four recent non-beta-lactamase producing gonococci isolated at St Mary's Hospital and two isolated at St Thomas's Hospital also were not related to use of spectinomycin.

Drug Resistance, Microbial↗
PubMed1983

Non-volatile fatty acids in the diagnosis of non-specific vaginitis.

In the vaginal washings of 100 women with symptomatic non-specific vaginitis a succinate/lactate ratio of greater than or equal to 0.4 had a diagnostic sensitivity of 80%, a specificity of 83% for this condition. The predictive value of a positive test was 94%, but that of a negative test was only 55%. A strong association between the presence of Gardnerella vaginalis, anaerobes, a vaginal pH of above 4.5, and amines was found not only in non-specific vaginitis, but also in trichomonal and gonococcal infection. A variety of primary changes may encourage the multiplication of both gardnerellae and anaerobes and their presence in non-specific vaginitis may be a secondary rather than a primary event.

Female↗
PubMed1983

Antimicrobial sensitivity of Neisseria gonorrhoeae. Comparison of penicillinase producing and non-penicillinase producing strains.

The sensitivity of 42 strains of penicillinase producing Neisseria gonorrhoeae (PPNG) and 46 strains of non-PPNG was tested against benzyl penicillin, spectinomycin, erythromycin, cefuroxime, ceftriaxone, tetracycline, sulphamethoxazole, and trimethoprim. The minimum inhibitory concentrations (MICs) of all antimicrobials, except trimethoprim and ceftriaxone, differed significantly for PPNG and non-PPNG strains. Ceftriaxone was the most active compound tested, the MIC for all strains being less than or equal to 0.015 mg/1. PPNG were less sensitive than non-PPNG strains to spectinomycin. It remains to be seen whether the increase in prevalence of PPNG strains is followed by a gradual increase in low level resistance to spectinomycin as well as the occasional finding of high level resistance to this antibiotic.

Anti-Bacterial Agents↗
PubMed1982

Comparison of culture and microscopy in the diagnosis of Gardnerella vaginalis infection.

A comparison was made between human blood agar containing amphotericin B, nalidixic acid and either gentamicin or colistin for the isolation of Gardnerella vaginalis from cases of non-specific vaginitis seen in a clinic for sexually transmitted diseases. The medium containing gentamicin was more inhibitory for non-Gardnerella species, but not sufficiently inhibitory to allow direct plating in the clinic without spreading for single colonies. The diffuse beta haemolysis produced by G vaginalis on human, but not on horse blood agar, proved very useful in differentiating it from other vaginal organisms and was not affected by the antibiotics used. This characteristic, together with Gram stain morphology, oxidase and catalase, provides a simple, reliable methods of identifying G vaginalis. Sixty women with symptoms of vaginitis, in whom no other pathogen was isolated, were examined by culture and microscopy. Gardnerella vaginalis was grown from 45 whereas only 31 had positive microscopy (clue cells or Gram-variable bacilli). There was no significant difference between the rate of isolation of G vaginalis in the group with positive microscopy (25/31) and that with negative microscopy (20/31).

Anti-Bacterial Agents↗
PubMed1982

Male carriage of Gardnerella vaginalis.

The prevalence of Gardnerella vaginalis in the urethra of 430 men attending a clinic for sexually transmitted disease was 11·4%; it was significantly higher in heterosexuals (14·5%) than in homosexuals (4·5%). There was no evidence of rectal or subpreputial carriage of G vaginalis, and urethral carriage was not associated with symptoms of urethritis.

Anal Canal↗
PubMed1982

Pharmacokinetics of metronidazole and its principal metabolites and their activity against Gardnerella vaginalis.

The hydroxy metabolite of metronidazole was found to be more active against 21 strains of Gardnerella vaginalis than the parent compound and less affected by culture in carbon dioxide. After 400 mg oral metronidazole (Flagyl) plasma concentrations of the two agents were below the minimum inhibitory concentrations (MICs) for most G vaginalis strains tested. With 2 g metronidazole the plasma concentrations exceeded the MICs of the more sensitive strains. Even with the lower dose of metronidazole clinically useful concentration of metronidazole and its hydroxy metabolite were present in the urine. Urinary excretion of these compounds may contribute to the efficacy of metronidazole in the treatment of vaginitis associated with G vaginalis.

Blood Bactericidal Activity↗