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Biomedical subjects

P M Waterworth

Publications and source records attributed to P M Waterworth.

At least 19 recordsLinked to original sources
PubMed1982

Sensitivity tests with cephalosporins.

The sensitivity of 127 strains of miscellaneous Gram-negative bacilli to various cephalosporins was determined by three methods. Disc tests with cephaloridine (CLOR), cephalothin (CTIN) and cephalexin (CLEX) made most strains of beta-lactamase-producing Escherichia coli appear sensitive. Eight cephalosporins were tested by the agar break-point method using concentrations of 16 and 4 mg/l for all except cefotaxime (CTAX), when 8 and 1 mg/l were used. In repeated tests there was considerable variation in the response of many strains to the lower concentration of CLOR, CTIN, CLEX and to a lesser extent, cefoxitin (CFOX) and cefuroxime (CROX), and beta-lactamase-producing E coli appeared as sensitive or moderately sensitive to all. Cephalosporins CLOR, CLEX, and CROX were then tested by inoculating 2 ml volumes of broth containing a 30 microgram disc; all the beta-lactamase-producing E coli grew in CLOR and CLEX but were inhibited by CROX.

Bacteria↗
PubMed1981

Penetration of penicillin into the cerebrospinal fluid of patients with latent syphilis.

Eighteen patients with latent syphilis were treated with 360 mg, 720 mg, 1080 mg or 1440 mg intramuscular procaine penicillin daily for 14 days. Penicillin was assayed in serum and cerebrospinal fluid collected 3 hours after the second injection in each patient. Penicillin was present in all sera in concentrations greater than the generally accepted fully treponemacidal level, but none was detected in cerebrospinal fluid from 11 patients. The significance of these results is discussed, particularly with a view to changes in standard treatment regimens for latent syphilis.

Adolescent↗
PubMed1980

A problem with the recognition of penicillin-resistant pneumococci.

A strain of Streptococcus pneumoniae requiring 0.25 mg/1 penicillin to inhibit its growth was isolated from the antrum of a child who had no history of either foreign contacts or previous treatment with penicillin. The penicillin resistance was recognised by chance because the disc used contained substantially less than its stated content of 1.5 unit. When discs containing 2 units were used there was little reduction in size of the zone of inhibition.

Child, Preschool↗
PubMed1980

An evaluation of the Replireader in the identification of Enterobacteriaceae isolated from urine and in the recording of sensitivity tests performed by an agar dilution method.

In the Replireader system for identifying Enterobacteriaceae, plates of biochemical media are inoculated with a replicator and the results are put into a computer. The machine correctly identified 92x2% of 734 strains of Gram-negative bacilli isolated from urine; it was incorrect in 0x8% and failed to recognise 7%. The Replireader was also used to record the results of sensitivity tests using a plate dilution method in which the drugs were provided by impregnated filter papers (Adapads).

Bacteriological Techniques↗
PubMed1979

Dissociated resistance among cephalosporins.

When disks containing cefuroxime (CXM) or HR 756 (756) were placed next to cefoxitin (FOX) on plates inoculated with Enterobacter resistant to FOX, there was marked flattening of the zones of inhibition produced by CXM or 756, but colonies growing near the CXM or 756 disks were found to be fully susceptible to these drugs on retesting. In contrast, when a checkerboard titration with CXM or 756 and FOX was done in broth, organisms growing in the presence of high concentrations of either of the former plus FOX were found to be resistant on retesting. Broth cultures of Enterobacter were found to contain small numbers of mutants which were resistant to and inactivated CXM and 756. Evidence is presented suggesting that the addition of FOX induces similar properties in the whole culture, which then becomes resistant to all of the nine cephalosporins tested and to four of six penicillins tested. Such cultures rapidly reverted to susceptible when FOX was removed or inactivated, and an explanation is offered as to why this did not happen in fluid media.

Cefoxitin↗
PubMed1979

Single-dose minocycline in the treatment of gonococcal urethritis. Clinical efficacy in relation to bacterial resistance and its effects on associated Chlamydia trachomatis infections.

Seventy-two men with gonococcal urethritis were given a single 300-mg dose of minocycline. The failure rate was 13% and the trial was terminated at an early stage. Failure was correlated with increased resistance of Neisseria gonorrhoeae to minocycline. The activity of penicillin, spectinomycin, erythromycin, tetracycline, sulphamethoxazole, cefuroxime, cefotaxime, rosamicin, thiamphenicol, and piperacillin against N. gonorrhoeae were examined in vitro. With the exception of spectinomycin, parallel patterns of resistance to the other antibiotics and minocycline were found. Resistance to spectinomycin was not found, confirming the usefulness of this antibiotic in the treatment of gonorrhoea. The incidence of PGU was significantly lower after a single dose of minocycline than in previous studies.

Anti-Bacterial Agents↗
PubMed1978

Incomplete anaerobiosis as a cause of metronidazole 'resistance'.

Clostridium welchii, used as a control, was found to grow well in a microaerophilic jar used for campylobacters but appeared resistant to a metronidazole disc although the campylobacter was sensitive. Minimum inhibitory concentrations for six strains of Cl. welchii were up to 64-fold higher in these conditions than when grown anaerobically. Zones of inhibition with both Cl. welchii and Bacteroides fragilis varied with the amount of air admitted to anaerobic jars.

Anaerobiosis↗
PubMed1978

Determination of antibiotic sensitivities by the Sensititre system.

The Sensititre system provides antibiotics dried in microtitre trays in appropriate concentrations for the determination of minimum inhibitory concentrations (MIC) when organisms are added in liquid culture medium and incubated overnight. Results with a variety of media--for Gram-negative bacilli tested with ampicillin, carbenicillin, cephaloridine, and gentamicin, staphylococci with penicillin, cloxacillin, fusidic acid, and gentamicin, and streptococci with penicillin, ampicillin, cephaloridine, and erythromycin--were usually very similar to those of agar dilution tests. Discrepant results are found in a few situations, and in some cases, especially those involving borderline resistance to fusidic acid and gentamicin among staphylococci and Gram-negative bacilli, we have been unable to suggest modfication to produce the right results. Despite these problems, fortunately few and identifiable, we recommend the system especially for use in laboratories that determine the MICs infrequently.

Anti-Bacterial Agents↗
PubMed1977

New cause of penicillin treatment failure.

A large empyema infected with a penicillin-sensitive haemolytic group B streptococcus failed to respond to high doses of penicillin. After two weeks' treatment the pus aspirated was found not only to contain no penicillin, but also to inactivate penicillin added to it. We believe that the inactivating agent is an enzyme that may destroy various penicillins and cephalosporins but has no effect on other common antibiotics. When treatment was changed to doxycycline the patient made a rapid recovery.

Empyema↗
PubMed1976

Dependability of sensitivity tests in primary culture.

Primary sensitivity tests were done on 90 specimens of infected urine, and the results were compared with those of secondary tests on pure cultures done by three diffusion methods. There was good correlation between the four methods. In a second study, the reliability of primary tests prepared in the clinical laboratory on specimens of pus was assessed, and the frequency with which a definitive result was obtained with different types of specimen was determined. Recommendations are made for the economic use of these tests.

Anti-Bacterial Agents↗
PubMed1975

Effects of minocycline and tetracycline on the vaginal yeast flora.

Two groups of women with non-specific genital infection were treated for two weeks with tetracycline 250 mg six-hourly and minocycline 100 mg twice daily respectively. Cultures for yeasts were performed before treatment and at the end of the first and second weeks. Before treatment yeasts, mostly Candida albicans, were recovered from 13% of the women. After one and two weeks' treatment yeasts were isolated from 22 and 29% of women treated with tetracycline, and from 19 and 29% of women treated with minocycline. It is concluded that despite inhibition of the growth of yeasts shown by minocycline in vitro, there is no evidence of any significant difference between the actions of tetracycline and minocycline on the vaginal yeast flora.

Candida albicans↗