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Biomedical subjects

J M Hamilton-Miller

Publications and source records attributed to J M Hamilton-Miller.

At least 235 records · Page 13Linked to original sources
PubMed1978

Evaluation of the Microcult system for isolating and identifying Neisseria gonorrhoeae.

Specimens from 95 patients attending a venereal diseases clinic were examined for gonococci by three methods--a conventional culture technique using modified Thayer-Martin medium, microscopy of a Gram-stained direct smear, and the Microcult system. For 56% of the specimens the results by all three methods agreed. Assuming the results obtained by culture on Thayer-Martin medium to be correct, the largest source of error was due to false-positive results: microscopy gave 26 and Microcult gave 15 such results. False-negative results were less common: Microcult gave 14, microscopy six. Microcult gave positive results more quickly than the conventional Thayer-Martin cultural method, but the gonococci were difficult to isolate by subculture from the Microcult culture pads. The Microcult medium was not absolutely specific for Neisseria gonorrhoeae. Nevertheless, the Microcult test may well prove to be a useful adjunct to the diagnosis of gonorrhoea, especially when laboratory facilities are not readily available.

Bacteriological Techniques↗
PubMed1978

Comparative in vitro activity of five nitrofurans.

Five nitrofurans- nitrofurantoin, nifuratel, nitrofurazone, furazolidone and and SQ 18,506--have been tested against 201 microbial strains. Escherichia coli, Streptococcus faecalis, micrococci and Staphylococcus epidermidis were sensitive to all five compounds; furazolidone and SQ 18,506 were the most active against these species. Klebsiella aerogenes was less sensitive, and Proteus spp., Providencia stuartii and Pseudomonas aeruginosa strains were resistant. Nifuratel was inhibitory for some Candida albicans strains, and SQ 18,506 was highly active against this species. Nifuratel was judged overall to have superior in vitro antimicrobial properties to nitrofurantoin.

Bacteria↗
PubMed1977

Can rifampicin use be safely extended? Evidence for non-emergence of resistant strains of Mycobacterium tuberculosis.

Data on the incidence of primary resistance to rifampicin in Mycobacterium tuberculosis strains have been collected from various countries. Strains isolated from those countries where rifampicin is used for both tuberculous and non-tuberculous conditions (Italy, Argentina, Brazil, and Spain) did not show a higher incidence of primary resistance than did strains from other countries (France, U.K., and U.S.A.) where rifampicin use is confined to tuberculosis. It is concluded that there is no evidence to justify fears of an increased incidence of resistance to rifampicin in M. tuberculosis if rifampicin were used discreetly for treating non-tuberculous infections.

Antitubercular Agents↗
PubMed1977

Laboratory studies on mecillinam: activity alone and combined with cephradine.

Mecillinam (MC) was found to be inhibitory at low concentrations to a wide range of Gram-negative bacteria; the sensitivity of such strains could be predicted by using a 10 microgram disk. Resistance to MC did not appear to be associated with beta-lactamase-mediated destruction of the antibiotic. Ampicillin-resistant strains tended to be less sensitive to MC. MC and cephradine acted synergistically against Proteus mirabilis, Pr. vulgaris, Prov. stuartii and Serratia marcescens, and the combination was additive against most Klebsiella aerogenes, Enterobacter spp. and Escherichia coli.

Ampicillin↗
PubMed1977

Sensitivity of Pseudomonas aeruginosa to sulphonamides and trimethoprim and the activity of the combination trimethoprim: sulphamethoxazole.

The activities of three sulphonamides and trimethoprim against strains of Pseudomonas aeruginosa have been studied. Sulphadiazine had most activity, sulphadimidine had little, and the activity of sulphamethoxazole was intermediate. According to their sensitivity to sulphamethoxazole, strains were divided into two groups: "highly resistant" (16%, MIC greater than 1000 microgram per ml) and "moderately resistant" (84%, MIC less than or equal to 1000 microgram per ml). The former were resistant on disk testing to Sulphatriad 300 microgram. Sulphamethoxazole and trimethoprim did not act in synergy against them. The moderately resistant strains were sensitive to Sulphatriad; trimethoprim and sulphamethoxazole showed marked synergy against them in agar-plate dilution tests. The concentrations of trimethoprim and sulphamethoxazole necessary for synergy lay for each drug within the range of concentrations at which they have been found in urine, and the ratio of their MICs when acting in synergy was similar to the ratio of their concentrations in urine. It is suggested that a disk containing trimethoprim and sulphamethoxazole in a ratio of 1 : 2 rather than 1 : 20 would be more appropriate when testing strains from urine for their sensitivity to co-trimoxazole.

Dose-Response Relationship, Drug↗
PubMed1977

Screening for bacteriuria: Microstix and dipslides.

The Microstix system has been tested, in parallel with dipslides, for suitability as a screening technique for the detection of bacteriuria. Results obtained using each method on 228 urine specimens were assessed by comparison with the results of quantitative counts. Dipslides had a higher sensitivity (86-7%) than Microstix. The best specificity (100%) was obtained from those results (77-6%) where both components of the Microstix system were in agreement. Advantages of Microstix are its greater shelf-life and its compactness.

Bacteriological Techniques↗
PubMed1977

Two new bioassay techniques for nitrofurans: Bacteroides fragilis and rec-Escherichia coli as indicator strains.

Techniques for the microbiological assay of nitrofurans are described. In one the indicator strain is Bacteroides fragilis; use of this system enables concentrations of nifuratel and furazolidone of down to 0.7 micrograms/ml to be estimated. The other system uses a recombination-deficient (recA-uvrA-) mutant of Escherichia coli; with this indicator, concentrations of 0.2 micrograms/ml, or less, of five nitrofurans can be assayed.

Bacteriological Techniques↗
PubMed1977

Methenamine and its salts as urinary tract antiseptics: variables affecting the antibacterial activity of formaldehyde, mandelic acid, and hippuric acid in vitro.

The activities of formaldehyde and of mandelic and hippuric acids, alone and in combination, have been tested against some 300 strains of bacteria typical of those causing urinary tract infections. In a chemically defined medium, which resembles urine in many respects, formaldehyde had a mean minimal inhibitory concentration of 13 mug per ml. Activity was several fold lower in media (nutrient agar and tryptic soy agar) that contained significant amounts of protein. The activity of formaldehyde is virtually unaffected by pH in the range of 5 to 8. Mandelic and hippuric acids (2 mg per ml) have limited antimicrobial activity at acid pH values only. The combination of formaldehyde with mandelic acid (2 mg per ml) was additive, most markedly at pH 5; the formaldehyde-hippuric acid combination, however, did not appear to be additive. Our findings suggest that, at pH values between 5 and 6, an antibacterial concentration of formaldehyde will be generated from methenamine within approximately 1 hr after being excreted into the urine.

Anti-Infective Agents, Urinary↗
PubMed1977

Trimethoprim-resistant bacteria: cross-resistance patterns.

One hundred and eighty one strains (clinically isolated) of trimethoprim-resistant bacteria were tested for sensitivity to proguanil, pyrimethamine, methotrexate and methasquin. All these agents had less intrinsic antibacterial activity than trimethoprim, and there was marked cross-resistance between trimethoprim on the one hand and pyrimethamine and methasquin on the other. Methotrexate was of very low activity against Gram-negative bacilli, but was highly inhibitory for streptococci. Proguanil had approximately the same activity for all the organisms tested, and appears not to act as an anti-folate agent.

Aspartic Acid↗
PubMed1976

New technique for investigating bacterial flora of female periurethral area.

The bacterial flora of the female periurethral area was studied by impression cultures taken by polystyrene sponges, the results being recorded by photographic contact printing. With this technique it is possible to observe the preferential colonisation of different areas by different organisms and to detect persistent colonisation by pathogens. In assessing the possible aetiological importance of these results, and especially in comparing them with the findings of other workers, it is essential to use correct anatomical nomenclature.

Bacteriological Techniques↗
PubMed1976

Diminished effect of gentamicin under anaerobic or hypercapnic conditions.

The in-vitro activity of gentamicin, judged by M.I.C. determinations, was much reduced when a normal aerobic atmosphere was replaced either by air +4% CO2 or by anaerobic conditions. The phenomenon was greatest for Staphylococcus aureus, where a decrease in activity of up to 20-fold was found. For Escherichia coli, Klebsiella aerogenes, Enterobacter spp., and Proteus spp. the factor of decrease was between 15-fold and 2-5-fold. Changes in medium pH, as a result of bacterial growth, can explain these findings for some, but not all, the species tested.

Anaerobiosis↗
PubMed1976

Microbiological studies on some bladder irrigation fluids.

A 1.5% glycine solution has recently been introduced as a bladder irrigation fluid. In this study, glycine solution was compared with two other recognised bladder irrigants (chlorhexidine and noxythiolin) for its inhibitory activity against common urinary tract pathogens. Glycine solution supported the growth of nearly 50% of the bacterial strains tested whereas chlorhexidine and noxythiolin were completely inhibitory. In quantitative studies with selected strains it was found that growth could be initiated from as few as 200 organisms/ml. It was concluded that glycine solution was capable of supporting bacterial growth and thus, from a microbiological viewpoint, was unsuitable as a bladder irrigant.

Bacteria↗
PubMed1976

Amikacin in treatment of infections caused by gram-negative bacteria resistant to gentamicin and other aminoglycosides: clinical and bacteriologic results.

Amikacin (250 or 500 mg) was administered intramuscularly twice daily at 12-hr intervals to 34 patients with infections due to various gram-negative bacteria. Usually one or more aggravating factors were present, such as serious underlying pathology or therapy with steroids or immunosuppressants. Clinical isolates from most patients were resistant to gentamicin and other aminoglycosides. The overall response to therapy was excellent in 20 patients; in eight patients clinical response was good, but the organism persisted. Six patients showed some improvement without complete resolution of the infection or eradication of the causative organism. There were no complete clinical or bacteriologic failures. Ototoxicity was not observed in any patient. Levels of blood urea nitrogen and serum creatinine increased in two patients but returned to pretreatment levels within two weeks after therapy. No other adverse reactions were noted. Amikacin may replace gentamicin as initial therapy in serious gram-negative bacillary infections, particularly when resistance to gentamicin is a problem.

Adolescent↗
PubMed1976

In vitro activity of amikacin and ten other aminoglycoside antibiotics against gentamicin-resistant bacterial strains.

Sixty-nine strains of gentamicin-resistant gram-negative bacilli obtained from different geographical sources were tested for susceptibility to 11 aminoglycoside antibiotics. From the results of determinations of minimal inhibitory concentrations, patterns of resistance were established for 45 strains of Enterobacteriaceae and 24 strains of Pseudomonas aeruginosa. Overall, 81% of the strains were sensitive to amikacin and 33% of the strains were sensitive to butirosin, the next most active compound. Results indicated that 54% of the P. aeruginosa strains were sensitive to amikacin and 33% were sensitive to tobramycin. From resistance patterns, enzymes responsible for inactivation of the antibiotics were deduced. The most common enzyme was aminoglycoside nucleotidyltransferase(2''), either alone or combined with either aminoglycoside phosphotransferase(3')-I or aminoglycoside phosphotransferase(3')-II. Aminoglycoside acetyltransferase(2) was identified exclusively in strains of Providencia stuartii. Specific enzymes could not be identified for 30 strains, 21 of which were P. aeruginosa.

Amikacin↗