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Biomedical subjects

B W Allen

Publications and source records attributed to B W Allen.

At least 37 records · Page 2Linked to original sources
PubMed1986

The bioavailability of isoniazid, rifampin, and pyrazinamide in two commercially available combined formulations designed for use in the short-course treatment of tuberculosis.

The bioavailability of isoniazid, rifampin, and pyrazinamide in 2 combined formulations of the 3 drugs (Rifater) for use primarily in the short-course chemotherapy of tuberculosis has been studied in Chinese patients in Singapore and Hong Kong. One formulation, containing 50 mg isoniazid, 120 mg rifampin, and 300 mg pyrazinamide per tablet is suitable for daily use, whereas the other, containing higher proportions of isoniazid and pyrazinamide, is designed for intermittent treatment, each tablet containing 125 mg isoniazid, 100 mg rifampin, and 375 mg pyrazinamide. Appropriate dosages for the Chinese patients, whose average weight was approximately 50 kg, were 5 and 6 tablets, respectively. Plasma concentrations of the 3 drugs after giving such dosages of the 2 combined formulations were compared in 16 patients, 8 in Singapore and 8 in Hong Kong, by means of a crossover study, with the concentrations obtained when identical doses of the 3 drugs were given using standard separate drug formulations. The concomitant urinary excretions of the drugs and their major metabolites were also estimated. Very similar results were obtained whether the drugs were given as the combined preparations or in their standard separate formulations, demonstrating the excellent bioavailability of all 3 drugs in each of the 2 combined formulations.

Acetylation↗
PubMed1985

In-vitro inhibition of mycobacteria by viridans streptococci.

Eleven strains of Mycobacterium tuberculosis and 13 other species of mycobacteria were examined for susceptibility to 26 strains of viridans streptococci. Susceptibility was detected by the simultaneous antagonism technique, but not by tests of deferred antagonism. It is concluded that in-vitro inhibition of mycobacterial growth by actively growing streptococci is due to a peroxide-mediated antagonism which is too variable to be of value for identification. However, a standard bactericidal test with hydrogen peroxide is worth investigation because this might provide a simple inexpensive aid for the identification of M. avium-intracellulare serotypes.

Antibiosis↗
PubMed1983

Amikacin in the treatment of pulmonary tuberculosis.

Sensitivity tests on strains from 11 patients with pulmonary tuberculosis, previously treated with kanamycin and/or capreomycin, showed incomplete cross-resistance between amikacin and capreomycin but complete cross-resistance between amikacin and kanamycin. Treatment with amikacin of 4 patients with multiply resistant strains resulted in no response as assessed by sputum smears and cultures, but resistance emerged to amikacin, kanamycin and capreomycin. Amikacin has no role in the treatment of tuberculosis as it cannot be given as an alternative to kanamycin, has no advantages over it and is more expensive.

Adult↗
PubMed1983

Selective Kirchner medium in the culture of specimens other than sputum for mycobacteria.

Over a two-year period, 2949 non-sputum specimens were cultured on two slopes of Löwenstein-Jensen (LJ) medium, two bottles of Kirchner liquid medium, made selective by adding polymyxin B, carbenicillin, trimethoprim and amphotericin B, and a selective 7H11 agar slope. Pus and CSF were inoculated into this set without prior treatment, but other specimens were decontaminated with sulphuric acid. Tissues and fluids were also inoculated without decontamination into additional selective media. The use of the selective media as well as the LJ slopes increased the yield of specimens with cultures of tubercle bacilli from 34 to 53 and decreased specimens with all media contaminated from 34 to 2. Results almost as good, 52 positive specimens and five totally contaminated, would have been obtained by the addition of a single selective Kirchner bottle to the two LJ slopes, and this is recommended for routine use.

Bacteriological Techniques↗
PubMed1983

Contamination of specimen container surfaces during sputum collection.

Sputum specimens from culture-positive tuberculosis patients were examined for the presence of Myobacterium tuberculosis on container surfaces. Although specimens were in transit for several days, M tuberculosis was isolated from 18 (6.5%) of 279 containers examined. Sputum specimens from local patients were examined for evidence of upper respiratory bacterial flora on the outside of containers as an indicator of contamination with sputum. Of 300 containers examined, 41 (14%) were contaminated. A technique for disinfecting specimen containers from tuberculosis patients has been evaluated and recommendations are made for handling sputum containers.

Decontamination↗
PubMed1983

Examination of operation specimens from patients with spinal tuberculosis for tubercle bacilli.

Operation specimens from 52 Hong Kong patients considered to have tuberculosis of the spine were sent at -78 degrees C to London where they were cultured on two Löwenstein-Jensen medium slopes, a slope of 7H11 medium made selective with antibiotics and in two bottles of selective liquid Kirchner medium. Cultures of M tuberculosis, usually with only scanty colonies, were obtained from 37 of the patients. Pus and caseous matter yielded more positive cultures and more numerous colonies than other specimens, but eight of the 37 patients yielded positive cultures only from tissues lining abscess walls or from bone or intervertebral disc specimens. Cultures in Kirchner medium were never contaminated and twice as many were positive as cultures on the slopes; nine patients had cultures positive only on Kirchner medium. It is recommended that (i) a variety of operation specimens, always including pus or caseous material in volumes of at least 1 ml, should be sent for bacteriology; (ii) specimens should be cultured in selective Kirchner medium, with or without Löwenstein-Jensen slopes; (iii) cultures should be incubated for a minimum of 8-9 wk.

Culture Media↗
PubMed1982

Role of lipid content and hydrogen peroxide susceptibility in determining the guinea-pig virulence of Mycobacterium tuberculosis.

Among isoniazid-sensitive strains of Mycobacterium tuberculosis, strong associations were found in 56 strains of phage type A and I from India, Burma and East Africa between attenuation in the guinea-pig, a low content of strongly acidic (SAL) and sulphatide (SL) lipids, the presence of the attenuation indicator (AI) lipid and phage type I, suggesting that lipid content might mediate attenuation. However, 22 strains of phage type B and I from Iran and Britain also had low contents of SAL and SL but were highly virulent. Although the finding of a strong association in all 78 strains between attenuation and H2O2 susceptibility in vitro supports other evidence that attenuation is often due to increased susceptibility to H2O2 secreted by macrophages, an alternative mediator of virulence probably exists since 8 of the strains were attenuated and also resistant to H2O2. Identification of South Indian attenuated strains for epidemiological purposes by in vitro tests would be best achieved by the presence of AI, H2O2 susceptibility and, if the strains originated in or near India, by phage type I.

Animals↗
PubMed1981

Extrapulmonary tuberculosis: a potential source of laboratory-acquired infection.

A three-year retrospective study has demonstrated the effect of extrapulmonary tuberculosis on safety within a routine bacteriology laboratory. The investigation showed that, from 112 patients, 162 specimens considered to present a risk to laboratory staff were processed outside of the B1 protective area. However, it was estimated that only 51 of those specimens were heavily positive. Of these 57% were sputum 30% pus, and 10% urine. Specimens of pus and urine account for 50% of specimens received for non-tuberculosis investigations, and it would be impossible to process all specimens that might present a risk in B1 accommodation and still maintain a high degree of safety. It is recommended that request forms which accompany specimens should clearly indicate potential high-risk specimens.

Humans↗
PubMed1981

Survival of tubercle bacilli in heat-fixed sputum smears.

Tubercle bacilli, which survived heat fixation, were detected with a slide culture technique which allowed the entire smear to be examined. Both conventional flame fixation and the use of a controlled hot-plate failed to render tuberculous sputum smears safe for further handling. Smears which were stained with the phenol-auramine method failed to yield growth on culture. If delay between preparation and staining is unavoidable, it is recommended that smears are given additional treatment to prevent the survival of tubercle bacilli.

Bacteriological Techniques↗