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Biomedical subjects

K T Holland

Publications and source records attributed to K T Holland.

At least 19 recordsLinked to original sources
PubMed1992

The effect of zinc and erythromycin on the growth of erythromycin-resistant and erythromycin-sensitive isolates of Propionibacterium acnes: an in-vitro study.

The effect of zinc and erythromycin on cultures inoculated with mixtures of different ratios of erythromycin sensitive (ES) and resistant (ER) Propionibacterium acnes cells was studied in vitro. Propionibacterium acnes ES outgrew P. acnes ER in the absence of erythromycin and zinc. At low levels of erythromycin ES outgrew ER, whilst the addition of 600 pg/ml zinc further reduced the growth of ER compared to ES. Growth of ER and ES were similar at levels of erythromycin near the minimum inhibitory concentration (MIC) of ES cells. Concentrations above the MIC for ES cells inhibited ES but not ER cells. At the higher concentrations of erythromycin, the addition of 96 ng/ml zinc delayed the growth of ER cells, whilst the addition of 300 micrograms/ml zinc prevented the growth of ER cells. The combination of erythromycin and zinc, at appropriate concentrations, inhibits both ES and ER.

Bacteriological Techniques↗
PubMed1992

The effect of dilution rate and pH on biomass and proteinase production by Micrococcus sedentarius grown in continuous culture.

Micrococcus sedentarius, an organism associated with pitted keratolysis, produced two proteinases in culture supernatant fluids, as shown by non-denaturing PAGE with overlaying with a casein substrate. A mixture had optimal activity at pH 10 with azocasein substrate. At pH 7.1 and 8.1 in continuous culture with varying dilution rates high proteinase production occurred at relative specific growth rates (mu rels) 0.39 and 0.77 and biomass concentrations decreased with increasing dilution rate. One proteinase was constitutive and varied little in production with different growth rates. The other proteinase was under control with high production at low growth rates and no production at high growth rates. With varying pH at mu rels 0.39 and 0.77 maximum biomass concentration and proteinase production occurred between pH 8.0 and 9.0 as did the highest specific growth rate. These results support the hypothesis that Mic. sedentarius produces pitting in the stratum corneum when the skin is hydrated and the pH rises above neutrality.

Cell Division↗
PubMed1992

Development of cutaneous microflora in premature neonates.

Coagulase-negative staphylococci (C-NS) are a frequent cause of bacteraemia in premature neonates. It is likely that the strains of C-NS causing bacterial sepsis in premature neonates have their origin on the patient's skin surface. We have studied the quantitative development of the skin microflora at eight sites on premature neonates. A swab wash method was used to sample and enumerate the cutaneous microflora of premature neonates admitted to an intensive care unit with respiratory distress syndrome. The numbers of bacteria present on the skin increased rapidly by 100-fold in the first week of life. The species of C-NS found on neonatal skin were similar to those found on adult skin. However, the bacterial population was 10(3) lower by comparison. There was considerable variation in numbers of bacteria and in the proportion resistant to antibiotics from day to day. There appeared to be no association between antibiotic usage and the proportion of isolates resistant to antibiotics, although the resident bacteria were in many cases resistant to a variety of antibiotics. C-NS were isolated from 92% of samples from which bacteria were isolated. Staphylococcus epidermidis was found at all sites and accounted for 82% of each colonial type of staphylococcus isolated. Other organisms isolated included Propionibacterium sp, alpha-haemolytic streptococci, aerobic spore-bearing bacilli, aerobic coryneforms, Candida albicans, Klebsiella oxytoca, Pityrosporum sp, Klebsiella pneumoniae, and Escherichia coli. The results of this study suggest that the skin of premature neonates is colonised with antibiotic resistant C-NS during the first week of life and that the chance of contamination of an intravascular catheter at insertion increases during this period.

Coagulase↗
PubMed1991

The in-vitro antimicrobial effects of azelaic acid upon Propionibacterium acnes strain P37.

The in-vitro antimicrobial activity of azelaic acid a new topical acne treatment, upon Propionibacterium acnes strain P37 was studied. In phosphate buffer at pH 6.0 500 mM azelaic acid had bactericidal activity whilst the addition of nutrients reduced susceptibility. Bactericidal activity was greatly enhanced by reducing the pH to 5.6. In a simple defined medium growth was inhibited by 100 microM azelaic acid. The accumulation of 14C azelaic acid was pH and temperature dependent with maximum uptake occurring at pH 4.6, 30 degrees C. Valinomycin, nigericin and CCCP (membrane-active inhibitors of energy transduction) inhibited uptake and azelaic acid was not accumulated by non-viable cells. The degradation of azelaic acid was repressed by glucose, and acetic acid was the major end-product of azelaic acid degradation in glucose depleted media. The incorporation of radiolabelled precursors into protein, DNA and RNA were inhibited in a dose dependent manner, and 50% inhibition occurred at 313, 3639 and 9226 microM respectively. The synthesis of proteins was shown to be significantly more sensitive to the action of azelaic acid than both RNA and DNA synthesis.

Bacterial Proteins↗
PubMed1979

Purification and partial characterization of hyaluronate lyase (EC 4.2.2.1) from Propionibacterium acnes.

Hyaluronidase from Propionibacterium acnes has been purified 13,000-fold from the culture supernatant to homogeneity (as determined by polyacrylamide disc gel electrophoresis). The molecular weight of the purified enzyme was 85,110 as determined by gel filtration. The purified enzyme had a pH optimum at 6.4, was stable between pH 5 and 5.8 and was completely inactivated after 15 min at 50 degrees C. Preliminary studies suggested that the enzyme is active against chondroitin 4- and 6-sulphates, but not against dermatan sulphate. Analysis by paper chromatography of the reaction products from the degradation of hyaluronic acid by bacterial, testicular and P. acnes enzymes suggested that the P. acnes enzyme is similar in its mode of action to other bacterial hyaluronate lyases. The enzyme from P. acnes may thus be tentatively classified as a hyaluronate lyase.

Buffers↗
PubMed1979

Intergeneric and intrageneric inhibition between strains of Propionibacterium acnes and micrococcaceae, particularly Staphylococcus epidermidis, isolated from normal skin and acne lesions.

Two hundred and forty-one strains or resident skin bacteria comprising 93 isolates of Propionob acterium acnes and 148 of Micrococcaceae derived from 36 acne patients and 8 control subjects were screened for their ability to inhibit 32 indicator strains, including 20 strains of P. acnes and 12 strains of Staphylococcus epidermidis derived from patients with all grades of acne and from normal skin. Fifty-three strains (22%) showed some activity against at least one indicator strain. Both broad- and narrow-spectrum inhibition was detected. Inhibitory isolates of P. acnes outnumbered inhibitory Micrococcaceae by four to one. There was a low frequency of inhibition of S. epidermidis by Micrococcaceae (2.7%) and by P. acnes (1.1%) and a higher frequency of inhibition of P. acnes by Micrococcaceae (9.5%) and by P. acnes (40.8%). Furthermore, 81.8% of the subjects sampled possessed strains inhibitory to P. acnes. The significance of this finding is, as yet, unknown. No difference in the prevalence of active strains in normal (20%) and acne (22.5%) skin was detected. These findings suggest that the possession of inhibitory strains and conversely the possession of sensitive strains does not predispose to acne.

Acne Vulgaris↗
PubMed1978

Cellular immunity to P. acnes in the normal population and patients with acne vulgaris.

Patients with varying degrees of acne, acne-free adult controls and samples of cord blood were investigated for cell mediated immunity to P. acnes using a leukocyte migration inhibition test. Despite the fact that the mean migration index tended to decrease with acne severity, only the patients with severe acne showed cell-mediated immunity. It is suggested that when cellular immunity arises it is a late event which may contribute to inflammation but is probably not a factor in its initiation.

Acne Vulgaris↗
PubMed1977

Acne vulgaris: an investigation into the number of anaerobic diphtheroids and members of the Micrococcaceae in normal and acne skin.

A quantitative study was made of the microflora of 174 acne and 68 non-acne subjects. Two groups of organisms were investigated, the anaerobic diphtheroids and members of the Micrococcaceae. The results showed high numbers of both groups of bacteria in skin bearing blackheads, papules or pustules and in non-acne adolescent skin. There were significantly lower numbers of bacteria in the pilosebaceous ducts of normal looking skin in acne areas and in pre-adolescent skin when compared with non-acne adolescent skin. It is suggested that increased numbers of bacteria alone do not predispose to acne, but that their interaction with the skin, which is a function of the localized skin environment, may be important.

Acne Vulgaris↗
PubMed1975

Optimum conditions for initiation of filamentation in Candida albicans.

A medium that initially produced filaments from almost all of its Candida albicans blastospore inoculum contained 1% mycological peptone and 0.2% glucose, final pH 7.4-7.5. The medium was inoculated to 10-6 cells/ml and incubated at 40 degrees C. Reversion to secondary blastospores began at a mean of 2.4 h after inoculation. The patterns of utilization of growth nutrients during optimal mycelial growth showed no correlation with the events of filamentation.

Alcohols↗