Temporal changes in sebum excretion and propionibacterial colonization in preadolescent children with and without acne
ABSTRACT It is generally accepted that the onset of sebum secretion occurs before puberty in boys and girls as a result of increasing androgen output during the adrenarche. Propionibacteria are part of the commensal skin flora and, in adults, are found in highest numbers in sebum-rich areas of skin such as the face and upper trunk. Previous studies investigating the association between sebum output and propionibacterial population densities have been cross-sectional and have been carried out mainly in adults.
The purpose of this study was to examine the association between the onset of sebum secretion and expansion of the propionibacterial flora in a population of early adolescent children aged between 5.5 and 12 years, and to evaluate the temporal relation between the two factors longitudinally. In addition, the study aimed to evaluate the change with age in sebaceous gland activity and propionibacterial colonization on the skin and in the nares between children who developed acne and those who did not.
Biannual examinations of volunteers included age, pubertal (Tanner) stage, weight and height, lesion counting on the face, propionibacterial colonization on the skin surface and in the nares and sebum secretion. A longitudinal analysis based on all observations of each subject throughout the study was applied to examine the change of sebaceous gland activity and propionibacterial colonization with age and pubertal stage. A generalized estimating equation was used with a 0.05 level of significance.
The commencement of sebum production was asynchronous, with only a small number of follicles initially starting to secrete sebum onto the skin surface. The number of secreting follicles and the area of sebum increased with age and pubertal stage (P < 0.0001, P < 0.05, respectively). Numbers of propionibacteria on the skin tended to increase after the age of 9 years, but not significantly so. In contrast, numbers of propionibacteria in the nares increased significantly with age (P < 0.0001) but not with pubertal maturation. Children who developed acne had higher sebum output and propionibacterial densities with increasing age than children who did not develop acne. This effect was significant for the increase of total sebum area with age in pubertal children (P = 0.0023), the increase in number of secreting follicles with age (P = 0.020) in prepubertal children, and the increase in propionibacteria densities in the nares with age (P = 0.0005) in pubertal children. Sebaceous gland activity and propionibacterial numbers on the skin surface remained unchanged with increasing age in children who did not develop acne. Propionibacterial population densities in the nares increased with age regardless of the development of acne.
Onset of sebum secretion and consequently expansion of the propionibacterial skin flora occur earlier in children who develop acne than in children of the same age and pubertal status who do not develop acne. These observations suggest that postponing the onset of sebum production or the expansion of the propionibacterial skin flora until after puberty may represent ways of preventing the disease or minimizing its severity. Determinants of propionibacterial colonization on the skin and in the nares may be different.
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ABSTRACT: Neisseria meningitidis is an important human pathogen that is capable of killing within hours of infection. Its normal habitat is the nasopharynx of adult humans. Here we identify a genomic island (the prp gene cluster) in N. meningitidis that enables this species to utilize propionic acid as a supplementary carbon source during growth, particularly under nutrient poor growth conditions. The prp gene cluster encodes enzymes for a methylcitrate cycle. Novel aspects of the methylcitrate cycle in N. meningitidis include a propionate kinase which was purified and characterised, and a putative propionate transporter. This genomic island is absent from the close relative of N. meningitidis, the commensal N. lactamica, which chiefly colonises infants not adults. We reason that the possession of the prp genes provides a metabolic advantage to N. meningitidis in the adult oral cavity, which is rich in propionic acid-generating bacteria. Data from classical microbiological and sequence-based microbiome studies provide several lines of supporting evidence that Neisseria meningitidis colonisation is correlated with propionic acid generating bacteria, with a strong correlation between prp-containing Neisseria and propionic acid generating bacteria from the genus Porphyromonas, and that this may explain adolescent / adult colonisation by N. meningitidis.Molecular Microbiology 06/2014; DOI:10.1111/mmi.12664 · 5.03 Impact Factor
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ABSTRACT: Strongyloides es un nematodo que puede persistir en el organismo durante largos períodos y tener como única manifestación eosinofilia asintomática. La enfermedad pulmonar obstructiva crónica (EPOC) puede ser una afección asociada a esta infección. La presencia de una alteración en la inmunidad celular o el uso de esteroides, frecuentes en el tratamiento de la exacerbación de la EPOC, podría provocar una hiperinfección de la larva, arrastrando en su paso al torrente sanguíneo bacterias entéricas. Así pues, la presencia no esperada de bacterias entéricas en la exacerbación de un caso de EPOC no grave con eosinofilia crónica sin filiar debería orientarnos a la búsqueda activa de larvas rabditiformes en las heces.
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ABSTRACT: The documented negative psychosocial effects of acne on self-esteem are significant. Acne is a common complaint among adolescents who present to family practice. Family nurse practitioners play a major role in the identification of acne, its effect on self-esteem, and proper treatment and referral. Both the adolescent and health care provider need to be aware that acne is a treatable skin condition. It is therefore essential that health care providers recognize and assess for the effects of acne on self-esteem and initiate treatment that could prevent permanent scarring—inside and out.The Journal for Nurse Practitioners 09/2008; 4(8):595-600. DOI:10.1016/j.nurpra.2008.01.021