Efficacy of oral isotretinoin in the control of skin and nasal colonization by antibiotic-resistant propionibacteria in patients with acne

BACKGROUND: Skin colonization by antibiotic-resistant propionibacteria is commonplace among acne patients globally. Increasing attention is now being paid to how resistance rates might be reduced to preserve the future efficacy of antibiotics, especially erythromycin and clindamycin in acne therapy. OBJECTIVE: To assess the efficacy of oral isotretinoin in the control of antibiotic-resistant propionibacteria. METHODS: Acne patients (72 in the U.K., 62 in the U.S.A.) colonized with high numbers of antibiotic-resistant propionibacteria were sampled before, during and 12 weeks after oral isotretinoin therapy. Propionibacterial samples were collected from five acne-prone skin surface sites using a detergent scrub method and from the anterior nares using moistened swabs. Total and antibiotic-resistant propionibacteria were enumerated by viable counting on media with and without selective antibiotics. RESULTS: After 16 weeks of oral isotretinoin therapy, mean population densities of viable propionibacteria and variants resistant to erythromycin, clindamycin or tetracycline had fallen by more than 90% at all skin sites and in the nares. The sole exception was a smaller reduction in tetracycline-resistant strains on the lower back. In general, greater reductions were observed on skin than in the nares. By the end of the treatment period only three patients (all in Philadelphia) yielded no antibiotic-resistant strains from any site. Post-treatment, propionibacterial counts remained well below pretreatment levels but had begun to recover on the face and in the nares. The recovering propionibacterial population included both susceptible and resistant strains. Changes during and post-treatment at the two centres were similar but not identical. CONCLUSIONS: Oral isotretinoin effectively reduced skin and nasal colonization by antibiotic-resistant propionibacteria. However, viable populations of resistant isolates persisted post-treatment at multiple sites. Novel methods are required to eradicate antibiotic-resistant propionibacteria completely, especially from the nasal reservoir.     

Prevalence of antibiotic-resistant propionibacteria on the skin of acne patients: 10-year surveillance data and snapshot distribution study

BACKGROUND: Cutaneous propionibacteria are implicated in acne pathogenesis, although their exact role in the genesis of inflammation is still poorly understood. Agents, including antibiotics, that reduce the numbers of propionibacteria on skin are therapeutic. Resistance in the target organism is a well-recognized consequence of antibiotic therapy for acne but formal prevalence and distribution data are lacking. OBJECTIVES: To monitor the prevalence of skin colonization by antibiotic-resistant propionibacteria in acne patients attending the dermatology out-patient clinic at Leeds General Infirmary over a 10-year period beginning in 1991, and to examine the distribution of resistant strains on acne-prone skin and in the nares. METHODS: Propionibacterial samples were obtained from the skin surface of the worst affected site (usually the face) of 4274 acne patients using a moistened swab. The swab was used to inoculate agar plates with and without selective antibiotics. After anaerobic incubation at 37 degrees C for 7 days, the amount of growth in the presence of each antibiotic was scored on a scale from 0 to 5+. A small number of patients (72) were selected for more detailed quantitative sampling at six different sites to examine the distribution of resistant propionibacteria on acne-prone skin and in the anterior nares. RESULTS: The proportion of patients carrying strains resistant to one or more commonly used antiacne antibiotics rose steadily from 34.5% in 1991 to a peak of 64% in 1997. The prevalence dropped to 50.5% during 1999 and then rose again to 55.5% in 2000. Resistance to erythromycin was the most common and the majority of erythromycin-resistant strains were cross-resistant to clindamycin. Resistance to tetracyclines was less common in all years and with little increase over time. The more detailed quantitative study in 72 patients showed that population densities of resistant propionibacteria varied considerably between sites and between individuals. Almost invariably, patients were colonized with resistant strains at multiple sites, including the nares. CONCLUSIONS: Skin colonization with antibiotic-resistant propionibacteria is much more common now than a decade ago. Resistant propionibacteria are widely distributed on acne-prone skin and in the nares. This suggests that they will be very difficult to eradicate using existing therapeutic regimens, especially from the nasal reservoir.     

The cutaneous microflora of adolescent, persistent and late-onset acne patients does not differ

The cutaneous microbiology and antibody status to Propionibacterium acnes of patients with persistent (males, n = 32; females, n = 33) and late-onset (females, n = 25) acne were compared with individuals with adolescent acne (males, n = 22; females, n = 18) and normal control volunteers (persistent acne: males, n = 26; females, n = 30; late-onset: females, n = 20). Males had significantly higher grades of acne compared with females (P < 0.05). The microflora consisted in the main of propionibacteria, staphylococci and Malassezia; other bacteria represented less than 0.01% of the total microflora. At all sites for all samples there were significantly more propionibacteria than staphylococci or Malassezia (P < 0.05). There were significantly higher (P < 0.05) numbers of microorganisms in follicular casts from patients compared with their control volunteers for female facial skin and male back skin. Twenty-six papules and 48 normal follicles were analysed. A bimodal distribution of microbial colonization was noted, with about 90% of normal follicles and about 10% of acne follicles having no detectable viable microorganisms. Anti-P. acnes IgG antibody titres were measured using a secondary fluorescein isothiocyanate antibody technique, and no significant differences in titre were found between any groups of patients (P > 0.05). Correlation analysis showed no association between the population densities of P. acnes and anti-P. acnes IgG titres. There were no differences in the microbiology of skin of adolescent acne patients, persistent acne patients or late-onset acne patients which could account for these various forms of acne.     

Superior antibacterial action and reduced incidence of bacterial resistance in minocycline compared to tetracycline-treated acne patients

Twenty-five previously untreated acne patients were monitored throughout a 6-month course of therapy with either tetracycline or minocycline for changes in the numbers of staphylococci, propionibacteria and yeasts of the genus Malessezia on the skin surface. Antibiotic resistant staphylococci and propionibacteria were also counted. Minocycline (50 mg b.d.) produced a 10-fold greater reduction in propionibacterial numbers compared to tetracycline (500 mg b.d.) after 12 (P less than 0.02, t-test) and 24 weeks (P less than 0.05) of therapy. As treatment progressed, propionibacteria were replaced by yeasts, numbers of which were significantly increased by week 12 (P less than 0.02) in tetracycline-treated patients and by week 24 (P less than 0.01) in minocycline-treated patients. This suggests that yeasts have no role in the pathogenesis of acne but may compete with propionibacteria for the same niche. Overgrowth of antibiotic resistant staphylococci prevented any decrease in staphylococcal numbers in tetracycline-treated patients, but minocycline produced a significant and sustained reduction in staphylococcal numbers after 1 week of therapy (P less than 0.001). An increase in the number of multiply resistant (greater than or equal to 3 resistances) staphylococci occurred in 67% of tetracycline-treated and 33% of minocycline-treated patients by the end of the treatment period. There was no evidence of propionibacterial resistance in either treatment group. This study shows that minocycline has much greater antibacterial activity in vivo against both staphylococci and propionibacteria and produces less staphylococcal antibiotic resistance than tetracycline.     

Recalcitrant acne vulgaris. Clinical, biochemical and microbiological investigation of patients not responding to antibiotic treatment

A small, but clinically significant proportion of acne patients fail to respond adequately to antibiotic therapy. All non-responding acne patients attending the Leeds General Infirmary between September 1985 and April 1986 (49 out of a total of 610 patients; 8%) were investigated with respect to changes in their acne grade, microbial flora and sebum excretion rate. They were compared with 22 age and sex matched untreated control subjects. It was found that in 65% of non-responding patients there was no microbiological abnormality, in 16% there was evidence of Gram-negative folliculitis and 20% carried predominantly antibiotic resistant propionibacteria compared with only 5% of untreated controls. There was a significant association between erythromycin therapy and the isolation of erythromycin resistant propionibacteria (P less than 0.001). A causal link, however, has yet to be established between carriage of antibiotic resistant propionibacteria and failure to respond to antibiotic therapy. Our results show that for most patients with recalcitrant acne a non-microbiological explanation must be sought for the lack of therapeutic success. The mean sebum excretion rate (SER) of the non-responding patients was significantly higher than that of matched untreated acne patients (P less than 0.001). A majority of non-responders (69%) had an SER above the upper 95% confidence limit of the control mean. The SER may affect treatment efficacy by influencing the antibiotic concentration within the pilosebaceous ducts.     

Application of computer taxonomic techniques to the study of cutaneous propionibacteria and skin-surface lipid

Summary Colonisation of the forehead by propionibacteria and the composition of both free fatty acid and fatty acid of the triglyceride fraction of skin-surface lipid were studied, and the results were analysed using numerical taxonomic techniques. The density and prevalence of propionibacteria increased with age in a population of 230 children aged 5–18 years. The fatty-acid composition of casual sebum on the forehead changed with age, suggesting that the prevalence and density of organisms may be related to lipid composition. Clusteranalysis techniques revealed groups of individuals who resembled each other with respect to their triglyceride and free-fatty-acid profiles. These groups tended to consist of subjects who were of a similar age and maturity, and who were similarly colonised with propionibacteria. However, no relationship was evident between the composition of lipid and clinical acne.     

Skin surface lipid composition, acne, pubertal development, and urinary excretion of testosterone and 17-ketosteroids in children.

Fifty-two children, age 5-10, from acne-prone families, were studied for a period of 1 year to examine the interrelationship between sebum, acne, pubertal development, and urinary steroid excretion. In each of the subjects, 30 boys and 22 girls, the composition of forehead skin lipid was determined 4 times yearly by thin-layer chromatography, with measurement of triglycerides, diglycerides, free fatty acids, wax esters, squalene, cholesterol, and cholesterol esters. Twice yearly, examination was made of the presence or absence of acne, pubertal maturation and the 24-hour urinary excretion of testosterone as determined by radioimmunnoassay, and of total 17-ketosteroids, dehydroepiandrosterone, androsterone, and etiocholanolone, as determined by paper chromatography. The relative amount of sebaceous lipids was positively correlated with age of the subjects (wax esters p less than .001, squalene p less than .05), as was the triglyceride-diglyceride component (p less than .05). No significant correlation was seen with the fatty acids. Acne, primarily comedonal, occurred in 27/52 subjects (15 girls, 12 boys) and was associated with higher sebum values. One-half of the children with acne had no signs of pubertal development. A significantly positive correlation was observed between the relative amount of sebaceous lipid and the urinary excretion of 17-ketosteroids, androsterone, and etiocholanolone in both sexes, and of testosterone and dehydroepiandrosterone in boys. The development of acne in children is an early pubertal event, often evident before other signs of pubertal maturation, and it is associated with an increase in sebum and in the urinary excretion of androgenic steroids.     

The effects of acne treatment with a combination of benzoyl peroxide and erythromycin on skin carriage of erythromycin resistant propionibacteria

Summary Concomitant application of 5% w/w benzoyl peroxide and 3% w/w erythromycin has previously been shown to prevent the overgrowth, on the skin of acne patients, of crythromycin-resistant coagulase-negative staphylococci, which occurs when the antibiotic is used alone. Two in vivo studies were carried out to assess the ability of the same therapeutic combination to inhibit the growth of pre-existing erythromycin-resistant propionibacteria and to prevent the selection of resistant strains during treatment. A double-blind clinical trial in 37 patients with mild to moderate acne vulgaris showed that the combination brought about a > 3 log₁₀ c.f.u. reduction in total propionibacterial numbers/cm² after 6 weeks therapy (P < 0.001, Wilcoxon's matched pairs) and also significantly reduced the number of erythromycin-resistant propionibacteria (P < 0.05). In contrast, erythromycin alone reduced the total propionibacterial count by < 1.5 log₁₀ c.f.u./cm² after 6 weeks (P < 0.05) and did not affect the number of erythromycin-resistant strains. The combined formulation was significantly more effective at reducing total propionibacterial numbers at 6 (P < 0.01, Mann-Whitney) and 12 weeks (P < 0.05) than erythromycin alone, although, after 12 weeks, the anti-propionibacterial efficacy of both preparations was less marked. Five patients on combination therapy, and five treated with erythromycin alone, acquired erythromycin-resistant strains de novo at week 6 or week 12. In an open study in 21 acne patients, who each carried > 10³ c.f.u. erythromycin-resistant propionibacteria/cm² skin pretreatment, the combination of erythromycin and benzoyl peroxide reduced the total propionibacterial count by > 2.5 log₁₀ and the number of erythromycin-resistant strains by a similar amount (P < 0.001, Wilcoxon). This was accompanied by highly significant reductions in acne grade and lesion counts (P < 0.001). These data suggest that the combination of 5% w/w benzoyl peroxide and 3% w/w erythromycin has greater in vivo antipropionibacterial activity than 3% w/w erythromycin alone, and brings about significant clinical improvement in acne patients with high numbers of erythromycin-resistant propionibacterial strains pretreatment.     

Acne and sebaceous gland function

The embryologic development of the human sebaceous gland is closely related to the differentiation of the hair follicle and the epidermis. The number of sebaceous glands remains approximately the same throughout life, whereas their size tends to increase with age. The development and function of the sebaceous gland in the fetal and neonatal periods appear to be regulated by maternal androgens and by endogenous steroid synthesis, as well as by other morphogens. The most apparent function of the glands is to excrete sebum. A strong increase in sebum excretion occurs a few hours after birth; this peaks during the first week and slowly subsides thereafter. A new rise takes place at about age 9 years with adrenarche and continues up to age 17 years, when the adult level is reached. The sebaceous gland is an important formation site of active androgens. Androgens are well known for their effects on sebum excretion, whereas terminal sebocyte differentiation is assisted by peroxisome proliferator-activated receptor ligands. Estrogens, glucocorticoids, and prolactin also influence sebaceous gland function. In addition, stress-sensing cutaneous signals lead to the production and release of corticotrophin-releasing hormone from dermal nerves and sebocytes with subsequent dose-dependent regulation of sebaceous nonpolar lipids. Among other lipid fractions, sebaceous glands have been shown to synthesize considerable amounts of free fatty acids without exogenous influence. Sebaceous lipids are responsible for the three-dimensional skin surface lipid organization. Contributing to the integrity of the skin barrier. They also exhibit strong innate antimicrobial activity, transport antioxidants to the skin surface, and express proinflammatory and anti-inflammatory properties. Acne in childhood has been suggested to be strongly associated with the development of severe acne during adolescence. Increased sebum excretion is a major factor in the pathophysiology of acne vulgaris. Other sebaceous gland functions are also associated with the development of acne, including sebaceous proinflammatory lipids; different cytokines produced locally; periglandular peptides and neuropeptides, such as corticotrophin-releasing hormone, which is produced by sebocytes; and substance P, which is expressed in the nerve endings at the vicinity of healthy-looking glands of acne patients. Current data indicate that acne vulgaris may be a primary inflammatory disease. Future drugs developed to treat acne not only should reduce sebum production and Propionibacterium acnes populations, but also should be targeted to reduce proinflammatory lipids in sebum, down-regulate proinflammatory signals in the pilosebaceous unit, and inhibit leukotriene B(4)-induced accumulation of inflammatory cells. They should also influence peroxisome proliferator-activated receptor regulation. Isotretinoin is still the most active available drug for the treatment of severe acne.     

Qualitative and quantitative investigations on the resident bacterial skin flora in healthy persons and in the non-affected skin of patients with seborrheic eczema

Summary The composition of the aerobic and anaerobic bacterial skin flora was investigated quantitatively and qualitatively in 25 patients with seborrheic eczema (SE) and in 35 healthy persons. In SE patients, the geometric mean count for propionibacteria in the pilosebaceous ducts of the forehead was reduced to a statistically significant extent in comparison with the control group. There was the same tendency with regard to the geometric mean count of the superficial anaerobic bacterial flora of the back, whereas the geometric mean counts of the coagulase-negative staphylococci were the same in the two groups. These results may explain earlier findings of a reduction of free fatty acids in the surface lipids in SE patients. According to the results of differentiation in 295 propionibacteria and 157 micrococcaceae, 7 biotypes and 10 phage types of propionibacteria which were so far unknown could be demonstrated. Significant differences between the groups with regard to the frequency of different biotypes, serotypes, and phage types could be demonstrated neither in propionibacteria nor in coagulase-negative staphylococci. The results of typing, however, showed that patients with SE displayed much more frequently several different propionibacterial species and types as well as several different micrococcal species and types than persons with healthy skin.Partly supported by research grants of the Deutsche Forschungsgemeinschaft     

Antibiotic-resistant acne: lessons from Europe

BACKGROUND: Propionibacterium acnes and P. granulosum are widely regarded as the aetiological agents of inflammatory acne. Their proliferation and metabolism are controlled using lengthy courses of oral and/or topical antibiotics. Despite numerous reports of skin colonization by antibiotic-resistant propionibacteria among acne patients, accurate prevalence data are available only for the U.K. OBJECTIVES: To determine the prevalence of skin colonization by antibiotic-resistant propionibacteria among acne patients and their contacts from six European centres. METHODS: Skin swabs were collected from 664 acne patients attending centres in the U.K., Spain, Italy, Greece, Sweden and Hungary. Phenotypes of antibiotic-resistant propionibacteria were determined by measuring the minimum inhibitory concentrations (MIC) of a panel of tetracycline and macrolide, lincosamide and streptogramin B (MLS) antibiotics. Resistance determinants were characterized by polymerase chain reaction (PCR) using primers specific for rRNA genes and erm(X), followed by nucleotide sequencing of the amplified DNA. RESULTS: Viable propionibacteria were recovered from 622 patients. A total of 515 representative antibiotic-resistant isolates and 71 susceptible isolates to act as control strains were characterized phenotypically. The prevalence of carriage of isolates resistant to at least one antibiotic was lowest in Hungary (51%) and highest in Spain (94%). Combined resistance to clindamycin and erythromycin was much more common (highest prevalence 91% in Spain) than resistance to the tetracyclines (highest prevalence 26.4% in the U.K.). No isolates resistant to tetracycline were detected in Italy, or in Hungary. Overall, there were strong correlations with prescribing patterns. Prevalence of resistant propionibacteria on the skin of untreated contacts of the patients varied from 41% in Hungary to 86% in Spain. Of the dermatologists, 25 of 39 were colonized with resistant propionibacteria, including all those who specialized in treating acne. None of 27 physicians working in other outpatient departments harboured resistant propionibacteria. CONCLUSIONS: The widespread use of topical formulations of erythromycin and clindamycin to treat acne has resulted in significant dissemination of cross-resistant strains of propionibacteria. Resistance rates to the orally administered tetracycline group of antibiotics were low, except in Sweden and the U.K. Resistant genotypes originally identified in the U.K. are distributed widely throughout Europe. Antibiotic-resistant propionibacteria should be considered transmissible between acne-prone individuals, and dermatologists should use stricter cross-infection control measures when assessing acne in the clinic.     

Differences in the lipid constituents of sebum from pre-pubertal and pubertal subjects

Significant differences have been reported in the composition of skin surface lipid in pre-pubertal subjects when compared to pubertal subjects. Analytical studies were performed to determine whether group mean changes in the fatty acid composition of the triglyceride and wax ester fractions of sebum could be detected in pre-pubertal versus pubertal subjects. Twenty males (ages 6–9), twenty females (ages 6–9) and twelve teenagers (ages 11–16) were studied. Skin surface lipid was examined by densitometry and gas chromatography. There were significant changes in the fatty acid composition of the wax fraction of sebum in the 11–16-year-old children when compared to the 6–9-year-old group. As wax is of sebaceous gland origin, this may represent a change in sebum composition probably in response to the hormonal stimulus. Changes in the fatty acid fraction of triglycerides were also noted with age, but this may be due to the change in source of triglyceride from predominantly epidermal origin to sebaceous gland origin.     

An updated review of the sebaceous gland and its role in health and diseases Part 1: Embryology,evolution, structure,and function of sebaceous glands

Sebaceous glands are sebum‐secreting components of pilosebaceous units. The embryological development of the sebaceous gland follows that of the hair follicle and epidermal tissue, beginning between weeks 13 and 16 of fetal development. New sebaceous glands do not normally develop following birth, but their size increases with age. Sebocytes express a multitude of hormone receptors and are heavily regulated to secrete sebum by androgens. There is a large increase of sebum excretion at birth and again at puberty, until approximately age 17. In adulthood, sebum production remains stable and declines to zero in postmenopausal women and in men aged 60‐70. Besides the production and release of sebum, sebaceous glands function to lubricate the skin and hair, provide thermoregulation, and exhibit antimicrobial activity. Research has shown sebaceous glands to possess the cellular capability to transcribe genes necessary for androgen metabolism. Dysfunction of the sebaceous gland can be seen primarily in steatocystoma simplex and multiplex, sebaceous gland hyperplasia, sebaceoma, sebaceous adenoma, sebaceous carcinoma, nevus sebaceus, and folliculosebaceous cystic hamartoma. Sebaceous glands are secondarily involved in acne vulgaris, seborrheic dermatitis, and androgenic alopecia.     

Sebaceous gland activity in black skin

Sebaceous gland secretion was measured in 649 male and female subjects, of whom 67 (10.3 per cent) were black. No consistent difference in sebaceous gland activity was found between black and white skin. As sebum is an integral etiologic factor in acne, these findings are consistent with the clinical impression and with epidemiologic data, albeit scant, that the incidence of acne vulgaris in the black population differs little, if at all, from the incidence in the white population.     

Is Antibiotic Resistance in Cutaneous Propionibacteria Clinically Relevant?

It is well recognized that some patients with acne do not respond adequately to antibiotic therapy. It is important to distinguish antibiotic recalcitrant acne which we would suggest represents acne that shows a diminished response to treatment irrespective of the cause as opposed to 'antibiotic-resistant acne' which is acne that is less responsive to treatment as a direct consequence of skin colonization with resistant propionibacteria. Here we show that antibiotic-resistant acne is not just a theoretical possibility but a real phenomenon that could have important consequences for patients and prescribers. The relationship between skin colonization by antibiotic-resistant propionibacteria and treatment outcomes is a complex one that is explained at the follicular level by physiological differences affecting local drug concentrations. A systematic review of the literature on antibiotic-resistant propionibacteria revealed methodological shortcomings in studies of their prevalence and a paucity of evidence on their clinical significance. Despite the elucidation of resistance mechanisms in cutaneous propionibacteria, our continuing inability to distinguish between strains of Propionibacterium acnes means that we still do not fully understand how resistance spreads, although person-to-person transfer is most likely. Finally, we present a decision tree for acne management in an era of prudent antimicrobial prescribing that provides an alternative to existing treatment algorithms by placing topical retinoids and not antibiotics at the cornerstone of acne management.     

The role of facial sebum secretion in acne pathogenesis: facts and controversies

Increased sebum secretion has been known as one of the major pathogenic factors in the development of acne; however, objective sebum measurement methods have been developed only recently. We have limited information about the association of sebum secretion, and the development of acne. There continues to be controversy about the role of sebum in the development of acne. This contribution will discuss sebum measurement techniques and the results of recent studies on the relationship of sebum, facial cosmetic skin type, and acne. New therapeutic modalities for inflammatory acne aim to control seborrhea. Superficial chemical peels, laser treatment for inflammatory acne, and photodynamic therapy are used as adjunctive therapies for acne; however, their sebosuppressive effects are only temporary.     

The Difference in Sebum Secretion Affecting Development of Acne

BackgroundAlthough sebum secretion is crucial for acne development, acne lesion distribution is not always similar to the topographic differences of sebum secretion.ObjectiveTo analyze whether sebum secretion affects acne development and distribution and to assess other factors possibly influencing the relationship between acne and sebum secretion.MethodsThis single-center retrospective study included 67 acne patients and 50 controls. Acne patients were divided into 3 groups based on acne lesion distribution: T-zone dominant, U-zone dominant, and mixed groups. The secreted sebum level in each zone of acne patients was compared with that of controls. We also conducted correlation analysis between secreted sebum level and acne number, depending on the facial zone.ResultsNo significant difference was found between acne patients and controls regarding age and sex ratio. The U-zone dominant group showed increased sebum levels compared with controls in the U-zone and whole face, but a similar result was not obtained in the T-zone dominant group. Moreover, there was a significant correlation between the number of lesions and secreted sebum level in the U-zone, but not in the T-zone. Further, there was a more significant relation in the U-zone of male and young patients.ConclusionWe found that increased sebum secretion compared with the condition may affect acne development, especially in the U-zone. Sex and age may also influence the relationship between acne and increased sebum secretion. Acne lesion distribution may vary from patient to patient because sebum secretion affects acne differently depending on multiple factors.     

A review of the role of sebum in the mechanism of acne pathogenesis

Acne is one of the most common skin disorders, and its occurrence is closely related to many factors, including sebum secretion, hormone levels, bacterial infection, and inflammatory reactions. Among these, changes in sebum secretion are believed to be one important factor of acne. Increased sebum secretion can induce acne occurrence, and increasing evidence indicates sebum component changes are also strongly related to acne occurrence. Recently, developments in lipidomics have provided effective lipid analysis methods. These can help elucidate the effects of different types of sebum on acne occurrence and provide a theoretical basis for research on the mechanisms of acne pathogenesis and treatment.     

The pathophysiology of acne vulgaris in children and adolescents, part 2: Tailoring treatment

Various pathophysiologic factors are involved in the development of acne lesions, microcomedones, comedones, and inflammatory lesions. These factors include follicular hyperkeratosis, increased colonization of follicles by Propionibacterium acnes, increased sebum production, and inflammatory mediators. Optimal treatment of acne involves the use of agents that address these various underlying pathogenetic factors.     

The clinical features of late onset acne compared with early onset acne in women

Background Little is known about the clinical characteristics of acne based on the age of onset. Objectives The aim of this study was to investigate the clinical characteristics of patients according to the age of onset of acne and evaluate whether the findings were related to regional differences in the density of Propionibacterium acnes or the levels of sebum secretion. Methods A total of 89 women were recruited. The acne lesions were assessed by counting the lesions using standard digital photographs. Digital fluorescent photography for the evaluation of the density of P. acnes were taken and quantitative measurements of facial sebum secretion were performed. Results In women with acne, the age of onset was negatively correlated with the number of comedones and the proportion of comedones. By comparing the number of comedones and the proportion of comedones, onset of acne after 21 years of age was defined as late onset acne. In the patients with late onset acne, the number of comedones, the total number of acne lesions and the proportions of comedones were significantly less than in the patients with early onset acne. However, there were no significant differences in the fluorescence density of P. acnes or the level of sebum secretion between the two groups. Conclusions The results of this study, using objective evaluation tools, suggest that late onset acne has different clinical characteristics. Other possible factors might explain the clinical differences in late onset acne.