Anika C. Jahns

An increased incidence of Propionibacterium acnes biofilms in acne vulgaris: a case–control study

Summary Background  Acne vulgaris is a disorder of the sebaceous follicles. Propionibacterium acnes can be involved in inflammatory acne.

Microbiology of hidradenitis suppurativa (acne inversa) : a histological study of 27 patients

Hidradenitis suppurativa (acne inverse) (HS) is a chronic skin disease primarily affecting hair follicles. The aetiology of HS is unknown, but infection is believed to play some role. This retrospective study investigated the microbial colonization directly in skin appendices in HS skin samples. Archival samples from 27 patients with HS were screened by immunofluorescence labelling with monoclonal and polyclonal antibodies against Gram‐positive bacteria, Propionibacterium acnes and Propionibacterium granulosum. Fluorescence in situ hybridization was used for further species identification of Staphylococcus spp. Overall, 17 patients (63%) were found positive for bacterial colonization. Of these, 15 showed colonization in hair follicles and/or sinus tracts. The most commonly identified bacteria were DAPI labelled coccoids that were seen in 71% of the positive patients in the form of biofilms and microcolonies. P. acnes was found as biofilms in hair follicles of two patients. Staphylococcus aureus and coagulase‐negative staphylococci were not detected in any sample. The results of this study indicate a common bacterial presence in HS skin lesions. Bacterial biofilms are not uncommon and their pathogenic role needs further evaluation.

Three dimensional distribution of Propionibacterium acnes biofilms in human skin

Propionibacterium acnes is regarded as a common member of the human skin microbiota, often occurring in biofilms. Little is known about the size of bacterial biofilms in hair follicles as a few sections of biopsy tissue are routinely evaluated. Transversal sectioning provides a better opportunity for histological analyses of hair follicles which can be followed through the different morphological levels. Direct visualization of P. acnes biofilms in hundreds of consecutive sections allowed insight into the 3D distribution in human hair follicles as well as investigating the depth of biofilm distribution within hair follicles. Four distinct colonization patterns of P. acnes biofilms were revealed. Results have shown that an individual P. acnes biofilm can spread for 1900 μm in a terminal hair follicle. This information can be of help while designing potential antibiofilm treatment.

propionibacterium species and follicular keratinocyte activation in acneic and normal skin

The pathogenesis of acne vulgaris is multifactorial with increased sebum production, alteration in the quality of sebum lipids, dysregulation of the hormone microenvironment, follicular hyperkeratinization and Propionibacterium acnes‐driven inflammation as major contributory factors. Hyperproliferation of keratinocytes is believed to contribute to hypercornification and eventually leads to comedone development. While the distribution of P. acnes is relatively well documented in acneic and healthy skin, little is known about P. granulosum and P. avidum.

Microbiology of folliculitis: a histological study of 39 cases

Folliculitis is a common inflammatory skin syndrome. Several microbial organisms have been put forward as causative agents, but few studies visualized microbes directly in inflamed hair follicles. This retrospective study investigated bacterial and fungal colonization of inflamed hair follicles in patients with clinically diagnosed non‐infectious folliculitis. Skin biopsies from 39 folliculitis patients and 27 controls were screened by fluorescence in situ hybridization (FISH) using broad‐range bacterial and fungal probes and by immunofluorescence microscopy using a monoclonal antibody towards Gram‐positive bacteria. Specific monoclonal and polyclonal antibodies towards Staphylococcus spp. and Propionibacterium acnes were applied for further species identification. Inflamed follicles were associated with bacterial colonization in 10 samples (26%) and fungal colonization in three samples (8%). Staphylococcus spp. were observed in inflamed follicles in seven samples (18%). Two samples were positive for P. acnes, which were identified as either type II or type IB/type III. Both Staphylococcus spp. and P. acnes were seen in macrocolonies/biofilm structures. In conclusion, one‐third of patients with clinically diagnosed, non‐infectious folliculitis exhibited microbial colonization with predominance of Staphylococcus spp.

Microbiology of folliculitis decalvans: a histological study of 37 patients

Editor It is interesting to read the article by Chia K.Y & Tey H.L. However, I would like to add on a few more entities here, which are pertinent to the subject. Leprosy remains one of the important causes of hypohidrosis in the third world. The hypohidrosis in leprosy results from the atrophy of the sweat glands subsequent to loss of nerve supply. The hypohidrosis in leprosy may either be lesional or diffuse due to autonomic dysfunction. Hypohidrosis often appears in early tuberculoid lesions where inflammatory damage is more. Indeed, pilocarpine sweat stimulation test has been used to diagnose early tuberculoid form of leprosy. In lepromatous leprosy on the other hand, hypohidrosis appears in the later stages. Syringotropic sarcoidosis may exhibit a reduced sweating response to thermal stimuli. Immunohistochemical analyses of the sweat glands surrounded by syringotropic granulomas depicts profoundly decreased expression of dermcidin and aquaporin 5, markers of sweat glands, suggesting functional defects. In addition, granulomatous mycosis fungoides may present with hypohidrosis and masquerade as leprosy.

Spatial distribution of bacterial-fungal communities in facial skin

The skin is a complex ecosystem, naturally hosting numerous bacterial species, fungi and arthropods. Sequencing of bacterial 16S rRNA genes obtained from skin samples revealed 205 bacterial detected in HFs. In the stratum corneum both bacterial and funga species were mostly seen as separate communities. The bacteria species in the stratum corneum were represented by Gram positive cocci (n = 2) and P. acnes (n = 1). In five samples an individual hair follicle contained both funga and bacterial species. The latter were represented by P. acne (n = 3), Gram-positive and unidentified cocci (n = 2). In three o these cases fungi and bacteria showed anatomically separate e ). d

Microbial colonization of normal skin: Direct visualization of 194 skin biopsies.

Recent genetic studies have suggested the presence of numerous microbial species on and in the skin. We characterised microbial colonization of a large collection of skin biopsies from 194 healthy subjects by fluorescence assay. Forty per cent of all biopsies did not show any evidence for microbial colonization. Propionibacterium acnes was the sole predominant bacterial species in both sebaceous and non-sebaceous areas. Non- P. acnes species were present in approximately 30% of all colonized samples. . Only hair follicles and stratum corneum were colonized. Understanding of cutaneous microbiota requires validation from a variety of approaches and techniques.

No link between Rosacea and Propionibacterium acnes

Rosacea is a common skin disease in adults affecting mainly the facial skin. Although inflammation appears to play a pathogenic role in rosacea, initiating factors are largely unknown. Microbial involvement in the development of rosacea has been suggested previously. We aimed to visualize Propionibacterium acnes in the skin compartments of rosacea patients. Facial skin biopsies from 82 rosacea patients and 25 controls were stained with a P. acnes‐specific monoclonal antibody (QUBPa3). Seven of 82 patients (8.5%) tested positive for P. acnes which was present either as a biofilm (57% of positive) or a microcolony (43%) in colonized patients. Our results suggest that P. acnes does not play a major role in the pathogenesis of rosacea.

Direct visualization of a gravid Demodex mite in human skin biopsy

Humans are commonly infested with Demodex mites. Two species are known to have humans as their sole host – Demodex folliculorum and Demodex brevis [1]. D. folliculorum is the most common permanent ectoparasite of human beings and is mainly found in facial hair follicles/sebaceous follicles [2]. Demodex mites belong to the normal skin fauna and their prevalence and numbers increase with age [3]. Upon poorly understood conditions, the normally symbiotic Demodex mites are thought to turn into opportunistic pathogens [4]. Over the years a connection between inflammation, especially in association with rosacea, and elevated numbers of Demodex mites has been suggested [5]. Commonly, mites are sampled using standardized skin surface biopsy with cyanoacrylate or fresh secretions from sebaceous glands [6]. We examined a facial skin biopsy from a rosacea patient. After deparaffinization and re-hydration, the sample was stained with DAPI (4’, 6’diamidino-2-phenylindole) for unspecific staining of DNA. DAPI staining revealed 100 eggs in a longitudinal cut mite of the species D. folliculorum (Figure 1). Eggs were identified due to size, number and position in the anterior part of the mite where the genital opening is located. To the best of our knowledge this is the first reported visualization of a gravid mite inside a human hair follicle. Hitherto, gravid mites have been observed and studied ex vivo in different media after epilation of eyelashes [7]. Demodex mites have been well studied regarding their exterior appearance, in particular the mouthparts have been described minutely [8]. Although the life cycle of these organisms is well known [9], the reproductive biology of Demodex mites in vivo has been rather neglected. Visualizing a female mite, presumably just before ovipositioning, will hopefully help to better understand mite biology.