Control of Propionibacterium acnes by natural antimicrobial substances: Role of the bacteriocin AS-48 and lysozyme.

We report the high susceptibility of several clinical isolates of Propionibacterium acnes from different sources (skin, bone, wound exudates, abscess or blood contamination) to the head-to-tail cyclized bacteriocin AS-48. This peptide is a feasible candidate for further pharmacological development against this bacterium, due to its physicochemical and biological characteristics, even when it is growing in a biofilm. Thus, the treatment of pre-formed biofilms with AS-48 resulted in a dose- and time-dependent disruption of the biofilm architecture beside the decrease of bacterial viability. Furthermore, we demonstrated the potential of lysozyme to bolster the inhibitory activity of AS-48 against P. acnes, rendering high reductions in the MIC values, even in matrix-growing cultures, according to the results obtained using a range of microscopy and bioassay techniques. The improvement of the activity of AS-48 through its co-formulation with lysozyme may be considered an alternative in the control of P. acnes, especially after proving the absence of cytotoxicity demonstrated by these natural compounds on relevant human skin cell lines. In summary, this study supports that compositions comprising the bacteriocin AS-48 plus lysozyme must be considered as promising candidates for topical applications with medical and pharmaceutical purposes against dermatological diseases such as acne vulgaris.

In vitro evaluation of bioactive potential of Bacillus methylotrophicus YML008 against Propionibacterium acnes.

Acne vulgaris is the most common skin diseases that people experience during their lives. Thirteen rhizosphere isolates were screened against Propionibacterium acnes. The bacterium exhibited the highest activity against P. acnes was identified as Bacillus methylotrophicus YML008 by 16S rRNA gene sequencing. Scanning electron microscopy was used to assess the changes in morphology of P. acnes. Preliminary studies on the antimicrobial substance demonstrated the hydrophilic nature of compound with MIC of 0.17mg/ml and MBC of 0.3mg/ml. The cytotoxic effect of the extract was least (80% survival) as compared to benzyperoxide (40% survival). These results suggest YML008 as a promising bioresource and may be useful as a lead bacterium to develop a new type of anti-acne skin care prep to cure or prevent acne. Further, mechanism of action and proper clinical trials may be promising for this research.

Etiologic aspect of sarcoidosis as an allergic endogenous infection caused by Propionibacterium acnes.

Sarcoidosis is a systemic granulomatous disease of unknown etiology. Propionibacterium acnes is the only microorganism that has been isolated from sarcoid lesions. Many P. acnes have been detected in sarcoid lymph nodes using quantitative PCR and in sarcoid granulomas by in situ hybridization. P. acnes trigger factor protein causes a cellular immune response only in sarcoid patients and induces pulmonary granulomas in mice sensitized with the protein and adjuvant, but only those with latent P. acnes infection in their lungs. Eradication of P. acnes by antibiotics prevents the development of granulomas in this experimental model. Although P. acnes is the most common commensal bacterium in the lungs and lymph nodes, P. acnes-specific antibody detected the bacterium within sarcoid granulomas of these organs. P. acnes can cause latent infection in the lung and lymph node and persist in a cell-wall-deficient form. The dormant form is activated endogenously under certain conditions and proliferates at the site of latent infection. In patients with P. acnes hypersensitivity, granulomatous inflammation is triggered by intracellular proliferation of the bacterium. Proliferating bacteria may escape granulomatous isolation, spreading to other organs. Latent P. acnes infection in systemic organs can be reactivated by another triggering event, leading to systemic sarcoidosis.

Antimicrobial and anti-inflammatory activity of chitosan-alginate nanoparticles: a targeted therapy for cutaneous pathogens.

Advances in nanotechnology have demonstrated potential application of nanoparticles (NPs) for effective and targeted drug delivery. Here we investigated the antimicrobial and immunological properties and the feasibility of using NPs to deliver antimicrobial agents to treat a cutaneous pathogen. NPs synthesized with chitosan and alginate demonstrated a direct antimicrobial activity in vitro against Propionibacterium acnes, the bacterium linked to the pathogenesis of acne. By electron microscopy (EM) imaging, chitosan-alginate NPs were found to induce the disruption of the P. acnes cell membrane, providing a mechanism for the bactericidal effect. The chitosan-alginate NPs also exhibited anti-inflammatory properties as they inhibited P. acnes-induced inflammatory cytokine production in human monocytes and keratinocytes. Furthermore, benzoyl peroxide (BP), a commonly used antiacne drug, was effectively encapsulated in the chitosan-alginate NPs and demonstrated superior antimicrobial activity against P. acnes compared with BP alone while demonstrating less toxicity to eukaryotic cells. Together, these data suggest the potential utility of topical delivery of chitosan-alginate NP-encapsulated drug therapy for the treatment of dermatologic conditions with infectious and inflammatory components.

Cathelicidin-BF, a snake cathelicidin-derived antimicrobial peptide, could be an excellent therapeutic agent for acne vulgaris.

Cathelicidins are a family of antimicrobial peptides acting as multifunctional effector molecules in innate immunity. Cathelicidin-BF has been purified from the snake venoms of Bungarus fasciatus and it is the first identified cathelicidin antimicrobial peptide in reptiles. In this study, cathelicidin-BF was found exerting strong antibacterial activities against Propionibacterium acnes. Its minimal inhibitory concentration against two strains of P. acnes was 4.7 µg/ml. Cathelicidin-BF also effectively killed other microorganisms including Staphylococcus epidermidis, which was possible pathogen for acne vulgaris. Cathelicidin-BF significantly inhibited pro-inflammatory factors secretion in human monocytic cells and P. acnes-induced O2.- production of human HaCaT keratinocyte cells. Observed by scanning electron microscopy, the surfaces of the treated pathogens underwent obvious morphological changes compared with the untreated controls, suggesting that this antimicrobial peptide exerts its action by disrupting membranes of microorganisms. The efficacy of cathelicidin-BF gel topical administering was evaluated in experimental mice skin colonization model. In vivo anti-inflammatory effects of cathelicidin-BF were confirmed by relieving P. acnes-induced mice ear swelling and granulomatous inflammation. The anti-inflammatory effects combined with potent antimicrobial activities and O2.- production inhibition activities of cathelicidin-BF indicate its potential as a novel therapeutic option for acne vulgaris.

Biofilm formation of the pathogens of fatal bacterial granuloma after trauma: potential mechanism underlying the failure of traditional antibiotic treatments.

The pathogen of a new type of disease - fatal bacterial granuloma after trauma (FBGT) - was found to be Propionibacterium acnes (P. acnes). Although in vitro studies showed that the pathogenic P. acnes are sensitive to conventional antibiotics, treatments of FBGT patients with these antibiotics were ineffective. The underlying mechanisms were not clear. Since P. acnes are able to form biofilm on orthopaedic biomaterials in vitro, and pathogenic P. acnes of acnes vulgaris was known to form biofilm in vivo, we hypothesize that the pathogens of FBGT are also able to form biofilm during the pathogenesis, which may be 1 of the reasons for antibiotics tolerance of FBGT. Biofilm forming capacity of the pathogens of FBGT were examined with XTT reduction method, as well as with scanning electron microscope. The effect of long-term subminimal inhibitory concentration (MIC) lincomycin on the biofilm forming ability of the pathogens was also tested. Our results show that both the type strain (NCTC737) and the pathogenic P. acnes of FBGT can form biofilm in vitro. These data demonstrated the biofilm formation of the FBGT pathogens in vitro, and its acceleration by lincomycin, which may be 1 of the major mechanisms for the failure of antibiotic treatment.

Biofilm formation by Propionibacterium acnes on biomaterials in vitro and in vivo: impact on diagnosis and treatment.

Propionibacterium acnes is found increasingly as a cause of delayed infection, usually involving implanted biomaterials. Despite susceptibility to common antibiotics, such infections are very difficult to treat and usually require surgical removal of the device. Three clinical isolates of P. acnes were assessed for ability to adhere to titanium, surgical steel and silicone, with and without a plasma conditioning film. After adherence, the biomaterials were then incubated for a further 6 days and examined for biofilm development. All three isolates adhered to all three biomaterials similarly. Importantly, we were able to demonstrate biofilm formation, including production of exopolymer similar in appearance to the polysaccharide intercellular adhesin of Staphylococcus epidermidis. A case summary also demonstrated failure to eradicate P. acnes infection in a hydrocephalus shunt after prolonged treatment. The removed shunt showed obvious biofilm formation, initially obscured by exopolymer when viewed by environmental scanning electron microscopy. Biofilm development by P. acnes explains the difficulties encountered in clinical management of such infections.

Propionibacterium acnes wound contamination at the time of spinal surgery.

UNLABELLED: Bacteria of the normal skin microbiota such as Propionibacterium acnes and coagulase-negative staphylococci often are dismissed as contaminants when detected in clinical samples. Propionibacterium acnes is described as a cause of spinal infection and more recently has been linked to sciatica. To date no researchers formally have examined the incidence of bacterial wound contamination during spinal surgery. Surgical specimens were removed from 79 patients having spinal surgery for analysis using agar culture detection, broth enrichment, and immunofluorescence microscopy. Bacteria were identified in 29.1% of skin samples, 21.5% of tissue samples and 16.5% of washings retrieved from operative wounds. Propionibacterium acnes was identified more frequently than Staphylococcus spp in each of the three sample types. Bacteria were detected using enrichment in 9 (11%) patients and using fluorescence microscopy in 15 (19%). The results of immunofluorescence microscopy suggest that Propionibacterium acnes detected in wounds originates from patient skin. Bacteria from contaminated wounds appeared as single cells using fluorescence microscopy; however previous work shows that bacteria from infected hip prosthesis are observed as large aggregates. Therefore, it is suggested that immunofluorescence microscopy is a useful tool to help discriminate between surgical contamination and infection. LEVEL OF EVIDENCE: Diagnostic study, Level I (prospective study). See the Guidelines for Authors for a complete description of levels of evidence.

Propionibacterium acnes endophthalmitis with bacterial sequestration in a Molteno's implant after cataract extraction.

PURPOSE: To report a case of Propionibacterium acnes endophthalmitis following uncomplicated cataract extraction with bacterial sequestration in a preexisting Molteno's drainage implant. DESIGN: Interventional case report. METHODS: A 7-year-old girl with congenital glaucoma and a preexisting Molteno's drainage implant developed anterior nongranulomatous uveitis 4 months following cataract surgery. P. acnes endophthalmitis was diagnosed by polymerase chain reaction, Southern blot, and electron microscopy. RESULTS: Extraction of the Molteno's implant was required to control the persistent intraocular inflammation and to convert the results of polymerase chain reaction and Southern blot testing of aqueous sample for P. acnes from positive to negative. CONCLUSION: P. acnes may be sequestered in glaucoma implants, potentially requiring implant removal to treat cases of P. acnes endophthalmitis.

Eradication of Propionibacterium acnes by its endogenic porphyrins after illumination with high intensity blue light.

Propionibacterium acnes is a Gram-positive, microaerophilic bacterium that causes skin wounds. It is known to naturally produce high amounts of intracellular porphyrins. The results of the present study confirm that the investigated strain of P. acnes is capable of producing endogenic porphyrins with no need for any trigger molecules. Extracts from growing cultures have demonstrated emission peaks around 612 nm when excited at 405 nm, which are characteristic for porphyrins. Endogenic porphyrins were determined and quantified after their extraction from the bacterial cells by fluorescence intensity and by elution retention time on high-performance liquid chromatography (HPLC). The porphyrins produced by P. acnes are mostly coproporphyrin, as shown by the HPLC elution patterns. Addition of delta-aminolevulinic acid (ALA) enhanced intracellular porphyrin synthesis and higher amounts of coproporphyrin have been found. Eradication of P. acnes by its endogenic porphyrins was examined after illumination with intense blue light at 407-420 nm. The viability of 24 h cultures grown anaerobically in liquid medium was reduced by less than two orders of magnitude when illuminated once with a light dose of 75 J cm(-2). Better photodynamic effects were obtained when cultures were illuminated twice or three times consecutively with a light dose of 75 J cm(-2) and an interval of 24 h between illuminations. The viability of the culture under these conditions decreased by four orders of magnitude after two illuminations and by five orders of magnitude after three illuminations. When ALA-triggered cultures were illuminated with intense blue light at a light dose of 75 J cm(-2) the viability of the treated cultures decreased by seven orders of magnitude. This decrease in viability can occur even after a single exposure of illumination for the indicated light intensity. X-ray microanalysis and transmission electron microscopy revealed structural damages to membranes in the illuminated P. acnes. Illumination of the endogenous coproporphyrin with blue light (407-420 nm) apparently plays a major role in P. acnes photoinactivation. A treatment protocol with a series of several illuminations or illumination after application of ALA may be suitable for curing acne. Treatment by both pathways may overcome the resistance of P. acnes to antibiotic treatment.

Pathogenesis of acne.

Acne vulgaris is a skin disorder of the sebaceous follicles that commonly occurs in adolescence and in young adulthood. The major pathogenic factors involved are hyperkeratinization, obstruction of sebaceous follicles resulting from abnormal keratinization of the infundibular epithelium, stimulation of sebaceous gland secretion by androgens, and microbial colonization of pilosebaceous units by Propionibacterium acnes, which promotes perifollicular inflammation. The clinical presentation of acne can range from a mild comedonal form to severe inflammatory cystic acne of the face, chest, and back. At the ultrastructural level, follicular keratinocytes in comedones can be seen to possess increased numbers of desmosomes and tonofilaments, which result in ductal hypercornification. The increased activity of sebaceous glands elicited by androgen causes proliferation of P. acnes, an anaerobe present within the retained sebum in the pilosebaceous ducts. The organism possesses a ribosome-rich cytoplasm and a relatively thick cell wall, and produces several biologically active mediators that may contribute to inflammation, for instance, by promoting leukocyte migration and follicular rupture. In inflamed lesions, numerous neutrophils and macrophages infiltrate around hair follicles and sometimes phagocytose P. acnes. To examine the participation of neurogenic factors in the pathogenesis of acne, we quantitatively assessed the effects of neuropeptides on the morphology of sebaceous glands in vitro using electron microscopy. Substance P, which can be elicited by stress, promoted the development of cytoplasmic organelles in sebaceous cells, stimulated sebaceous germinative cells, and induced significant increases in the area of sebaceous glands. It also increased the size of individual sebaceous cells and the number of sebum vacuoles for each differentiated sebaceous cell, all of which suggests that substance P promotes both the proliferation and the differentiation of sebaceous glands. In this review, we introduce the general concept of pathogenic factors involved in acne, including typical electron microscopic findings and recent evidence of stress-induced exacerbation of acne from a neurological point of view. An improved understanding of the pathogenesis of acne should lead to a rational therapy to successfully treat this skin disease.

Immunohistochemical and ultrastructural analyses of in situ activation of hepatic stellate cells around Propionibacterium acnes-induced granulomas in the rat liver.

Stellate cells embrace the hepatic sinusoids as pericytes. To demonstrate their activation in juxta-sinusoidal location, we induced hepatic granulomatous inflammation, which did not accompany liver injury nor fibrosis, by administrating a low dose (10 mg/kg b.w.) of heat-killed Propionibacterium acnes into rats. Macrophages and lymphocytes migrated out of the sinusoid and made compact granulomas in the space of Disse. Stellate cells which faced on the granulomas were closely attached to the sinusoidal endothelial cells and extended projections into the spaces between the constituent mononuclear cells of granulomas. They did not migrate into granulomas nor displayed mitosis. Immunohistochemically, stellate cells around the granulomas expressed alpha-smooth muscle actin (alpha-SMA), whereas those in the non-granulomatous regions did not. Small deposits of type III collagen were found at the periphery of granulomas. Biochemical analysis showed an increased amount of alpha-SMA protein and type III collagen mRNA in the granuloma-bearing liver. Transforming growth factor-beta and platelet-derived growth factor were detected within the granulomas. The present study has revealed that stellate cells are activated in situ by extrasinusoidal macrophages in a paracrine manner without being detached from the sinusoidal wall.

Intraocular lens removal from eyes with chronic low-grade endophthalmitis.

Intraocular lenses (IOLs) were removed from 11 eyes with chronic low-grade endophthalmitis after cataract extraction to restore useful vision and prevent recurrence. One anterior chamber lens, one iris-supported lens, and nine posterior chamber lenses were removed. In the eyes with posterior chamber lenses, the posterior capsule was intact; total (n = 7) or partial (n = 2) capsulectomy was performed in these eyes. Aqueous humor specimens obtained at surgery were positive for bacteria in five eyes, but scanning electron microscopy showed bacteria on all removed IOLs and capsular bags. Final best corrected visual acuity was 20/40 or better in seven eyes. Reduced visual acuity, between 20/50 and 20/400 in three eyes and counting fingers in one eye, was related to retinal detachment (n = 2) and age-related macular degeneration (n = 2). Transient hyphema was seen in one eye. With a mean follow-up of 21 months (range 10 to 31 months), no recurrence of inflammation was observed. The results show that negative cultures do not preclude a bacterial cause for infection and that primary IOL removal with partial or total capsulectomy provides a surgical approach to the treatment of chronic low-grade endophthalmitis not responsive to medical therapy.

Propionibacterium, Corynebacterium, Mycobacterium and Lepra bacilli.

Evidence is presented which suggests that certain key markers of lepra bacilli reside collectively in Proprionibacterium acnes, Corynebacterium tuberculostearicum and Mycobacterium leprae. The unrestricted replication of Mycobacterium leprae depends most probably upon the presence of an immune-deficiency-inducing viral agent or possibly on the combined effects of the organisms considered.

Induction of chemiluminescence during interaction of tumoricidal effector cell populations and tumor cells is dependent on the presence of mycoplasma.

A variety of host cells, such as activated macrophages, natural killer (NK) cells, and polymorphonuclear leukocytes (PMNL), are cytotoxic for an array of non-antibody-coated tumor cells. Because such effector cells appear to use oxygen-dependent mechanisms to effect tumor cell destruction in certain systems, the possibility of an involvement of toxic oxygen species has been considered. To investigate whether interaction of effector cells with neoplastic cells induces the generation of reactive oxygen species, resting and activated rat macrophages and rat spleen cells (as a source of NK activity) were exposed to viable tumor cells of varied origin, and chemiluminescence was monitored. This sensitive indicator of reactive oxygen generation was stimulated only when tumor cells or culture supernatants were contaminated with mycoplasma. Mycoplasma-free tumor cells and culture supernatants were in no case able to trigger chemiluminescence in any of these effector cell populations. On the other hand, tumor targets were equally susceptible to killing by effector cells irrespective of whether mycoplasma were present. The data suggest that generation of chemiluminescence during interaction of natural cytotoxic cells and neoplastic cells is an artifact and that reactive oxygen species do not function as an effector mechanism in antibody-independent natural killing effected by activated macrophages and NK cells.

Fate of vaccines of Propionibacterium acnes after phagocytosis by murine macrophages.

Stationary-phase (48 h) cells of Propionibacterium acnes VPI 0009, a potent stimulator of the reticuloendothelial system, persist unchanged within phagocytes for at least 24 h after ingestion. In contrast, exponential-phase (12 h) cells of the same strain (which do not induce splenomegaly) are extensively degraded within 5 h of phagocytosis. Suspensions of P. granulosum VPI 6500, which fails to induce splenomegaly in mice, also show considerable degradation after phagocytosis. Stationary-phase cells of strain VPI 0009 treated with sodium metaperiodate or with trichloroacetic acid, although without ability to induce splenomegaly, resist destruction almost as well as untreated vaccines. However, bacteria inactivated by acetic anhydride show about 50% breakdown in 24 h.

Relationship between cell wall synthesis in Propionibacterium acnes and ability to stimulate the reticuloendothelial system.

The addition of chloramphenicol or tetracycline to exponentially growing cells of Propionibacterium acnes, which are not normally able to induce splenomegaly until they reach stationary phase, resulted in a rapid development of ability to induce splenomegaly in mice. However, the activity resulting from chloramphenicol treatment was arrested by the addition of penicillin or vancomycin, which showed that the activity was dependent on cell wall synthesis.

The isolation of a lectin-like molecule from Corynebacterium parvum (NCTC 10390).

A mannose specific lectin has been isolated by affinity chromatography from the cell wall of C. parvum. Polyacrylamide gel electrophoresis indicates that the lectin molecules lie in the molecular weight range 57,000--72,000. It appears that C. parvum like E. coli and salmonellae express lectins that bind to cells expressing mannose in their membranes. This may partly account for the interaction between C. parvum and the macrophage leading to the various immunological phenomena associated with C. parvum administration.