Superficial Cutaneous Infections Research Articles

KERATINASE ENZYME: VIRULENCE FACTOR IN PATHOGENITY OF DERMATOPHYTES

Pathogenic dermatophytes are prevalent causes of a superficial cutaneous infection, which have the ability to invade keratinized structures such as skin, hairs and nails. Dermatophytes infection in the host involves three main steps: adherence to the host tissue, invading, and the development of a host response. In the first stage of infection, dermatophytes adhere to the surface of the keratinized tissue to reach the epidermis by using some factors that mediate adherence of dermatophytes. Various virulence factors are secreted from dermatophytes during the invading process in order to penetrate the host tissue, to obtain nutrients and survive. The aim of this study was to select keratin degrading fungi isolated from from clinical samples of patients with dermatophytosis. Application of soluble preparation of keratin (KS) of chicken feathers enables a preliminary evaluation of the growth of the fungi and screening of fungal isolates that possesed keratinolytic activity and keratinase enzyme. Five dermatophytes i.e. T.rubrum, T.mentagrophytes, M.gypseum, M.canis and C.tropicum were used in our study for keratinase activity. Out of five dermatophytes species studied, all tested fungal species showed a keratinase activity except one species i.e. M.canis. From our findings, these results provide a scientific validation that dermatophytes have keratinase enzyme activity and responsible for virulence factor in pathogenicity of dermatophytes.

Diagnosis of cutaneous primary nocardiosis in patients with normal immune function by metagenomic next-generation sequencing.

Nocardia primarily affects immunocompromised individuals, and Infection with Nocardia is uncommon and primary cutaneous nocardiosis caused by percutaneous inoculation is even rarer. Primary cutaneous nocardiosis remains a diagnostic challenge and should be considered in the differential diagnosis for any superficial cutaneous infection that arises in patients with normal immune function. We report a case that was diagnosed with primary cutaneous Nocardia by metagenomic next-generation sequencing technology.

Nannizzia species causing dermatophytosis in cats and dogs: First report of Nannizzia incurvata as an etiological agent in Brazil.

Dermatophytosis is a superficial cutaneous infection, most commonly caused by fungal species such as Microsporum canis, Nannizzia gypsea (Microsporum gypseum), and Trichophyton mentagrophytes in dogs and cats. The zoonotic potential of these species is concerning, as companion animals are increasingly close to their owners. Therefore, the objectives of the study were to evaluate the current prevalence of Nannizzia-causing canine and feline dermatophytosis in Curitiba and Metropolitan Region, as well as perform phenotypic and phylogenetic characterizations of these isolates. Thus, 241 skin and fur samples from 163 dogs and 78 cats were analyzed from 2020 to 2021. The samples were obtained from animals of three sources: Veterinary Hospital of the Federal University of Paraná, animal shelters, and private clinics. The diagnosis was performed through phenotypic characterization and sequencing ITS rDNA region. Among 97 positive samples for dermatophytes, Nannizzia was identified in 14 (14.4%) samples, while other dermatophyte genera were found in the remaining 83 (85.6%) samples. Among the canine samples, nine (90%) were N. gypsea, and one (10%) was N. incurvata. Whereas in feline samples, three (75%) were N. gypsea, and one (25%) was N. incurvata. It was concluded that among 97 animals infected with dermatophytes, dogs (24.4%; 10/41) were significantly more affected by Nannizzia than cats (7.1%; 4/56) (P<.05). According to molecular analyses, the ITS rDNA region provided satisfactory results for species-level identification of Nannizzia, confirming the first report of N. incurvata as an etiological agent of canine and feline dermatophytosis in Brazil.

Erythrasma: A Superficial Cutaneous Bacterial Infection Overlooked in Clinical Practice

Erythrasma is a common superficial cutaneous bacterial infection caused by Corynebacterium minutissimum, a normal inhabitant of the skin surface. Under favourable conditions, the organism invades the stratum corneum, where it multiplies and produces clinically evident lesions. Increasing age, excessive sweating, diabetes mellitus, obesity, overcrowding and immunosuppression, including HIV, are risk factors for the disease. The condition can be confused with other infectious and non-infectious skin diseases, chiefly dermatophytosis. Erythrasma clinically presents in the groin, axilla, submammary, inguinal, intergluteal cleft and web spaces between the toes. Coinfection with fungi and superinfection upon primary dermatosis are common. Erythrasma can be diagnosed with a characteristic coral-pink fluorescence with Wood‘s lamp examination. Smears, biopsy and cultures are seldom required but are useful when the Wood‘s lamp test is negative. Atypical presentations do occur and require astute clinical judgment. This condition should be distinguished from other dermatosis as treatment is different. Treatment is with topical or oral antimicrobials, depending on the site and extent of the lesions. Recurrence can occur, and methods to prevent it should be in place. Novel treatments need robust testing prior to inclusion in the therapeutic armamentarium.

Clinico mycological profile of Dermatophytosis in patients attending tertiary care hospital in Northern India

Background: Dermatophytoses refers to superficial fungal infection of keratinized tissue caused by keratinophilic dermatophytes. It is most common superficial cutaneous infection of stratum corneum affecting hair, nail, and skin. Aims and Objective: The aim of this study was to study the clinico-mycological profile of dermatophytic infection that are prevalent in this region. Materials and Methods: Samples were collected from 104 patients which included skin, nail, and hair samples after the detail history and examination of patients. The samples were subjected to direct microscopy and culture. Further identification was done by microscopic and macroscopic characteristics of fungal pathogens. Results: A total of 104 cases were positive for dermatophytic infection. Among the dermatophytic infections, Tinea corporis (63.4%) was most common clinical type followed by Tinea cruris (18.3%). Males (66.3%) were affected more than females (33.6%) and the age group most affected was 31-45 yrs (46.2%) followed by 16-30 yrs (32.7%) in the current study. Of all the dermatophyte isolates T.rubrum was the most common (77.4%) cause of infection, followed by T. mentagrophytes (12.7%). Conclusion: The present study reveals the varying trend in the incidence of dermatophyte species which is important to implement treatment regimens and to recommend control measures.

Prevalence and Risk Factors of Zoonotic Dermatophyte Infection in Pet Rabbits in Northern Taiwan.

Dermatophytes are the group of keratinophilic fungi that cause superficial cutaneous infection, which traditionally belong to the genera Trichophyton, Microsporum, and Epidermophyton. Dermatophyte infection is not only a threat to the health of small animals, but also an important zoonotic and public health issue because of the potential transmission from animals to humans. Rabbit dermatophytosis is often clinically identified; however, limited information was found in Asia. The aims of this study are to investigate the prevalence and to evaluate the risk factors of dermatophytosis in pet rabbits in Northern Taiwan. Between March 2016 and October 2018, dander samples of pet rabbits were collected for fungal infection examination by Wood’s lamp, microscopic examination (KOH preparation), fungal culture, and PCR assay (molecular identification). Z test and Fisher’s exact test were performed to evaluate the potential risk factors, and logistic regression analysis was then performed to build the model of risk factors related to dermatophyte infection. Of the collected 250 dander samples of pet rabbits, 29 (11.6%) samples were positive for dermatophytes by molecular identification. In those samples, 28 samples were identified as the T. mentagrophytes complex and 1 sample was identified as M. canis. Based on the results of the Firth’s bias reduction logistic analyses, animal source (rabbits purchased from pet shops) and number of rearing rabbits (three rabbits or more) were shown as the main risks for dermatophyte infection in the pet rabbits in Taiwan. The results of the present study elucidate the prevalence of rabbit dermatophyte infection, pathogens, and risk factors in Taiwan, and provide an important reference for the prevention and control of rabbit dermatophytosis.

The Role of Dermoscopy in Diagnosis of Superficial ungal Cutaneous Infections

The Role of Dermoscopy in Diagnosis of Superficial ungal Cutaneous Infections

Factors influencing epidemiology of dermatomycoses at Gdansk, Poland and Grodno, Belarus.

IntroductionAn increase in numbers of cutaneous fungal infections is being observed around the world. Dermatomycoses occur in every age group and can significantly decrease quality of life. Examining the prevalence and epidemiological trends of cutaneous fungal infections is necessary for developing new effective preventive, diagnostic and therapeutic methods. Many factors can influence the growth and patterns of global spread of the different species of fungi.AimTo investigate the differences between the prevalence of dermatophytes and cutaneous fungal infections observed at two mycological laboratories and their plausible causes.Material and methodsMycological examination was performed in 7324 patients in Gdansk, Poland and in 4729 patients in Grodno, Belarus who exhibited clinical signs and symptoms of cutaneous fungal infections. Direct preparations was made in 20% KOH with 40% DMSO. Additionally cultures were prepared on modified Sabouraud dextrose agar.ResultsDermatophytes were cultured in 642 (53.58%) cases in Gdansk. The most common species of dermatophytes were Trichophyton rubrum (306 cases), Trichophyton mentagrophytes var. granulosum (193 cases) and Microsporum canis (127 cases). Yeasts were isolated in 531 (44.40%) cases out of which Candida albicans was the most frequently identified in 323 cases. Similarly, dermatophytes were the most common in 1158 (68.72%) cases in Grodno. Candida were isolated in 527 (31.28%) cases. Analysing the localization of dermatomycoses onychomycosis was observed in majority of the infected patients in Gdansk. In Grodno the most common location of superficial cutaneous infection was tinea corporis In the Gdansk region dermatomycoses were observed in 688 female patients and in 508 male patients. In Grodno the prevalence is inverted with the majority of cases observed in 921 males and 764 females.ConclusionsThe prevalence of superficial fungal infections is higher in Grodno, Belarus when compared to Gdansk, Poland. Similarly, dermatophytes were most commonly observed in both Laboratories.

Erysipelas lymphedema: Two case reports and literature review

Erysipelas, a variant of cellulitis, is a superficial dermal bacterial infection. This superficial cutaneous infection may cause lymphangitis with resultant lymphedema in poorly treated cases. Reports of erysipelas preceding lymphedema are rare, rather many have reported the occurrence of erysipelas in patients with subclinical or overt lymphedema. Two case reports of erysipelas preceding lymphedema after appropriate parenteral antibiotics therapy and limb elevation are here presented. Following diagnosis, admission, and commencement of therapy, the second patient (Case 2) discontinued hospital treatment halfway for native treatment and returned after about 3 weeks. All patients recovered successfully but later presented with lymphedema after 8 weeks and 6 weeks, respectively. Both patients made a sustained functional recovery of their limbs with conservative management including elastic compression stocking and limb elevation. Erysipelas infection preceding lymphedema may develop when it occurs, prompt and appropriate treatment modalities for erysipelas infection may forestall the development of lymphedema.

Survey of the Germ Antibiorésistance Implied In Infections of the Surgical Site Infection (SSI) To the General Hospital Of National Reference (HGNR) Of N’Djamena (CHAD)

Surgical Site Infections (SSI) are caused in most cases by the resistant or multi-resistant bacteria. Gravities go from a simple superficial cutaneous infection to the potentially deadly infections as the stern septicemia. The objective of this survey is to study the antibiorésistance of germs implied in infections of the operative site to the General Hospital of National Reference (HGRN) of Ndjamena to Chad . The survey had taken place of July to November 2018. A total of 51 cases of infections of the Surgical Sites has been recorded then appropriated and sowed on the Chapman, Mac Conkey, gélose to the Cétrimide, Sabouraud and chocolate gelose in view of an isolation of germs implied. The classic gallery, the API20ES gallery permitted the identification of the different stumps. The classic antibiogramm on a middle gelose of Muller Hinton permitted the survey of the antibiorésistance. The Vitek2 permitted the confirmation of identification, the survey of the antibiorésistance and the detection of stumps of betalactamases enterobacteries producers. The implied germs were: E. coli (29,4%), follow-up of Klebsiella spp (22,5%), Staphylococcus aureus (16,6%), Pseudomonas aeroginosa (11,7%), Proteus mirabilis (8,8%), Enterobacter cloacae (5,8%), Serratia odorifera, Shigella sonnei, Corynebacterium spp (0,98%) each, Candida albicans (1,9%). The identified germs multiresistantes were E. coli, Klebsiella spp, Enterobacter cloacae, Serratia odorifera and Shigella spp. A level of resistance (4%) to the imipenème at entérobactérieses has been recorded. One also notes a resistant of stumps of Staphylococcus aureus 100% to the penicillin and the oxacilline, as well as a resistance to the vancomycine (3%). &#x0D; The identification of stumps isolated showed that the stump E. coli (29,4%) is the germ the more implied. Also, the survey of the antibiorésistance permitted to note a strong resistance of bacteria isolated opposite the tested antibiotics. &#x0D; &#x0D; Surgical site infections (SSI) are caused in most cases by resistant or multi-resistant bacteria. Gravities range from simple superficial skin infections to potentially fatal infections such as severe sepsis. The objective of this study is to study the antibiotic resistance of germs involved in surgical site infections at the Hôpital Général de Référence Nationale (HGRN) in Ndjamena, Chad.&#x0D; &#x0D; The study took place from July to November 2018. A total of 51 surgical site infections were recorded, then sampled and inoculated on Chapman, Mac Conkey, Cetrimid agar, Sabouraud and chocolate agar media to isolate the germs involved. The classical gallery, the API20E gallery allowed the identification of the different strains. The classical antibiogram on a Muller Hinton agar medium allowed the study of antibiotic resistance.&#x0D; &#x0D; Vitek2 enabled confirmation of the identification, study of antibiotic resistance and detection of strains of enterobacteria producing beta-lactamases. The frequency of surgical site infections obtained was 33.6% (51/152). The germs involved were: E. coli (29.4%), followed by Klebsiella spp (22.5%), Staphylococcus aureus (16.6%), Pseudomonas aeroginosa (11.7%), Proteus mirabilis (8.8%), Enterobacter cloacae (5.8%), Serratia odorifera, Shigella sonnei, Corynebacterium spp (0.98%) each, Candida albicans (1.9%). The multi-resistant germs identified were: E. coli, Klebsiella spp, Enterobacter cloacae, Serratia odorifera and Shigella spp. A level of resistance (4%) to imipenem in Enterobacteriaceae was recorded. Resistance of Staphylococcus aureus strains to penicillin and oxacillin (100%) and resistance to vancomycin (3%) were also noted&#x0D; The identification of the strains isolated showed that the E. coli strain (29.4%) is the most involved germ. Also, the study of antibiotic resistance showed that the bacteria isolated were highly resistant to the antibiotics tested.

Ultraviolet imaging in dermatology.

Visual examination plays a central role in the diagnosis of skin diseases. Many dermatologists use magnification, or dermoscopy, to improve diagnostic certainty when assessing the skin under visible light. In addition to magnification, other technological advances have been made over the last century to improve our visual assessment of the skin. Examination of skin under ultraviolet (UV) radiation, with Wood's light, gained traction for its utility in assessing superficial cutaneous infections and pigmentary changes. During Wood's light examination, UV light is directed at the skin and fluorescence is detected by our eyes. The variable fluorescent characteristics of endogenous and exogenous cutaneous chromophores help us better diagnose skin disease. UV fluorescent photography is based on the same concept as the Wood's light, but also allows image analysis and documentation of the captured image. In addition to UV-induced fluorescence, the differential reflection and absorption of UV light captured in the UV spectral range can also provide a new contrast for diagnosing skin diseases during UV reflectance photography. This review discusses the most widely used UV imaging techniques and provides an overview of the role of UV imaging in dermatology.

Clinico-epidemiologic profile of dermatophytosis in koh positive patients in a tertiary care hospital in Gurugram, Haryana

BackgroundDermato phytosis is a superficial cutaneous fungal infection of the dead keratinized tissues of skin, hair and nails. These dermatophytic fungi are amongst the most common fungal infections worldwide. In the past few years, the chronicity, severity, clinical presentation, relapse rates and resistance to treatment patterns have drastically changed in India. Keeping forth its evolution as a disease of great public health importance, a study was undertaken to know the epidemiological and clinical patterns of the disease. Aim: To analyze the clinical and epidemiological scenario of dermatophytosis in patients enrolled at a tertiary care centre of Gurugram, Haryana from December 2018 to December 2019.MethodA total of 220 clinically diagnosed patients with dermatophytosis were subjected to potassium hydroxide (KOH) microscopy. Out of them, 170 positive cases were analyzed for their epidemiological and clinical profile.ResultsMale population (ratio 1.8:1) and the age group of 21 to 30 years were found to be the most affected. Mixed infection (tinea corporis et cruris) with 86 cases (50.59%) was the commonest clinical form of dermatophytosis documented followed by tinea cruris with 21 cases (12.35%). Tinea corporis (p-&lt;0.001) and tinea cruris (p-&lt;0.001) were found to be significantly higher in adults as compared to children. Majority belonged to rural background (60.6%). A significant number (45%) had moderate to extensive disease depending upon body surface area of involvement and almost half of them (45.9%) had the disease for 1-6 months duration.Dermatophytosis has been found to be more common in 3^rd and 4^th decade with a male to female ratio of 1.8:1. More number of cases with chronic and extensive disease have been found in our study.

Cervical necrotizing fasciitis of odontogenic origin: tissue regeneration with L-PRF

Background: The most part of oral infections has an odontogenic origin, and can be treated by dental extraction, endodontic therapy or surgical treatment. The skin, subcutaneous tissue, fascia or muscle can also be compromised in infectious diseases of odontogenic origin, ranging from superficial cutaneous infections to very severe necrotizing fasciitis, which affects especially the subcutaneous tissues and the fascia, being quickly progressive and potentially fatal (1).

Innate immune response of human epidermal keratinocytes and dermal fibroblasts to invitro incubation of Trichophyton benhamiae DSM 6916.

Superficial cutaneous infection caused by the zoophilic dermatophyte Trichophyton benhamiae is often associated with a highly inflammatory immune response. As non-professional immune cells, epidermal keratinocytes and dermal fibroblasts contribute to the first line of defence by producing pro-inflammatory cytokines and antimicrobial peptides (AMP). Purpose of this study was to gain a deeper understanding of the pathogenesis and the fungal-host interaction as not much is known about the innate immune response of these cutaneous cells against T.benhamiae. Using a dermatophytosis model of fibroblasts and keratinocytes incubated with T.benhamiae DSM 6916, analyses included determination of cell viability and cytotoxicity, effects on the innate immune response including expression and secretion of pro-inflammatory cytokines/chemokines and expression of AMP, as well as alterations of genes involved in cell adhesion. Trichophyton benhamiae DSM 6916 infection led to severe cell damage and direct induction of a broad spectrum of pro-inflammatory cytokines and chemokines in both cutaneous cells. Only keratinocytes differentially up-regulated AMP genes expression after T.benhamiae DSM 6916 infection. Expression of AMPs in fibroblasts was not inducible by fungal infection, whereas their absences potentially contributed to a continuous increase in the fungal biomass on fibroblasts, which in turn was reduced in keratinocytes possibly due to the antimicrobial actions of induced AMPs. On mRNA level, T.benhamiae DSM 6916 infection altered cell-cell contact proteins in keratinocytes, indicating that targeting specific cell-cell adhesion proteins might be part of dermatophytes' virulence strategy. This study showed that in addition to immune cells, keratinocytes and fibroblasts could participate in antimicrobial defence against an exemplary infection with T.benhamiae DSM6916.

Common Child and Adolescent Cutaneous Infestations and Fungal Infections

Cutaneous infections and infestations are common among children and adolescents. Ectoparasitic infestations affect individuals across the globe. Head lice, body lice, scabies, and infestations with bed bugs are seen in individuals who reside in both resource poor areas and in developed countries. Superficial cutaneous and mucosal candida infections occur throughout the life cycle. Dermatophyte infections of keratin-containing skin and skin structures result in tinea capitis (scalp), tinea corporis (body), tinea pedis (foot), and tinea unguium (nails). Less frequent endemic fungal infections such as blastomycosis, coccidiodomycosis, and histoplasmosis may present with skin findings. This article will describe the epidemiology and transmission of these conditions as well as their clinical manifestations. The approach to diagnosis will be addressed as well as primary prevention and current therapies.

Enzymatic and Non-Enzymatic Virulence Activities of Dermatophytes on Solid Media.

Dermatophytes are keratinophilic fungi causing superficial cutaneous infections that account 20-25% of the global population. As per literature search, there is a dearth in the study on virulence factors of dermatophytes from the Indian sub-continent and moreover the association of the virulence factors and the host tissue in vitro helps in understanding the host-pathogen interaction. To analyse the enzymatic and non-enzymatic virulence activities of dermatophytes on solid media. A total of 11 isolates, three standard American Type Culture Collection (ATCC) strains- Trichophyton rubrum- 28188, Trichophyton mentagrophytes- 9533, Trichophyton tonsurans- 28942, one CBS KNAW Fungal Biodiversity Centre strain- Arthroderma grubyi- 243.66, five clinical isolates- T. rubrum, T. mentagrophytes, Trichophyton rubrum var. raubitschekii, Trichophyton interdigitale, Epidermophyton floccosum, and two laboratory isolates - Microsporum gypseum and Microsporum canis were screened for the production of virulence enzymes such as phospholipase, lipase, protease, gelatinase and non-enzyme virulence factors (haemolytic activity) of dermatophytes. The clinical isolates were identified from a tertiary care hospital, Chennai. These dermatophytes were tested upon specific substrates on solid media such as egg yolk, tween 80, bovine serum albumin, gelatin powder and sheep blood respectively. The virulence activity of phospholipase, lipase, protease and gelatinase was observed from all the dermatophyte species. T. rubrum, T. rubrum ATCC strain, T. rubrum var. raubitschekii, T. mentagrophytes, T. mentagrophytes ATCC strain, T. interdigitale and A. grubyi CBS strain produced complete haemolysis, whereas other dermatophytes showed no haemolytic activity. Phospholipase, lipase, protease and gelatinase act as enzymatic virulence marker and the T. rubrum complex, T. mentagrophytes complex and A. grubyi showed complete haemolysis and hence they may also act as a non-enzymatic virulence marker for dermatophytes.

Infekcje grzybicze skóry i tkanki podskórnej u chorych po transplantacji narządów

Infekcje grzybicze skóry i tkanki podskórnej u chorych po transplantacji narządów

Efficacy and safety of 1% clotrimazole powder as an adjuvant therapy in patients with superficial fungal cutaneous infection in intertriginous areas

Efficacy and safety of 1% clotrimazole powder as an adjuvant therapy in patients with superficial fungal cutaneous infection in intertriginous areas

Estudio fase iii de la seguridad y la eficacia de ciclopirox olamina crema en niños afectados de dermatomicosis

BackgroundThere is scarce information on the use of ciclopirox olamine in children. AimsThe aim of this study was to evaluate the efficacy and safety of ciclopirox olamine cream 1% for the treatment of dermatomycosis in pediatric patients. MethodsA multicenter, non-randomized, open-label, phase iii study was conducted on patients aged 3 months to 9 years diagnosed with dermatomycosis confirmed by direct microscopy and culture, and treated with ciclopirox olamine cream 1% for 28 days. Clinical and microbiological evaluations were performed before starting the treatment therapy, at 7, 14 and 28 days after starting the treatment, and 28 days after its completion. ResultsTwenty-one patients with a median age of 2.7 years (range 3 months-9 years) were included. The most frequent mycosis location was the inguinal region (72%). The most frequently isolated etiological agent was Candida spp. (71%). No adverse events were reported in 62% of the patients. Among the mild and moderate reported adverse events, only one, irritative dermatitis, was considered as possibly related to the treatment. Safety evaluation was excellent in 95% of the patients, and good in 5%. After the first week of treatment, 12 patients out of 13 (92%) showed a clinical improvement, and 5 out of 7 (71%) had both clinical and mycological improvements. At the end of the treatment, clinical cure was observed in 7 out of 9 patients (78%). No relapses occurred. ConclusionsCiclopirox olamine cream 1% is a safe and feasible treatment for superficial cutaneous mycotic infections, especially Candida spp. infection, in children aged between 3 months and 10 years.

Staphylococcus aureus α-Toxin-Dependent Induction of Host Cell Death by Membrane-Derived Vesicles

Staphylococcus aureus causes a wide spectrum of infections in humans, ranging from superficial cutaneous infections, infections in the circum-oral region, to life-threatening bacteremia. It was recently demonstrated that Gram-positive organisms such as S. aureus liberate membrane-derived vesicles (MVs), which analogously to outer membrane vesicles (OMVs) of Gram-negative bacteria can play a role in delivering virulence factors to host cells. In the present study we have shown that cholesterol-dependent fusion of S. aureus MVs with the plasma membrane represents a route for delivery of a key virulence factor, α-toxin (α-hemolysin; Hla) to human cells. Most S. aureus strains produce this 33-kDa pore-forming protein, which can lyse a wide range of human cells, and induce apoptosis in T-lymphocytes. Our results revealed a tight association of biologically active α-toxin with membrane-derived vesicles isolated from S. aureus strain 8325-4. Concomitantly, α-toxin contributed to HeLa cell cytotoxicity of MVs, and was the main vesicle-associated protein responsible for erythrocyte lysis. In contrast, MVs obtained from an isogenic hla mutant were significantly attenuated with regards to both causing lysis of erythrocytes and death of HeLa cells. This is to our knowledge the first recognition of an S. aureus MV-associated factor contributing to host cell cytotoxicity.