[Dermatophytosis caused by rare anthropophilic and zoophilic agents]. / Dermatophytosen, verursacht durch seltene anthropophile und zoophile Erreger.

The basis for effective treatment of any dermatomycosis is the correct and timely identification of the pathogen, which allows the targeted choice of the most suitable antimycotic and is important for the prevention of repeated infections. In recent years, infections with dermatophytes seem to have increased. In fact, from 2007 to 2018, there was an increase in the number of samples processed in the Mycology Laboratory of the Department of Dermatology at the University Hospital Jena. The most common isolated dermatophytes between 2007 and 2018 were Trichophyton (T.) rubrum, T. interdigitale, Microsporum (M.) canis and T. benhamiae. However, dermatophytoses may also be caused by rare anthropophilic agents such as Epidermophyton floccosum, zoophiles such as T. verrucosum, T. quinckeanum or Nannizzia (N.) persicolor as well as by geophiles such as N. gypsea. Therefore, these dermatophytes should at least be known, so that in case of unusual observations investigations can be performed accordingly. Changes in the pathogen spectrum of dermatophytoses have taken place over time and it is expected that the occurrence of dermatophytes will be subject of continuous fluctuations, which may mean that the incidence of some of these "rare" dermatophytes, as described here in five clinical examples, may be changing.

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

BACKGROUND: 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). OBJECTIVE: 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. METHODS: 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. RESULTS: 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. CONCLUSION: This study showed that in addition to immune cells, keratinocytes and fibroblasts could participate in antimicrobial defence against an exemplary infection with T. benhamiae DSM 6916.

Mating analyses of Trichophyton benhamiae offspring reveals linkage of genetic markers used in taxonomy.

Mating experiments were conducted with four clinical Trichophyton benhamiae isolates, genetically similar to the Trichophyton benhamiae CBS 112371, featuring the plus mating type and with two minus type strains. One minus type strain belonged to the white subgroup, and the other minus type strain, DSM 6916, showed genetic kinship to the yellow subgroup. Only two plus type strains were able to form mature, pigmented gymnothecia with DSM 6916. These two plus type strains demonstrated dark pigmentation and powdery mycelium on Takashio agar, whereas the other three strains exhibited a low degree of pigmentation on the same medium. All five plus strains were able to mate with the minus type strain of their own white subgroup. Cultures from single ascospore isolates showed highly variable morphology and pigmentation. Three genetic markers (ITS, mating type, EF1 alpha) were analyzed in polymerase chain reaction (PCR) experiments with optimized primers and PCR conditions to discriminate between subgroups. Furthermore, RAPD-PCR was used to generate a DSM 6916-specific DNA-fragment which served as an additional genetic marker. Assessing the isolates with recombinant genotypes, it was found that three genetic markers behave like linked genes. The recombination of plus mating type went together with ITS, EF1 alpha and RAPD marker of the DSM 6916 parental strain and was most frequently isolated, whereas plus types recombinants in this case were completely missing. This shows a high imbalance in mating type distribution of recombinants.

Multiphotonic staging of chronic wounds and evaluation of sterile, optical transparent bacterial nanocellulose covering: A diagnostic window into human skin.

BACKGROUND: Diagnostics of healing, infection, and inflammation in chronic wounds in comparison with physiological wound healing in acute wounds may help for therapy decisions toward individualized therapy management. With emerging new optical techniques the coupling of optical diagnostic devices with tissue provides a great challenge. Traditional coupling with cover slips is used since the early days of microscopy. In modern health care, hygienic covering of surfaces is necessary to avoid infections and cross-contaminations. METHODS: Measurements in chronic wounds were performed at three different areas including the center of the wound, the border of the wound and healthy skin as comparison area. For each measurement area, three vertical stacks were taken by MPT. Additionally, three different optical measuring procedures (MPT, OCT, CLSM) were used for the examination of BNC foil. Examinations of BNC foil were carried out at two different areas of healthy skin compared to a standard setup as control. RESULTS: The MPT evaluation revealed a distinct difference in the second harmonic generation-to-autofluorescence aging index of dermis (SAAID) behavior between the vertical stacks taken at central wound areas and wound margins as well as unaffected skin. Through BNC foil covers, MPT CLSM and OCT images were captured with good quantitative and qualitative results. CONCLUSIONS: Phases in chronic wounds could be matched with physiologically healing in acute wounds according to SAAID and MPT imaging. BNC provided an alternative covering for MPT, OCT, and CLSM with clear morphological images.

CALCIUM HYDROXYLAPATITE MICROSPHERES - BIOCOMPATIBILITY AND CLINICAL EFFECTS.

Soft tissue fillers are used in aesthetic medicine for volumizing and for contouring. Calcium hydroxylapatite (CaHA) is a fully biodegradable biostimulatory filler. The study presents results of in vitro biocompatibility and cytotoxicity investigations performed on CaHA and illustrates its clinical effects. We used a human cell culture model for in vitro studies with HaCaT keratinocytes and human dermal fibroblasts, known to be a sensitive cell type for biocompatibility and cytotoxicity. Cells were exposed to different concentrations of CaHA (Radiesse®). Cell proliferation was calculated by luminometric adenosine triphosphate (ATP) measurement using the ATPLiteTM-M Assay. Possible cytotoxic effects were detected by the calorimetric Cytotoxicity Detection Kit. Clinical data were obtained from our own treatment files. CaHA did neither inhibit cell proliferation nor cause cytotoxicity. Clinical data suggest an excellent tolerability and long-term efficacy superior to hyaluronic acid-based fillers. CaHA is a versatile and well-tolerated biodegradable and biostimulatory filler.

[Tinea capitis and onychomycosis due to Trichophyton soudanense : Successful treatment with fluconazole-literature review]. / Tinea capitis und Onychomykose durch Trichophyton soudanense : Erfolgreiche Behandlung mit Fluconazol ­ Literaturübersicht.

Two African girls who moved to Germany only 4 weeks ago presented to the dermatological office with itchy and scaling skin lesions of the scalp and the thighs. The entire scalp of both girls was affected by a white, dry dandruff and a squamous crust. Dry centrifugal spreading erythematosquamous lesions were found on the thighs. The surface of the left thumbnail of the younger girl was whitish. The Blancophor® preparations which were performed under the suspicion of a tinea capitis et corporis and onychomycosis from skin scrapings of the scalp and the thighs, and from the thumbnail of the younger child were positive. Cultivation of three samples from the affected body sites-hair, skin and nail-revealed Trichophyton (T.) soudanense. For confirmation of the species identification, the isolates were subject of sequencing of ITS region of the rDNA and also of the translation elongation factor 1 α (TEF 1 α) gene. The phylogenetic analysis of the strains-the dendrogram of fungal strains-demonstrated the genetic differences between T. soudanense and T. rubrum. In contrast, sequencing of the TEF 1 α gene did not allow any discrimination between T. soudanense and T. rubrum. Both girls were treated orally with fluconazole. For topical treatment of both girls, ciclopirox olamine solution and terbinafine cream were administered, each once daily. After 8 weeks oral fluconazole therapy the dermatomycoses of skin, scalp, and thumbnail of both children were completely healed. Currently, in Germany and Europe, in immigrants from West African countries (e. g., from Angola) dermatophytoses due to T. soudanense have to be expected. Cultural identification of the pathogen is relatively simple. However, only molecular methods allow the exact discrimination of T. violaceum and T. rubrum.

Non-invasive evaluation of human mucosal structures by multiphoton laser scanning tomography in vitro.

BACKGROUND: Mucous membranes may be affected by various diseases and the diagnostic accessibility is limited. Multiphoton laser tomography (MPT) is a useful tool for in vivo evaluation of superficial skin structures and might also be useful for the imaging of mucosa. OBJECTIVES: In order to investigate the suitability of MPT for the evaluation of mucous membranes, tissue samples of different donors and anatomical localizations have been imaged. METHODS: Human mucosa samples from the urinary bladder, palatine tonsil and ocular conjunctiva were investigated by MPT and subsequently compared with conventional histology. RESULTS: Horizontal images of the epithelium and the underlying connective tissue were obtained using the autofluorescence and second harmonics generation signals by MPT. The stratification of multilayered epithelium was consistently reproduced. Also inflammatory changes like lymphocytic infiltrates and widened intercellular spaces were imaged in some cases. CONCLUSION: Mucous tissue samples were obtained and MPT imaging was successfully performed. In the direct comparison with histology of the same tissue samples, the characteristic morphology of the epithelia was found. Further studies are necessary in order to compare images of healthy and diseased mucosal epithelium and the use of MPT for its evaluation in vivo.

Disturbed glutathione antioxidative defense is associated with structural brain changes in neuroleptic-naïve first-episode psychosis patients.

BACKGROUND: Oxidative stress and impaired antioxidant defense are reported in schizophrenia and are thought to be associated with disturbed neurodevelopment, brain structural alterations, glutamatergic imbalance, negative symptomatology, and cognitive impairment. To test some of these assumptions we investigated the glutathione (GSH) antioxidant defense system (AODS) and brain structural abnormalities in drug-naïve individuals with first acute episode of psychosis (FEP). METHOD: The study involved 27 drug-naïve FEP patients and 31 healthy controls (HC). GSH AODS markers and TBARS (thiobarbituric acid reactive substances) were measured in blood plasma and erythrocytes. High-resolution T1-weighted 3T MRI were acquired from all subjects. To investigate brain structural abnormalities and effects of illness on interactions between GSH metabolites or enzyme activities and local grey matter density, voxel-based morphometry (VBM) with the computational anatomy toolbox (CAT12) was used. Symptomatology was assessed using the Positive and Negative Syndrome Scale (PANSS) and the Symptom Checklist 1990 revised (SCL-90-R). RESULTS: (i) In FEP patients, glutathione reductase activity (GSR) was lower than in the HC group. GSR activity in plasma was inversely correlated with SCL-90-R scores of depression and PANSS scores of the negative symptom subscale. (ii) A reduction of GM was observed in left inferior frontal, bilateral temporal, as well as parietal cortices of FEP patients. (iii) Interaction analyses revealed an influence of illness on GSR/GM associations in the left orbitofrontal cortex (BA 47). CONCLUSION: Our findings support the notion of altered GSH antioxidative defense in untreated acute psychosis as a potential pathomechanism for localized brain structural abnormalities. This pathology relates to a key brain region of social cognition, affective motivation control and decision making, and is clinically accompanied by depressive and negative symptoms.

Cold atmospheric pressure plasmas exhibit antimicrobial properties against critical bacteria and yeast species.

OBJECTIVE: Cold atmospheric pressure plasmas (CAPPs) have been used to sterilise implant materials and other thermally unstable medical products and to modify chemical surfaces. This study investigates the antimicrobial effect of the gas and input power used to generate CAPPs on microorganisms causing skin infections, such as Staphylococcus aureus, Pseudomonas aeruginosa, Candida albicans and Malassezia pachydermatis. METHOD: Microorganisms were cultivated on Mueller Hinton 2 (MH2) agar plates. CAPP treatment was performed using the Plasma BLASTER MEF. To investigate the antimicrobial effects the following CAPP parameters were varied: the gas used, input power, as well as number of treatments and treatment time. RESULTS: The antimicrobial efficacy of the CAPPs was found to increase with increasing input power and treatment time (or cycles). Furthermore the plasma generated from nitrogen is more effective than from air. CONCLUSION: The study showed that CAPPs demonstrate strong bactericidal and fungicidal properties in vitro. The selective application of CAPPs for the treatment of wound infections may offer a promising supplementary tool alongside current therapies.

[Trichophyton species of Arthroderma benhamiae : Clinical therapeutic aspects of a new pathogen in dermatology]. / Trichophyton Spezies von Arthroderma benhamiae : Klinisch therapeutische Aspekte eines neuen Erregers in der Dermatologie.

Cutaneous infections with Trichophyton species of Arthroderma (A.) benhamiae are increasingly being detected in Germany. This dermatophyte typically causes tinea corporis, tinea faciei or tinea capitis with in part heavy clinical manifestation like kerion celsi. In special cases diagnosis and therapy can be difficult. In this article, four clinical cases are presented, whereby attention is given to special clinical situations and therapeutic aspects with regard to Trichophyton species of A. benhamiae: Case 1: Kerion celsi by in a 6-year-old boy; Case 2: Deep trichophytia at the mons pubis in a 32-year-old man working in a pet shop and his 27-year-old female partner; Case 3: Tinea manuum in a 7-year-old girl; Case 4: Tinea corporis in an 8­year-old girl.

[Trichophyton violaceum : Main cause of tinea capitis in children at Mbarara Regional Referral Hospital in Uganda]. / Trichophyton violaceum : Haupterreger der Tinea capitis bei Kindern im Mbarara Regional Referral Hospital in Uganda.

BACKGROUND: Tinea capitis is caused by anthropophilic, zoophilic or geophilic dermatophytes of the genera Microsporum or Trichophyton. OBJECTIVE: The aim of this study was to analyze the clinical presentation of tinea capitis among children in western Uganda. PATIENTS AND METHODS: From February to June 2012, skin and hair samples were obtained from 115 patients aged from 1 to 16 years presenting at Mbarara Regional Referral Hospital (MUSC) with clinically suspected tinea capitis. Conventional mycological diagnostics comprised Blancophor preparation and cultivation of fungi for species identification. RESULTS: Tinea capitis among the children included in the MUSC study was mainly noninflammatory showing mostly a seborrhoeic pattern or "black dot" and "gray patch" form and highly inflammatory kerion celsi. Blancophor preparation identified 82.6 % positive and 17.4 % negative samples. Cultural species differentiation showed Trichophyton (T.) violaceum as the causative agent for tinea capitis in 56.6 % of the patients. In 13 %, Microsporum (M.) audouinii was isolated followed by T. soudanense (2.6 %), and T. rubrum (1.7 %). In addition, moulds (contamination?) such as Scopulariopsis brevicaulis, Aspergillus niger, and Fusarium oxysporum were found as well as mixed infections. CONCLUSION: The anthropophilic dermatophyte T. violaceum represents the most frequent cause of tinea capitis in western Uganda. For successful management oral antifungal therapy is necessary together with supportive topical treatment.

Epidermal changes during UVB phototherapy assessed by multiphoton laser tomography.

BACKGROUND: Multiphoton laser tomography (MPT) is a non-invasive technique that allows imaging of skin in vivo with very high spatial resolution and contrast. Previous work of our group has demonstrated that known morphological changes due to erythematogenic ultraviolet B (UVB) irradiation may be imaged in vivo by MPT. The present work investigated if morphological skin changes known from experimental erythematogenic UVB irradiation are also demonstrable in the course of a standard phototherapy regime that implies suberythematogenic doses of narrow band UVB. METHODS: Sixteen patients with psoriasis vulgaris receiving a narrow band phototherapy were included. A test field and a light-protected control field were measured with the multiphoton tomograph DermaInspect® at four time points: at baseline, the next day, after 3 days and at the day of the last exposure. RESULTS: In the course of the UVB phototherapy, spongiosis and pleomorphy as parameters of inflammation and cellular damage did not show significant changes. By contrast, an adaptive skin reaction with significant changes of keratosis and pigmentation was observed. CONCLUSION: MPT is a suitable technique for the investigation of qualitative and quantitative skin changes after UVB irradiation. After suberythematogenic UVB irradiation, photoadaptive skin changes, but no cellular damage can be observed with MPT.

Acute UVB-induced epidermal changes assessed by multiphoton laser tomography.

BACKGROUND: In vivo multiphoton tomography (MPT) of human skin has become a valuable tool for non-invasive examination of morphological and biophysical skin properties and their alterations. So far, skin changes after UVB irradiation were mainly evaluated clinically and histologically. The present study aimed at non-invasive imaging of histological changes during acute UVB irradiation by multiphoton laser tomography. METHODS: In 10 volunteers, five areas were irradiated once with an erythematous UVB dose. Multiphoton measurements were performed four times, i.e. before irradiation (baseline), and 24, 48 and 72 h after irradiation, respectively. The data were evaluated for changes of epidermal pleomorphy, spongiosis, pigmentation and thickness. RESULTS: The four parameters were altered significantly by acute UVB irradiation, i.e. epidermal pleomorphy, spongiosis, pigmentation and thickness increased within 72 h after irradiation. CONCLUSION: Thus, the study has shown that typical epidermal changes induced by acute UVB irradiation can be evaluated by MPT.

Omega-3 fatty acid supplementation changes intracellular phospholipase A2 activity and membrane fatty acid profiles in individuals at ultra-high risk for psychosis.

The identification of an ultra-high risk (UHR) profile for psychosis and a greater understanding of its prodrome have led to increasing interest in early intervention to delay or prevent the onset of psychotic illness. In a randomized placebo-controlled trial, we have identified long-chain ω-3 (ω-3) polyunsaturated fatty acid (PUFA) supplementation as potentially useful, as it reduced the rate of transition to psychosis by 22.6% 1 year after baseline in a cohort of 81 young people at UHR of transition to psychosis. However, the mechanisms whereby the ω-3 PUFAs might be neuroprotective are incompletely understood. Here, we report on the effects of ω-3 PUFA supplementation on intracellular phospholipase A2 (inPLA(2)) activity, the main enzymes regulating phospholipid metabolism, as well as on peripheral membrane lipid profiles in the individuals who participated in this randomized placebo-controlled trial. Patients were studied cross-sectionally (n=80) and longitudinally (n=65) before and after a 12-week intervention with 1.2 g per day ω-3 PUFAs or placebo, followed by a 40-week observation period to establish the rates of transition to psychosis. We investigated inPLA(2) and erythrocyte membrane FAs in the treatment groups (ω-3 PUFAs vs placebo) and the outcome groups (psychotic vs non-psychotic). The levels of membrane ω-3 and ω-6 PUFAs and inPLA(2) were significantly related. Some of the significant associations (that is, long-chain ω-6 PUFAs, arachidonic acid) with inPLA(2) activity were in opposite directions in individuals who did (a positive correlation) and who did not (a negative correlation) transition to psychosis. Supplementation with ω-3 PUFA resulted in a significant decrease in inPLA(2) activity. We conclude that ω-3 PUFA supplementation may act by normalizing inPLA(2) activity and δ-6-desaturase-mediated metabolism of ω-3 and ω-6 PUFAs, suggesting their role in neuroprogression of psychosis.

Antimicrobial impact of cold atmospheric pressure plasma on medical critical yeasts and bacteria cultures.

OBJECTIVES: Plasma medicine focuses on the application of cold atmospheric pressure plasmas (CAPs) in or on the human body. So far, plasmas have been used to sterilize implant materials or other thermally unstable medical products and have been applied for chemical surface modifications. This study investigates the antimicrobial effect of physical plasmas on microorganisms which cause skin infections, such as Staphylococcus aureus, Pseudomonas aeruginosa and Candida albicans, depending on the plasma source and the kind of plasma excitation used. MATERIALS: Microorganisms were plated onto MH2 agar plates. Plasma treatment was performed using the plasma sources BLASTER MEF and kinpen 09. To investigate the antimicrobial effects, the following plasma parameters have been varied: working gas, distance from nozzle to surface, electrical power, grid spacing of treatment lines, number of treatments and work piece velocity. RESULTS: The generated plasmas had an antimicrobial effect that depended on the chosen plasma parameters, in particular on the process gas used, the plasma power and the number of treatments performed. Thus, different reactive species were observed by optical emission spectroscopy measurement in the generated plasmas. CONCLUSIONS: The study showed that CAPs exhibit profound bactericidal and fungicidal properties in vitro. However, an important factor for the antimicrobial efficacy is the composition of the 'chemical soup' supplied by the CAP system which can be regulated by the process gases used.

In vitro studies on the beneficial effect of a hydrokinetic fiber dressing on wound healing by reduction of protease activity.

OBJECTIVE: To test the binding capacity of a hydrokinetic fiber dressing for PMN elastase, MMP-2 and MMP-9 in vitro, and to determine whether testing of dressing material samples in vitro is sufficient to predict the performance of the whole dressing. METHOD: In vitro protease binding assays for PMN elastase, MMP-2 and MMP-9 were used to evaluate the protease modulating capacity of sorbion sachet EXTRA, a superabsorbant dressing that consists of special hydrokinetic fibers, which are formed from cellulose and sodium polyacrylate in a mechanical process without any bonding agents or adhesives. The ability of the hydrokinetic fiber dressing to inhibit elastase and collagenase activity was also tested at 0%, 50% and 100% saturation volume. RESULTS: The hydrokinetic fiber wound dressing was able to bind considerable amounts of elastase, reducing elastase activity by approximately 84%. Moreover, it significantly decreased MMP-2 and MMP-9 concentrations in vitro and was able to completely inhibit collagenase activity. CONCLUSION: In summary, the hydrokinetic fiber dressing sorbion sachet EXTRA was able to significantly reduce the concentration and activity of proteolytic enzymes in vitro. These results suggest that sorbion sachet EXTRA should have a beneficial action by reducing the detrimental effects of proteolytic enzymes in vivo. DECLARATION OF INTEREST: This work was supported by Sorbion GmbH & Co. KG, Senden, Germany.

SAP-containing dressings exhibit sustained antimicrobial effects over 7 days in vitro.

OBJECTIVE: To investigate the antimicrobial activity of SAP-containing wound dressings in vitro over a prolonged period of time (7 days) and to assess their ability to sustain the antimicrobial effect. METHOD: SAP dressings were tested according to the JIS L 1902:2002 against the pathogens Staphylococcus aureus, Pseudomonas aeruginosa, Klebsiella pneumoniae, Escherichia coli and Candida albicans.Additionally, effect on S. aureus and P. aeruginosa growth was investigated after a prolonged incubation period of 7 days. Furthermore, both SAP dressings were repeatedly inoculated with P. aeruginosa suspension and, after 7 days, microbial growth under the dressings was evaluated. RESULTS: Both SAP-containing wound dressings tested exhibited a significant to strong antimicrobial activity against Staphylococcus aureus, MRSA, Pseudomonas aeruginosa, Klebsiella pneumoniae, Escherichia coli, and Candida albicans in vitro. Moreover, it could be shown that they were able to sustain antibacterial efficacy over a prolonged period of time. Using a direct incubation method with repeated re-inoculation of the dressing samples, it could be shown that growth of P. aeruginosa was reduced after 4 days of treatment and completely inhibited after 7 days. No significant differences were observed between the two SAP-dressings tested. CONCLUSION: These in vitro experiments impressively demonstrated the antimicrobial mechanism of SAP-containing wound dressings: rapid up-take of fluid, binding of microorganisms to the SAP-core, and retention of the bacteria inside the dressing. Moreover, it could be shown that they are able to exhibit their antimicrobial activity over a prolonged period of time unless the amount of fluid present exceeds their fluid-handling capacity.

Analysis of the adaptation capacity of Staphylococcus aureus to commonly used antiseptics by microplate laser nephelometry.

BACKGROUND: Bacterial colonization and infection are important factors in compromised wound healing. Antiseptics have become an alternative for antimicrobial applications as antibiotic resistance is increasing; they have multiple targets with a broad spectrum of activity. Hence, the risk for developing resistance should be low. However, concerns have been raised that their growing use may result in bacteria that are less susceptible. METHODS: The capacity of common antiseptics such as silver nitrate, polihexanide, octenidine, chlorhexidine and polyvinylpyrrolidone (PVP)-iodine to induce adaptation in a Staphylococcus aureus strain was analyzed in vitro using microplate laser nephelometry. S. aureus was repeatedly incubated with the respective half maximal inhibitory concentration (IC(50)) over a time period of 100 days. The influence of the continued treatment was determined by in situ monitoring of changes in the dose-response curves and calculation of the current IC(50) values for the substances tested. RESULTS: During the experiment, S. aureus quickly adapted to high concentrations of the antibiotic mupirocin during repeated treatment. Moreover, a significant increase of the IC(50) for silver nitrate was observed over time. On the other hand, no significant difference was observed for polihexanide or chlorhexidine. While the IC(50) for octenidine was also found to increase significantly, although the change was only marginal, reiterated incubation with PVP-iodine led to a decrease in the IC(50). CONCLUSION: Repeated treatment of S. aureus with polihexanide, chlorhexidine, octenidine and PVP-iodine did not trigger bacterial adaptation to these substances.