The cutaneous microbiology of normal human feet

Footwear microclimate and its effects on the microbial community of the plantar skin

The association between the footwear microclimate and microbial community on the foot plantar skin was investigated by experiments with three participants. Novel methods were developed for measuring in-shoe temperature and humidity at five footwear regions, as well as the overall ventilation rate inside the footwear. Three types of footwear were tested including casual shoes, running shoes, and perforated shoes for pairwise comparison of footwear microclimate and corresponding microbial community on the skin. The major findings are as follows: (1) footwear types make a significant difference to in-shoe temperature at the instep region with the casual shoes sustaining the warmest of all types; (2) significant differences were observed in local internal absolute humidity between footwear types, with the casual shoes sustaining the highest level of humidity at most regions; (3) the perforated shoes provided the highest ventilation rate, followed by running and casual shoes, and the faster the gait, the larger the discrepancy in ventilation rate between footwear types; (4) the casual shoes seemed to provide the most favorable internal environment for bacterial growth at the distal plantar skin; and (5) the bacterial growth at the distal plantar skin showed a positive linear correlation with the in-shoe temperature and absolute humidity, and a negative linear correlation with the ventilation rate. The ventilation rate seemed to be a more reliable indicator of the bacterial growth. Above all, we can conclude that footwear microclimate varies in footwear types, which makes contributions to the bacterial growth on the foot plantar skin.

Does the Application of a Semiocclusive Dressing Alter the Microflora of Healthy Intact Skin on the Foot?

BACKGROUND

The skin on human feet presents unique environments for the proliferation of potentially pathogenic commensals. This study examined microflora changes on healthy intact skin under a semiocclusive dressing on the medial longitudinal arch of the foot to determine changes in growth, distribution, and frequency of microflora under the dressing.

METHODS

Nine human participants wore a low-adherent, absorbent, semiocclusive dressing on the medial longitudinal arch of the left foot for 2 weeks. An identical location on the right foot was swabbed and used as a control. Each foot was swabbed at baseline, week 1, and week 2. The swabs were cultured for 48 hours. Visual identification, Gram staining, DNase test agar, and a latex slide agglutination test were used to identify genera and species.

RESULTS

Microflora growth was categorized as scant (0-10 colony-forming units [CFU]), light (11-50 CFU), moderate (51-100 CFU), or heavy (>100 CFU). Scant and light growth decreased and moderate and heavy growth increased under the dressing compared with the control. Seven different genera of bacteria were identified. Coagulase-negative Staphylococcus spp appeared most frequently, followed by Corynebacterium spp.

CONCLUSIONS

Changes in microflora distribution, frequency, and growth were found under the dressing, supporting historical studies. Microflora changes were identified as an increase in bioburden and reduction in diversity. The application of similar methods, using more sophisticated identification and analysis techniques and a variety of dressings, could lead to a better understanding of bacterial and fungal growth under dressings, informing better dressing selection to assist the healing process of wounds and prevent infection.

The foot microbiome

BACKGROUND

The human skin microbiome is represented by bacteria, fungi, viruses, and mites.

AIMS

Every human being possess their own unique skin microbiome because intrinsic and environmental factors have a significant impact on the quality and quantity of microorganism. Every site of the body is a separate microbial niche.

PATIENTS

The feet are one of the most unique and heterogeneous microbial niches of human body with areas that differ by skin thickness, anatomical features, distribution of sweat glands, pH, and the availability of oxygen.

RESULTS

Healthy skin of the foot is inhabited by Corynebacteriaceae, Micrococcaceae, Propionibacteriaceae, Actinobacteria, Clostridiales, Lactobacillaceae, Streptococcaceae, Enterobacteriaceae, Moravellaceae, Neisseriaceae, Pastereullaceae, and Proteobacteria. The most common fungi present on the feet are Malassezzia, Cryptococcus, Aspergillus, Rhodotorula, Epicoccum, Saccharomyces, Candida, Epidermophyton Microsporum, and Trichophyton.

CONCLUSIONS

The disturbance of the foot microbiome causes dysbiosis and may lead to pitted keratolysis, fungal, and viral infections or even to protothecosis.

Characterization of Skin Microbiome in Tinea Pedis

Tinea pedis has been associated with Trichophyton rubrum infection. However, it's not clear whether other microbes were implicated in disease pathogenesis. The composition of microbial communities of patients with tinea pedis and healthy controls were analyzed to identify the characteristics of tinea pedis and differences associated with clinical patterns. We found that microbial community structures were different in patients with tinea pedis compared with healthy controls. Moreover, skin microbiome varied in different forms of tinea pedis. Healthy controls exhibited greater fungal diversity than patients with tinea pedis. In patients with tinea pedis, the dominant bacterial and fungal genera were Staphylococcus and Trichophyton. Compared with healthy controls, Corynebacterium tuberculostearicum was decreased and T. rubrum was increased. C. tuberculostearicum was more abundant in vesicular tinea pedis than in hyperkeratotic and interdigital tinea pedis. Interdigital tinea pedis had a higher detection rate of Corynebacterium minutissimum and T. rubrum than the other forms. These results indicated that bacterial microbes may take part in the development of tinea pedis.

Prevention of Infection in Foot and Ankle Surgery

The literature for prevention of surgical infection related primarily to foot and ankle surgery is sparse, with most attention on total joint replacement and abdominal surgery. Attention should be paid to preoperative, intraoperative, and postoperative elements, which can have an effect on the development of postoperative infection. Although antibiotic prophylaxis typically is discussed in isolation, inclusion of this step into the process enhances the overall evaluation of surgery with respect to infection. This evolution provides for better patient outcomes and decreases the likelihood of an infection incurred after foot and ankle surgery.

Wound healing complications in patients with and without systemic diseases following hallux valgus surgery

There are many defined risk factors for wound healing. Comorbidities and their treatment are identified to be one of them. The aim of this study is to verify whether there are significant differences in wound healing between patients with and without systemic diseases, who underwent hallux valgus correction with Scarf osteotomy. A total of 155 consecutive patients were included into this prospective study. All of the patients underwent Scarf osteotomy for hallux valgus correction. In 60,6% of patients comorbidities were present, most often hypertension (57 patients, 36,8%), hypothyroidism (19 patients 12,3%) and diabetes (7 patients, 4,5%) occurred. Most of the patients were women (96,1%). During the study complication rate was noted. Patients underwent follow-up: 1,2, 3, 6 and 12 weeks and 6 months after the surgery. Preoperatively and during the last visit treatment results were assessed with AOFAS HMI scale. Scar assessment was performed by independent observer with VAS followed by patient scar assessment with VSS. In 30 patients complications were noted (19,4%). Surgical site infection was found in 6 patients (3,9%). In 13 patients (8,4%) partial wound dehiscence occurred, in 5 of them (3,2%) additional skin closure (Steri-Strips) was applied. Treatment results assessed with AOFAS HMI scale were good and very good in both healthy and comorbidity group, and the results improved significantly after surgical procedure. Scar assessment with VAS was on the average 1,5 pts. Average result in VSS was 2 pts. Results in both scales were rated as very good. No statistically significant differences were found in both healthy and comorbidity group in scar assessment. Based on the results of the study authors believe there are no significant differences between patients with and without comorbidities in aspects like: complication rate, surgery result and scar assessment as long as foot surgery is concerned.

Butane-2,3-dione: the key contributor to axillary and foot odor associated with an acidic note

Human body odor, which contains several volatile organic compounds, possesses various odor qualities. To identify key volatile compounds responsible for the common unpleasant odors derived from human axillae and feet, the odor quality and intensity of 118 human axillae and feet were directly evaluated by sniffing, and odor compounds obtained from the subjects were identified. Furthermore, the sensory differences in odor intensity and quality with and without addition of butane-2,3-dione were evaluated by using the visual analog scale (VAS). An acidic odor was a common unpleasant note in human axillae and feet. Butane-2,3-dione was identified as a key compound associated with this odor. Strong positive correlations between the amount of butane-2,3-dione, and the odor intensities of axillae and feet were observed, and the addition of butane-2,3-dione solution to blended short-chain fatty-acid solutions caused significantly increased VAS values of axillary-like odor, unpleasantness, and odor intensity compared to those of each solution without added butane-2,3-dione.

A clinical perspective on musculoskeletal infection treatment strategies and challenges

Orthopaedic implants improve the quality of life of patients, but the risk of postoperative surgical site infection poses formidable challenges for clinicians. Future directions need to focus on prevention and treatment of infections associated with common arthroplasty procedures, such as the hip, knee, and shoulder, and nonarthroplasty procedures, including trauma, foot and ankle, and spine. Novel prevention methods, such as nanotechnology and the introduction of antibiotic-coated implants, may aid in the prevention and early treatment of periprosthetic joint infections with goals of improved eradication rates and maintaining patient mobility and satisfaction.

Microbial volatile compounds in health and disease conditions

Microbial cultures and/or microbial associated diseases often have a characteristic smell. Volatile organic compounds (VOCs) are produced by all microorganisms as part of their normal metabolism. The types and classes of VOC produced is wide, including fatty acids and their derivatives (e.g. hydrocarbons, aliphatic alcohols and ketones), aromatic compounds, nitrogen containing compounds, and volatile sulfur compounds. A diversity of ecological niches exist in the human body which can support a polymicrobial community, with the exact VOC profile of a given anatomical site being dependent on that produced by both the host component and the microbial species present. The detection of VOCs is of interest to various disciplines, hence numerous analytical approaches have been developed to accurately characterize and measure VOCs in the laboratory, often from patient derived samples. Using these technological advancements it is evident that VOCs are indicative of both health and disease states. Many of these techniques are still largely confined to the research laboratory, but it is envisaged that in future bedside 'VOC profiling' will enable rapid characterization of microbial associated disease, providing vital information to healthcare practitioners.

Cultured skin microbiota attracts malaria mosquitoes

BACKGROUND

Host-seeking of the African malaria mosquito, Anopheles gambiae sensu stricto, is guided by human odours. The precise nature of the odours, and the composition of attractive blends of volatiles, remains largely unknown. Skin microbiota plays an important role in the production of human body odours. It is hypothesized that host attractiveness and selection of An. gambiae is affected by the species composition, density, and metabolic activity of the skin microbiota. A study is presented in which the production and constituency of volatile organic compounds (VOCs) by human skin microbiota is examined and the behavioural responses of An. gambiae to VOCs from skin microbiota are investigated.

METHODS

Blood agar plates incubated with skin microbiota from human feet or with a reference strain of Staphylococcus epidermidis were tested for their attractiveness to An. gambiae in olfactometer bioassays and indoor trapping experiments. Entrained air collected from blood agar plates incubated with natural skin microbiota or with S. epidermidis were analysed using GC-MS. A synthetic blend of the compounds identified was tested for its attractiveness to An. gambiae. Behavioural data were analysed by a chi(2)-test and GLM. GC-MS results were analysed by fitting an exponential regression line to test the effect of the concentration of bacteria.

RESULTS

More An. gambiae were caught with blood agar plates incubated with skin bacteria than with sterile blood agar plates, with a significant effect of incubation time and dilution of the skin microbiota. When bacteria from the feet of four other volunteers were tested, similar effects were found. Fourteen putative attractants were found in the headspace of the skin bacteria. A synthetic blend of 10 of these was attractive to An. gambiae.

CONCLUSIONS

The discovery that volatiles produced by human skin microorganisms in vitro mediate An. gambiae host-seeking behaviour creates new opportunities for the development of odour-baited trapping systems. Additionally, identification of bacterial volatiles provides a new method to develop synthetic blends, attractive to An. gambiae and possibly other anthropophilic disease vectors.

Quantitative analysis of bacteria in forefoot surgery: a comparison of skin preparation techniques

BACKGROUND

Currently a lack of consensus exists on the optimum solution and preparation methods needed to decrease bacteria present during forefoot surgery. We therefore compared the effect of povidine-iodine and chlorhexidine gluconate on lowering bacterial load and to study any additional benefits gained by pre-treatment with the use of a bristled brush.

MATERIALS AND METHODS

Fifty consecutive patients undergoing forefoot surgery were recruited into the study and randomized to receive one of two surgical skin preparations (Povidine-iodine 1% with isopropyl alcohol 23% or Chlorhexidine gluconate 0.5% with isopropyl alcohol 70%). In addition to the skin preparation of the foot with the randomized solution, the subjects other foot was also scrubbed with a sterile surgical bristled brush for three minutes and then painted with the same solution. Swabs were taken from three sites and analyzed via qualitative and quantitative analysis before and after prepping.

RESULTS

All four preparation methods significantly decreased (p < 0.001), in all three sites, the number of colony forming units. Using two-way analysis of variance, no significant interaction was observed between preparation method and number of colony-forming units, suggesting that no difference in bacterial inhibition between preparation methods.

CONCLUSION

We suggest that either povidone-iodine with no more that 23% isopropyl alcohol or chlorhexidine gluconate with 70% isopropyl alcohol be used for surgical preparation in forefoot surgery. No additional benefit in reduction in bacterial load was gained by scrubbing the foot with bristles prior to painting.

Isolation and in vitro antibacterial activity of astilbin, the bioactive flavanone from the leaves of Harungana madagascariensis Lam. ex Poir. (Hypericaceae)

Harungana madagascariensis is well known for its topical antibacterial properties used in the elaboration of a lot of skin hygiene products. The aim of this study was, on the one hand, to evaluate the in vitro antibacterial activities of aqueous, ethanolic and ethyl acetate crude extracts of Harungana madagascariensis leaves against bacterial strains representative of skin microflora and, on the other hand, to determine the chemical structure of the active compound. Only the ethyl acetate leaf extract presented important antibacterial activity. Its fractionation was carried out by column chromatography using silica gel 60 and it yielded 11 fractions. A bioautographic method, revealed in these fractions the presence of a flavanone as the active compound astilbin or 3-O-alpha-L-rhamnoside-5,7,3',4'-tetrahydroxydihydroflavonol which was identified on the basis of its spectroscopic data. Concerning the antibacterial activity against the representative skin microflora of the armpit and feet, MIC and MBC ranged from 25 to 250 and 100 to 750 microg ml-1, respectively. The results showed that some bacteria considered to be responsible for bad odours at the armpit and feet levels, were destroyed at 200 microg ml-1 (MBC), a concentration sparing most of the useful saprophytic microflora. The minimal inhibitory quantity (MIQs) of astilbin ranged from 50 to 100 microg.

Efficacy of surgical preparation solutions in foot and ankle surgery

BACKGROUND

Previous studies have demonstrated higher infection rates following orthopaedic procedures on the foot and ankle as compared with procedures involving other areas of the body. Previous studies also have documented the difficulty of eliminating bacteria from the forefoot prior to surgery. The purpose of the present study was to evaluate the efficacy of three different surgical skin-preparation solutions in eliminating potential bacterial pathogens from the foot.

METHODS

A prospective study was undertaken to evaluate 125 consecutive patients undergoing surgery of the foot and ankle. Each lower extremity was prepared with one of three randomly selected solutions: DuraPrep (0.7% iodine and 74% isopropyl alcohol), Techni-Care (3.0% chloroxylenol), or ChloraPrep (2% chlorhexidine gluconate and 70% isopropyl alcohol). After preparation, quantitative culture specimens were obtained from three locations: the hallux nailfold (the hallux site), the web spaces between the second and third and between the fourth and fifth digits (the toe site), and the anterior part of the tibia (the control site).

RESULTS

In the Techni-Care group, bacteria grew on culture of specimens obtained from 95% of the hallux sites, 98% of the toe sites, and 35% of the control sites. In the DuraPrep group, bacteria grew on culture of specimens obtained from 65% of the hallux sites, 45% of the toe sites, and 23% of the control sites. In the ChloraPrep group, bacteria grew on culture of specimens from 30% of the hallux sites, 23% of the toe sites, and 10% of the control sites. ChloraPrep was the most effective agent for eliminating bacteria from the halluces and the toes (p < 0.0001).

CONCLUSIONS

The use of effective preoperative preparation solution is an important step in limiting surgical wound contamination and preventing infection, particularly in foot and ankle surgery. Of the three solutions tested in the present study, the combination of chlorhexidine and alcohol (ChloraPrep) was most effective for eliminating bacteria from the forefoot prior to surgery.

Molecular detection and isolation of facultatively methylotrophic bacteria, including Methylobacterium podarium sp. nov., from the human foot microflora

This is the first study to demonstrate that diverse methylotrophic bacteria occur in the human foot microflora. Polymerase chain reaction (PCR) amplification of DNA from the soles and toe clefts of feet of five subjects indicated Methylobacterium strains to be present in all cases. Polymerase chain reaction amplification also showed the gene for the alpha-subunit of methanol dehydrogenase (mxaF) to be present in all samples. Two types of mxaF were recovered, one closest to that of Methylobacterium extorquens and the other most similar to that of Hyphomicrobium methylovorum. Numerous methylotrophic strains able to grow on methylamine were isolated with ease from the feet of nine volunteers. These were found by 16S rRNA analysis to be most closely related to Methylobacterium species, Brevibacterium casei, Pseudomonas strain NZ099 and P. migulae. Three strains from two subjects were of a novel species, Methylobacterium podarium sp. nov. This facultatively methylotrophic, obligately aerobic, pink-pigmented, non-motile rod grew with a wide range of multicarbon and one-carbon compounds including citrate, xylose, mono-, di-, and trimethylamine, dimethylsulphide, methanethiol, dimethylsulphoxide, dimethylsulphone and methanol.

Inhibiting bacteria and skin pH in hemiplegia: effects of washing hands with acidic mineral water

OBJECTIVE

To evaluate bacterial flora in hemiplegic hands as a possible pathogen of endogenous infection in a rehabilitation unit and to examine the effect of cleansing hands with acidic mineral water on the flora.

DESIGN

Case-control study in a university affiliated hospital. Seventy-two patients with hemiplegia caused by cerebrovascular diseases were included in this study. Bacterial flora by the swab method, bacterial frequency on the palm by the stamp method, and skin surface pH were examined before and after single cleansing by immersion in plain or acidic mineral water.

RESULTS

The bacterial frequencies of patients with hemiplegia and diabetes were higher than those of normal healthy subjects. After cleansing with acidic mineral water, skin surface pH was decreased and bacterial frequency was markedly decreased. A prolonged decrease in skin surface pH was observed in patients with hemiplegia in contrast to normal healthy subjects who presented a short-term decrease.

CONCLUSION

Increased bacterial frequencies were associated with a high skin surface pH caused by disordered skin systems in patients with hemiplegia. Acidic mineral water may be useful for inhibiting bacterial growth in patients with hemiplegia.

General anti-microbial properties of the integument in fleece producing sheep and goats

Based on lectin histochemical methods, this study describes the production and distribution of various terminal sugars in the integument of Merino sheep and Angora goats. Additionally, pH measurements were performed for information about environmental conditions of microbes on the skin surface and in the fleece. The results demonstrated strongly positive reactions for alpha-L-fucose in the stratum corneum of Merino sheep, and in the secretions of the skin glands of Angora goats. Moreover, alpha-D-mannose, beta-D-N-acetylglucosamine, alpha-D-N-acetylgalactosamine, alpha-D-galactose and beta-D-galactose were very distinct in the secretions of the skin glands of both species. The skin products containing saccharide residues are deposited on the skin surface and in the fleece as part of wool grease, and the terminal sugars may be liberated by bacterial and fungal activities. All of these sugars are of specific interest because of their ability of inhibiting the adherence of different bacteria and fungi to the epidermal cells. Thus, free sugars impede attacks of skin micro-inhabitants against the integrity of the epidermal barrier. In contrast to these results, the skin pH-conditions were strongly alkaline, particularly in the fleece of Merino sheep (pH 6-9), so that proliferation of microbes may be promoted. This negative influence can only be countered by high production rates of sugar-containing skin products, which is normally the case based on long and intense activity of hair follicles in fine-wool producing sheep and goats.In conclusion, this study demonstrates that a basic anti-microbial biological system exists on the skin surface and within the hair coat, that operates with free sugars before the immune system is activated.

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

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

Capillary gas chromatography with chemical ionization negative ion mass spectrometry in the identification of odorous steroids formed in metabolic studies of the sulphates of androsterone, DHA and 5alpha-androst-16-en-3beta-ol with human axillary bacterial isolates

The products of metabolism of the sulphates (0.5 micromol/l) of androsterone, dehydroepiandrosterone (DHA) and 5alpha-androst-16-en-3beta-ol have been investigated after incubation with 72 h cultures of human axillary bacterial isolates for 3 days at 37 degrees C. The medium used, tryptone soya broth (TSB), contained yeast extract and Tween 80. The isolates used were Coryneform F1 (known previously to metabolize testosterone and to be involved in under-arm odour (UAO) production, i.e. UAO +ve), Coryneform F46 (inactive in both the testosterone metabolism and UAO tests, i.e. UAO -ve) and Staphylococcus hominis/epidermidis (IIR3). Control incubations of TSB alone, TSB plus each of the steroid sulphates and TSB plus each of the bacterial isolates were also set up. After termination of reactions and addition of internal standards, 5alpha-androstan-3beta-ol and 5alpha-androstan-3-one (50 ng each), extracted and purified metabolites were subjected to combined gas chromatography-mass spectrometry with specific ion monitoring. Steroidal ketones were derivatized as their O-pentafluorobenzyl oximes; steroidal alcohols (only androst-16-enols in this study) were derivatized as their tert-butyldimethylsilyl ethers. Analysis was achieved by negative ion chemical ionization mass spectrometry for the pentafluorobenzyl oximes at [M-20]- and electron impact positive ion mass spectrometry for the tert-butyldimethylsilyl ethers at [M-57]+. The incubation broth contained two compounds which had gas chromatographic and mass spectrometric properties identical to those of DHA and 4-androstenedione. It was not possible, therefore, to show unequivocally that DHA sulphate (DHAS) was converted microbially into DHA, although this is implied by the finding of small quantities of testosterone and 5alpha-dihydrotestosterone in incubations with F1. With androsterone S, no free androsterone was recorded and only very small (5 pg or less) amounts of testosterone. Two odorous steroids, androsta-4,16-dien-3-one and 5alpha-androst-2-en-17-one (Steroid I) were formed (mean quantities 40 and 45 pg, respectively). The sulphate of 5alpha-androst-16-en-3beta-ol was metabolized with F1 into large quantities of the odorous steroids, 5alpha-androst-16-en-3-one and Steroid I. In addition, much smaller quantities of androsta-4,16-dien-3-one were formed. In contrast, incubations of DHAS with F46 resulted in no metabolites except, possibly, DHA, but the sulphate moiety of androsterone S was also cleaved to yield the free steroid together with large amounts of Steroid I. In incubations of DHAS and androsterone S with F1, no 16-unsaturated steroids were formed, although 5alpha-androst-16-en-3beta-yl S was de-sulphated and the free steroid further metabolized. No evidence was obtained for androst-16-ene metabolism in incubations with F46. In incubations with S. hominis/epidermidis (IIR3), androsterone S was converted into androsterone and, in high yield, to Steroid I plus some 5alpha-androst-16-en-3-one. Both DHAS and androsterone S were converted into androst-16-enols. Sulphatase activity was also manifested when 5alpha-androst-16-en-3beta-yl S was utilized as substrate with IIR3, large quantities of Steroid I and 5alpha-androst-16-en-3-one being formed, together with further metabolism of androst-16-enes. In view of the fact that both DHAS and androsterone S occur in apocrine sweat, the metabolism of these endogenous substrates by human axillary bacteria to several odorous steroids may have important implications in the context of human odour formation.

Comparison of 16-androstene steroid concentrations in sterile apocrine sweat and axillary secretions: interconversions of 16-androstenes by the axillary microflora--a mechanism for axillary odour production in man?

The concentrations of five 16-androstene steroids were determined, by a GC-MS method, in freshly-produced apocrine sweat (adrenaline-induced), in 8 men and 2 women. The ranges of concentrations (nmol/microliter) in apocrine sweat were: 5 alpha-androst-16-en-3-one (5 alpha-A), 0.1-2.0 and 4,16-androstadien-3-one (androstadienone), 0-1.9, 5,16-Androstadien-3 beta-ol (androstadienol) was also found in 5 of the subjects (range 0.05-1.05). 5 alpha-Androst-16-en-3 alpha- or 3 beta-ols [3 alpha (beta)-androstenols] were only found in small amounts (< 0.1 nmol/microliters) in a few subjects. In the second study, prior to apocrine sweat collection (adrenaline injection), the axillary skin of 6 of the male subjects was washed with diethyl ether on an adjacent site of the axillary vault. The concentrations of 16-androstenes were compared in the ethereal extracts and apocrine sweat. The former contained detectable levels (pmol/cm2) of androstadienone (17.9 +/- 2.4), 3 alpha-androstenol (6.9 +/- 3.7), 3 beta-androstenol (1.8 +/- 1.0) and androstadienol (1.9 +/- 0.5) (means +/- SEM) in all 6 subjects. All but 1 subject also had 5 alpha-androstenone, the mean value for the others being 2.5 +/- 0.6. The axillary skin levels of 3 alpha- and 3 beta-androstenols, androstadienol and, in 3 subjects, androstadienone exceeded those in the apocrine sweat obtained from the same subjects, whereas levels of 5 alpha-androstenone in the skin extracts were all lower than in apocrine sweat samples, when related to the corresponding areas of skin sampled. The metabolism of 16-androstenes was studied in vitro in the presence of two aerobic coryneform bacteria, previously shown to metabolize testosterone as well as being capable of producing odour from extracts of axillary sweat in an odour-generation test. Although both coryneforms caused complex metabolic reactions and were capable of oxidation or reduction at C-3 and C-4, the overall direction favoured reduction. For example, large quantities of the more odorous 5 alpha-androstenone and 3 alpha-androstenol were formed from androstadienol and androstadienone. In contrast, strains of corynebacteria, unable to produce odour and incapable of metabolizing testosterone, were also unable to metabolize 16-androstenes.(ABSTRACT TRUNCATED AT 400 WORDS)

Comparative study on the antimicrobial effects of Hexomedine and Betadine on the human skin flora

Studies were carried out to detect the modifications, if any, on the peri-umbilical flora of six healthy volunteers after two or three daily applications of Hexomedine solution (HEX) and Betadine solution (PVI) repeated for five consecutive days. A standardized scrubbing method was used for bacterial sampling. Surviving bacteria were selected with both selective and non-selective media, and then identified by gas chromatographic fatty acid analysis. Both antiseptics were highly effective, showing both immediate and residual antimicrobial activities. The use of HEX led to a slight increase in Gram-positive cocci and a small decrease in coryneforms, but PVI produced a marked increase in Gram-positive cocci and a sharp decrease in coryneforms. The two antiseptics, however, caused no major alteration in the cutaneous microbial population. Indeed, neither the overgrowth of Gram-negative bacilli nor the emergence of resistant species was observed.

Characterization of aerobic non-lipophilic coryneforms from human feet

Aerobic coryneform bacteria from human feet have been studied by analysis of the cell-wall sugars, lipids and diamino acids and by phenotypic tests. Although many isolates studied fall into the established genus Brevibacterium at least two previously unreported taxa of coryneform have been identified bringing the number of aerobic, non-lipophilic taxa known on skin to four. Simple tests can be used to distinguish between these taxa. Studies on the human skin flora continue to reveal the diversity of organisms present.

In-vitro and in-vivo studies of human axillary odour and the cutaneous microflora

The axillary microflora of 34 male subjects were studied in relation to their underarm odour intensity. The predominant groups of micro-organisms were aerobic coryneforms, Micrococcaceae and propionibacteria. There was no competition for habitat between these groups (Fisher's exact test P greater than 0.05). There was an association between the population density of aerobic coryneforms and the intensity of odour (Spearman, P = 0.001). Dominance of aerobic coryneforms within the axillary microflora was associated with high odour intensity (chi 2, P = 0.005). An in-vitro odour model was developed using a diethyl ether extract of axillary skin incubated with test bacteria. Underarm odour was produced exclusively by aerobic coryneform bacteria. Of aerobic coryneforms, 71.4% were odour producers and these were identified as Corynebacterium xerosis.

The distribution and ecology of Malassezia furfur and cutaneous bacteria on human skin

The prevalence and abundance of Malassezia furfur on clinically normal skin at 20 sites has been determined. All of the 16 subjects studied (young adults) had high counts on the upper trunk and on at least one site on the head. Counts obtained from the lower trunk and upper thighs of male subjects were considerably higher than those from female volunteers. Organisms isolated, grouped according to their colony morphologies, had distributions consistent with those noted for 'Pityrosporum ovale' and 'P. orbiculare' in previous studies. Mean M. furfur counts were compared with aerobic and anaerobic bacterial counts performed at the same sites. Propionibacteria and M. furfur distributions were similar but not identical. Some factors which might limit the range of M. furfur are discussed.

Microbiology of the skin: resident flora, ecology, infection

Humans exist in an environment replete with microorganisms, but only a few become resident on the skin surface. The skin possesses protective mechanisms to limit colonization, and the survival of organisms on the surface lies in part in the ability of the organisms to resist these mechanisms. Microbial colonization on the skin adds to the skin's defense against potentially pathogenic organisms. Although microbes normally live in synergy with their hosts, occasionally colonization can result in clinical infection. Common infections consist of superficial infections of the stratum corneum or appendageal structures that can respond dramatically to therapy but commonly relapse. In rare circumstances, these infections can be quite severe, particularly in immunocompromised patients or in hospitalized patients with indwelling foreign devices. These infections are often resistant to conventional antibiotics and can result in infection with other opportunistic pathogens.

A comparative study of the cutaneous microflora of normal feet with low and high levels of odour

A comparison of the cutaneous microflora found on normal feet with varying levels of odour has been made. High population densities of staphylococci and aerobic coryneform bacteria predispose to foot odour. There was no association between odour and the carriage on feet of any particular micro-organism, including brevibacteria. All organisms isolated were screened for exoenzyme activity. Only staphylococci produced lipase (78% of the staphylococci), whereas 97% of micrococci, 68% of aerobic coryneform bacteria, 25% of staphylococci and 94% of propionibacteria produced proteinase. The ability to degrade callous was exhibited by 47% of micrococci, 24% of aerobic coryneforms and 17% of the staphylococci. Feet with high odour had significantly higher population densities of micro-organisms with the ability to produce these exoenzymes than feet with low odour. No association was observed between foot odour and the carriage of micro-organisms capable of producing methanethiol. A hypothesis for the role of micro-organisms in the production of foot odour is proposed.