PubMed Health⌕ Search

Biomedical subjects

R Aly

Publications and source records attributed to R Aly.

At least 19 recordsLinked to original sources
PubMed1992

Antimicrobial activity of sphingosines.

The antimicrobial activity of stratum corneum lipids was examined by screening in vitro various representative phospholipids and sphingolipids. Of mixed galacto-cerebrosides; phosphatidic acid; phosphatidic acid-monomethylester-dioleoyl; phosphatidylethanolamine; phosphatidylethanolamine-beta-oleoyl-gamma-palmitoyl; phosphatidylcholine; D-sphingosine; D,L-sphinganine; 4-D-hydroxysphinganine; oleoyl-sphingosine; N,N-dimethylsphingosine; and stearylamine, only the sphingosines and, to a lesser extent, stearylamine were clearly and profoundly effective against Staphylococcus aureus (4-log reduction at 6.25 micrograms/ml [20 microM]; 2-log reduction at 0.78 mu/ml [2.5 microM]). The sphingosines were similarly active against Streptococcus pyogenes, Micrococcus luteus, Propionibacterium acnes, Brevibacterium epidermidis, and Candida albicans, moderately active against Pseudomonas aeruginosa, and ineffective against Escherichia coli and Serratia marcescens. Both erythro- and threo-isomers were effective. Optimal inhibition was at 60 min incubation at 37 degrees C and at pH 6.5. Antimicrobial activity, which was Ca++ dependent, was confirmed in vivo by topical application and microbial challenge. Because free sphingosines are available in the stratum corneum and other epidermal layers, these lipids may contribute to the cutaneous antimicrobial barrier.

Bacteria↗
PubMed1992

Simplified experimental human dermatophytosis model.

The authors have improved and simplified previous methods for producing localized mycotic skin infections in an attempt to compare topical antifungal agents for their bioequivalency. Healthy human volunteers who had negative results for commercial, purified Trichophyton antigen (Trichophytin) were inoculated with Trichophyton mentagrophytes on two sites on each forearm in a randomized study designed to compare the antifungal activities of two ciclopirox olamine formulations. The lesions, easily induced by the authors' method, were localized and did not spread under the occlusive dressings. Infections established at the four sites on 26 subjects were treated twice daily for 14 days with the two active drug formulations and their vehicles. There were no significant differences in culture-documented cure rates or alleviation of clinical signs and symptoms between ciclopirox olamine lotion and cream. Each drug was significantly better than its vehicle. The authors' method seems to be effective and suitable for therapeutic studies.

Adult↗
PubMed1992

Inhibition of microbial adherence by sphinganine.

Sphingosines (precursors and degeneration products of complex sphingolipids) are mediators in membrane second-messenger cascades and in a wide variety of functions in eukaryotic cells. Sphingosines are also lethal for gram-positive microorganisms. In addition to its direct effect, sphinganine is here reported to affect the adherence of Streptococcus mitis to buccal epithelial cells and of Staphylococcus aureus to nasal mucosal cells after incubation for 90 min at 37 degrees C. When the bacteria were pretreated with 8.1, 16.2, 32.5, or (for Strep. mitis) 65 microM sphinganine for 60 min at 37 degrees C, adherence counts were reduced for Staph. aureus by 27, 37, and 60% and for Strep. mitis by 19, 44, 54, and 73%, respectively (p < 0.001). In contrast, pretreatment of buccal cells with 81.2 microM lipid increased adherence by 14% (p < 0.01), but no change occurred at either 16.2 or 325 microM lipid. These results further demonstrate the double-edged ability of sphingosines to regulate cellular activities and their potential as multifunctional therapeutic agents for infectious diseases.

Bacterial Adhesion↗
PubMed1989

Antimicrobial activity of stratum corneum lipids from normal and essential fatty acid-deficient mice.

Among the cutaneous effects of an essential fatty acid deficient (EFAD) diet are hyperdesquamation, increased transepidermal water loss (TEWL), and altered lipid profiles, characteristics also common to inflammatory dermatoses. Because fatty acids are antimicrobial, we examined the indigenous skin flora of normal and EFAD hairless mice, and compared the antimicrobial efficacy of lipids extracted from their stratum corneum. EFAD mice supported 100-fold more bacteria than normal mice, and were the only group from which Staphylococcus aureus were routinely isolated. Despite this greater carriage, in vitro experiments demonstrated that EFAD lipids are more lethal than normal lipids against Streptococcus pyogenes, S. aureus, S. epidermidis, Micrococcus sp., and a coryneform. Skin fungi were equally susceptible to both extracts. After thin layer chromatography, the most active fractions were found to be glycosphingolipids and phospholipids. EFAD extracts had 35% more free fatty acids and 75% more glycosphingolipids; normal extracts had more triglycerides and phospholipids. S. aureus strain 502A survived equally well on EFAD as on normal mice. Normal lipids applied on EFAD mice had no additional effect, but EFAD lipids on normal mice brought about a 35% reduction of the inoculated bacteria. If the mice were pretreated with alcohol, carriage of strain 502A was reduced by 71%. If instead the mice were previously washed with acetone to increase TEWL, a 97% reduction of the staphylococcus occurred. The application of normal flora to such acetone-washed mice decreased the efficacy to 76%. EFAD and normal lipids on human subjects were equally ineffective in eliminating strain 502A.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Comparative antibacterial efficacy of a 2-minute surgical scrub with chlorhexidine gluconate, povidone-iodine, and chloroxylenol sponge-brushes.

Chlorhexidine gluconate (Hibiclens), povidone-iodine (E-Z Scrub 201), and chloroxylenol (ParaSoft) sponge-brushes were compared for antibacterial efficacy in 2-minute surgical scrubs. Thirty-nine volunteers completed a 7-day baseline period and a 5-day treatment period. Thirteen participants were assigned to a chlorhexidine group, 12 to a povidone-iodine group, and 14 to a chloroxylenol group. Subjects followed a standardized protocol, performing 11 scrubs during the treatment period. Bacterial counts were taken by the glove-juice procedure immediately after scrubbing and at 3 and 6 hours later on days 1, 2, and 5. The use of chlorhexidine achieved significantly (p less than 0.01) greater adjusted mean log10 bacterial count reductions than did povidone-iodine and chloroxylenol at all sampling times, with greater reductions as the study progressed.

Adult↗
PubMed1988

Restriction of bacterial growth under commercial catheter dressings.

The effect on the normal cutaneous flora after iodine and alcohol disinfection of the skin of three commercially available moisture-permeable polyurethane dressings was compared with that of a gauze-and-tape dressing. Dressings also were evaluated clinically for membrane adhesion and skin erythema, pruritus, hyperpigmentation, vesiculitis, and tenderness. Each of 50 healthy volunteers and 49 long-term inpatients, 25 of whom were receiving antibiotic therapy, received simultaneously on their volar forearm patches of Op-Site, Tegaderm, Uniflex, and gauze dressings. Controls consisted of one exposed skin site and one covered with moisture-retaining vinylidene film (Saran Wrap). Although after 3 days of adhesion, commercial dressings prevented indigenous flora from returning to normal population densities, no significant quantitative differences were found between them and the gauze-and-tape dressing. Generally, all clinical dressings maintained normal flora at one tenth the population of the uncovered site; the Saran Wrap control supported 100-fold more bacteria than the exposed site. No differences were discovered in the levels of gram-negative bacteria, or among patient groups and between patients and healthy subjects, except for the lower incidence of erythema and itching among patients compared with healthy subjects.

Adult↗
PubMed1988

In vitro and in vivo antistaphylococcal activity of human stratum corneum lipids.

Despite the assumption that sebum-derived fatty acids are responsible for cutaneous antimicrobial defense, no studies have assessed the contribution of epidermis-derived lipids. Herein, we tested the antistaphylococcal effects of human stratum corneum lipids, enriched in endogenous, keratinocyte-derived species obtained by lipid extraction and thin-layer chromatography, for antimicrobial activity in both in vitro and in vivo systems. Whereas the most potent species in vitro were the free fatty acids, polar lipids and glycosphingolipids also demonstrated antistaphylococcal activity in vitro, while other neutral lipids displayed virtually none, results that were confirmed with authentic standards in vitro. In a pilot study on delipidized forearm test sites in human volunteers, naturally occurring free fatty acids, polar lipids, and glycosphingolipids exhibited significantly more antistaphylococcal activity than other stratum corneum lipids or vehicle controls. Finally, biopsy specimens of incubated skin sites demonstrated penetration of staphylococci through lipid-enriched intercellular domains. These results provide the first evidence that endogenous, epidermis-derived skin lipids may contribute to cutaneous antimicrobial resistance.

Fatty Acids, Nonesterified↗
PubMed1987

Microbial adherence to vulvar epithelial cells.

Under uniform experimental conditions, different degrees of selective attachment of Staphylococcus aureus and Candida albicans to epithelial cells of the labium majus, the labium minus, and the vagina were compared and contrasted with those found in studies with cells of the buccal and nasal mucosa and forearm skin by a novel analysis of adherence density. For both micro-organisms, the larger, rougher cells of the labium majus gave the highest adherence scores matched only by the interaction of S. aureus with fully keratinised nasal epithelial cells. Increasing acidity to pH 3.5 enhanced microbial adherence to vaginal cells. Menstruation also influenced attachment; highest densities were reached between the third and fourth weeks of the cycle. Autogenous ribitol teichoic acid was found to block the attachment of S. aureus to labium majus and labium minus cells by 76% and 81% respectively, and to vaginal cells by 66%. Adherence is considered to be an important attribute of vulvar ecology and may be a determinant of infectious disease.

Adhesiveness↗
PubMed1979

Quantitative microbiology of human vulva.

The microbial flora of the vulva is described and compared with the flora of the forearm by utilizing the detergent scrub method. Microbial counts were higher on the vulva (2.8 x 10(6)/cm2) than on the forearm (6.4 x 10(2)/cm2). Lipophilic diphtheroids, coagulase negative staphylococci, micrococci, non-lipophilic diphtheroids and lactobacilli formed the dominant flora of the vulva. Streptococci, Gram negative rods and yeasts were also noted. The highest incidence of S. aureus was noted on the vulva (67%) followed by perianal (30%), nose (30%), and the forearm (11%).

Adult↗
PubMed1979

Comparative study on the antimicrobial effect of 0.5% chlorhexidine gluconate and 70% isopropyl alcohol on the normal flora of hands.

A gloved-hand wash method was used to compare the antimicrobial effect of chlorhexidine gluconate alcohol emollient hand wash (HIBISTAT) with that of 70% isopropyl alcohol on the normal flora of the hands (81 subjects) under conditions designed to mimic use by surgeons. Results of the immediate postwash effects on the bacterial counts for all 3 tests days showed that chlorhexidine significantly reduced the normal flora of the hands. When compared with the base line bacterial counts, there was 85, 96, and 98% reduction with chlorhexidine treatment and 84, 93, and 90% reduction with alcohol treatment on days 1,2, and 5, respectively. The difference between chlorhexidine and alcohol treatments was not statistically significant on days 1 and 2, but was significant on day 5 (P less than 0.01). For delayed postwash bacterial counts (for persistent antimicrobial effects), the overall log means were 4.9943 and 5.4684 for chlorhexidine and alcohol treatments, respectively. The difference between the two treatments was significant (P less than 0.01). After the chlorhexidien treatment, there was no significant growth of bacteria over a period of 6 h when compared with the base line bacterial counts.

1-Propanol↗
PubMed1979

Quantitation of skin bacteria: lethality of the wash solution used to remove bacteria.

A widely used technique for the quantitative removal of bacteria from the skin uses a detergent, Triton X-100 (p, t-octylphenoxynonaethoxyethanol), to remove and suspend the bacteria. We determined the half-life for the survival of five common skin bacteria suspended in the solution. The shortest-lived was Streptococcus pyogenes with a half-life of 0.9 hours. All of the others (Propionibacterium acnes, Staphylococcus epidermidis, Staphylococcus aureus, and Klebsiella pneumoniae) had half-lives of 1.5 hours or longer. K. pneumoniae, the only Gram-negative species tested, had a half-life of more than 30 hours. Thus, a one hour delay in plating and incubation of samples suspended in this detergent solution inhibits quantitation of most species tested.

Bacteria↗
PubMed1978

Effect of prolonged occlusion on the microbial flora, pH, carbon dioxide and transepidermal water loss on human skin.

The effects of prolonged occlusion on the normal microbial skin flora, pH, transepidermal water loss (TEWL) and carbon dioxide emission rate (CDER) were studied. The total average counts before occlusion were 1.8 X 10(2)/cm(2) and increased to 4.5 X 10(6) on day 5. The highest counts were noted on day 4(9.8 X 10(7)/cm(2)). The composition changed: controls comprised of 63% coagulase negative staphylococci, 6% micrococci, 17% diphtheroids and 6% bacilli. After 5 days of occlusion, the percent compositon was: 63% coagulase negative staphylococci, 11% micrococci, 4% diphtheroids, 19% lipophilic diphtheroids and less than 0.003% gram negative rods. The pH of the skin before occlusion was 4.38 and increased to 7.05 on day 5. After 5 days of occlusion TEWL increased from 0.56 mg/cm2/hr to 1.87 mg/cm2/hr and CO2 emmission increased from 25 nl/cm2/min to 118 nl/cm2/min.

Bacillus↗
PubMed1978

Quantification of anaerobic diphtheroids on the skin.

The widely used technique for sampling skin bacteria employs a detergent (Triton X-100) in buffer solution to remove and suspend the microorganisms. The fraction of the total population of anaerobes on the forehead removed by scrubbing with this solution was estimated. We calculated that approximately 10% of the resident anaerobes were removed by one minute of scrubbing with the detergent solution and two 1-min washes remove approximately 19.5% of the resident anaerobes (8.8 X 10(5)/CM2).

Acne Vulgaris↗
PubMed1977

Aerobic microbial flora of intertrigenous skin.

The incidence and density of intertrigenous microflora were determined in subjects using nonmedicated soap. The axilla, groin, toe web, and finger web were examined. The incidence of gram-negative rods was 17% for the axilla, 13% for the groin, 10% for the toe web, and 9% for the finger web. Klebsiella, Proteus, and Enterobacter were the predominant organisms, in that order. The highest incidence of Staphylococcus aureus was in the groin (12%) and toe web (11%). Lipophilic diphtheroids were the most prevalent bacteria in the groin (1.1 X 10(6)/cm2) and toe web (1.2 X 10(6)/cm2). Nonlipophilic diphtheroids were the predominant flora in the axilla (1.3 X 10(7)/cm. Micrococci had the highest counts in the toe web (7.6 X 10(5)/cm2). The incidence of coagulase-negative staphylococci was highest in the finger web, but the major flora were those of micrococci.

Acinetobacter↗
PubMed1977

Bacterial adherence to nasal mucosal cells.

The ability of several bacterial species to adhere to human nasal mucosal cells and their distribution on nasal mucosal surfaces was studied. Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pyogenes, and Pseudomonas aeruginosa adhered to scraped nasal mucosal cells. In contrast, viridans streptococci and Klebsiella pneumoniae exhibited feeble or no adherence to nasal mucosal cells. S. aureus affinity for the nasal mucosal cells of carriers of S. aureus was greater than for those of the noncarriers (P less than 0.005). Heat treatment of S. aureus did not block, but slightly reduced, its binding to mucosal cells. The data suggest a high degree of specificity involved in the adherence of bacteria to nasal mucosal cells. The greater affinity of S. aureus for the nasal mucosal cells of carriers (than noncarriers) seems to be a property of mucosal cells rather than bacteria.

Antigens, Bacterial↗
PubMed1977

Microbial flora of atopic dermatitis.

The microbial flora of dermatitic skin, uninvolved skin, and the anterior nares of subjects with atopic eczema were investigated. The carriage rate of Staphylococcus aureus was 79% for the anterior nares, 76% for the uninvolved skin (normal skin), and 93% for lesions. The counts of S aureus were 7.5 X 10(4)/sq cm in lesions and 7.1 X 10(3)/sq cm on adjacent normal skin. Staphylococcus aureus was the predominant organism in the lesions and constituted 91% of the total aerobic bacterial flora. The coagulase-negative staphylococci were the second predominant organisms (9%). On normal skin, coagulase-negative staphylococci were the predominant organisms, constituting 63% of the total flora, followed by S aureus (30% of the bacterial flora). The micrococci counts were lower in the lesions (1.6 X 10(2)/sq cm) and higher on normal skin (9.5 X 10(2)/sq cm). Lipophilic diphtheroids were fewer on normal skin (6.7 X 10/sq cm), and there were none in the lesions. Fifty-eight percent of the strains belonged to group 3, and 38% were nontypeable. Staphylococcus aureus strains belonging to phage groups 2 and 4 were not detected.

Adolescent↗
PubMed1976

Bacterial flora in psoriasis.

The aerobic bacterial flora of psoriatic plaques, uninvolved skin and the anterior nares of forty psoriatic patients was studied. The incidence od Staphylococcus aureus was 30% in the anterior nares, 20% on the plaques and 13% on the uninvolved skin. S. aureus counts were 3 x 10(2)/cm2 on the plaques and 1-5 x 10/cm2 on the normal skin. The total bacterial counts were also higher on plaques (7-9 x 10(3)/cm2) than on normal skin (3-0 x 10(3)/cm2). The incidence of lipophilic diphtheroids was significantly lower on the plaques (4%) than the normal skin (30%). Eighty percent of the strains of S. aureus isolated from psoriatic patients were resistant to 10 units of penicillin. Because of increased desquamation, psoriatic skin is a public health hazard.

Drug Resistance, Microbial↗