Biomedical subjects
Publications and source records attributed to R Aly.
The effect of occlusion on the cutaneous microbial flora in patients with atopic dermatitis and psoriasis was measured. Significant increases in the density of Staphylococcus aureus and lipophilic diphtheroids were noted after occlusion in eczematous and psoriatic skins. While the incidence of S. aureus increased in psoriatic skin after occlusion, this trend was not noted in dermatitic skin.
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The role of teichoic acid in the adherence of Staphylococcus aureus to nasal epithelial cells was investigated. Epithelial cells treated with teichoic acid demonstrated decreased binding of S. aureus. A 71% reduction of adherence was noted with teichoic acid-treated epithelial cells as compared with controls (P less than 0.001). Reduction in adherence of S. aureus was also noted with lipoteichoic acid (obtained from streptococci)-treated epithelial cells. The data provide evidence that teichoic acid mediates the adherence of S. aureus to nasal mucosal cells.
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A total of 1,101 patients was studied for the incidence and distribution of dermatophytes in the San Francisco Bay Area from 1974 to 1978. 267 dermatophytes were isolated and identified. Trichophyton rubrum and Trichophyton tonsurans were the most prevalent dermatophytes. T. rubrum caused 83% of tinea pedis, 82% of tinea unguium, 80% of tinea manuum and 66% of tinea cruris. T. tonsurans was the major cause of tinea capitis (60%) followed by Microsporum canis. Microsporum audouinii was not encountered in this survey.
A new vehicle preparation has proved effective in enhancing the penetration of antibiotics. The vehicle seems to maintain stability of the incorporated antibiotic.
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%).
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.
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.
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.
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).
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.
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.
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.
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.
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The qualitative and semiquantitative changes in the aerobic microbial flora of normal skin with the prolonged use of a chlorhexidine scrub (6 months) were investigated. More samples in the chlorhexidine scrub group had gram-negative bacilli in their axilla (63 of 96, 66%) and groin (36 of 96, 38%) than the controls (32 of 66, 49%, for axilla and 7 of 66, 11%, for groin; P = 0.01). Klebsiella and Enterobacter were the predominant organisms in the control and chlorhexidine groups, respectively. The chlorhexidine scrub produced a reduction in the total aerobic counts in the axilla, groin, and between the toes and the fingers. Fewer samples from the chlorhexidine-treated areas revealed the presence of lipophilic diphtheroids than did the controls. Lipophilic diphteroids were also reduced quantitatively in the groin and axilla with chlorhexidine treatment. No consistent pattern for the other major groups of bacteria was noted between the treatments.
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