JOURNAL OF CLINICAL MICROBIOLOGY, Feb. 1987, p. 216-2210095-1137/87/020216-06$02.00/0Copyright ©D 1987, American Society for Microbiology

Diaper Area Skin Microflora of Normal Children and Children withAtopic Dermatitis

BRUCE H. KESWICK,* JON L. SEYMOUR, AND M. C. MILLIGANThe Procter & Gamble Company, Cincinnati, Ohio 45224

Received 7 July 1986/Accepted 16 October 1986

In vitro studies established that neither cloth nor disposable diapers demonstrably contributed to the growthof Escherichia coli, Proteus vulgaris, Staphylococcus aureus, or Candida albicans when urine was present as agrowth medium. In a clinical study of 166 children, the microbial skin flora of children with atopic dermatitiswas compared with the flora of children with normal skin to determine the influence of diaper type. Nobiologically significant differences were detected between groups wearing disposable or cloth diapers in termsof frequency of isolation or log mean recovery of selected skin fora. Repeated isolation of S. aureus correlatedwith atopic dermatitis. The log mean recovery of S. aureus was higher in the atopic groups. The effects of eachdiaper type on skin microflora were equivalent in the normal and atopic populations.

Previous studies of normal flora in children and adultshave demonstrated the variety and variability of microorga-nisms present on skin (15, 16, 19, 20). Factors such as

moisture, temperature, pH, and CO2 were demonstrated toinfluence the normal or endogenous flora. In young children,factors influencing the normal flora of skin covered by adiaper are of special interest because of the desire tomaintain healthy skin and the potential of diaper rash tobecome secondarily infected with bacteria or Candida albi-cans (3, 8, 15).

Since the endogenous microbial skin flora may provideprotection against colonization of potential pathogens likeStaphylococcus aureus (2), conditions which influence thegrowth and survival of normal flora microorganisms mayaffect colonization and disease production by pathogenicstrains.The skin flora of normal populations has been studied, but

it is also desirable to study other populations, since somegroups of individuals with altered skin conditions seem to bemore sensitive to specific organisms than those with normalskin. For example, individuals with atopic dermatitis werecolonized by S. aureus more frequently than individuals withnormal skin (3, 5, 10, 12, 13, 17). Certain cutaneous infec-tions are also more common in atopic populations (6, 12).Therefore, in studying changes in normal flora, this groupcan be viewed as a more sensitive population than the groupwith normal skin.The flora of diaper area skin has been studied; however,

the effects of diaper materials on the growth of microorga-nisms have not been reported. Diapers wetted with urine orsoiled with feces have abundant nutrients available for thegrowth of microorganisms on skin. The role of materialsused to make diapers as a nutrient source for microorga-nisms is not known.The purpose of this study was to learn more about the

microbiology of skin in the diaper area by comparing thegrowth of representative skin flora in diapers and by com-

paring the skin flora of children wearing three types ofdiapers. Specifically, areas which were addressed includewhether diapers support the growth of microorganisms,

* Corresponding author.

modify the balance of normal flora on the skin, or select forany of the major groups of organisms associated with cuta-neous or urinary tract disease. This was approached via aseries of in vitro tests followed by a prospective clinicalstudy of the occurrence of microorganisms on the diaperedand nondiapered skin of normal or atopic children.

MATERIALS AND METHODS

Culture media. For in vitro experiments, urine used asgrowth medium was collected from 10 children (1 to 4 yearsold), pooled, and filter sterilized through a 0.45-,um-poremembrane filter. The urine was kept frozen until use. Tryp-ticase soy agar (BBL Microbiology Systems, Cockeysville,Md.), mannitol salt agar (Difco Laboratories, Detroit,Mich.), tergitol-7 agar (BBL), and Sabouraud dextrose agar(BBL) supplemented with 0.05 g of gentamicin (SigmaChemical Co., St. Louis, Mo.) per liter and 0.05 g ofchloramphenicol (Sigma) per liter were used to enumeratetest organisms. For the clinical studies, Vogel-Johnson(Scott Laboratories, Inc. Fiskeville, R.I.), MacConkey(GIBCO Laboratories, Grand Island, N.Y.), and blood agarmedia (Scott Laboratories, Fiskeville, R.I.) were used inaddition to the Sabouraud dextrose agar supplemented withantibiotics.

Organisms. S. aureus ATCC E6538, Escherichia coliATCC E8739, Proteus vulgaris ATCC 33420, C. albicansATCC 10231, and Pseudomonas aeruginosa ATCC 9027were obtained from the American Type Culture Collection.Clinical isolates of S. aureus, C. albicans, and E. coli werealso utilized.

Diaper materials. Three types of commercially availablediapers were tested: a conventional disposable diaper with acellulose pulp core (Pampers or Huggies; Procter & GambleCo., Cincinnati, Ohio, or Kimberly-Clark, Neenah, Wis.,respectively), a disposable diaper with a cellulose pulp core

containing absorbent gelling material (AGM) (Ultra Pam-pers; Procter & Gamble), and a cotton cloth diaper (Curity;Kendall Co., Boston Mass.).Growth studies. In preliminary studies we examined

whether the diaper material itself could contribute to thegrowth of microorganisms. To do this, the growth of micro-organisms on diaper swatches was studied. Representative

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DIAPER SKIN MICROFLORA IN ATOPIC DERMATITIS 217

TABLE 1. Growth of microorganisms on diaper swatches

LogStarting CFUmLog10 changeinoculum Dipr incubationfrm0haOrganism (log1o Diaper time (h) fincubationCFU/ml) time (h):

5 24 5 24

C. albicans 3.5 None 3.9 7.2 0.5 3.6Disposable 3.9 6.8 0.5 3.3AGM disposable 4.1 6.9 0.6 3.5Cloth 3.9 7.7 0.4 4.2

S. aureus 4.3 None 4.8 8.0 0.5 3.7Disposable 5.0 7.8 0.7 3.5AGM disposable 4.2 6.9 -0.2 2.5Cloth 5.1 8.0 0.8 3.7

E. coli 3.4 None 4.1 8.9 0.7 5.5Disposable 4.6 9.3 1.1 5.9AGM disposable 4.3 8.9 0.8 5.6Cloth 4.3 9.1 0.8 5.6

P. vulgaris 3.6 None 3.7 7.8 0.2 4.5Disposable 4.0 8.3 0.4 5.1AGM disposable 3.8 8.6 0.3 5.4Cloth 3.6 7.5 0.0 4.3

Diaper swatches (diameter, 2 in. [5.08 cm]) were inoculated with the testorganisms suspended in urine at 10 times the volume per weight and incubatedfor either 5 or 24 h at 37°C. Values are the means of duplicate experiments.

organisms from the endogenous flora of the area covered bya diaper were selected for study because of their knowninvolvement in skin and urinary tract disease. Since orga-nisms do not usually exist as pure cultures in vivo, mixedcultures of the test organisms were also examined. Testorganisms were grown for 18 to 24 h on Trypticase soy agar,washed, and used to inoculate duplicate or triplicate 300-mlcultures at a density of 103 CFU/ml of urine. Diaperswatches (diameter, 2 in. [5.08 cm]) were inoculated withurine at 10 times the volume per weight and incubated withconstant shaking (200 rpm) at 37°C. After 5 and 24 h ofincubation, the swatches were homogenized in a blenderwith 150 ml of phosphate-buffered saline, and the homoge-nate was plated in duplicate on the appropriate selective andnonselective media. These incubation times represent atypical daytime and maximum practical wearing period fordiapers.

Clinical studies. A clinical study was conducted to confirmand extend results of the in vitro studies and to study theinfluence of diapers on the growth and occurrence of micro-organisms in vivo. Since it is not practical to identify everypossible or each individual isolate in samples in which thenumber of microorganisms may be as large as 108 CFU/cm2,a limited number of organisms associated with specificdisease states were chosen for study. These included C.albicans, E. coli, staphylococci, and streptococci. In addi-tion to skin covered by the diaper, an area on the abdomenapproximately 5 cm outside the diaper area on each childwas sampled for comparison. Permission was obtained fromparents of 90 normal, healthy participants as well as fromparents of 90 children satisfying diagnostic criteria for atopicdermatitis (11). In all, 166 subjects completed the study. Allchildren were less than 20 months of age. Other details of theprotocol are presented elsewhere (I. L. Seymour, B. H.Keswick, J. M. Hanifin, W. P. Jordan, and M. C. Milligan,submitted for publication). Children already wearing clothdiapers continued wearing cloth diapers during the test

period. The other children were randomly assigned to weareither conventional disposable or AGM disposable diapers.The investigators were unaware of the diaper type, as werethe participants. All children wore identical, commerciallyavailable disposable diapers for a minimum of 2 weeksbefore test product use. The study ran for a total of 30 weeksfrom April through November 1985. Eleven samples werecollected over the 30-week duration of the study at weeks 0,2, 4, 6, 8, 10, 14, 18, 22, 26, and 30.Samples were collected by a modified skin scrub tech-

nique with a cotton swab (9; B. H. Keswick, J. L. Seymour,F. C. Sarbaugh, L. C. Stone, and M. C. Milligan, Abstr.Annu. Meet. Am. Soc. Microbiol. 1986, C208, p. 362.). Aswab was wetted in 5 ml of Williamson-Kligman (22) bufferat pH 7.9 containing 0.01% Triton X-100. An area 24 mm indiameter delineated by a sterile glass cylinder was scrubbedfor 30 s. The swab was returned to the buffer, mixed, andheld at refrigerator temperature until plated within 30 min.The two areas sampled were the suprapubic area of theabdomen covered by a diaper and an area on the abdomenapproximately 5 cm outside the diaper area.Samples were mixed for 1 min before dilution and plating

with a mixer and spiral plater (Spiral Systems, Bethesda,Md.). C. albicans was confirmed by a germ tube test, E. coliby a spot indole test (18), S. aureus by a coagulase tube test,and streptococci by hemolysis and Streptex (WellcomeDiagnostics, Research Triangle Park, N.C.). Counts werecorrected for the dilution factor and reported as CFU persquare centimeter. Data were analyzed by chi-square test,Student's t test, or covariance analysis as previously de-scribed (21).

RESULTS

In vitro growth studies. The results showed that diapers donot contribute to the nutrient pool of the diaper area orenhance the substrate surface. At 24 h, from an initialinoculum of approximately 103, chosen as representative ofthe inoculum size under natural use conditions, the growthof each organism in diaper-containing cultures was similar togrowth detected in control cultures medium alone (Table 1).

a0demais (58.1%) w Atopic Dermatitisc

00

square, P < 0.05) more likely to carry S. aureus than were normalcontrol subjects. The percentage of each group is indicated abovethe bars.

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TABLE 2. Log mean count of organisms isolated from skin

Log mean county (CFU/cm2)Beta- GopD Viridans Coagulase- Non-E. Gram-neg-Diaper type- Total plate etstrepto- group C.aVbi-

S. aureus negative E. coli coli lactose ative non-subject count strepto- cocci strepto- cans staphylococci fermenters fermenters

cocci cocci

Outb In' Out In Out In Out In Out In Out In Out In Out In Out In Out In

AGM-atopicLog meand 2.5§ 4.3t§ 0.0 0.4' 0.1 0.7 0.1 0.5 0.0 0.0 0.1 0.4' 2.0t 3.8*§ 0.0 0.0 0.0 0.0 0.1 0.1*SD 0.8 0.8 0.2 0.5 0.2 0.9 0.2 0.5 0.0 0.1 0.2 0.5 0.8 0.9 0.0 0.1 0.1 0.1 0.1 0.2Maximume 5.6 7.1 3.3 3.3 3.3 5.4 3.9 4.6 0.0 2.1 3.5 4.5 5.8 6.2 0.0 2.4 1.3 2.5 2.5 4.4

AGM-normalLog mean 2.1*11 3.511 0.0 0.2" 0.1 0.4 0.1* 0.3 0.0 0.0 0.0 0.1 1.5" 2.8`11 0.0 0.0 0.0 0.0 0.1 0.2SD 0.7 1.3 0.0 0.4 0.2 0.8 0.1 0.5 0.0 0.0 0.0 0.3 0.8 1.4 0.0 0.1 0.1 0.1 0.1 0.4Maximum 4.8 6.5 0.0 3.3 4.2 4.8 2.4 4.7 1.6 0.0 1.8 3.4 5.2 6.2 0.0 4.2 2.8 2.2 3.5 6.0

Disposable-atopicLog mean 2.9 4.8 0.0 0.5 0.1 0.7 0.2 0.6 0.0 0.0 0.1 0.4 2.3 4.4 0.0 0.0 0.0 0.0 0.1 0.2*SD 0.6 0.6 0.1 0.5 0.2 0.7 0.2 0.5 0.1 0.0 0.2 0.4 0.7 0.7 0.0 0.1 0.1 0.1 0.2 0.3Maximum 6.2 6.9 3.3 3.3 3.3 6.3 4.3 3.8 1.3 1.8 3.3 5.3 6.0 6.5 1.3 3.0 1.3 2.7 2.6 6.0

Disposable-normalLog mean 2.8* 4.7* 0.0 0.5* 0.1 0.6 0.1 0.6 0.0 0.0 0.0 0.2 2.3* 4.3t 0.0 0.0 0.0 0.0 0.1 0.0SD 0.6 0.7 0.1 0.5 0.2 0.6 0.2 0.5 0.0 0.1 0.0 0.3 0.7 0.7 0.0 0.1 0.1 0.0 0.1 0.1Maximum 5.9 6.7 3.3 3.3 3.3 4.8 3.3 4.4 0.0 2.9 1.3 4.3 6.0 6.7 0.0 3.0 1.3 1.6 1.8 2.4

Cloth-atopicLog mean 2.7 4.5 0.0 0.4 0.1 0.7 0.1 0.5 0.0 0.0 0.1 0.3 2.2 4.3* 0.0 0.0 0.0 0.1 0.1 0.3SD 0.6 0.4 0.1 0.4 0.4 0.8 0.2 0.4 0.1 0.1 0.3 0.7 0.7 0.5 0.1 0.1 0.1 0.2 0.2 0.4Maximum 5.6 6.6 3.3 3.3 3.3 5.1 4.1 5.3 2.3 3.9 4.7 4.4 5.5 6.1 1.3 1.6 1.9 3.1 2.3 6.0

Cloth-normalLog mean 2.5 4.2 0.0 0.3 0.1 0.7 0.2 0.5 0.0 0.0 0.0 0.1 1.8 3.8 0.0 0.0 0.0 0.0 0.0 0.2SD 0.6 0.7 0.0 0.4 0.1 0.6 0.2 0.6 0.0 0.1 0.0 0.2 0.6 0.8 0.0 0.0 0.1 0.1 0.1 0.3Maximum 5.0 7.1 0.0 0.3 2.4 5.4 4.2 5.0 1.3 2.3 0.0 5.3 4.9 6.3 1.9 1.3 1.3 1.3 3.5 6.0a Specific comparisons made by Student's t test: AGM-atopic versus AGM-normal; disposable-atopic versus disposable-normal; cloth-atopic versus cloth-

normal; AGM-atopic versus disposable-atopic; AGM-atopic versus cloth-atopic; disposable-atopic versus cloth-atopic; AGM-normal versus disposable-normal;AGM-normal versus cloth-normal; disposable-normal versus cloth-normal. Symbols denote statistical significance (P < 0.05) as compared with the indicateddiaper type-subject: *, cloth-atopic; t, normal subjects using the same product; 1, cloth-normal; §, disposable-atopic; Il, disposable-normal.

b Out, Outside the diaper area.C In, Inside the diaper area.d Calculated from the mean count of each of the sample periods while on test product.e In any sample.

Significant growth in test cultures was determined by com-

parison of the 95% confidence intervals for the test andcontrol cultures. At 5 h none of the diaper-containing cul-tures had growth 10-fold greater than the control culture(medium alone). There was a difference in response by thevarious organisms. For example, the gram-negative bacteria,E. coli and P. vulgaris grew most readily, whereas C.albicans and S. aureus grew the least, possibly reflectingtheir basic nutritional requirements. S. aureus also had adifferential response in the various diaper types tested; inAGM diapers S. aureus growth was consistently less than itwas in other diaper types.

In mixed cultures of E. coliand S. aureus or S. aureus andC. albicans, the growth of each organism was similar to thatdetected in single cultures; no growth-potentiating interac-tion was detected.

Clinical study. Summary data of the overall frequency ofisolation of each organism recovered from the diaper areawere derived by calculating the mean of the weekly meanfrequencies. Staphylococcus epidermidis (75.5 to 96.2%)was the most frequently recovered organism, whereas groupD streptococci (11.9 to 21.6%), viridans group streptococci

(8.9 to 14.0%), beta-hemolytic streptococci (4.3 to 11.7%), S.aureus (4.2 to 10.8%), C. albicans (O to 1.2%), E. coli (0.3 to1.1%), non-E. coli fermenters (0.6 to 3.0%), and gram-negative nonfermenters (2.5 to 11.4%) were recovered lessfrequently in the samples from the diaper area. Variations inthe frequency of isolation of some organisms were observedweekly between diaper groups, but since they were due tosmall differences in the numbers of isolates (often only oneor two), they were not considered biologically significant,even though statistically significant (P < 0.05) differencescould be demonstrated with the Newman-Keuls multiplecomparison test. Notably, C. albicans, an important orga-nism in diaper dermatitis, was isolated infrequently from theskin. In a separate culture survey, C. albicans was detectedin the stools of 52 of 168 (31%) of the subjects on week 26. C.albicans was not isolated from the skin of any subject thesame week.There was a significant difference (chi square, P < 0.025)

between subjects with atopic dermatitis and normal controlsubjects in the frequency of isolation of S. aureus. S. aureuswas isolated at least once from 60% of the atopic subjectsand 42% of the normal control subjects. Subjects with atopic

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TABLE 3. Covariance analysis of selected microorganisms at each sample period

Adjusted group count mean (log CFU/cm2) at week:Diaper type-subject4b 6 8 10 14 18 22 26 30

Total plate countAGM-atopic 3.9 4.0§ 3.8§ 4.0§ 4.3'5 4.6' 4.4' 4.6' 4.7AGM-normal 3.9 3.3t' 3.61" 4.211 3.711 3.2*11 3.611 3.5 3.7"Disposable-atopic 3.9 4.8 4.9 4.6 4.9 4.8 4.8 4.5 4.8Disposable-normal 3.9 4.8 4.5 4.8 5.0k 4.4 4.6 4.3 5.0Cloth-atopic 3.9 43 4.3 4.2 4.7 4.8 4.7t 4.0 4.6Cloth-normal 3.9 4.2 4.0 4.6 4.3 4.3 3.9 4.3 4.3

Coagulase-negative staphylococciAGM-atopic 3.4 3.s*§ 3.3§ 3.7§ 4.1§ 4.Ot 4.t 3 .7t 4.0AGM-normal 3.4 2.5t' 3.01" 3.511 3.511 2.7*1k 2.7*1' 2.6*11 3.4"Disposable-atopic 3.4 4.5 4.5 4.4 4.9 4.3 4.6 3.7 4.3Disposable-normal 3.4 4.5k 4.2 4.5 4.5 3.8 4.1 3.5 4.4Cloth-atopic 3.4 4.4 3.8 4.0 4.5 4.5t 4.4t 3.5 4.1Cloth-normal 3.4 3.7 3.7 4.2 4.0 3.7 3.5 3.6 4.0

C. albicansAGM-atopic 0.0 0.0 0.0 0.0 0.1 0.0 0.0 0.0 0.0AGM-normal 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0Disposable-atopic 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.1 0.0Disposable-normal 0.0 0.0 0.0 0.0 0.2 0.1 0.0 0.0 0.0Cloth-atopic 0.0 0.0 0.1 0.0 0.2 0.0 0.0 0.0 0.0Cloth-normal 0.0 0.1 0.0 0.0 0.1 0.0 0.0 0.0 0.0

S. aureusAGM-atopic 0.1 0.4 0.2 0.1 0.5 0.2 0.6*t§ 0.6* 0.5AGM-normal 0.1 0.1 0.0 0.0 0.1 0.2 0.0 0.2 0.4Disposable-atopic 0.1 0.2 0.0* 0.1 1.1 0.3 0.4 0.5 0.5Disposable-normal 0.1 0.0 0.0 0.1 0.8 0.1 0.0 0.2 0.6Cloth-atopic 0.1 0.3 0.4t 0.0 0.5 0.1 0.2 0.0 0.3Cloth-normal 0.1 0.1 0.0 0.0 0.6 0.0 0.1 0.0 0.2a Specific comparisons made by Student's t test: AGM-atopic versus AGM-normal; disposable-atopic versus disposable-normal; cloth-atopic versus cloth-

normal; AGM-atopic versus disposable-atopic; AGM-atopic versus cloth-atopic; disposable-atopic versus cloth-atopic; AGM-normal versus cloth-normal;disposable-normal versus cloth-normal. Symbols denote statistical significance (P < 0.05) as compared with the indicated diaper type-subject: *, cloth-atopic; t,normal subjects using the same product; $, cloth-normal; Î, disposable-atopic; ", disposable-normal.

b Base line.

dermatitis differed significantly from normal subjects on 3 ofthe 11 sample periods for S. aureus and 4 of the 1i sampleperiods for coagulase-negative staphylococci. Repeated iso-lations of S. aureus from skin inside the diaper area of thesame individual correlated (r = 0.96) with atopic dermatitis(Fig. 1). Only 48% of subjects with one S. aureus isolationwere atopic, while 67% of those with three isolations and allsubjects with four or more isolations of S. aureus wereatopic. A similar trend was detected in S. aureus isolationsfrom samples outside the diaper area. Isolation rates fromatopic and normal subjects differed for other organisms aswell, but the differences were small. The isolation frequen-cies of organisms in samples obtained from outside thediaper area were similar among the six groups.The overall log mean plate count and range (maximum

value) of each organism are shown in Table 2. It ranged fromundetected (<2 x 101) to 7.1 log CFU/cm2. Test groups werecompared by using Student's t test (21). Statistically signif-icant differences (P < 0.05) are shown in Table 2.

Overall, counts of each organism isolated from the six testgroups were similar. At specific weeks, counts of selectedmicroorganisms were compared with the method ofcovariance analysis (21). This technique attempts to correctfor differences in group means at base line by predicting themean microorganism count of each group if each group hadstarted at exactly the same count. The results ofthe analyses

were adjusted (to a common overall base line) means asshown in Table 3. The adjusted group means were com-pared, taking into account the respective standard errors, todetermine whether statistically significant differences ex-isted at the 95% confidence level (P < 0.05). For example, inseven of the eight sample periods during test product use,total plate counts were significantly lower in the AGM diapergroup than in the cloth diaper group or the disposable diapergroup. Results for the most frequently isolated organism,coagulase-negative staphylococci, were similar. C. albicans,S. aureus, and others exhibited fewer differences. Since inall cases the difference was less than 2 log CFU/cm2 andwithin the normal range reported for skin, it was not consid-ered biologically significant. In general, the atopic groupswere similar to the normal groups in the overall number oforganisms on the skin, but the numbers of some specificorganisms varied. For S. aureus, the log mean recovery washigher in the atopic group than in the normal groups, but thedifferences were small. Individuals with the highest isolationfrequency did not necessarily have the highest counts of S.aureus. Log mean counts of coagulase-negative staphylo-cocci were lower in the AGM diaper group than in otherdiaper groups.

For comparison, à sample was also collected from outsidethe area covered by the diapér (Table 2). As expected, thetotal plate count outside the diaper area was lower than that

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220 KESWICK ET AL.

in the diaper area. This was true in general for otherorganisms but not for each individual subject, as someorganisms were recovered only from outside the diaper area.

DISCUSSION

The effects of three types of diapers on the microflora ofthe skin were evaluated. In these studies, the disposable andcloth diapers examined were equivalent in their effects onmicrobial growth in vitro. It is evident from these studiesthat diaper materials have little effect on the growth ofmicroorganisms in vitro. The in vitro results were confirmedby the clinical study results, which demonstrated no effect ofindividual diaper types on the normal microbial flora. Cloth,disposable, and AGM disposable diapers generally did notdiffer significantly in their ability to promote the growth ofmicroorganisms on skin, to select for any particular orga-nism, or to significantly alter the balance of microflora.As indicated, the in vitro growth studies demonstrated

that diapers themselves do not contribute to the growth ofmicroorganisms. In contrast, urine and feces clearly sup-ported growth as expected, given the nutrient capacity ofurine and feces. The growth of organisms under ideal con-ditions in vitro is considerably greater than that found onskin in vivo and so must be interpreted with caution. It canbe predicted that in vivo it is likely that even if there were acontribution from the diaper, it would be overwhelmed bythe contribution from urine or feces. Furthermore, based onthe in vitro data, it is unlikely that materials with minimalnutrient capacity, as in diapers, contribute to the growth andsurvival of microorganisms in the diaper area.

Since urine is a good nutrient for many microorganisms,diapers that keep nutrients away from skin are less likely tocontribute to microbial growth on skin. Disposable diapershave been found to be superior to cloth diapers in this regard(4, 7, 14, 14a, 23).

Multiple recovery of S. aureus from the skin of atopicchildren suggests that staphylococcal colonization may in-clude some infants with atopic dermatitis. In this study, onlyuninvolved skin was sampled, and relatively few subjectswere consistently colonized with S. aureus. Additionally,the children in this study, although satisfying criteria foratopic dermatitis (11), did not necessarily have active der-matitis at the time the samples were taken. This explains thelow frequency of recovery compared with the 75 to 100%rates previously reported (2, 5, 10, 12, 13, 17). Since dry skinis characteristic of atopic dermatitis, the hydrated area underthe diaper is often the most normal skin in atopic children. Inthis study, little difference in the colonization of skin wasdetected between diaper groups, except for the multipleisolation of S. aureus from some individuals with atopicdermatitis. Additionally, subjects with atopic dermatitiswere significantly more likely to carry S. aureus than normalcontrol subjects were. Overall, there was no difference in thenumber and type of microorganisms isolated from the diapergroups. The relationship of diaper type to rash and atopyevaluation is presented elsewhere (Seymour et al., submit-ted). The factors which control the colonization of atopicskin by S. aureus remain poorly understood and are worthyof further study.

It has been reported that the number of individual orga-nisms on skin is important. For example, Leyden et al. (17)established that 106 CFU of S. aureus per cm2 of skinindicates a secondary infection of dermatitic skin. Since onlytwo samples had S. aureus counts of -106/cm2 and thoseoccurred in subjects with atopic dermatitis at the initial

pretest visit, it is clear that none of the diapers examined inthis study significantly contributed to an increase in the S.aureus counts to the levels necessary for infection.We established that diapers neither support the growth of

microorganisms in the presence of urine nor select for any ofthe major groups of pathogens associated with cutaneous orurinary tract disease. Additionally, the diapers tested did notalter the balance of flora on the skin. The use of diaperswhich keep skin drier results in numbers of organisms closerto those of undiapered skin. We also confirmed that youngchildren with atopic dermatitis have a greater frequency ofS. aureus carriage than do children with normal skin.

ACKNOWLEDGMENTS

We thank Hilltop Research lnc., Miamiville, Ohio, for providingthe facilities and staff for this study; S. Glenn, University Hospital,Cincinnati, Ohio, for assistance with the microbiology laboratory;and D. Frank for technical assistance and F. C. Sarbaugh for datamanagement and analysis.

LITERATURE CITED1. Aly, R., H. I. Maibach, and H. R. Shinefield. 1977. Microbial

flora of atopic dermatitis. Arch. Dermatol. 113:780-782.2. Aly, R., H. 1. Maibach, H. R. Shinefield, A. Mandel, and W. G.

Strauss. 1974. Bacterial interference among strains of Staphylo-coccus aureus in man. J. Infect. Dis. 129:720-724.

3. Beare, J. M., E. A. Cheesman, and W. F. MacKenzie. 1968. Theassociation between Candida albicans and lesions of seborrheicdermatitis. Br. J. Dermatol. 80:675-681.

4. Berg, R. W., K. W. Buckingham, and R. L. Stewart. 1986.Etiologic factors in diaper dermatitis: the role of urine. Pediatr.Dermatol. 3:102-106.

5. Bibel, D. J., J. H. Greenberg, and J. L. Cook. 1977. Staphylo-coccus aureus and the microbial ecology of atopic dermatitis.Can. J. Microbiol. 23:1062-1068.

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