Skin flora varies from one site of the body to another. Individual's health, age and gender determine the type and the density of skin flora. A 1  cm² of the skin on the sternum was rubbed with sterile cotton swab socked in 0.9% normal saline and plated on blood agar. This was cultured at 35 °C. The bacteria were identified by culturing on MacConkey agar, coagulase test, catalase test and gram staining. Swabs were obtained from 66 individuals affected by albinism and 31 individuals with normal skin pigmentation. Those with normal skin were either relatives or staying with the individuals affected by albinism who were recruited for the study. The mean age of the 97 recruited individuals was 30.6 (SD ± 14.9) years. The mean of the colony forming units was 1580.5 per cm2. Those affected by albinism had a significantly higher mean colony forming units (1680  CFU per cm²) as compared with 453.5  CFU per cm² in those with normally pigmented skin (p = 0.023). The skin type and the severity of sun- damaged skin was significantly associated with a higher number of colony forming units (p = 0.038). Individuals affected by albinism have a higher number of colony forming units which is associated with sun- damaged skin

Baraka M Chaula

Bernard Naafs

EA Grice

EL Larson

HH Kong

J Faergemann

JJ Leyden

John E Masenga

KK Hanneman

LF Borges

N Fierer

RR Marples

Samson K Kiprono

V Thamlikitkul

WC Noble

BMC Dermatology

Springer - Publisher Connector

Kiprono et al. BMC Dermatology 2012, 12:12
http://www.biomedcentral.com/1471-5945/12/12RESEARCH ARTICLE Open AccessSkin flora: Differences between people affected
by Albinism and those with normally pigmented
skin in Northern Tanzania – cross sectional study
Samson K Kiprono1*, John E Masenga1†, Baraka M Chaula1† and Bernard Naafs1,2Abstract
Background: Skin flora varies from one site of the body to another. Individual’s health, age and gender determine
the type and the density of skin flora.
Methods: A 1 cm2 of the skin on the sternum was rubbed with sterile cotton swab socked in 0.9% normal saline
and plated on blood agar. This was cultured at 35°C. The bacteria were identified by culturing on MacConkey agar,
coagulase test, catalase test and gram staining. Swabs were obtained from 66 individuals affected by albinism and
31 individuals with normal skin pigmentation. Those with normal skin were either relatives or staying with the
individuals affected by albinism who were recruited for the study.
Results: The mean age of the 97 recruited individuals was 30.6 (SD ± 14.9) years. The mean of the colony forming
units was 1580.5 per cm2. Those affected by albinism had a significantly higher mean colony forming units
(1680 CFU per cm2) as compared with 453.5 CFU per cm2 in those with normally pigmented skin (p = 0.023). The
skin type and the severity of sun- damaged skin was significantly associated with a higher number of colony
forming units (p = 0.038).
Conclusion: Individuals affected by albinism have a higher number of colony forming units which is associated
with sun- damaged skin.
Keywords: Skin flora, Albinism, AfricanBackground
Human skin microbiome refers to entire collection of
microbes which include bacteria, archaebacteria, fungi,
virus and mites [1]. The type and the number of skin
microbiomes vary from one individual to another and
from one site of the body to another [2,3]. Cultures and
molecular analysis are used to identify the microbial
inhabitants of the skin. Culture based methods are essen-
tial in isolating and identifying viable cutaneous
microbes such as bacteria. However, some bacteria have
factitious growth requirements and are therefore difficult
to isolate [1]. Microbial genomics such as pyrosequen-
cing is used to examine the entire complex microbial
inhabitants [1]. The skin is one of the most important* Correspondence: kipsam2@yahoo.com
†Equal contributors
1Department of Dermatology, Regional Dermatology Training Center, Box
8332, Moshi, Tanzania
Full list of author information is available at the end of the article
© 2012 Kiprono et al.; licensee BioMed Centra
Commons Attribution License (http://creativec
reproduction in any medium, provided the orreservoirs of hospital acquired infections [3]. However,
the skin is also regarded as a major protection barrier
against invasion by various microorganisms through
different mechanisms including the normal skin micro-
biome. There is both an intrapersonal and an interper-
sonal variation in skin microbiota. Bacterial colonization
depends on the physiology of the site sampled with hu-
midity and sebaceous environment influencing the type
of bacteria [2]. Interpersonal variation depends on intrin-
sic factors such as the individual’s state of health, age
and sex [4-6] and extrinsic factors such as clothing, hy-
giene, humidity and occupation [1,2]. There are few
studies on skin flora and most of these studies involved
patients and medical personnel [7,8]. The majority of
studies on skin flora were done on Caucasians and to
our knowledge no study has been reported in Africans
with normal skin pigmentation and those affected by al-
binism. Those affected by albinism living in the tropicsl Ltd. This is an Open Access article distributed under the terms of the Creative
ommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and
iginal work is properly cited.
Kiprono et al. BMC Dermatology 2012, 12:12 Page 2 of 4
http://www.biomedcentral.com/1471-5945/12/12are at high risk of developing skin tumors and therefore,
have to undergo many surgical interventions. It was
noticed that infected wounds were encountered more
often in those affected by albinism than those who were
not. Identification, qualification and quantification of
skin flora may help in the preoperative antiseptic mea-
sures in these patients. Therefore, the objective of this
study was to determine and to compare the normal aer-
obic bacterial skin flora in Africans affected with Albin-
ism with those with normally pigmented skin.Materials and methods
Setting and sample
This study was conducted in eight of the Regional
Dermatology Training Center Albino outreach clinics.
Most of them served farmers. The study was approved
by the Tumaini University Research and Ethics com-
mittee and conducted according to the guidelines by
the committee. Sixty-six individuals affected with Al-
binism and 31 individuals with normally pigmented
skin (ratio of 2:1) were recruited for the study. Those
with ulceration, abscesses or other skin diseases were
excluded.Table 1 A comparison of characteristics of Albinos and
those with pigmented skin
Albino Pigmented P value
N= 66 N=31
Age in years (mean) 28.6 34.8 .057†
Gender (Female) 33(50) 17(54.8) .662*
Bathing within 12 hours 49(74.2) 25(80.5) .523*
Medicated soap 12(18.2) 8(25.8) .412*
Daily bathing 54(81.9) 21(67.7) .843*
Changing clothes daily 38(57.6) 20(64.5) .518*
Pustules in previous month 6(9.1) 1(3.2) .424∞
Skin sun damage 34(51.5) 0 .000∞
*Chi-square test.
†Independent samples t test.
∞Fisher’s Exact test.Procedure
A structured questionnaire was used to collect data on
the demographics and possible factors influencing the
skin flora. The pre-sternal area 4 cm below the sterno-
clavicular joint, which is exposed and easily accessible,
was used as site for sample collection. The sample col-
lection area was mapped using an aluminum squared
rim with a total free area of 1 cm2. The squared rims
were cleaned with 70% alcohol for three minutes and
left to dry before being reused. The samples were col-
lected using a sterile cotton swab, moistened with ster-
ile 0.9% sodium chloride. A five stroke swabbing was
done with a clockwise movement with a pressure simi-
lar to that of a pencil eraser. All samples were col-
lected by the same individual. The swab was placed in
a tripticase soy broth transport media and plated
within 4 hours on blood agar. The blood agar plates
were incubated at 35 °C and examined at 24- and 48
hours and the bacterial colonies were identified using
standard procedures and recorded as colony forming
unites (CFU) per cm2. CFU/cm2 is used as a measure
of the number of microorganisms present on the sur-
face of the sample. Culture on MacConkey agar, coagu-
lase test, catalase test and gram stain were used to
classify aerobic bacteria and identify staphylococcus,
streptococcus, gram-negative cocci and bacilli, which
may be potentially pathogenic. Anaerobes were not
looked for.Data analysis
A statistical package for social scientists (SPSS Chicago
Inc.) software was used for data analysis. A descriptive
analysis was done to characterize the sample, while chi-
square, Fisher’s Exact test and t-test were used to deter-
mine the association between variables depending on the
sample size or for comparing the means. Sun damage
was classified as absent (none and mild erythema) and
present (moderate and severe erythema). Assessment of
erythema in Black Africans is difficult, especially distin-
guishing between no erythema and mild erythema.
Therefore, both were grouped into the group without
sun damage. The cut-off for considering the CFU/cm2 as
low or high was set at 600 CFU/cm2 similar to that
reported in other studies [4,5]. All statistical analysis
were 2-tailed and considered significant at p < 0.05.
Results
A total of 97 individuals of whom 50 (51.5%) were
females giving a male to female ratio of 1:1.1 were
included in this study. Their mean age was 30.6 years
SD± 14.9 and a median of 30 years (range 5-77 years).
Seventy-four (76.2%) individuals had bathed not more
than12 hours earlier and 20 (20.6%) individuals had used
medicated soaps. The mean age of Albinos was 28.6 years
(SD± 13.8) and was 34.8 years (SD± 16.5) for those with
normally pigmented skin. This difference was not statis-
tically significant (p = 0.057). Sun damage was found to
be statistically different between the two groups as
shown in Table 1.
The mean CFU for the combined population was
1580.5 CFU/cm2 (SD± 30294). The mean CFU in indivi-
duals with normally pigmented skin was 453.5 CFU/cm2
(SD± 1795) and 1680 CFU/cm2 (SD± 35596 in those
affected by albinism. This difference was statistically sig-
nificant (p = 0.023). A bivariate analysis showed that skin
type and sun- damaged skin was significantly (p = 0.038)
Kiprono et al. BMC Dermatology 2012, 12:12 Page 3 of 4
http://www.biomedcentral.com/1471-5945/12/12associated with high number of colony forming units
(more than 600 CFU/cm2) as shown in Table 2. Sun
damage was still a significant factor (p = 0.046) for high
number of colony forming units when analysis is done
for albino group.
The cultures of the 97 samples showed Coagulase
negative staphylococcus in 94.8%, whereas Coagulase
positive staphylococcus was found in 13.4% of the sam-
ples. Gram negative bacteria (28.9%), Bacillus spp
(22.7%), α-hemolytic streptococcus (5.2%) and β-
hemolytic streptococcus (3.1%) were also isolated.Discussion
The characteristics of the study groups were similar
except for the sun damage. The mean CFU/cm2 for
the African population in this study was significantly
higher than that in most reported studies. Larson et al
[5] reported a significantly higher number of colony
forming units among African Americans. The variation
may be because of external factors like humidity, wea-
ther conditions, type of clothing and the level of hy-
giene, which has been reported to influence bacterial
skin colonization [9].Table 2 Bivariate analysis of factors associated with High
CFU (>600 CFU/cm2)
Characteristic Total High CFU p value
Age
16 years and younger 19(19.6%) 6(31.6%) .600*
Older than 16 years 78(80.4%) 25(32.1%)
Type of skin
Albino 66(68%) 27(40.9%) .006†
Pigmented skin 31(32%) 4(12.9%)
Gender
Male 47(48.5%) 15(31.9%) .593*
Female 50(51.5%) 16(32.0%)
Type of employment
Medical 2(2.1%) 1(50.0%) .539†
Non-medical 95(97.8%) 30(31.6%)
Bathing within 12hours
Yes 70(72.2%) 22(31.4%) .520*
No 27(27.8%) 9(33.3%)
Type of soap
Medicated 20(20.6%) 5(25.0%) .322*
Non-medicated 77(79.4%) 26(33.8%)
Sun damage
Absent 63(65.0%) 14(22.2%) .005*
Present 34(35.0%) 17(50%)
*Chi-square test.
†Fisher’s Exact test.The mean number of CFU/cm2 in individuals affected
with albinism was statistically higher than those in indi-
viduals with normally pigmented skin. The differences in
the study populations in recent studies [4,5] make it dif-
ficult to compare the results with the results of this
study. For instance, the mean number of CFU/cm2 in
normally pigmented skin (453.5 CFU/cm2) was higher
than the 320 CFU/cm2 among patients in Thailand [4],
but the median was similar.
Leyden et al [8] in USA reported that the density of
the micro-flora on the dry areas of the skin including the
sternum ranged from 103-104 CFU/cm2 ,which is similar
to our findings in the normally pigmented skin, but
lower than that in individuals affected by albinism. Sun
damage was significantly associated with a higher num-
ber of colony forming units. Ultra-violet (UV) light is
known to be bactericidal [10] and therefore, it is
expected that bacterial colonization would be lower in
regions close to the equator. The bactericidal effect may
be counteracted by the immunosuppressive effect of UV
light on the local and systemic immunity [11]. Sun-
damaged skin loses the barrier function increasing the
susceptibility to colonization by bacteria. However, nei-
ther the skin barrier function nor the antimicrobial pep-
tides (AMPs) were assessed in this study. Sun- damaged
skin is often slightly thickened and not entirely smooth
providing areas of invaginations that act as reservoirs
where bacteria flourish and from which the skin surface
is re-colonized [1].
Bathing and the use of antimicrobial soap had no stat-
istical influence on the number and the density of CFU/
cm2. Larson et al [12] reported that hand washing and
the use of antimicrobial soaps was associated with a
slight reduction in the number of CFU/cm2, but that no
individual was free of organisms. Single use of antimicro-
bial soaps, duration of bathing and the frequency of
bathing may influence re-colonization [13]. Moreover,
the use of antimicrobial soaps may even damage the nor-
mal barrier function of the skin.
Staphylococcus was the commonest microorganism
isolated, which concurs with other studies, which
reported staphylococcus to be present in more than 90%
of the samples [4,5]. However, gram- negative bacteria
were present in more (28.5%) samples than that reported
by Larson et al [4] among inpatient (9.2%) and outpati-
ents (17.2%).Conclusion
In Africa, individuals affected by albinism have a higher
density of skin micro-flora than the normally pigmented
African population. Staphylococcus is the most common
organism isolated. However, there is relatively more
colonization with gram- negative bacteria. The impact of
Kiprono et al. BMC Dermatology 2012, 12:12 Page 4 of 4
http://www.biomedcentral.com/1471-5945/12/12these results on bacterial skin infections and surgical site
infection needs further investigation.
Competing interests
The authors declare that they have no competing interests.
Authors’ contribution
SK and BC made substantial contribution in the concept and the study
design, collection, analysis and interpretation of the data and drafting of the
manuscript, whereas JM and BN contributed in the concept and the design,
data interpretation and critical revision of the manuscript with regards to the
intellectual content. All authors read and approved the final manuscript.
Acknowledgement
Dr B. Tank is thanked for correcting the English.
Author details
1Department of Dermatology, Regional Dermatology Training Center, Box
8332, Moshi, Tanzania. 2Stichting Tropendermatologie, Munnekeburen, The
Netherlands.
Received: 6 December 2011 Accepted: 26 July 2012
Published: 30 July 2012
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doi:10.1186/1471-5945-12-12
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Skin flora: Differences between people affected by Albinism and those with normally pigmented skin in Northern Tanzania – cross sectional study

Kiprono, Samson K

Masenga, John E

Chaula, Baraka M

Naafs, Bernard

Digital Library of the Tanzania Health Community

Skin flora: Differences Between People Affected by Albinism and Those with Normally Pigmented Skin in Northern Tanzania - Cross Sectional Study.

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Skin flora: Differences Between People Affected by Albinism and Those with Normally Pigmented Skin in Northern Tanzania - Cross Sectional Study.

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