infection control and hospital epidemiology july 2006, vol. 27, no. 7
Acinetobacter Skin Colonization of US Army Soldiers
Matthew E. Griffith, MD; Julia M. Ceremuga, RN, CRNP, MS; Michael W. Ellis, MD; Charles H. Guymon, MA;
Duane R. Hospenthal, MD, PhD; Clinton K. Murray, MD
nondeployed US Army soldiers and, if present, how it might relate to the infections seen in current war casualties.
To evaluate whether skin colonization with Acinetobacter calcoaceticus-baumannii complex exists in a population of healthy,
prevalence of colonization. We then used ribotyping and antimicrobial susceptibility profiles to compare the isolates we recovered with A.
calcoaceticus-baumannii complex isolates from injured soldiers.
We sampled various skin sites of soldiers to test for the presence of A. calcoaceticus-baumannii complex and to establish the
setting.Fort Sam Houston, Texas.
participants. A population of healthy, nondeployed US Army soldiers in training.
from those recovered from injured soldiers.
A total of 17% of healthy soldiers were found to harbor A. calcoaceticus-baumannii complex. However, the strains differed
in the strains isolated from healthy soldiers, compared with the strains from injured soldiers, makes it difficult to identify skin colonization
as the source of infection.
Skin carriage of A. calcoaceticus-baumannii complex exists among soldiers before deployment. However, the difference
Infect Control Hosp Epidemiol 2006; 27:659-661
From the Infectious Disease Service, Department of Medicine, Brooke Army Medical Center (M.E.G., J.M.C., M.W.E., D.R.H., C.K.M.), and the US Army
Institute of Surgical Research (C.H.G.), Fort Sam Houston, Texas.
Received August 20, 2005; accepted November 10, 2005; electronically published June 12, 2006.
This article is in the public domain, and no copyright is claimed. 0899-823X/2006/2707-0004.
The military medical system has recently seen an increase in
the rates of Acinetobacter infection. Between 2002 and 2004,
5 military hospitals saw 102 bloodstream infections caused
by Acinetobacter calcoaceticus-baumannii complex, primarily
in soldiers who were wounded in Afghanistan or Iraq.1The
epidemiology behind this occurrence is unclear. Prior stud-
ies have revealed that healthy people can have Acinetobacter
skin colonization.2-5We undertook this study to determine
whether the skin of the average, healthy US Army soldier
might harbor A. calcoaceticus-baumannii complex, thereby
serving as a potential reservoir for these infections. To further
test this hypothesis, the genetic relatedness of these isolates
with those recovered from injured soldiers was investigated.
Study participants were active-duty US Army soldiersincom-
bat medic training at Fort Sam Houston, Texas. Soldiers were
recruited when theypresented totheoutpatienttroopmedical
clinic for acute care sick call (primarily for orthopedicinjuries
and upper respiratory tract infections; data not shown). Sol-
diers were excluded from the study if they had significant
exposure to inpatient medical facilities or a history of de-
ployment to Iraq or Afghanistan. The demographic charac-
teristics of the study population were assessed by means of
a short questionnaire. This protocol was approved by the
Brooke Army Medical Center institutional review board.
Participants were sampled for the presence of A. calcoace-
ticus-baumannii complex at 5 different body sites: the fore-
head at the hairline, one axilla, the finger webs of one hand,
one side of the groin, and the toe webs of one foot. These
sites were chosen because they have been identified in pre-
vious studies as potential sites of colonization.2-5Sampleswere
obtained by swabbing the area with a dry swab (BBL Culture-
Swab; Becton Dickinson). Cultures were taken to the labo-
ratory and processedusingstandardmicrobiologytechniques.
Isolates obtained by this protocol were then compared with
clinical isolates from soldiers injured in Iraq or Afghanistan
on the basis of ribotyping findings (Qualicon RiboPrinter;
DuPont) and antimicrobial susceptibility profiles (Vitek2, bio-
Me ´rieux Vitek).
One hundred two soldiers participated in the study. A. cal-
coaceticus-baumannii complex was detected in samples from
17 individuals (in samples from the forehead, for 5 subjects,
and in samples from the feet, for 12 subjects). Demographic
characteristics of the study participants colonized with A.
calcoaceticus-baumannii complex are given in Table 1. These
660infection control and hospital epidemiology july 2006, vol. 27, no. 7
Complex Colonization Status
Characteristics of Study Participants, According to Acinetobacter calcoaceticus-baumannii
(n p 102)
(n p 17)
(n p 85)
Age in years, mean (range)
Rooming with someone deployedain the past year
Foreign travel in the past year
Hospitalized in the past year
Self-reported chronic medical condition
Antibiotic use in the past 6 months
63.7 64.7 63.5
between groups in any characteristic (
aDeployed to Iraq or Afghanistan.
Data are % of study participants, unless otherwise indicated. No significant difference was found
, Fisher exact test).P ! .05
mannii Complex Isolates Recovered From HealthyUSArmySoldiers
and Soldiers Injured While Deployed in Afghanistan and Iraq
Susceptibility profiles of Acinetobactercalcoaceticus-bau-
Percentage of isolates susceptible
(n p 17)
(n p 15)
characteristics did not statistically differ between colonized
and noncolonized study participants. The antimicrobial sus-
ceptibility patterns of these isolates, as well as those of clinical
isolates, are listed in Table 2.
Thirty-nine clinical isolates from injured soldiers were
available foranalysis. Theisolateswereobtainedfrominfected
wounds (18), respiratory-tract cultures (13), urine cultures
(2), and skin (6). Among these isolates, 9 unique strains were
identified. Of the 17 isolates from colonized healthy soldiers,
16 were available for analysis, among which 14 strains were
identified. None of these isolates showed genetic similarities
with the clinical isolates. Ribotyping patterns of each unique
strain are shown in the Figure.
Our assessment of specimens from various skin sites of
healthy US Army soldiers revealed that skin colonization with
A. calcoaceticus-baumannii complex is common. This finding
supports the possibility that skin colonization may serve as
a source of these infections. However, the recovered isolates
had distinctly different ribotyping patterns and antimicrobial
susceptibility profiles, compared with those of isolates from
injured soldiers. These differences make it difficult to fully
implicate skin colonization as the cause of A. calcoaceticus-
baumannii infection in injured soldiers. To definitively make
this connection, colonized soldiers would need to be followed
up prospectively over time to see whether they have a higher
risk of developing A. calcoaceticus-baumannii complex infec-
tion with the same strain.
Our study has some limitations. We examined only soldiers
in the United States who had no history of deployment to
Iraq or Afghanistan. It is possible that soldiers deployed to
these areas, because of differences in climate and hygiene,
may develop colonization with different strains, which may
more closely resemble those seen in injured soldiers. In ad-
dition, because the soldiers were not followed up over time,
it is difficult to say whether their skin carriage represents true
colonization or simply transient contamination of the skin
from the environment. Although it is not known whether
these particular strains of A. calcoaceticus-baumannii com-
plex exist in the study’s geographic locale, A. calcoaceticus-
baumannii complex is found widely in the environment, and
so transient skin contamination is a possibility.
Another aspect of our results deserves mention. Current-
ly, in an attempt to decrease the nosocomial spread of A.
calcoaceticus-baumannii complex through military hospitals,
patients from Iraq and Afghanistan admitted to hospitals are
screened for the presence of the organism and placed in con-
tact isolation if found to be colonized. This screening is done
through the use of axilla and groin swab samples. Because
A. calcoaceticus-baumannii complex was found on the skin
of 17% of healthy soldiers but not in the axilla and groin,
screening these sites alone may frequently miss colonized
acinetobacter skin colonization of us soldiers661
ticus-baumannii complex strain isolated from healthy soldiers and
Ribotyping profiles of eachunique Acinetobactercalcoace-
patients. We have proposed that skin surveillance at our hos-
pital be extended to include additional body sites.
Since the beginning of hostilities in Afghanistan and Iraq,
infections caused by A. calcoaceticus-baumannii complexhave
become a significant problem in military hospitals. Clearly
defining the epidemiology of these infections is important if
they are to be prevented in the future. Our study examined
A. calcoaceticus-baumannii complex skin colonization before
deployment. Further work is necessary to evaluate other po-
tential sources of infection, such as skin colonization after
deployment, environmental contamination of wounds, or
nosocomial transmission in combat hospitals. This work, al-
though technically difficult, is ongoing.
Address reprint requests to Matthew E. Griffith, MD, CPT, MC, USA,
Infectious Disease Service (MCHE-MDI), BrookeArmyMedicalCenter,3851
Roger Brooke Drive, Fort Sam Houston, TX 78234 (matthew.griffith@
The opinions or assertions contained herein are the private views of the
authors and are not to be construed as official or reflecting the views of the
US Department of the Army, the US Department of Defense, or the US
government. The authors are employees of the US government.
Presented in part: 43rd Annual Meeting of the Infectious Disease Society
of America, San Francisco, California, October 6-9, 2005.
We thank the staff of McWethy Troop Medical Clinic, Fort Sam Houston,
Texas, and the staff of the Brooks Army Medical Center Microbiology Lab-
oratory for their help with this project.
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