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ORIGINAL ARTICLE
The gentamicin–collagen sponge for surgical site infection
prophylaxis in colorectal surgery: a prospective case-matched
study of 606 cases
Olivier Brehant &Charles Sabbagh &Philippe Lehert &
Abdennaceur Dhahri &Lionel Rebibo &
Jean Marc Regimbeau
Accepted: 31 July 2012
#Springer-Verlag 2012
Abstract
Purpose Surgical site infection (SSI) is a major concern in
colorectal surgery (CRS). It accounts for 60 % of all post-
operative complications and has an incidence of between 10
and 30 %. The gentamicin–collagen sponge (GCS) was
developed to help avoid SSI. The aim of this study was
the evaluation of the efficacy of a GCS in preventing SSI
after CRS.
Method This study was a retrospective analysis of data
collected in a prospective database. Six hundred six CRS
patients were enrolled in the study and prospectively
assigned to one of two groups. From January 2007 to
December 2008, all procedures were performed without
the use of GCS (forming the non-GCS group). From Janu-
ary 2009 to July 2011, all procedures included a GCS
(forming the GCS group). The primary endpoint was the
presence or absence of SSI at postoperative day 30.
Results The incidence of SSI was 29.7 and 20.8 % in the
non-GCS and GCS groups, respectively (p00.019). By
using a stepwise logistic regression, the predictors of SSI
were found to be ASA grade (p<0.001), operating time
(log-transformed value, p<0.001), gender (p00.021), and
GCS use (p<0.001). By adjusting on these variables, a mean
reduction in postoperative hospitalization of 8.3 days was
found in the GCS group. The proportions of Clavien IIIB–V
were 16.6 and 8.9 % for the non-GCS and GCS groups,
respectively (p00.041).
Conclusions This study provides additional evidence of the
efficacy of the GCS in reducing SSI rates and shortening
hospitalization after CRS.
Keywords Colorectal surgery .Surgical site infection .
Gentamicin–collagen sponge .NNIS index
Introduction
Postoperative surgical site infection (SSI) constitutes a ma-
jor concern in colorectal surgery (CRS). It accounts for 60 %
of all postoperative complications and has an incidence of
between 10 and 30 % [1–3]. Surgical site infections increase
morbidity, length of hospitalization, and cost and may ne-
cessitate invasive endoscopic or surgical procedures. It has
been suggested that some nonpharmacological treatments
can reduce the incidence of SSI: skin preparation, mechan-
ical bowel preparation, wound protectors, hyperoxia, and
warming [4–6]. The gentamicin–collagen sponge (GCS)
was developed to avoid wound infections by providing high
local gentamicin concentrations but not the high systemic
concentrations associated with nephrotoxicity [4]. The
sponge's collagen matrix is biodegradable and can be
inserted as an inlay or in the organ space. The GCS was
first approved in Germany in 1985 and is currently used in
O. Brehant :C. Sabbagh :A. Dhahri :L. Rebibo :
J. M. Regimbeau (*)
Department of Digestive Surgery,
Amiens University Medical Center,
Place Victor Pauchet,
80054, Amiens cedex 01, France
e-mail: regimbeau.jean-marc@chu-amiens.fr
P. Lehert
Faculty of Medicine, Department of Community Health,
University of Melbourne,
Melbourne, Australia
P. Lehert
Statistics Department, Faculty of Economics, FUCAM,
Louvain Academy,
Louvain, Belgium
Int J Colorectal Dis
DOI 10.1007/s00384-012-1557-9
over 60 countries. The GCS's efficacy and safety in diges-
tive surgery have been assessed in several controlled stud-
ies. A literature review [7], four randomized, controlled
trials (RCTs) [8–11], and a prospective, nonrandomized
study [12] all concluded that use of a GCS reduced the
incidence of SSI. In view of these results, our university
medical center started to use GCSs in early 2009. More
recently, an RCT [5] with a large patient population (n0
602) contradicted the literature results by evidencing a
higher SSI rate in a group of patients having received a
GCS during digestive surgery. Given these contrasting find-
ings and with a view to taking a definitive decision on GCS
use in our institution, we decided to contribute additional,
center-specific data concerning the efficacy of the GCS by
comparing a historical non-GCS cohort of patients with a
prospective GCS cohort on the basis of the same prospective
database dedicated to SSI surveillance.
Patients and methods
Trial design
Between January 2007 and July 2011, 606 patients under-
went colorectal surgery in the Department of Digestive
Surgery at Amiens University Medical Center. All patients
were operated on by one of our two colorectal surgeons
(OB, AD). In order to assess the value of GCS in preventing
post-CRS SSI, we assigned the patients into one of two
groups by time period. From January 2007 to December
2008, surgical procedures were performed without a GCS
(forming the non-GCS group). From January 2009 to July
2011, a GCS was systematically used (forming the GCS
group). Data on the historical control group (non-GCS
group) and the treatment group (GCS group) were prospec-
tively collected in an electronic database. There were no
significant changes to the surgical and care teams during the
overall study period (see section “Perioperative data
collection”).
Ethics
The GCS has been approved in France since 2001, and we
have used it routinely since January 2009. All patients were
informed of the use of GCS before surgical procedure. The
study's objectives and procedures were approved by our
institution's independent investigational review board as a
noninterventional research (CEERNI 42).
Inclusion and exclusion criteria
Included patients were aged 18 or over and had undergone
elective or emergency colorectal laparoscopy or laparotomy.
We excluded those of ages under 18 and patients with
aminoside allergy or kidney failure.
Patients
Patients were operated on for colorectal cancer or
benign lesions (diverticulitis, inflammatory bowel dis-
ease, ischemia, and miscellaneous conditions). Colon
resection was always performed. Anastomosis or Hart-
man procedure was performed depending on the type
of surgery, pathology, local conditions (i.e. peritonitis),
or general conditions. Whenever possible, we per-
formed an anastomosis. Sometimes, in cases of perito-
nitis, preoperative fecal incontinence, or cardiovascular
collapsus, we preferred to achieve a stoma without
anastomosis. When anastomosis was performed, a
diverting stoma was created in some (but not all)
cases.
Definitions
Postoperative surgical site infections
We recorded the presence or absence of SSIs occur-
ring within 30 days of the surgical procedure. SSIs are
usually classified into three categories [13](Table1).
Postoperative morbidity and mortality were described
according to Clavien’s classification [14](Table1).
The Altemeier classification characterizes surgical
wounds [15](Table1). The risk of infection was
assessed with the use of the National Nosocomial
Infection Surveillance System (NNIS), a composite
index that aggregates the Altemeier classification, the
American Society of Anesthesiology score (ASA), and
the operating time [16].
Surgical procedure
Preoperative work-up was performed according to the
current guidelines [17,18]. All patients were admitted
on the day before surgery. Colon enema was not
performed for colon resection [17]. For rectal resec-
tion, the bowel was prepared by administration of oral
laxatives and retrograde enemas [18]. Senna solution
(X-Prep® from Laboratoires Sarget, Mérignac, France)
was provided 24 h before the operation. Perioperative
prophylactic antibiotics (500 mg of metronidazole and
1 g of ceftriaxone in 125 mg of saline solution) were
infused intravenously for 15 min following the induc-
tion of anesthesia. Prophylactic antibiotics were again
infused 30 min after skin incision and then every 2 h
during the surgical procedure (in accordance with
French national guidelines [19]).
Int J Colorectal Dis
Sponge insertion
Collatamp® sponges (10 by 10 cm, from Eusapharma,
Limonest, France) contained 280 mg of collagen and
200 mg of gentamicin sulfate. The implantation of one
gentamicin–collagen sponge (corresponding to a genta-
micin dose of 130 mg) results in local-tissue gentamicin
concentrations of 170 μg per milliliter. Systemic con-
centrations of gentamicin remained below 2 μgper
milliliter 24 h after implantation [20]. Sponges were
placed directly onto the tissue without prior wetting.
For procedures with anastomosis and under laparotomy
or laparoscopy, a circular perianastomotic sponge was
inserted after anastomosis creation. For procedures in
the absence of anastomosis, Collatamp® sponges were
inserted close to a suture (e.g., at the rectal stump).
Collatamp® sponges were placed at every time (laparot-
omy or laparoscopy) around the colorectal anastomosis
or around the rectal stump in case of Hartmann proce-
dure. For laparotomy procedures, a sponge was inserted
into the abdominal wall.
Perioperative data collection: SSIs, Clavien grading,
and follow-up
Since January 2007, we have fully documented each
operation in a prospective database (DxCare® from
Medasys, Gif-sur-Yvette, France) by recording preoper-
ative variables (height, weight, BMI, diabetes antece-
dents, age, gender, ASA score, etiology (cancer,
diverticulitis, inflammatory bowel disease or other),
emergency, or elective surgery), preoperative variables
(organ group, operating time, Altemeier classification,
type of surgery, presence or absence of anastomosis,
and presence or absence of a protective stoma), under-
lying disease (cancer, diverticulitis, inflammatory bowel
disease), and postoperative variables (medical or surgi-
cal complications, SSI occurrence, length of postopera-
tive hospitalization (LPH), NNIS grade, and Clavien
grade) [21]. A total of 606 patients who underwent
colorectal surgery were enrolled in this study. We
assigned the patients into two groups by period of time.
From January 2007 to December 2008, all procedures
were performed without the use of GCS (non-GCS
group). From January 2009 to July 2011, all procedures
included a GCS (GCS group). Morbidity was docu-
mented at the time of occurrence (Clavien I–V) or, in
the absence of complications, at discharge (Clavien 0).
The SSI data were completed at postoperative day 30.
In the event of SSI occurrence before postoperative day
30, the data were completed at the time of occurrence.
Standard preoperative demographic and intraoperative
characteristics were also recorded. At the time of study,
full information on 4,990 patients was available. Data
were extracted as a Excel® file (Microsoft Corporation,
Redmond, WA, USA) by using Business Objects® soft-
ware (version 12.1.0.882) (SAP France S.A Capital 8–
32 rue de Monceau 75008 Paris).
Outcome measures
The primary endpoint was the presence or absence of SSI at
postoperative day 30. Secondary endpoints were the LPH
(in days) and the proportion of patients with severe postop-
erative outcomes (surgical, endoscopic, or radiological rein-
tervention for SSI or Clavien III–V postoperative day 30
morbidity and mortality).
Table 1 Definitions of the SSI, Clavien classification, and the Altemeier classification
Surgical site infection
Superficial SSI SSI involving only skin and subcutaneous tissue of the incision
Deep SSI SSI which involves deep soft tissues (whether inlay or underlay)
SSI of organ
spaces
SSI of organ spaces opened or handled during surgery
Clavien classification
Grade I Any deviation from the normal course after surgery with no need for pharmacological, surgical, endoscopic and radiological
interventions
Grade II Complications requiring pharmacological treatment
Grade III Complications requiring surgical, endoscopic or radiological intervention
Grade IV Life-threatening complications requiring intermediate or intensive care unit management
Grade V Death
Altemeier classification
1 Clean
2 Clean-contaminated
3 Contaminated or dirty
Int J Colorectal Dis
Data monitoring committee
The occurrence and nature of Clavien-graded surgical com-
plications was systematically reviewed and assessed by the
study's two lead investigators (OB, JMR). Case report forms
were checked for validity. In the event of aberrant findings
or mismatch between the two interpretations, the reviewers
met and reached a consensus.
Statistical analysis
In this prospective matched-case study, each patient in the
GCS group was matched for age, gender, surgery duration,
Altemeier classification, ASA score, and circumstances with
two patients of the control historical non-GCS group (ratio
1:2). Matching was organized following the optimal method
[22], discarding control units outside the convex hull of the
treated units [23]. The primary analysis was based on an
intent-to-treat principle, in which all the patients
sequentially admitted were included into the analysis, with-
out any possible exclusion. We used a mixed model featur-
ing a logistic regression in using blocks as random factor,
matching variables as covariates, other available covariates
(BMI, diabetes antecedents, use of anastomosis, and under-
lying disease), and treatment as fixed factor. The proportion
of patient experiencing SSI was compared between groups
within each NNIS category and age category (Mantel–
Haenszel test). Time to discharge was compared between
the two groups by a linear model using baseline variables.
Finally, the proportion of patients with severe outcome
(Clavien IIIb–V) was compared in adjusting for age (Man-
tel–Haenszel test). Under these assumptions, and based on a
matching ratio 1:2, a sample size of at least 202 patients
treated with GCS was needed to detect a SSI reduction of at
least 10 % with a power of 90 %, at two-sided significance
level of 0.95. No formal interim analysis was planned. An
independent data and safety monitoring committee moni-
tored the trial. All statistical analyses were performed with
Table 2 Comparison of the two
patient groups (pvalue)
Comparison between treatment
groups
NNIS National Nosocomial
Infection System
The superscripted numbers are
pvalue for each item
No GCS GCS Total
Gender
0.568
(404) 42.6 % (202) 40.1 % (606) 41.7 %
Age
0.085
64.52 ±16.42 62.11 ±16.32 63.72 ±16.41
Weight
0.568
72.09 ±16.13 73.03 ±15.08 72.31 ±15.88
Height
0.332
1.67 ±0.08 1.68 ±0.09 1.68 ±0.09
BMI
0.928
25.71 ±5.38 25.75 ±4.72 25.72 ±5.23
Surgery duration
0.251
198.24 ±105.23 208.32 ±95.38 201.60 ±102.08
Altmeier
0.116
Clean 1.2 % 5 0.0 % 0 0.8 % 5
Clean + contaminated 59.2 % 239 66.8 % 135 61.7 % 374
Contaminated 28.7 % 116 25.7 % 52 27.7 % 168
Dirty 10.9 % 44 7.4 % 15 9.7 % 59
ASA index
0.269
Healthy patient 5.2 % 21 4.5 % 9 5.0 % 30
Mild disease 42.3 % 171 49.0 % 99 44.6 % 270
Severe disease 39.6 % 160 38.1 % 77 39.1 % 237
Threat for life 12.9 % 52 8.4 % 17 11.4 % 69
NNIS
0.183
Grade 0 13.9 % 56 17.3 % 35 15.0 % 91
Grade 1 42.6 % 172 44.1 % 89 43.1 % 261
Grade 2 31.9 % 129 32.2 % 65 32.0 % 194
Grade 3 11.6 % 47 6.4 % 13 9.9 % 60
Underlying disease
0.969
Cancer 48.5 % 196 48.6 % 67 48.5 % 263
Diverticulitis 32.4 % 131 34.1 % 47 32.8 % 178
Inflammatory bowel 10.1 % 41 9.4 % 13 10.0 % 54
Other 8.9 % 36 8.0 % 11 8.7 % 47
Anastomosis
0.146
64.3 % 260 70.9 % 100 66.0 % 360
Diabetes
0.180
15.1 % 61 10.4 % 13 14.0 % 74
Emergency Surgeries
0.112
36.6 % 148 30.2 % 61 34.5 % 209
Int J Colorectal Dis
the use of R software (version 2.11.1) (Free Software Foun-
dation, Inc. 51 Franklin St, Fifth Floor, Boston, MA 02110–
1301 USA).
Results
Patient description and intergroup comparisons
Once 202 patients were available in the GCS group (as
planned by the sample size calculation), they were matched
with 404 untreated patients (non-GCS group). No patient
was lost to follow-up. The sample was constituted by 42 %
of women and a mean age of 63 years (range 68–79)
(Table 1). The two groups matched well on all the variables,
for matching variables as well as for all the other baseline
characteristics (diabetes, preoperative conditions, underly-
ing disease, BMI, emergency of elective conditions, and
underlying disease) (Table 2).
Incidence of surgical site infection
The incidences of SSI were 29.7 % in the non-GCS group
and 20.8 % in the GCS group, (odds ratio (OR)00.514,
95 % CI 0.306–0.865, p00.013). The comparison of SSI
proportion between the two groups within each NNIS cate-
gory (Table 3) provides evidence of a constant relative
efficacy of GCS compared with control across the four
categories of severity (Mantel–Hanszel, p00.019). By using
a stepwise logistic regression, the predictors of SSI were
found to be ASA grade (p<0.001), operating time (log-
transformed value, p<0.001), gender (p00.021), and GCS
use (p<0.001). After adjusting on these previous variables,
all the other variables (anastomosis, BMI, diabetes duration,
emergency or elective conditions of surgery, underlying
disease differentiating cancer, diverticulitis, and inflamma-
tory bowel) were not found significantly determinant of SSI.
By adjusting on these variables, a mean reduction in post-
operative hospitalization of 8.3 days was found in the GCS
group. The proportions of Clavien IIIB–V were 16.6 and
8.9 % for the non-GCS and GCS groups, respectively
(p00.041).
Secondary endpoints
We compared the mean LPH in the two treatment groups by
applying a stepwise linear regression model based on base-
line covariates (Table 4). The main predictors were operat-
ing time (with an increase of 1.13 days per additional hour
of surgery, 95 % CI 0.34–1.91, p<.001), ASA grade (with
an increase of 6.69 days per each additional grade 95 % CI
4.93–8.45), and gender (with a decrease of 3.15 days for
291 women, 95 % CI −5.82, −0.48, p00.021). Finally, GCS
had the effect of a mean reduction of LPH of 8.3 days [95 %
CI −11.09, −5.51, p<0.001]. When the previous variables
were considered in the model, the other tested covariates
(BMI, diabetes antecedents, underlying disease, type of
surgery, anastomosis) were non significant,
The proportion of patients with severe outcome (Clavien
Grade IIIb–V) was compared between the two treatments
across age categories (Table 5). Proportions of 16.6 and
8.9 % were found for non-GCS and GCS group, respective-
ly. (risk ratio, RR
Control/Treated
00.58, 95 % CI 0.344–0.097,
p00.041). In cases of SSI, a systematical bacteriological
examination was performed. There were three bacteria in
Table 3 Incidence of SSIs in the two patient groups and for each
NNIS subgroup (p00.019 in a Mantel–Haenszel test)
No GCS GCS Total
Count Percent Count Percent Count Percent
Grade 0 56 17.9 35 5.7 91 13.2
Grade 1 172 22.7 89 12.4 261 19.2
Grade 2 129 37.2 65 33.8 194 36.1
Grade 3 47 48.9 13 53.8 60 50.0
Total 404 29.7 202 20.8 606 26.7
SSI category by NNIS by treatment (count, percent)
Tab l e 4 Stepwise linear regression on length of postoperative
hospitalization
Coef 95 % CI Pvalue
Mean duration 11.658 7.871; 15.445 <0.001
Length of postoperative
hospitalization
1.128 0.344; 1.913 0.005
ASA score 6.697 4.935; 8.459 <0.001
Female patients −3.153 −5.823; −0.482 0.021
GCS effect −8.302 −11.090; −5.514 <0.001
Adjusted R
2
00.1418, Altemeier Index, age, circumstances, underlying
disease, anastomosis use, BMI, and diabetes antecedents were exclud-
ed by stepwise regression. Mean duration corresponds to mean esti-
mated hospitalization duration corresponding to male patients with
surgery duration of 2 h, and ASA 0grade 1
Table 5 Count and percentage of patients with Clavien grade IIIb or
IV or V in the two treatment groups stratified by age
No GCS GCS (%)
Less than 60 years 141 (4.3) 77 (3.9)
60–80 years 183 (20.8) 96 (11.5)
More than 80 years 80 (28.7) 29 (13.8)
Total 404 (16.6) 202 (8.9)
Mantel–Haenszel test adjusting for age, p00.017
Int J Colorectal Dis
10 % of cases (n017), two bacteria in 40 % (n064), a single
one in 40 % (n064), and no bacteria in 10 % (n017). The
most frequent bacteria were Escherichia coli in 50 % (n0
81), Enterobacter aerogenes in 20 % (n033), Enterobacter
cloacae in 10 % (n017), and Enterococcus spp in 30 % (n0
50). Table 5shows the number and percentage of patients
with Clavien grade IIIb or IV or V in the two treatment
groups stratified by age.
Discussion
The primary endpoint (SSI at postoperative day 30) was
compared between the two groups in estimating the differ-
ence of SSI between both groups in stratifying between each
category of NNIS. We found a significant higher incidence
of SSI in the control non-GCS group than in the GCS group
(29.7 vs. 20.8 %, respectively). This result is in line with
that of other studies on Collatamp®, with the exception of
that of Bennett-Guerrero et al. [5]. Nowachi et al. found a
lower postoperative complication rate in the GCS group,
relative to the control group (20.7 vs. 37.5 %) [10]. De
Bruin et al. found significantly lower wound complication
rate (11 vs. 29 % in the GCS and non-GCS groups, respec-
tively) [12]. Rutten et al. found lower SSI rate in the GCS
group (5.6 vs. 18.4 % in the non-GCS group) [8]. In con-
trast, Bennett-Guerrero et al. found a higher SSI rate in the
GCS group than in the control group. Bennett-Guerrero et
al. suggested that the length of follow-up (not mentioned in
the other studies) could explain the difference of results
between their study and the others. In our study, SSI was
evaluated on postoperative day 30. Cases of later complaints
by the patient were fully documented in our prospective
database [12]. The apparent lack of benefit of a GCS in
the report of Bennett-Guerrero et al. [5] may be explained
by the inlay location of GCS in their cases (compared with
inlay and abdominal cavity sites in our present work).
Moreover, Bennett-Guerrero et al. [5] only included patients
with elective procedures, whereas our study featured both
emergency and elective CRS. Our results showed that
patients in the GCS group were hospitalized for 8 days less
than those in the non-GCS group (on average) and thus
confirmed the positive effect of Collatamp®. This finding
confirms the report by de Bruin et al. on shorter hospitali-
zation in a GCS group (15 vs. 25 days in a non-GCS group)
and the report by Rutten et al. (13.8 days in a GCS group vs.
16.3 days in a non-GCS group). The shorter stay may be due
to a lower SSI rate in GCS-treated patients. In our study, we
had no group of patients with collagen sponge without
gentamicin, and collagen is usually not used alone around
the anastomoses. Collagen is used for hemostasis in general
surgery, in the treatment of the liver cross section following
hepatectomy, but not for an antiseptic effect [24]. Our study
had a number of limitations. It was not an RCT; a consec-
utive series of patients received standard care, but only the
last 202 were treated with a GCS. Although this design is
known to be less accurate than an RCT, it has been already
used in a surgical context [25]. Moreover, the study proce-
dures were designed to minimize sources of bias: (a) before
analyzing any other results, we confirmed the absence of
trend over time in the SSI rate; (b) we sequentially treated all
the patients, with no exclusions or exceptions; and (c) we
controlled for possible baseline discrepancies. Our tests
were stratified into baseline severity categories, and so the
small observed intergroup differences are less likely to have
influenced our results.
Conclusion
Our study provides additional evidence of the efficacy of GCS
in reducing SSI rates and shortening hospitalization after
colorectal surgery. In view of the recent conflicting results,
further clinical studies are required.
Acknowledgments The Association for Research in Surgery, Gas-
troenterology and Hepatology (Chairperson, JM Regimbeau; Secretary,
O. Brehant) has received an unconditioned grant from EUSA Pharma
(3 Allée des Sequoias, F-69760 Limonest, France) to conduct the trial.
Professor Ph Lehert has received an unconditioned grant from EUSA
Pharma to conduct the statistical analysis of this trial.
Conflict of interest The sponsor of the study had no role in study
design, data collection, data analysis, data interpretation, or writing of
the report. The GCS was not provided free of price by the sponsor. No
contract of confidentiality or request of the company to review the
results was signed. The remaining authors have nothing to declare.
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