Harvest surgical site infection following
coronary artery bypass grafting: Risk
factors, microbiology, and outcomes
Mamta Sharma, MD,a,bMohamad G. Fakih, MD, MPH,a,b,cDorine Berriel-Cass, RN, MA,dSusan Meisner, RN,e
Louis Saravolatz, MD,a,band Riad Khatib, MDa,b
Background: Our goals were to evaluate the risk factors predisposing to saphenous vein harvest surgical site infection (HSSI), the
microbiology implicated, associated outcomes including 30-day mortality, and identify opportunities for prevention of infection.
Methods: All patients undergoing coronary artery bypass grafting (CABG) procedures from January 2000 through September 2004
were included. Data were collected on preoperative, intraoperative, and postoperative factors, in addition to microbiology and
resistant S aureus (MRSA) 5 7]). Gram-negative organisms were recovered in 50% of cases, with Pseudomonas aeruginosa predomi-
nating in 11 (22%) because ofa single pathogen. Multiple pathogens were identified in 14 (22%) cases. The 30-day mortality was not
significantly different in patients with or without HSSI. Multivariate analysis showed age, diabetes mellitus, obesity, congestive heart
failure, renal insufficiency, and duration of surgery to be associated with increased risk.
Conclusion: Diabetes mellitus, obesity, congestive heart failure, renal insufficiency, and duration of surgery were associated with
increased risk for HSSI. S aureus was the most frequently isolated pathogen.
Key Words: Saphenous vein harvesting; surgical site infection; coronary artery bypass; risk factors; microbiology.
Copyright ª 2009 by the Association for Professionals in Infection Control and Epidemiology, Inc.
(Am J Infect Control 2009;37:653-7.)
The saphenous vein remains the most commonly
harvested conduit for revascularization in coronary
artery bypass grafting (CABG). The incidence of saphe-
nous vein harvest surgical site infection (HSSI) has
been reported to range from 1% to 24%.1-10These
complications rarely require surgical intervention and
stay and require debridement with possible lower ex-
tremity revascularization and limb loss.11
Risk factors previously identified for HSSI include
peripheral vascular disease,1,2,11and traditional open
methods of saphenous vein harvesting.16-21Whereas
the majority of studies has been performed in sternal
SSI, fewstudies have addressed the prevalence, microbi-
ology, and outcomes associated with HSSI alone. The
disposing to HSSI, the microbiology implicated, associ-
ated outcomes including 30-day mortality, and identify
opportunities for prevention of infection.
The study was conducted at St. John Hospital and
Medical Center, a 608-bed, tertiary care urban commu-
ipates in collecting data for both the Society of Thoracic
Surgeons and National Nosocomial Infections Surveil-
lance (NNIS), now known as National healthcare Safety
Network (NHSN). All CABG from January 2000 through
September 2004 were included for analysis. The study
was evaluated by the Institutional Review Board and
From the Division of Infectious Diseases, Department of Medicine, St.
John Hospital and Medical Center, Detroit, MIa; Wayne State University
School of Medicine, Detroit, MIb; and Infection Control Department,c
Department of Quality Management,dand Department of Cardiotho-
racic Surgery,eSt. John Hospital and Medical Center, Detroit, MI.
Address correspondence to Mamta Sharma, MD, St. John Hospital and
Medical Center, Division of Infectious Diseases, Department of Medi-
cine, Medical Education, 19251 Mack Ave, Suite 340, Grosse Pointe
Woods, MI 48236. E-mail: firstname.lastname@example.org.
Presented at the 46th AnnualInterscienceConference on Antimicrobial
Agents and Chemotherapy, September 28, 2006, San-Francisco CA,
(Slide session: K-626).
Conflicts of interest: None to report.
Copyright ª 2009 by the Association for Professionals in Infection
Control and Epidemiology, Inc.
was found to be exempt from further review. No patient
study. Patient risk factors and comorbidities were
entered prospectively into the Society of Thoracic Sur-
geons database, which included preoperative patient
risk factors (age, sex, body mass index [BMI], diabetes
mellitus, renal insufficiency [defined as documented
history of renal failure or a creatinine .2 mg/dL],
peripheral vascular disease, congestive heart failure,
New York Heart Association score, use of systemic
immunosuppressive therapy, hypertension, hypercho-
lesterolemia, history of a previous cardiovascular
days from admission to surgery, transfer from another
hospital, American Society of Anesthesiologists score
(ASA), use of the internal mammary artery, and use of
the intraaortic balloon pump. Data on duration of sur-
gery, postoperative mechanical ventilation, and inten-
sive care unit (ICU) stay were available starting January
2002. The NNIS risk index score was calculated using
the ASA score, wound class, and duration of the opera-
tion. One point is given for each ASA score .2, duration
of surgery .T hours (75th percentile for the operation,
which is 5 hours for CABG), and a wound class that is
contaminated or dirty. Outcome measures included
30-day mortality (defined as all deaths occurring during
the hospitalization in which the operation was per-
after discharge from the hospital, but within 30 days of
the procedure), HSSI, and mortality related to HSSI.
Chlorhexidine bathing for all patients the night
before and the morning of their surgery was per-
formed. Surgical hair removal was only done using
clippers, and access torazors wasprohibited. Antibiotic
prophylaxis at our institution is standardized to cefaz-
olin 2 g intravenously preoperatively (within 60 min-
utes of first incision), redosed with 1 g at 240 minutes
if duration of surgery more than 4 hours, and to be
continued for 24 hours postoperatively. If the patient
had either a life-threatening allergy to penicillin or
allergy to cephalosporin, then vancomycin was the
antibiotic administered perioperatively. Vancomycin
was infused within 120 minutes prior to first incision.
Standard guidelines have been prepared for purpose
of tight glycemiccontrol.Algorithmforinsulininfusion
is used to keep target blood glucose below 200 mg/dL
intraoperatively and in the range of 80 to 110 mg/dL
Saphenous veinwasharvestedbymeans of the open
technique with traditional longitudinal incision. This
was performed by the physician’s assistant preparing
the leg circumferentially and making an incision
from the groin to the knee and, if necessary, to below
the knee. Once dissected, the vein was removed. The
wound was closed in 1- or 2-layer fashion with
absorbable sutures. The skin was approximated with
surgical staples. The leg was immediately wrapped
with a sterile elastic bandage. A cardiovascular surgeon
who was certified with the procedure performed endo-
scopic saphenousveinharvesting. A 2- to3-cm incision
was made on the medial aspect of the leg above the
knee. With the help of the endoscopic dissector, the
saphenous vein was dissected. If more length was
required and the dissection had to be extended, a sec-
ond incision was made on the medial aspect of the
thigh. After adequate hemostasis, the incision was
closed with absorbable sutures and skin approximated
with the staples.
Case patients were identified through inpatient and
postdischarge surveillance. Active surveillance was
both inpatient surveillance and postdischarge surveil-
lance. Inpatient surveillance included direct observation
and indirect detection by the infection control profes-
sional through review of laboratory reports, patient rec-
ords, and discussions with providers. Postdischarge
surveillance included review of outpatient laboratory
reports and direct examination of patients during
follow-up visit by surgeon or home care nurses. The
Society of Thoracic Surgeons coordinator contacted all
patients 30 days postoperatively and would notify the
infection control professional of any suspected HSSI.
An integrated health information system was also uti-
lized to identify patients admitted to facilities within
our health system or others in the metropolitan area.
Definition of infection
Superficial SSI and deep SSI were identified accord-
ing to NNIS criteria.22Superficial infection SSI involved
onlyskin orsubcutaneous tissue of the incision, and, in
addition, SSI included at least 1 of the following: (1)
purulent drainage; (2) isolation of an organism from
the site; (3) at least 1 of the following clinical findings:
tenderness, redness, or heat along with incision and
drainage by the surgeon; or (4) diagnosis was made by
the surgeon or attending physician. Deep SSI was
defined as infection involving fascial or muscle layers
of the incision and must be accompanied by purulent
ing by a surgeon in a patient with fever, local pain, ten-
derness, abscess, or diagnosis by a physician.
Data were analyzed using SPSS 12 (SPSS, Inc,
Chicago, IL). Categorical variables were analyzed by
using 1-way ANOVA. A 2-sided P value , .05 was
Sharma et al.
American Journal of Infection Control
considered to be significant. A multivariate analysis
(forward stepwise logistic regression) was also used to
identify significant independent factors.
During the study period, a total of 3578 CABG proce-
dures were performed. All patients had CABG: 3057
(85.4%) CABG only, 421 (11.8%) CABG and valve
replacement, and 100 (2.8%) CABG and another proce-
(n 5 205, 5.7%), history of cerebrovascular accident
(n 5 325, 9.1%), peripheral vascular disease (n 5 535,
of or current smoking (n 5 2210, 61.8%), immunosup-
pressive treatment (n 5 110, 3.1%), and previous
cardiovascular intervention (n 5 1119, 31.3%). A
large number of our patients were overweight or
obese (mean BMI 5 29.4, median BMI 5 28.3, 75th
percentile 5 32.2).
Eighty-six cases (2.4%) were identified with HSSI
over the 57 months of the study: 28 (32.6%) of
whom were deep, 18 (20.9%) had concomitant sternal
SSI (SSSI). One hundred forty-four cases (4%) were
identified with sternal SSI over this study period. One
hundred twenty-six cases with only SSSI were ex-
cluded from analysis of risk factors. The median time
to HSSI was 17 (range, 4-51) days. Cases were diag-
nosed on the same surgical admission (n 5 23,
26.7%), on readmission (n 5 45, 52.3%), and on post-
discharge surveillance (n 5 18, 21%). Most of the pa-
tients (61.3%) were males. The preoperative and
perioperative risk factors for HSSI are shown in Table
1. The preoperative factors associated with HSSI on
univariate analysis included age, female sex, obesity,
renal insufficiency, and diabetes mellitus. The periop-
erative factors included the duration of surgery and
postoperative intensive care unit (ICU) stay .72 hours.
The introduction of endoscopic vein harvesting was
not associated with reduction of HSSI; however, the
sample size was very small (149 cases). Use of internal
mammary arteries was not significantly different be-
tween the 2 groups.
We included all possible preoperative and periopera-
gression). Both duration of surgery and duration of ICU
stay postoperatively were available starting in 2002.
We ran the multivariate analysis twice: including these
2 variables (1533 cases) and not including them (3445
(BMI $ 30 [kg/m2]) were independently associated with
HSSI (Table 2). In the second model (excluding duration
of surgery and postoperative ICU stay), age, diabetes
mellitus, renal insufficiency, and obesity (BMI $ 30)
were independently associated with HSSI (Table 3).
The 30-day mortality was not significantly different
in patients with (1.8% excluding 18 cases of concomi-
tant SSSI, 4.7% including concomitant SSSI) or without
HSSI (3.2%). No significant differences in postoperative
length of stay were found for those who were diag-
nosed either on readmission or postdischarge surveil-
lance compared with those with no HSSI.
Table 1. Risk factors for HSSI from January 2000 to
(n 5 3366)
(n 5 86)P value
Age, yr (6SD)
Sex, female (%)
index $30 (kg/m2) (%)
Renal insufficiency (%)
Diabetes mellitus (%)
heart failure (%)
NYHA 3 or 4 (%)
Mean duration surgery,
NNIS risk index 2 (%)
Endoscopic harvest (%)*
Mean ICU stay,
ICU stay .72 hr (%)
pump use (%)
67.13 6 11.04
69.76 6 10.29
484 (14.4)18 (20.9).09
251.11 (79.8) 285.9 (74.7) .006
92.3 6 135.8
.273152.4 6 283.6
NYHA, New York Heart Association; NNIS, National Nosocomial Infection Surveil-
lance; ICU, intensive care unit.
*Data on duration of surgery, postoperative mechanical ventilation, and ICU stay
from January 2002. Endoscopic harvest graft performed from December 2003.
Table 2. Multivariate analysis of independent risk factors
associated with HSSI: 1533 cases including duration of
surgery and postoperative ICU stay .72 hours
VariableP valueOdds ratio (95% CI)
Congestive heart failure
BMI .30 (kg/m2)
Duration of surgery (min)
Vol. 37 No. 8
Sharma et al.
The microbiology was identified in 64 (74.4%) cases.
Single pathogen was implicated in 50 (78%) instances
data are presented in Table 4. Staphylococcus aureus was
the most frequently isolated pathogen (n 5 19, 38%):
methicillin-susceptible S aureus (MSSA) (n 5 12, 24%)
cases, methicillin resistant S aureus (MRSA) (n 5 7,
14%). Gram-negative bacilli were recovered in 50% of
cases, with Pseudomonas aeruginosa predominating
(n 5 11, 22%) because of a single pathogen. Of the poly-
microbial infections, the majority was with gram-
negative bacilli 68% (P aeruginosa, n 5 6; Klebsiella
pneumoniae, n 5 4; Enterobacter cloacae, n 5 2; Acineto-
bacter baumanii, n 5 2; Escherichia coli, n 5 2; Proteus
mirabilis, n 5 2; Citrobacter freundii, n 5 1); gram-posi-
tive organisms were seen in 32% (MSSA, n 5 3; MRSA,
n 5 1; Enterococcus species, n 5 5). S aureus was associ-
ondary bacteremia was noted in 4 instances (n 5 3
S aureus, n 5 1 coagulase-negative staphylococcus) and
HSSI, and the donor site was not the implicated source.
HSSI following CABG complicated 2.4% of cases
from our hospital. Our incidence of HSSI is well within
the national average.23Routine guidelines in prevent-
ing SSIs were followed,including skin preparation, pro-
phylactic antibiotic use, proper surgical technique, and
wound management. Hospital Infection Control Prac-
tices Advisory Committee guidelines for prevention of
SSI were implemented in 1999 at our institute.24
tion control surveillance. Postdischarge surveillance—
or questionnaires to involved physicians or home
ing. Nevertheless, with passive reporting, some cases
may be missed, and the overall rate may be underesti-
mated for superficial HSSI.
We looked at preoperative (host) factors and periop-
erative factors (surgical and postoperative). Host factors
include sex, age, comorbidities, and previous interven-
tions, whereas perioperative factors are modifiable
and include duration of surgery and postoperative
care. Multiple factors have been associated with
increased rates of HSSI including increased age,7,11
peripheral vascular disease,1,2,11
hemoglobin concentration,6open saphenous vein har-
vest,16-21extension of leg wound incision,9and intra-
aortic balloon pump use. In our study, preoperative
factors associated with HSSI were older age, female
sex, obesity, renal insufficiency, and diabetes. Obesity,
congestive heart failure, and renal insufficiency had a
strong association with HSSI. These factors may affect
prompt wound healing and increase the risk of HSSI. It
is important to note that, although diabetes mellitus
did not factor in as an independent factor associated
with HSSI when we looked at our cohort from 2002-
in infection over the total duration of the study (exclud-
ing duration of surgery). The implementation of tight
glycemic control intraoperatively and postoperatively
has been associated with reduction of morbidity and
of 2004 has been initiated at our hospital. Perioperative
glucose control was initially started intraoperatively in
of postoperative glucose control in the cardiovascular
intensive care unit through the use of standing orders
by April 2004.
The intraoperative factor associated with HSSI was
the duration of surgery. Antibiotic redosing intraopera-
vein harvesting has been reported to decrease preva-
lence of woundinfection.16-21We did not find anyasso-
ciation with a reduction of HSSI; however, our study
involved a small number of patients who underwent
Table 3. Multivariate analysis of independent risk factors
associated with HSSI: 3445 cases excluding duration of
surgery and postoperative stay .72 hours
VariableP valueOdds ratio (95% CI)
BMI .30 (kg/m2)
Table 4. Microbiology of harvest surgical site cultures
Isolate SingleMixed SingleMixed
Sharma et al.
American Journal of Infection Control
endoscopic veinharvesting, making itdifficult to evalu- Download full-text
ate this factor.
Our microbiologic findings showed gram-negative
organisms as the most frequently implicated in our
patients, as in previous studies.3,7Gram-negative orga-
nisms accounted for more than 50% of cases with
P aeruginosa predominating in deep HSSI. Assuming
that intraoperative wound contamination is a prerequi-
site for the majority of infection, it is the patientapos;s
perineal flora representing the primary pathogen for
the development of leg infections because of greater
intraoperative contamination of leg wound, particu-
larly those because of Enterobacteriaceae.3S aureus
was isolated in the majority of HSSI. S aureus has
also been implicated as a major pathogen in HSSI in
a previous study by Swenne et al.6Nasal carriage of
S aureus has been identified as a major risk factor for
SSI after cardiac surgery. A double-blind, randomized
placebo trial failed to show any reduction in rate of
sternal and HSSI among S aureus carriers receiving
intranasal mupirocin; however, the sample size was
small.25Current evidence does not support mupirocin
use for routine surgical prophylaxis. Single strain out-
breaks suggesting a point source were not identified
during the study period.
Identification of risk factors is important to prevent
infection and to identify patients at high risk who may
need further monitoring for development of infections.
A multidisciplinary effort that includes cardiothoracic
services and infection control may identify the areas
that need improvement to help further decrease the
incidence of HSSI in high-risk patients.
The authors thank Dr. Ruth Moore for her help in the statistical analysis.
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