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SA JOURNAL OF DIABETES & VASCULAR DISEASE
RESEARCH ARTICLE
VOLUME 13 NUMBER 2 • DECEMBER 2016
75
of 73 patients (45 male, mean age 61 ± 8 years). They did not
receive a local antibiotic.
The local ethics committee approved the study. Written informed
consent was obtained from the patients. It was determined prior
to the initiation of the study that patients developing SSWI would
be treated by the administration of antibiotics alone. Patients
developing DSWI would be treated by the administration of
antibiotics plus surgery.
During the pre-operative period, all patients were assessed for the
risk of mediastinitis according to the ACC/AHA 2004 guideline for
CABG surgery,
5
using eight parameters including age, presence of
obesity, diabetes or COPD, the need for dialysis, ejection fraction (EF) <
40%, and scheduled for emergency surgery. Baseline characteristics,
parameters used to assess the risk of mediastinitis, and post- and
intra-operative data of the patients are presented in Table 1.
Skin cleansing was performed in all patients prior to surgery.
Combined insulin therapy with regular human insulin (Humulin
®
R
100 U/ml) and insulin glargine (Lantus
®
100 U/ml) was administered
to control blood glucose levels below 200 mg/dl during pre-, intra-
and postoperative periods. Insulin infusion was initiated in patients
as required. The standard prophylactic antibiotic regimen used in
our clinic was administered to patients, that is 1 g cefazolin sodium
(Cefamezin-IM/IV
®
) 30 minutes before surgery and 1 g every eight
hours after surgery for 48 hours.
Cardiopulmonary bypass (CPB) duration, cross-clamping times
and number of grafts in both groups are shown in Table 1. Only
left internal mammary artery grafts were used in all patients.
Meticulous aseptic techniques were used during the operation and
unnecessary use of electrocautery and excessive perfusion in CPB
were avoided.
All patients were kept in the intensive care unit for 24 hours
and the patients were referred to a regular ward within the second
24 hours after drains and arterial catheters were removed. Central
venous catheters were removed on the second postoperative day.
The patients were discharged on postoperative day 6 ± 3.
In the rifamycin group, mediastinum, sternum and suprasternal
tissues were irrigated after surgery using rifamycin SV i.m. (Rif
®
250 mg/3-ml ampoule) diluted with 10 ml isotonic solution. In the
control group, irrigation was not performed. The two groups were
compared with regard to risk for sternal infection.
Statistical analysis
Statistical analysis was performed using statistical package for
social sciences 13.0 (SPSS Inc, Chicago, IL, USA). The Kolmogorov-
Smirnov test was used to determine the distribution of numerical
parameters. Continuous variables are presented as mean ± standard
deviation. For comparison of independent continuous variables,
the Student’s
t
-test or Mann-Whitney
U
-test was used where
appropriate. Categorical data were compared using the Fisher’s
exact test or chi-square test. For all statistics, a
p
-value < 0.05 was
considered statistically significant.
Results
There were no significant differences between the two groups in
terms of baseline characteristics and mediastinitis risk percentages
(Table 1).
The patients were followed up for the development of SWI for
30 days after the surgery. In neither group did DSWI occur. While no
SSWI was observed in the rifamycin group, it was observed in one
patient in the control group (0/78 vs 1/73,
p
= 0.303). This patient,
who used oral anti-diabetic medication, was 75 years old and had a
serum creatinine level below 2.5 mg/dl, had a low risk profile (total
risk score: 3 and pre-operative mediastinitis risk percentage: 0.5%),
according to the ACC/AHA 2004 guideline.
5
Wound culture was performed and coagulase-negative
staphylococci (CoNS) were observed. The patient was put on
appropriate antibiotic therapy with sodium fusidate (Stafine
®
tablet
500 mg) three times daily and rifampicin (Rifcap
®
capsule 150 mg)
twice daily. The infection regressed and the patient was discharged
after a full recovery.
The amount of drainage in the control group, particularly in four
patients, was higher than in the patients in the rifamycin group,
however, the difference was not statistically significant. This was
attributed to the pre-operatively administered antiplatelet agents
rather than to surgical reasons, and re-exploration was not required.
However, none of the four patients developed sternal infection.
None of the patients required re-exploration due to bleeding,
tamponade or for other reasons.
Discussion
Rifamycin was first isolated in 1957 from a fermentation culture of
Nocardia mediterranei
and used as a novel antibiotic compound.
Rifamycin SV is a relatively effective agent for the treatment of gram-
positive bacteria,
Mycobacterium tuberculosis
and certain gram-
negative bacteria. Rifampicin, an orally active agent that possesses
higher antimicrobial activity, is derived from rifamycin SV. It has
lower antimicrobial activity compared to its orally active derivative
of rifampicin; however, both are effective against gram-positive
cocci, especially staphylococci. Moreover, they possess higher
antimicrobial activity against
Staphylococcus aureus, S epidermidis,
Streptococcus viridans
and
Mycobacterium tuberculosis
, even
in very low doses. There is only one study reporting improved
outcomes in DSWI with the use of rifampicin.
6
CoNS are part of normal skin flora.
7
They are omnipresent and
cause infection in patients as well as in hospital staff.
7,8
CoNS are
multiple-drug-resistant pathogens that can infect deep surgical
wounds and have the potential to threaten life.
9
Stahle
et al
.
10
Table 1.
Baseline clinical characteristics of the study groups.
Group 1
Group 2
(
n
= 78)
(
n
= 78)
p
-value
Age (years)
62 ± 8
61 ± 8
0.605
Sex (F/M)
26/52
28/45
0.635
BMI (kg/m
2
)
28.9 ± 4.6
29.1 ± 4.2
0.796
Mediastinitis risk score
0.7 ± 0.4
0.7 ± 0.4
0.570
Number of grafts (
n
)
3.2 ± 1.0
3.3 ± 1.0
0.557
CABG time (min)
104 ± 30
105 ± 27
0.896
Cross-clamp (min)
70 ± 21
71 ± 20
0.687
24-hour drainage (ml)
508 ± 200
549 ± 317
0.350
Total drainage (ml)
515 ± 202
587 ± 334
0.113
COPD
6 (7.7%)
4 (5.5%)
0.746
Dialysis
2 (2.6%)
3 (4.1%)
0.673
Ejection fraction (< 40%)
13 (16.7%)
12 (16.4%)
0.856
Urgent surgery
1 (1.3%)
3 (4.1%)
0.353
Emergency surgery
0 (0%)
0 (0%)
1.0
Sternal infection
0 (0%)
1 (1.4%)
0.303
Categorical variables are expressed as number (percentage) and continuous
variables as mean = SD. BMI = body mass index; CABG = coronary
artery bypass graft; COPD = chronic obstructive pulmonary disease.