CARDIOVASCULAR JOURNAL OF AFRICA • Volume 25, No 3, May/June 2014
98
AFRICA
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
reported the rate of CoNS in surgical wound infections as
14%. It is known that CoNS are also the predominant bacteria
in DSWI.
11
SWI are divided into two subgroups: superficial sternal
wound infection (SSWI) and deep sternal wound infection
(DSWI). While SSWI involves only subcutaneous tissue, DSWI
is associated with sternal osteomyelitis and sometimes with
infected retrosternal space (termed mediastinitis).
12
Studies have
reported that DSWI occurs in 0.25 to 2.3% of patients.
13-17
While re-opening and debridement of the mediastinum is
required in the treatment of DSWI, administration of antibiotics
is generally sufficient to treat SSWI. In the present study, only
one patient (1/151, 0.66%) in the control group developed SSWI
and was treated with the administration of antibiotics.
DSWI occurring after CABG operation has a multifactorial
aetiology, with a potential risk of death and high hospital
costs.
18
Many studies have suggested the underlying aetiology
of DSWI occurring after CABG to be obesity, advanced age,
prolonged CPB duration, diabetes, high creatinine levels, use of
bilateral internal mammary artery grafts, and unnecessary use of
electrocautery.
14,18-21
Recent studies have suggested that DSWI is
associated with obesity and re-operation, and also indicated that
use of bilateral internal mammary artery grafts, duration and
complexity of the operation, and diabetes are other risk factors.
22
It is well known that mobilisation of the internal mammary
artery causes sternal devascularisation and the resultant
ischaemia contributes to sternal dehiscence or infection.
14,22
In the
present study, according to the ACC/AHA 2004 guideline,
5
the
pre-operative mediastinitis risk percentage of one patient who
developed SSWI was 0.5%, due to the risk factors, advanced
age and the presence of diabetes. Although this patient was not
a dialysis patient, he/she had a high creatinine level (2.5 mg/dl).
In a 10-year retrospective study of 5 440 patients who
underwent cardiac surgery, Khanlari
et al.
6
evaluated 100
patients with staphylococcal DSWI developing after cardiac
surgery. They reported that a rifampicin-containing antibiotic
regimen significantly improved the outcomes during a one-year
follow-up period.
Many factors have been implicated in the occurrence of
DSWI after cardiac surgery. However, there is no consensus
on which is the most important and best predictive factor.
23
On the other hand, diabetes has emerged as a significant risk
factor of cardiovascular surgeons, for the development of DSWI
after CABG operation. In terms of the pathophysiological
consequences of diabetes, microvascular changes and elevated
blood glucose levels impair the healing process of surgical
wounds.
24,25
The present study is distinctive in that it examined
patients who were on oral anti-diabetic agents or insulin therapy.
Conclusion
Although the difference in the rate of superficial sternal wound
infection between the rifamycin and control groups was not
statistically significant, locally applied rifamycin SV during
closure of the sternum after CABG surgery may have had a
protective affect against SWI.
We thank Associate Prof Ismail Keskin of the Department of Biometry and
Genetics, Selçuk University, Konya, Turkey for his contribution to evaluation
of the results and statistical analysis.
References
1.
Farinas MC, Gald PF, Bernal JM,
et al
. Suppurative mediastinitis after
open-heart surgery: a case-control study covering a seven-year period in
Santander, Spain.
Clin Infect Dis
1995;
20
(2): 272–279.
2.
Toumpoulis IK, Anagnostopoulos CE, DeRose JJ. The impact of deep
sternal wound infection on long-term survival after coronary artery
bypass grafting.
Chest
2005;
127
(2): 464–471.
3.
Hollenbeak CS, Murphy DM, Koenig S,
et al.
The clinical and econom-
ic impact of deep chest surgical site infections following coronary
artery baypas graft surgery.
Chest
2000;
118
(2): 397–402.
4.
Mossad SB, Serkey JM, Longworth DL,
et al
. Coagulase-negative
staphylococcal sternal wound infections after open heart operations.
Ann Thorac Surg
1997;
63
(2): 395–401.
5.
ACC/AHA 2004 Guideline Update for Coronary Artery Bypass Graft
Surgery.
Circulation
2004;
110
; e340-e437.
6.
Khanlari B, Elzi L, Estermann L, Weisser M, Brett W,
et al.
A rifampi-
cin-containing antibiotic treatment improves outcome of staphylococcal
deep sternal wound infections.
J Antimicrob Chemother
2010;
65
(8):
1799–1806.
7.
Kloos WE, Musselwhite MS. Distribution and persistence of
Staphylococcus
and
Micrococcus
and other aerobic bacteria on human
skin.
Appl Microbiol
1975;
30
(3): 381–385.
8.
Babb JR, Lyman P, Ayliffe GA. Risk of airborne transmission in an
operating theatre containing four ultraclean units.
J Hosp Infect
1995;
31
(3): 159–168.
9.
Emori TG, Gaynes RP. An owerview of nosocomial infections, includ-
ing the role for the microbiology laboratory.
Clin Microbiol Rev
1993;
6
(4): 428–442.
10. Stahle E, Tammelin A, Bergstrom R, Hambreus A, Nystrom SO,
Hansson HE. Sternal wound complications – incidence, microbiology
and risk factors.
Eur J Cardiothorac Surg
1997;
11
(6): 1146–1153.
11. Loop FD, Lytle BW, Cosgrove DM,
et al
. J. Maxwell Chamberlain
memorial paper: sternal wound complications after isolated coronary
artery bypass grafting: early and late mortality, morbidity, and cost of
care.
Ann Thorac Surg
1990;
49
(2): 179–186.
12. El Oakley RM, Wright JE. Postoperative mediastinitis: classification
and management.
Ann Thorac Surg
1996;
61
(3): 1030–1036.
13. Sarr MG, Gott VL, Townsend TR. Mediastinal infection after cardiac
surgery.
Ann Thorac Surg
1984;
38
(4): 415–423.
