POST CAESAREAN SECTION SURGICAL SITE INFECTION: INCIDENCE, ASSOCIATED FACTORS AND ANTIBIOTIC SENSITIVITY AT THE UNIVERSITY OF ILORIN TEACHING HOSPITAL, ILORIN, NIGERIA

Abstract

BACKGROUND:
Caesarean section (CS) is one of the most common operations performed on women
worldwide. Surgical site infection (SSI) following caesarean section increases maternal
morbidity and medical cost. The effect of this morbidity may be felt even in subsequent
pregnancies. The risk of postpartum infection is higher with caesarean delivery compared
with vaginal births. Several risk factors have been documented in the literature.
Staphylococcus aureus is the commonest organism isolated. Antibiotic prophylaxis has been
found to be the most significant protective factor in reducing both the rate of post-caesarean
section wound infection and costs.
Debate is on-going on the efficacy of wound swab culture technique when compared with
wound biopsy culture technique which is regarded as the gold standard technique in the
diagnosis of wound infection.
OBJECTIVES:
The purpose of this study is to determine the incidence, risk factors, pattern of pathogenic
organism and their antibiotic sensitivity for post-caesarean SSI. To also determine the
efficacy of wound swab culture technique in the diagnosis of post caesarean wound infection
using wound biopsy culture technique as the gold standard.
STUDY DESIGN/ SETTING:
A prospective case-controlled study of women delivered by caesarean section at the
University of Ilorin Teaching Hospital, Ilorin, Nigeria.

METHODS:
Women who had emergency CS (cases) were matched with those who had elective CS
(controls) from 1st January 2012 to 31st August 2012. Two hundred and twenty five women
(225) in each arm of the study who met the inclusion criteria were recruited over a period of
eight months, using purposive non-probability sampling method. All patients had transverse
lower segment caesarean section and antibiotic prophylaxis was given with intravenous
Ceftriaxone 1.0 gm after the clamping of umbilical cord. Patients were followed up after
surgery. Wound biopsy and wound swab specimens were used to confirm the diagnosis of
wound infection in each patient with clinical symptoms and signs of wound infection.
Outcome was recorded and data was analyzed with the statistic package for social sciences
(SPSS 20) software package (SPSS Inc., Chicago, IL).
RESULTS:
Caesarean section rate during the study was 28.4%. Fifty four women (12.0%) developed
surgical site infection. The mean postoperative day wound infection was detected was 5.93 +
3.74 (3 to 17days). The mean hospital stay for women with and without SSI was 12.44 + 3.14
(7 to 19days) and 7.23 + 0.83 (4 to 10days) respectively. Significant risk factors identified
are; obesity (P < 0.001), booking status (P < 0.001), low educational status (P < 0.001), low
social class (P = 0.002), prolonged rupture of membrane (P < 0.001), presence of meconium
in liquor (P < 0.001), emergency surgery (P < 0.001), prolonged operation time (P = 0.021),
cadre of surgeon (P < 0.001) and intraoperative blood loss (P = 0.021). Surgical site infection
was significantly associated with prolonged hospital stay in this study (P < 0.001). Although
wound biopsy culture yielded more positive cultures and was 1.7 times better than wound
swab culture technique in the diagnosis of post caesarean SSI, it was not statistically
significant (χ2 = 0.79, df = 1, P = 0.375, OR 1.70; 95% CI 0.46 – 6.54). Wound swab had a
sensitivity of 91.8%, specificity of 80%, positive predictive value of 97.8% and negative
predictive value of 50% compared with wound biopsy. Staphylococcus aureus was the most
commonly isolated organism in both wound biopsy and wound swab cultures. Other
organisms isolated are Pseudomonas spp, Klebsiella spp, Proteus spp, coagulase negative
Staphylococcus and Bacteroides fragilis. The organisms were mainly sensitive to
cephalosporins, quinolones and metronidazole.
CONCLUSION:
The incidence of post-caesarean SSI in this study was 12.0%. Statistically significant risk
factors identified are obesity, booking status, lower educational status, lower social class,
prolonged rupture of membrane, presence of meconium in liquor, emergency surgery,
prolonged operation time, cadre of surgeon and intraoperative blood loss. Staphylococcus
aureus sensitive to cephalosporins and quinolones was the most commonly isolated
organism. The efficacy of wound swab culture technique was comparable to that of wound
biopsy culture technique in the diagnosis of post caesarean wound infection.

POST CAESAREAN SECTION SURGICAL SITE INFECTION: INCIDENCE, ASSOCIATED FACTORS AND ANTIBIOTIC SENSITIVITY AT THE UNIVERSITY OF ILORIN TEACHING HOSPITAL, ILORIN, NIGERIA