A local study that investigated the impact of kefazolin plus metronidazole compared with kefazolin alone on postpartum infection rates in women undergoing Caesarean section at Kalafong Provincial Tertiary Hospital found no statistically significant differences between the two treatments.
The authors of the research, published in the SA Medical Journal, said the addition of a second antibiotic “is currently not recommended for all patients but can be considered for HIV-infected women”.
However, UTIs post-Caesarean sections were high, added the team, which was led by the University of Pretoria, and more meticulous monitoring of urine at antenatal visits was recommended.
High complications
Lifesaving Caesarean sections are linked to high rates of maternal and neonatal complications. Globally, it’s estimated there are 29.7m annual births by C-section.
The procedure is also the most important risk factor contributing to postpartum infection, the risk being five to 10 times higher than with normal vaginal delivery.
After Caesarean section, the pathogenesis of infection is multifactorial – however, two common mechanisms are known: first, wound contamination by skin flora, and second, the spread of contaminants from the genital tract and intra-uterine cavity.
Postpartum infection is manifested in the form of endometritis, wound infections, intra-abdominal abscesses and urinary tract infections (UTIs), and can lead to maternal sepsis, which, in both high-income and low-income environments, can lead to mortality, serious morbidity and consumption of healthcare resources.
Pregnancy-related sepsis was the third most common direct cause of maternal mortality in SA in 2021.
Strategies to prevent maternal sepsis include measures to reduce postpartum infection. Current clinical practice guidelines recommend antibiotics that are effective against gram-positive, gram-negative and anaerobic bacteria. ACOG suggests the administration of 1g kefazolin an hour before incision, 2g kefazolin in obese patients, and 3g in women ≥120 kg.
There is currently insufficient data to suggest kefazolin plus metronidazole is superior to kefazolin alone in the reduction of postpartum infection.
One trial conducted at the University of Tennessee randomised 160 women into prophylaxis with 2g kefazolin or 1g kefazolin and 500mg metronidazole. There was a significant reduction in postpartum infections in the kefazolin and metronidazole group compared with kefazolin alone.
Although this trial showed significant differences in the two groups, the sample size is inadequate to draw conclusions for an entire population.
Metronidazole was selected as the treatment option because postpartum infections are well-documented to involve multiple types of micro-organisms.
It is known that kefazolin primarily targets gram-positive and gram-negative bacteria, excluding anaerobes, while metronidazole proves to be a cost-effective medication with minimal side-effects.
Data on sepsis rates after C-section in SA are scarce, and according to published literature they range between 2.91%% and 12.5%.
Postpartum sepsis is a serious complication, and effective measures to reduce it should be investigated.
This study aimed to investigate the impact of kefazolin plus metronidazole compared with kefazolin alone on postpartum infection rates in women undergoing Caesarean section at Kalafong Provincial Tertiary Hospital.
The trial showed no statistically significant differences between patients receiving kefazolin only or kefazolin and metronidazole as prophylaxis in the prevention of postpartum infection at C-section.
The current sepsis rate is low, indicating that current interventions are sufficient in the prevention of surgical site infection post C-section. The addition of a second antibiotic is currently not recommended for all patients but can be considered for HIV-infected women. UTIs post-Caesarean sections were high, and more meticulous monitoring of urine at antenatal visits is recommended
Study details
A randomised trial comparing preoperative administration of single-dose kefazolin to kefazolin plus metronidazole as prophylactic antibiotics at Caesarean section
R Lamfel, L Snyman, L Seopela, G Jahn, P Becker,
Published in the SA Medical Journal in May 2024
Background
Caesarean section is a life-saving procedure which is associated with high rates of maternal and neonatal complications. It has been estimated that globally, 29.7 million births occur by caesarean section annually. The risk of postpartum infection is estimated to be five to ten times higher compared to normal vaginal delivery. Pregnancy-related sepsis was listed as a top six cause of maternal mortality in the South African Saving Mothers report between 2017 and 2019. Multiple trials have been conducted in an attempt to optimise administration of prophylactic antibiotics in an effort to reduce postpartum infection and maternal sepsis, and current practice guidelines suggest that there is sufficient evidence that extended spectrum antibiotics, in combination with kefazolin, result in reduction of postpartum infections
Objectives
To investigate the effect of perioperative administration of kefazolin alone compared to kefazolin plus metronidazole on postpartum infection in women undergoing caesarean section at Kalafong Provincial Tertiary Hospital.
Method
All patients undergoing emergency or elective Caesarean section were randomised and then sequentially numbered in opaque sealed envelopes, which were placed in the Caesarean section operating theatre. The intervention group received kefazolin and a sealed envelope with metronidazole. The control grou preceived kefazolin and a sealed envelope with normal saline.
Results
A total of 57/1 010 patients (5.64%) had surgical site infections, of which 27 (5.33%) were in the control group, and 30 (5.96%) were in the intervention group (p=0.66). Two patients in each arm (0.40% in the intervention arm and 0.39% in the control arm) underwent laparotomy procedures, while three women (0.60%) in the intervention arm and four women (0.79%) in the control arm underwent hysterectomy procedures. There were no statistically significant differences in all the measured secondary outcomes between the two groups.
Conclusion
The overall sepsis rate in this study was 5.64%. Postpartum infection is multifactorial and there are multiple factors that can be addressed in strengthening the sepsis care bundle. We do not recommend the addition of metronidazole to kefazolin as prophylaxis at Caesarean section.
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SA’s 'too high' Caesarean birth rate must be reversed