Pathogens Causing Surgical Site Infections After Lower Uterine Caesarean Sections and Recommendations for Antibiotic Guidelines.

Abstract

Background: Caesarean section surgical site infections (SSIs) have the potential to cause major complications however there remains a paucity of data on its microbiology and causative organisms.

Aims: The aim of this study was to identify the organisms causing SSIs in hospitalised patients after lower uterine caesarean section (LUCS). Secondary aims included investigating the differences in organisms isolated from elective versus emergency caesarean sections, and to compare the microbiology of superficial and deep SSIs.

Materials and methods: This was a large retrospective study reviewing all SSIs after LUCS in Western Australian (WA) public hospitals from 2001 to 2021 with data obtained from the Healthcare Infection Surveillance of Western Australia (HISWA).

Results: There were 687 patients identified with an SSI following LUCS over this twenty-year period. The five most common organisms or organism groups isolated were methicillin-susceptible Staphylococcus aureus (MSSA) (30.4%), methicillin-resistant Staphylococcus aureus (MRSA) (14.7%), Enterobacterales (9.5%), Pseudomonas aeruginosa (9.3%), Staphylococcus lugdunensis (5.7%). Group A and B Streptococcus were isolated cumulatively in more than 5% of cases. There were a significantly higher number of superficial SSIs than deep SSIs, and SSIs were significantly more common post emergency LUCS.

Conclusions: Current Australian guidelines may not be appropriate in a considerable proportion of patients with LUCS SSIs, and patients with systemic features of infection should receive antibiotics with activity against P. aeruginosa and MRSA. Critically ill patients with features of sepsis or septic shock should be administered a carbapenem agent which has activity against AmpC/ESBL producing Enterobacterales, instead of piperacillin/tazobactam. Staphylococcus lugdunensis may be an under recognised pathogen in LUCS SSIs. This study also highlighted the importance of wound site sampling in SSIs to establish appropriate directed antimicrobial therapy.