Peritoneal Fluid Sampling During Emergency Laparotomy Influences Subsequent Antimicrobial Prescriptions in the ICU

September 8, 2021

By Nancy Melville

BRUSSELS -- September 7, 2021 -- The sampling of peritoneal fluid during emergency laparotomy influences subsequent antimicrobial prescriptions in the intensive care unit (ICU), according to a study presented at the 40th International Symposium on Intensive Care and Emergency Medicine.

“Our results suggest that sampling peritoneal fluid during emergency laparotomy may alter 40% of antibiotic prescriptions in the ICU,” stated Eliza Pye, MD, Royal United Hospitals Bath, Bath, United Kingdom.

National Emergency Laparotomy Audit (NELA) recommendations suggest that patients who undergo emergency laparotomy should be admitted to the ICU, where a key aspect of their management should be the administration of empirical antibiotics and may require adjustment based on microbiological findings from peritoneal fluid sampling. To assess the adherence to the recommendations and the degree to which the microbiological findings could change prescribing at their center, the researchers conducted a 6-month baseline audit and found the frequency of intraoperative peritoneal fluid sampling during emergency laparotomy to be low -- at just 31%, despite the recommendations.

Following a quality improvement initiative to improve peritoneal sampling rates, including the use of informational posters and ensuring the correct sampling equipment was readily available for surgeons to increase the sampling, a follow-up review was conducted over 18 months. During that period, 120 emergency laparotomies were performed on 110 patients.

Among microbiological results for peritoneal samples that were noted were resistance to any antibiotic, as well as antibiotics for abdominal sepsis, including amoxicillin, metronidazole, and gentamicin. Blood culture results were also noted. The review showed that during the period, peritoneal sample utilisation improved, with samples sent for 76 (63%) operations.

Of the intraoperative samples, 53 yielded positive growth. While 17 of those were fully sensitive, 36 (68%) showed patterns of antibiotic resistance, including 22 (42%) having resistance to amoxicillin/co-amoxiclav, 3 (6%) to gentamicin, and 4 cultures (7%) with resistance to both. In addition, 6 (11%) of the samples grew candida, including 1 of which was found to be resistant to voriconazole.

Overall, 31 of the peritoneal samples yielded positive growth that would influence a change in antibiotic prescriptions.

“When we considered whether these results would impact our post-operative prescribing, we found that 40% of all samples sent would result in a prescription change post-operatively, due to resistance to1 or more empirical antibiotics or the finding of a candida requiring the addition of an antifungal,” said Dr. Pye

She noted that of the 76 samples sent, only 5 of the patients had positive blood cultures, 2 of which grew 1 or more of the organisms that were identified in the peritoneal fluid sample. One blood culture sample grew an organism that was not identified in the peritoneal sample and 2 grew organisms that were believed to be unrelated to abdominal sepsis.

“We found that blood cultures alone do not reliably identify these organisms [that were found in peritoneal fluid samples],” said Dr. Pye. “Further work is required to understand how this affects patient outcome, but in the absence of these data it seems reasonable, based on our current findings, to advocate peritoneal fluid sampling during emergency laparotomy to guide subsequent antibiotic decision making on the ICU.”

[Presentation title: Sampling Peritoneal Fluid During Emergency Laparotomy Influences 40% of Subsequent Antimicrobial Prescriptions in the ICU. Abstract A23]