Differences in isolated bacteria between perforated and non-perforated appendicitis: an analysis of 680 consecutive appendicectomies in a single institution

Intraoperative bacterial cultures fail to reliably predict the bacterial spectrum encountered during infectious complications after appendicitis

Acute appendicitis is a common surgical emergency. Complicated appendicitis usually warrants perioperative antibiotic treatment in order to prevent infectious complications. Whether routine microbiological testing benefits the individual patient is a topic of debate. The goal of our study was to assess perioperative antibiotic prescriptions as well as the benefit of microbiological testing during the appendectomy as a predictor for bacteria encountered in infectious complications. This is a retrospective analysis of 1218 consecutive patients that underwent appendectomy at a tertiary referral center between 2014 and 2021. The patient charts were systematically analyzed regarding intraoperative outcome, microbiologic results, and postoperative infectious complications. 1218 patients were included in this study of which 768 were uncomplicated appendicitis (UA) and 450 were complicated appendicitis (CA). Microbiological testing was performed in 39.2% of UA cases (33.6% of which grew bacteria) compared to 74.9% of CA cases (78.6% positive cultures). The strongest individual predictors for SSI were gangrenous and perforated appendicitis. A total of 58 surgical-site infections developed, of which 49 were intra-abdominal fluid collections or abscesses. Thirty-two patients had revision surgery or CT-guided drainage for SSI. In the cases where microbiological testing was done both during the appendectomy and the SSI, 13/18 showed different bacteria on culture testing. The infectious outcome was favorable in 98.3%. While microbiological testing offers insights into resistance patterns, it is of little benefit for the individual patient, given the low predictive value for bacteria found during SSI. Achieving source control combined with empiric antibiotic coverage leads to favorable outcomes independent of culture results.

Association of the Bacteria of the Vermiform Appendix and the Peritoneal Cavity with Complicated Acute Appendicitis in Children

BACKGROUND

Primary infection has been questioned as the pathogenetic cause of acute appendicitis. We attempted to identify the bacteria involved and to investigate if their species, types, or combinations affected the severity of acute appendicitis in children.

METHODS

Samples from both the appendiceal lumen and the peritoneal cavity of 72 children who underwent appendectomy were collected to perform bacterial culture analysis. The outcomes were studied to identify if and how they were associated with the severity of the disease. Regression analysis was performed to identify any risk factors associated with complicated appendicitis.

RESULTS

Escherichia coli, Pseudomonas aeruginosa, and Streptococcus species were the most common pathogens found in the study population. The same microorganisms, either combined or separate, were the most common in the appendiceal lumen and the peritoneal cavity of patients with complicated appendicitis. Gram-negative bacteria and polymicrobial cultures in the peritoneal fluid and in the appendiceal lumen were associated with complicated appendicitis. Polymicrobial cultures in the peritoneal cavity presented a four times higher risk of complicated appendicitis.

CONCLUSIONS

Polymicrobial presentation and Gram-negative bacteria are associated with complicated appendicitis. Antibiotic regimens should target the combinations of the most frequently identified pathogens, speculating the value of early antipseudomonal intervention.