Metagenomic NGS optimizes the use of antibiotics in appendicitis patients: bacterial culture is not suitable as the only guidance.

backgroundPrevious treatment guidelines have suggested that bacteria are associated with the severity of appendicitis, and the use of postoperative antibiotics should be guided according to the bacteria culture results derived from intraoperative samples. However, this approach has many limitations. Patients were commonly administrated antibiotics during the perioperative period, which can lead to inaccurate culture result.

aimTo assess the relationship between pathogenic bacteria and appendicitis and optimize the process of antibiotic selection.

methodsA nonconsecutive case series analysis was conducted from January to July 2017. Nineteen patients were divided into two groups according to their postoperative histological results (Non-perforated: phlegmonous/Perforated: gangrenous, n = 9/10) and postoperative bacterial culture results (Negative/Positive, n = 8/11). Patients were administrated same antibiotics during the perioperative period. During appendectomy, the diseased appendixes were collected, and whole metagenomic sequencing was used to identify the pathogenic bacteria in the specimens. Conventional technology was used to culture bacteria from appendix samples.

resultsWe identified 361 species in the appendix samples. Six species in the appendix samples had relative abundances > 5%. No significant differences were observed in the bacterial composition of the two assayed groups. In particular, according to the grouping of culture results, the sequencing analysis results were completely different from those of the culture-based method.

conclusionIn clinical practice, because patients are regularly administrated antibiotics during the perioperative period, these antibiotics inevitably affect the results of bacterial culture. Therefore, bacterial culture results are not suitable for exclusively guiding the use of antimicrobial agents after appendicitis. Next-generation sequencing has numerous advantages, such as precisely characterizing the profiles of microbiota and their antibiotic resistance in appendicitis patients. Based on the above results, we propose that a combination of bacterial culture and next-generation sequencing should be used to improve the efficacy of antibiotic therapy.