Bacteriological Profile and Antimicrobial Resistance in Intraoperative Purulent Samples From Acute Appendicitis: A 3-Year Retrospective Analysis.

OBJECTIVE

To investigate the bacteriological spectrum and antimicrobial resistance of intraoperative purulent samples from patients with acute appendicitis and provide evidence for empirical therapy.

METHODS

A retrospective study was performed on 110 patients treated between 2021 and 2023. Intraoperative samples were cultured, and susceptibility testing against 20 antibiotics was conducted according to CLSI guidelines.

RESULTS

Ninety-eight isolates were obtained. Gram-negative bacteria predominated (91.84%), mainly Escherichia coli (71.43%), Klebsiella pneumoniae (7.14%), and Pseudomonas aeruginosa (6.12%). E. coli showed complete susceptibility to meropenem, imipenem, and amikacin, high susceptibility to piperacillin-tazobactam (97.14%) and cefoxitin (88.57%), but high resistance to amoxicillin (94.29%). K. pneumoniae was universally susceptible to carbapenems, cefoxitin, and amikacin, but resistant to amoxicillin, piperacillin, ticarcillin, cephalothin, and gentamicin. P. aeruginosa was fully susceptible to carbapenems, cefoxitin, amikacin, and piperacillin-tazobactam, but resistant to most first- and second-generation cephalosporins and several aminoglycosides.

CONCLUSION

Gram-negative enteric bacteria, particularly E. coli , are the dominant pathogens in appendiceal infections. Carbapenems and amikacin retain excellent efficacy, whereas amoxicillin and several commonly used antibiotics show poor activity. Piperacillin-tazobactam represents a reasonable first-line empirical choice, while carbapenems should be reserved for severe infections or patients at risk for resistant organisms. These findings highlight the importance of local resistance surveillance to guide institution-specific antibiotic protocols.