Effect of peritoneal lavage on bacterial isolates in 40 dogs with confirmed septic peritonitis

Objective To evaluate bacterial isolates, antimicrobial drug susceptibility, and change in resistance among pre- and post-lavage culture samples in dogs with septic peritonitis. Design Prospective observational study. Setting Private practice referral hospital. Animals Forty client-owned dogs with confirmed septic peritonitis requiring surgical intervention. Interventions All dogs had perioperative abdominal lavage following source control with 200 to 300 mL/kg 0.9% sterile saline. Pre- and post-lavage aerobic and anaerobic culture samples were evaluated. Measurements and main results Thirty-five of 40 dogs (87.5%) survived to hospital discharge. The likelihood of an aerobic organism to have multidrug resistance (resistance to 3 or more antimicrobial classes) post-lavage was a third of that pre-lavage (odds ratio [OR] 0.34, 95% CI [0.17-0.68], P = 0.01). Thirty-nine of 40 dogs (97.5%) received appropriate empiric antimicrobial therapy based on pre- and post-lavage culture results, of which 5 (12.8%) did not survive to discharge. The single dog with inappropriate antimicrobial therapy survived to discharge. The most frequent isolates detected included Escherichia coli, Clostridium perfringens, and Enterococcus faecalis. The same organism based on species was isolated in pre- and post-lavage cultures in 32 dogs, accounting for 59 anaerobic and aerobic isolates. There was a new bacterial isolate detected in 20 dogs, accounting for 46 isolates and an overall total decrease of 14 isolates between pre- and post-lavage culture (P = 0.09). Conclusions This study suggests that there is a significant decrease in the likelihood of isolating a multidrug resistant organism following peritoneal lavage, and aerobic and anaerobic culture results have the potential to change following peritoneal lavage, although this cannot be confirmed without further studies. Overall survival rates were higher than previously reported in the literature for septic peritonitis.