First-line treatment with cephalosporins in spontaneous bacterial peritonitis provides poor antibiotic coverage

Spontaneous bacterial peritonitis is a common infection in cirrhosis, associated with a high mortality. Third-generation cephalosporins are recommended as first-line treatment. The aim was to evaluate the epidemiology of microbiological ascitic fluid findings and antimicrobial resistance in Denmark.

All patients with cirrhosis and a positive ascitic fluid culture, at three university hospitals in the Copenhagen area during a 7-year period, were retrospectively evaluated. Patients with apparent secondary peritonitis were excluded from the study.

One hundred and forty cases with 187 microbiological isolates were identified. The findings were: Gram-positive cocci, n = 86 (45.9%); Enterobacteriaceae, n = 59 (31.7%), with Escherichia coli identified in 31 cases; anaerobes, n = 14 (7.5%); yeast, n = 12 (6.4%); and cutaneous flora, n = 15 (8.0%). One case of Listeria monocytogenes was identified (0.5%). Overall antibiotic coverage was 57% for cephalosporins, 73% for piperacillin-tazobactam, and 72% for meropenem. Mortality rates in patients with isolates susceptible or resistant to the initial antibiotic treatment at 30 days follow-up were 35% and 55%, respectively (p = 0.017, Log-rank test).

Almost half of the isolates were Gram-positive cocci, and as the overall antibiotic coverage with a cephalosporin was only 57%, and survival significantly dependent on whether the microbial etiology was susceptible to initial antibiotic treatment or not, a change of standard empiric antibiotic regime should be considered. Piperacillin-tazobactam could be a favorable choice.