Does First-Line Treatment with Ceftriaxone Still Provide Sufficient Antibiotic Coverage in Spontaneous Bacterial Peritonitis?

Introduction: Spontaneous bacterial peritonitis (SBP) represents an important cause of morbidity and mortality in patients with liver cirrhosis. Early diagnosis and treatment are thus essential. The results of bacterial cultures can help to optimize the treatment in this group of patients. The most frequent etiology is Enterobacteriaceae spp., principally Escherichia coli. In our center, the gram-negative bacteria present an estimated rate of resistance to third-generation cephalosporines of around 10% in community-acquired infections and of nearly 20% in nosocomial infections. Objectives: To establish the rate of ascitic fluid culture positivity and the resistance rates to antibiotics to improve the initial empiric treatment. Material and methods: We performed a retrospective study including all the episodes of SBP that required hospitalization in our center between January 2007 and December 2011, in total 113 episodes of SBP in 108 patients. We registered the most clinically and microbiologically relevant characteristics and the mortality during the episode and after 3 and 6 months. We analyzed our data using the SPSS program version 19.0. Results: 75% of all patients were men, the mean age was 61.3 years (40–85 years). The most frequent etiology for liver cirrhosis was viral and alcoholic (56.7% and 54%, respectively). Among the clinical characteristics of our patients stands out the presence of hepatocellular cancer in 32.7% (63.2% of these presented advanced stage of disease), basal mean MELD of 15.2, and mean Child Pugh score of 9 points. The microbiology results showed an ascitic fluid culture isolation rate of 31% (35/113 cases). Blood cultures were extracted in 56 episodes of SBP (thus representing 49.6%), usually in the context of fever, and were positive in 23.3% of cases. Interestingly, in half of these patients the ascitic fluid cultures resulted sterile. In 51% of the positive ascitic fluid samples, gram positive bacteria (mostly Streptococcus spp.) were isolated, gram negatives (principally E. coli) represented 41%. We only detected one case of extended-spectrum beta-lactamase (ESBL) and no case of methicillin-resistant Staphylococcus aureus (MRSA) was described. The most frequently used empiric treatment was Ceftriaxone in 65% of the cases of SBP, followed by Meropenem in 12%. In thirty-eight cases a second antibiotic was needed, mostly if second diagnostic paracentesis at 48 hours showed no improvement in leucocyte count. During the hospitalization, there were 23 cases (21%) of deaths directly associated to the SBP, and 20 patients (17.6%) died during the following six months. However, there was an important number of patients (38.9% in total) who did not participate in the six-month follow-up. Conclusion: Gram-positive bacteria represent the most frequent cause of SBP in our group of patients, with overall excellent sensibility to third-generation cephalosporins. Thus, Ceftriaxone remains the treatment of choice in our centre. Based on our results, we changed the form of extraction of ascitic fluid and initiated a new prospective study aimed at improving the rate of culture positivity and avoiding unnecessary antibiotic use.