Increasing frequency of gram-positive cocci and gram-negative multidrug-resistant bacteria in spontaneous bacterial peritonitis

BackgroundSpontaneous bacterial peritonitis (SBP) is historically caused by Gram-negative bacteria (GNB) almost exclusively Enterobacteriaceae. Recently, an increasing rate of infections with Gram-positive cocci (GPC) and multidrug-resistant (MDR) microorganisms was demonstrated. AimsTo assess possible recent changes of the bacteria causing SBP in cirrhotic patients. MethodsWe retrospectively recorded 47 cases (66% males) during a 4-year-period (2008-2011). ResultsTwenty-eight (60%) patients had healthcare-associated infections while 15 (32%) received prophylactic quinolone treatment. GPC were found to be the most frequent cause (55%). The most prevalent organisms in a descending order were Streptococcus spp (n=10), Enterococcus spp (n=9), Escherichia coli (n=8), Klebsiella pneumonia (n=5), methicillin-sensitive Staphylococcus aureus (n=4) and coagulase-negative Staphylococcus spp (n=3). Nine of the isolated bacteria (19%) were MDR, including carbapenemase-producing K. pneumonia (n=4), followed by extended-spectrum beta-lactamase-producing E. coli (n=3) and Pseudomonas aeruginosa (n=2). MDR bacteria were more frequently isolated in healthcare-associated than in community-acquired infections (100% vs 50%, P=0.006), in patients receiving long-term quinolone prophylaxis (67% vs 24%, P=0.013) and in those with advanced liver disease as suggested by higher MELD score (28 vs 19, P=0.012). More infections with GNB than GPC were healthcare-associated (81% vs 42%, P=0.007). Third-generation cephalosporin resistance was observed in 49% and quinolone resistance in 47%. ConclusionsGPC were the most frequent bacteria in culture-positive SBP and a variety of drug-resistant microorganisms have emerged. As a result of high rates of resistance in currently recommended therapy and prophylaxis, the choice of optimal antibiotic therapy is vital in the individual patient.