Increasing frequency of Gram-positive bacteria in spontaneous bacterial peritonitis

Aim: To evaluate the characteristics and possible recent changes of the microbial causes of spontaneous bacterial peritonitis (SBP) in cirrhotic patients. Methods: We retrospectively evaluated 42 cirrhotic patients with positive ascitic fluid culture and without evidence of secondary peritonitis who were admitted consecutively to our Department between 1998 and 2002. Results: Twenty (48%) of 42 patients with positive ascitic fluid culture were diagnosed during 1998-1999 (period A) and the remaining 22 (52%) patients during 2000-2002 (period B). Gram-negative bacteria were the cause of SBP in 15 (75%) of the 20 patients during period A and in only nine (41%) of the 22 patients during period B (P=0.026). SBP patients with Gram-positive bacteria compared with those with Gram-negative bacteria were less frequently in Child class C (P=0.058) and had significantly higher ascitic fluid protein (P=0.014) and albumin concentrations (P=0.009) and lower ascitic fluid neutrophil count (P=0.008). Resistance to quinolones was detected significantly more frequently in the isolated Gram-positive than Gram-negative bacteria (P<0.001). Conclusion: Culture-positive SBP in cirrhotic patients are caused more frequently by Gram-positive bacteria during the recent years, which are, in their vast majority, resistant to quinolones.