Spontaneous bacterial empyema in cirrhotic patients: a prospective study

Abstract

Spontaneous bacterial empyema (SBEM) is an infection of a preexisting hydrothorax in cirrhotic patients and has seldom been reported. To determine its incidence and primary characteristics, all cirrhotic patients with pleural effusion underwent thoracentesis at our hospital either on admission or when an infection was suspected. Pleural fluid (PF) study included biochemical analysis, polymorphonuclear (PMN) leukocyte count, and culture by two methods: conventional and modified (inoculation of 10 mL of PF into a blood culture bottle at the bedside). SBEM was defined according to previously reported criteria: PF culture positive or PMN count greater than 500 cells/micro L, and exclusion of parapneumonic effusions. Sixteen of the 120 (13 percent) cirrhotic patients admitted with hydrothorax had 24 episodes of SBEM. In 10 of the 24 episodes (43 percent), SBEM was not associated with spontaneous bacterial peritonitis (SBP). PF culture was positive by the conventional method in 8 episodes (33 percent) and by the modified method (blood culture inoculation) in 18 (75 percent) (P = .004, McNemar). The microorganisms identified in PF were Escherichia coli in 8 episodes, Streptococcus species in 4, Enterococcus species in 3, Klebsiella pneumoniae in 2, and Pseudomonas stutzeri in 1. All episodes were treated with antibiotics without inserting a chest tube in any case. Mortality during treatment was 20 percent. We conclude that SBEM is a common complication of cirrhotic patients with hydrothorax. Almost half of the episodes were not associated with SBP; thus, thoracentesis should be performed in patients with cirrhosis, pleural effusion, and suspected infection. Culture of PF should be performed by inoculating 10 mL into a blood culture bottle at the bedside.