Spontaneous bacterial peritonitis: causative microorganisms, factors influencing the bacterial growth in ascitic fluid culture and antibiotic susceptibility

This study was aimed to identify causative microorganisms in spontaneous ascitic infections and compare them with the current literature, analyse factors facilitate their growth in ascitic fluid, determine sensitivity various antibiotics and analyse responses empirical treatment protocols frequently used in clinics. Inclusion criteria to the the study were portal hypertensive ascites without intraabdominal infection, absence of previous spontaneous bacterial peritonitis attack, accompanying hepatocellular carcinoma and antibiotic prophylaxis. A total of 218 patients (129 male and 89 female; mean age 59±13 years) with miscellaneous etiologies, were enrolled. MELD (Model End stage Liver Disease) scores were determined for each patient. According to growth in culture and polymorphonuclear leukocytes counts (PMNL) above 250/mm³, the patients were classified to spontaneous bacterial peritonitis, culture negative neutrocytic ascites, monomicrobial nonneutrocytic bacteriascites and simple ascites groups. Bedside inoculation of ascitic fluid was done into the blood culture bottles. Patient characteristics were compared between or among the groups, i.e. culture positive vs negative, spontaneous bacterial peritonitis vs simple ascites and within subgroups of spontaneous ascitic infections. The factors for the early prediction of bacterial growth in culture and the variables effective on the development of spontaneous ascitic infections were evaluated with multivariate analysis. A decrease of more than 25% in ascitic leucocyte count in the 3rd day of treatment was accepted as a response to treatment. During the period of the study, the empirical antibiotics were cefepim and cefotaxime. Of the patients, 24.8% had spontaneous bacterial peritonitis, 10.1% had monomicrobial nonneutrocytic bacteriascites, 44.6% had culture negative neutrocytic ascites, and 21.6% had simple ascites. Growth in culture was observed in 76 patients (34.9%). The most frequent 3 bacteria were in order Escherichia coli (33.8%), Staphylococcus epidermidis (19.7%) and Streptococcus species (spp) (13.1%). vi In patients with ascites PMNL ≥250/mm³ or those with positive culture, the eryhtrocyte sedimentation rate and C-Reactive Protein were higher (p<0.001). In the group with positive culture, ascites protein and pH were significantly lower compared to those with negative culture (p<0.001). Response rate to the treatment was 73.8%. Although Escherichia coli showed a good level of sensitivity to cefepim and cefotaxime (82%), Staphylococcus epidermidis, second frequently grown, did not (44%). Levofloxacine had high effectivety against both microorganisms (71% against Escherichia coli, 90% against Staphylococcus epidermidis). The most important factor determining the treatment failure was the antibiotic resistance, as expected. Growth of Staphylococcus epidermidis in ascitic fluid seemed to be important in treatment failure. In this study positive bacterial growth rates in ascetic fluid were concurrent with present literature, except for Staphylococcus epidermidis which was second in order. The observation that some biochemical measurements were related with bacterial growth in ascites, suggested that these factors facilitated spontaneous ascitic infections and that some parameters could be used for early detection of growth. Levofloxacine can be an alternative treatment in the patients with uncomplicated spontaneous ascitic infections. Key words: Spontaneous ascites infections, ascites culture, ascites biochemistry, microorganism species, antibiotic resistance