Dynamics of polymorphonuclear neutrophil leukocytes as a criterion of the effectiveness of treatment of spontaneous bacterial peritonitis

Background. Spontaneous bacterial peritonitis (SBP) is a life-threatening complication of decompensated liver cirrhosis (LC) with ascites and is associated with high mortality. Despite modern treatment approaches, the efficacy of empirical antibiotic therapy remains variable, particularly in nosocomial SBP, which is frequently caused by multidrug-resistant organisms. Early diagnosis and evaluation of treatment efficacy require routine paracentesis with polymorphonuclear neutrophil (PMN) count. However, the optimal PMN reduction thresholds and their prognostic significance across different SBP forms remain poorly defined. Objective: to evaluate PMN dynamics in ascitic fluid after 48 hours as a marker of response to empirical antibiotic treatment in patients with SBP and LC, and to compare this indicator between community-acquired and nosocomial SBP. Materials and methods. A prospective cohort study was conducted in 101 patients with LC and confirmed SBP, hospitalized at the Kyiv City Clinical Emergency Hospital from 2023 to 2025. They were divided into two groups: community-acquired (n = 51) and nosocomial SBP (n = 50). Diagnostic paracentesis was performed with PMN count (≥ 250 cells/mm3) and microbiological culture of ascitic fluid. Follow-up paracentesis was done after 48 hours to assess PMN dynamics. Statistical analysis was performed using Statistica v10, MedCalc v23.2.1, and Microsoft Excel. For quantitative variables, mean ± standard deviation and/or median with interquartile range were calculated. Intergroup comparisons were conducted using Student’s t-test or the Mann-Whitney U test. Categorical variables were analyzed with Pearson’s test. The prognostic value of PMN dynamics was assessed by receiver opera­ting characteristic (ROC) analysis, with calculation of area under the ROC curve, 95% confidence intervals, Youden index, sensitivity and specificity. Results. In 31.7 % of patients, SBP was asymptomatic or presented with nonspecific symptoms, complicating diagnosis. This underscores the importance of routine paracentesis in all patients with clinically significant ascites. Overall, empirical antibiotic therapy was effective in 67.3 % of cases, with better outcomes in the community-acquired group (70.5 %) compared to the nosocomial group (48 %). Neutrophil dynamics differed significantly between groups: the average PMN reduction after 48 hours was higher in community-acquired SBP. ROC analysis showed optimal thre­sholds of > 36.8 % PMN reduction for community-acquired SBP and > 16 % for nosocomial SBP. Conclusions. Routine diagnostic paracentesis on admission and repeated after 48 hours should be performed regardless of SBP symptoms. PMN dynamics in the ascitic fluid after 48 hours of antibiotic therapy is a reliable marker of treatment efficacy. The findings support using different PMN thresholds depending on SBP form. Nosocomial SBP is associated with reduced treatment response, warranting broader-spectrum antibiotics from the outset, taking into account the prevalence of resistant microflora.