P58 Antimicrobial resistance patterns and outcomes in spontaneous bacterial peritonitis: real-world retrospective study

<h3></h3> The incidence of multidrug resistant (MDR) organisms in spontaneous bacterial peritonitis (SBP) is increasing, shifting from gram-negative to gram-positive organisms. There are recent safety concerns regarding the use of long-term fluoroquinolones. These factors will impact on the choice of antibiotics we use in SBP treatment and prophylaxis. We sought to evaluate the microbial populations and patterns of antimicrobial resistance in culture-positive SBP patients. Additionally we studied the outcomes of clinical SBP including culture-negative cohorts. This is a single centre retrospective study within a large tertiary teaching hospital. All positive ascitic cultures from patients with cirrhosis were obtained between 01/01/2021 and 31/12/2023, including those with ascitic total white cell count (WCC) &lt;0.3 i.e. bacterascites. A second cohort consisted of patients with culture-negative SBP (ascitic WCC &gt; 0.3). All patients were treated with antibiotics for SBP and there was no patient overlap between the two cohorts. Exclusion criteria were secondary peritonitis, non-hepatology causes and those deemed to be contaminants clinically. 97 SBP events from 89 patients were included. Median age was 61 years (53–70). The commonest aetiology was alcohol-related liver disease (61%). Median MELD score was 22 (16–29) and median UKELD score 57 (53–63). Culture-positive SBP cohort consisted of 29 samples from 27 patients. Escherichia coli was the most common pathogen (34%), followed by Enterococcus faecalis/enterococcus faecium (28%). Gram positive bacteria were present in 56% of cases. There was a corresponding bacteraemia in 53%. Resistance to cefuroxime (first line for SBP treatment in our hospital) and ciprofloxacin (first line for SBP prophylaxis) was 13% and 21%, respectively (see graph 1). Prevalence of MDR organisms was 10% (all coagulase-negative staphylococcus). Notably, there were no cases of ESBL, MRSA or VRE. 21% of patients were on prophylactic antibiotics at time of SBP. Median length of hospital stay was 10 days. 30 day and 90 day all-cause mortality all SBP patients was 30% and 40%, respectively. Culture-positive SBP cohort had a significantly increased 90 day all-cause mortality compared to culture-negative SBP (p=0.02). Our data showed prevalence of MDR bacteria causing SBP and antimicrobial resistance is relatively low in our local cohort. However, SBP remains associated with high mortality and in particular, culture-positive SBP is associated with worse outcomes. Empirical antibiotic choice need to consider the emerging gram-positive organisms, and careful selection of patients for primary long-term antibiotic prophylaxis is required to reduce burden of antimicrobial resistance and must take into account recent fluoroquinolone guidance.