Identification of bacterial DNA in neutrocytic and non-neutrocytic cirrhotic ascites by means of a multiplex polymerase chain reaction

Use of Bacterial DNA Concentration in Ascites as a Marker for Spontaneous Bacterial Peritonitis

Background and aims

Spontaneous bacterial peritonitis (SBP) is a common and serious complication in patients with decompensated cirrhosis. Precise quantification of bacterial DNA (bactDNA) and the related inflammatory response might add further information on the course of disease. The aim of the study was to evaluate the association between bactDNA, cytokine levels and clinical outcome.

Methods

Ascites and serum samples of 98 patients with decompensated liver cirrhosis (42 with SBP and 56 without SBP) as well as serum samples of 21 healthy controls were collected. BactDNA in ascites and serum was detected and quantified by 16S rRNA PCR. Concentrations of IL-1β, TNF-α, IL-6, IL-8 and IL-10 were measured by a LEGENDplexTM multi-analyte flow assay. Clinical data were collected and analyzed retrospectively.

Results

BactDNA was detected more frequently in ascites of patients with SBP (n = 24/42; 57.1%) than in ascites of patients without SBP (n = 5/56; 8.9%; P < 0.001). Additionally, IL-6 levels in both ascites and serum were significantly higher in patients with SBP (ascites P < 0.001, serum P = 0.036). The quantity of bactDNA in ascites was strongly correlated with polymorphonuclear neutrophil count in ascites (r = 0.755; P < 0.001) as well as ascites IL-6 levels (r = 0.399; P < 0.001). Receiver operating characteristic (ROC) curve analysis to diagnose SBP provided an AUC of 0.764 (95% CI: 0.661-0.867) for serum IL-6 levels, an AUC of 0.810 (95% CI: 0.714-0.905) for ascites IL-6 levels, and an AUC of 0.755 (95% CI: 0.651-0.858) for bactDNA levels in ascites.

Conclusions

The correlation between the amount of bactDNA and IL-6 confirms the pathophysiological relevance of bactDNA and IL-6 as potential biomarkers for the diagnosis of SBP.

Culture-Negative Neutrocytic Ascites in a Patient With Cardiac Ascites From End-Stage Heart Failure

There are two significant groups of infection regarding ascitic fluid: spontaneous bacterial peritonitis (SBP) and culture-negative neutrocytic ascites (CNNA). SBP and CNNA typically occur in patients with cirrhosis. A 46-year-old male with end-stage biventricular heart failure presented with a heart failure exacerbation. He was treated with intravenous diuretics with the improvement of hypervolemia. He remained hospitalized to undergo an evaluation for tricuspid valve repair, but given the severity of his bi-ventricular heart failure, he underwent a heart transplant evaluation. As part of the work-up, he underwent an abdominal ultrasound that was significant for severe ascites but did not note an abnormal hepatic architecture suggestive of cirrhosis. A liver biopsy was then performed, which confirmed no evidence of cirrhosis. His hospitalization was complicated by refractory cardiac ascites, which required a bi-weekly paracentesis. The serum albumin-ascites gradient (SAAG) from his initial paracentesis was 1.4, indicating the etiology was from portal hypertension. The total protein was greater than 2.5 in multiple studies, so the etiology was less concerning for cirrhosis and secondary to his heart failure. About two weeks into his hospital course, he developed a leukocytosis but remained hemodynamically stable and asymptomatic from an infectious standpoint. Analysis of his ascitic fluid initially was negative for infection, but he later developed an elevated total neutrophil count on a subsequent ascitic fluid analysis study. The body fluid culture remained negative for bacterial growth. Hepatology was consulted, and he met the criteria for CNNA, so treatment with ceftriaxone was initiated. After initiating antibiotics, his leukocytosis and elevated ascitic fluid total neutrophil count resolved. Ascitic infections such as CNNA generally occur in patients with liver cirrhosis but may occur in patients without cirrhosis, as observed in our patient. This case highlights that patients with cardiac ascites can develop ascitic fluid infections that may have an impact on their mortality. The precipitating factor that enabled the patient to develop CNNA is unclear but may be related to the translocation of bacteria during his congestive heart failure exacerbation. Although uncommon in a patient with cardiac ascites, an early diagnosis of CNNA and the initiation of antibiotics can be important in preventing patient mortality.

Bacterial DNA is a prognostic factor for mortality in patients who recover from spontaneous bacterial peritonitis

Background

Spontaneous bacterial peritonitis (SBP) is associated with a high mortality. The aim was to investigate whether bacterial deoxyribonucleic acid (bactDNA) could offer an accurate identification of pathogens and to explore its prognostic role during and early after an SBP episode.

Methods

Consecutive patients with SBP (SBP-group) and patients with decompensated cirrhosis without SBP/bacterascites (control-group) were enrolled. Standard culture methodology was used to isolate and identify pathogens from blood and ascitic fluid (AF). The SeptiFast test was used to identify bactDNA directly from AF.

Results

Fifty-five patients, median age 60 (interquartile range [IQR] 53-74), model-for-end-stage liver disease (MELD) score 18 (IQR 13-29), with SBP were prospectively included. AF cultures were positive in 52.7% (17.2% drug-resistant bacteria) and bactDNA in 29.1% (58.2% combined sensitivity). BactDNA results were 84.6% concordant with AF cultures. Three patients had positive bactDNA in the culture-negative SBP-group. BactDNA was negative in all 36 of the control group (100% specificity). In multivariate analysis for 7-day survival, factors adversely affecting outcome were MELD (P=0.049) and C-reactive protein (P=0.012). After patients who died during the first week post-admission were excluded, patients with positive bactDNA had a poor prognosis compared to those with a negative test (log-rank P=0.005). Variables independently associated with 30-day mortality were neutrophil-to-lymphocyte ratio (P=0.011) and positive bactDNA (P=0.020).

Conclusions

No evidence was found for the usefulness of bactDNA to improve bacterial identification during an SBP episode. However, bactDNA was a predictor of 30-day mortality in the subset of patients who recovered from the infection episode.

Combination of vial culture and broad-range PCR for the diagnosis of spontaneous bacterial peritonitis: experience in a Greek tertiary care hospital

Spontaneous bacterial peritonitis (SBP) is often difficult to diagnose because bacteria in ascites cannot be detected accurately by conventional culture. In this study, we evaluated the use of broad-range 16S rRNA PCR, applied either directly to a total of 32 ascitic fluids (AFs) or to the AF vial cultures, after a long incubation of 14 days; the results were compared with those of AF vial cultures. Escherichia coli was isolated in four of 32 AF vial cultures (12.5%). The application of 16S rRNA PCR directly to AF detected only one of the four positive samples (sensitivity 25%, specificity 100%, positive predictive value (PPV) 100%, negative predictive value (NPV) 90.32%). However, the application of 16S rRNA PCR to AF vial cultures after 14 days of incubation correctly identified all the positive samples, including one more that was positive for Brucella mellitensis (sensitivity 100%, specificity 80%, PPV 80%, NPV 100%). The elongation of the incubation period of the AF vial cultures, combined with the use of 16S rRNA in negative vials, increases the possibility of identifying the causative agents of SBP and could be applied in the clinical laboratory.

Amplification of bacterial genomic DNA from all ascitic fluids with a highly sensitive polymerase chain reaction

Due to varying positive rates of polymerase chain reaction (PCR) amplification, interpretation of conventional PCR results for non-infectious ascites remains problematic. The present study developed a highly sensitive PCR protocol and investigated the positive rate of PCR for the 16S ribosomal (r)RNA gene in non-infectious ascites. Following the design of a new PCR primer pair for the 16S rRNA gene (800F and 1400R), the sequences of PCR products were analyzed and the lower limit for bacterial DNA detection evaluated. The positive rate of PCR for 16S rRNA gene in non-infectious ascites was also evaluated. PCR with the primer pair amplified the genomic DNA of 16S rRNA genes of major disease-causing bacterial strains. Additionally, PCR with this primer pair provided highly sensitive detection of bacterial genomic DNA (lower limit, 0.1 pg of template DNA). When DNA samples isolated from ascites were used, the 16S rRNA gene was amplified independently of the presence of bacterial infection. PCR products contained the genomic DNA fragments of multiple bacterial species. Bacterial genomic DNA can be amplified from all ascitic fluids using a highly sensitive PCR protocol. Careful attention is required to interpret the results based on simple amplification of 16S rRNA gene with conventional PCR.

Bacterial translocation and clinical progression of HCV-related cirrhosis in HIV-infected patients

The aim of the study was to evaluate whether bacterial translocation (BT) predicts the clinical outcome in HIV/HCV-coinfected patients with compensated cirrhosis. A cohort of 282 HIV/HCV-coinfected patients with cirrhosis and no previous liver decompensation (LD) was recruited. Serum levels of the DNA sequences encoding the well-conserved 16S rRNA subunit (16S rDNA), the lipopolysaccharide (LPS) and soluble CD14 (sCD14) at diagnosis of cirrhosis were measured. Primary endpoint was the emergence of the first LD and/or death of any cause. Secondary endpoints were LD, liver-related death (LRD) and death of any cause. After a median (Q1-Q3) follow-up of 51 (27-72) months, 67 patients (24%; 95% CI: 19-29) developed their first LD or died during follow-up. Baseline levels of 16S rDNA, LPS and sCD14 were not associated with the probability of developing the primary endpoint of the study. The mean (SD) survival time free of LD and/or death according to levels of 16S rDNA (<83, 83-196, 197-355, >355 [copies/μL]) was 78 (5), 72 (5), 81 (4) and 82 (4) months, respectively (P = .5). The corresponding figures for LPS (<0.1, 0.1-0.6, 0.6-1.5, > 1.5 [IU/mL]) were 76 (5), 71 (5), 77 (5) and 81 (4) months, respectively (P = .4). Baseline levels of BT serum markers were not associated with any of the secondary endpoints analysed in the study. Thus, BT does not seem to be a relevant predictor of clinical outcome in HIV/HCV-coinfected patients with compensated cirrhosis.

Bacterial translocation markers in liver cirrhosis

Bacterial translocation (BT) is an important mechanism in the development of infection in liver cirrhosis. The migration and colonization of bacteria and/or bacterial products from the bowel to mesenteric lymph nodes is a controlled process in healthy persons. Increased intestinal permeability, bacterial overgrowth and defect of gut-associated lymphatic tissue promote impaired BT in cirrhotics. We reviewed the reports on markers used for the evaluation of BT published between 1987 and 2016. We focused on the clinical consequences of BT in cirrhosis, as indicated by the values of the BT markers. Patients with cirrhosis are reported to have elevated levels of surrogate markers associated with BT compared with controls. The most widely used BT parameters are C-reactive protein, procalcitonin, bacterial DNA, endotoxin or lipopolysaccharide, lipopolysaccharide binding protein, calprotectin, and bactericidal/permeability increasing protein. High levels of these factors in serum and/or ascitic fluid in humans may be associated with advanced liver disease, hemodynamic instability, high levels of proinflammatory cytokines, susceptibility to the development of severe or recurrent infections, acute-on-chronic liver failure, hepatic encephalopathy, hepatorenal syndrome and poor prognosis during follow up. In conclusion, high levels of BT markers are associated with a high inflammatory response, increased complications of liver cirrhosis and occasionally high fatality rates.

Detection of molecular bacterascites in decompensated cirrhosis defines a risk with decreased survival

BACKGROUND

The prognostic relevance of bacterial DNA (bactDNA) detection in ascitic fluid of patients with cirrhosis is still under debate. Using quantitative real-time PCR with broad-range primers targeting the V3 and V4 variable region of the 16S rRNA gene, we measured bactDNA concentrations in patients with and without leukocytic ascites and evaluated the impact on short-term survival.

PATIENTS AND METHODS

Ascites samples from 173 patients with decompensated cirrhosis were consecutively collected between February 2011 and December 2012. BactDNA-positive ascites samples were sequenced and chromatograms were identified using RipSeq. Clinical data collection and survival analyses were carried out retrospectively and correlated with ascites bactDNA levels.

RESULTS

BactDNA was detected qualitatively with a similar frequency in both nonleukocytic and leukocytic ascites [40% (57/144) and 43.5% (10/23), respectively; P=0.724]. However, the median bactDNA level was significantly higher in leukocytic ascites than in nonleukocytic ascites (1.2×10 vs. 5.7×10 copies/ml; P=0.008). Patients' survival was associated significantly with bactDNA level. The 30-day and 180-day survival was reduced if bactDNA was above the quantification limit of 520 copies/ml (84 and 63% vs. 72 and 43%, respectively; P<0.05) and worst if bactDNA was above 5000 copies/ml. The bacterial spectrum was dominated by Gram-positive strains as shown by direct sequencing.

CONCLUSION

BactDNA quantification in ascitic fluid samples using culture-independent 16S rRNA gene-based methods seems to be an interesting approach to identify patients at risk of reduced survival. Our study warrants further evaluation of antibiotic treatment in patients with molecular bacterascites.

The prognostic significance of bacterial DNA in patients with decompensated cirrhosis and suspected infection

BACKGROUND & AIMS

Circulating and peritoneal fragments of microbial DNA (bactDNA) are evidence for bacterial translocation in decompensated cirrhosis and may serve as a rational approach for antibiotic therapy when infection is suspected.

METHODS

Prospective multicenter study to investigate whether identification of bactDNA from blood or ascitic fluid (AF) by multiplex polymerase chain reaction (PCR) is associated with increased 90-day mortality in 218 patients with cirrhosis and signs of infection.

RESULTS

BactDNA in either compartment was detected in 134 (61%) patients, comprising 54 with bactDNA in blood and AF, 48 with AF bactDNA only, and 32 with blood bactDNA only. BactDNA was associated with spontaneous bacterial peritonitis and blood stream infections (SBP/BSI), acute-on-chronic liver failure (ACLF), encephalopathy and markers of inflammation. The prevalence of bactDNA in patients with proven SBP/BSI (36/49; 73%) was similar to that in patients with sterile ACLF (37/52; 71%). Actuarial 90-day survival was 56 ± 5% in the absence of bactDNA in both compartments and did not differ if bactDNA was detected in blood only (63 ± 9%), AF only (63 ± 7%), or in blood and AF (52 ± 7%). Predictors of 90-day mortality were SBP (HR = 3.10; 95% CI: 1.90-5.06), BSI (HR = 4.94; 95% CI: 2.71-9.02), and ACLF (HR = 2.20; 95% CI: 1.44-3.35). The detection of resistance genes in blood or AF in the absence of SBP/BSI (n = 11) was associated with poor 1-year survival (HR = 2.35; 95% CI: 1.03-5.35).

CONCLUSIONS

BactDNA in sterile body fluids did not indicate increased mortality in cirrhotic patients with suspected infection. Using multiplex PCR for risk stratification cannot be recommended in these patients.

Nucleotide-Binding Oligomerization Domain-Containing Protein 2 Variants in Patients with Spontaneous Bacterial Peritonitis

BACKGROUND

The occurrence of spontaneous bacterial peritonitis (SBP) is significantly increased in carriers of nucleotide-binding oligomerization domain-containing protein 2 (NOD2) variants, suggesting that local immune alterations might be implicated in bacterial translocation (BT).

AIMS

We aimed to assess the role of the NOD2 gene in conferring susceptibility to SBP. We also sought to determine whether levels of serum interleukin-6 (IL-6), lipopolysaccharide-binding protein, and soluble TNF-α receptor, along with the presence of bacterial DNA (bactDNA) in ascitic fluid, are appropriate markers for BT in patients with liver cirrhosis and SBP.

METHODS

A cohort of 171 patients was divided into two groups: patients with SBP (n = 82) and those without SBP (n = 89). The presence of the most common NOD2 variants (p.R702W, p.G908R, and c.3020insC) was determined in these patients.

RESULTS

We detected the p.G908R variant in four patients (4.9 %) of the SBP group. No significant difference was observed between the SBP and non-SBP groups for NOD2 risk variants. The frequency of bactDNA in ascitic fluid was higher for patients with NOD2 variants than for patients without variants (p = 0.021). Serum IL-6 levels in the SBP group were higher than those in the non-SBP group.

CONCLUSIONS

The frequent detection of bactDNA in ascites of patients with the p.G908R variant suggests there is a strong association between NOD2 risk variants and BT in SBP patients. In addition, increased serum IL-6 levels and bactDNA in ascitic fluid could be considered surrogate markers for BT in patients with cirrhosis.

Alteration of the serum microbiome composition in cirrhotic patients with ascites

The progression of cirrhosis is associated with alterations in the composition of the gut microbiome. To assess microbial translocation, we compared the serum microbial composition of patients with and without ascites and characterized the ascitic fluid microbiome using 16S rDNA high-throughput sequencing data. A complex and specific microbial community was detected in the serum and ascitic fluid of patients with cirrhosis but barely detectable in the serum of healthy controls. The serum microbiome of patients with ascites presented higher levels of lipopolysaccharide binding protein, a marker of microbial translocation, associated with higher diversity and relative abundance of Clostridiales and an unknown genus belonging to the Cyanobacteria phylum compared to patients without ascites. The composition of the fecal microbiome was also more altered in patients with than without ascites, confirming previous studies on fecal microbiome. We propose that alteration of the serum and fecal microbiome composition be considered indicators of cirrhosis progression.

Spontaneous bacterial peritonitis: The clinical challenge of a leaky gut and a cirrhotic liver

Spontaneous bacterial peritonitis (SBP) is a frequent, life-threatening bacterial infection in patients with liver cirrhosis and ascites. Portal hypertension leads to increased bacterial translocation from the intestine. Failure to eliminate invading pathogens due to immune defects associated with advanced liver disease on the background of genetic predisposition may result in SBP. The efficacy of antibiotic treatment and prophylaxis has declined due to the spread of multi-resistant bacteria. Patients with nosocomial SBP and with prior antibiotic treatment are at a particularly high risk for infection with resistant bacteria. Therefore, it is important to adapt empirical treatment to these risk factors and to the local resistance profile. Rifaximin, an oral, non-absorbable antibiotic, has been proposed to prevent SBP, but may be useful only in a subset of patients. Since novel antibiotic classes are lacking, we have to develop prophylactic strategies which do not induce bacterial resistance. Farnesoid X receptor agonists may be a candidate, but so far, clinical studies are not available. New diagnostic tests which can be carried out quickly at the patient’s site and provide additional prognostic information would be helpful. Furthermore, we need tools to predict antibiotic resistance in order to tailor first-line antibiotic treatment of spontaneous bacterial peritonitis to the individual patient and to reduce mortality.

Toward culture-free Raman spectroscopic identification of pathogens in ascitic fluid

The identification of pathogens in ascitic fluid is standardly performed by ascitic fluid culture, but this standard procedure often needs several days. Additionally, more than half of the ascitic fluid cultures are negative in case of suspected spontaneous bacterial peritonitis (SBP). It is therefore important to identify and characterize the causing pathogens since not all of them are covered by the empirical antimicrobial therapy. The aim of this study is to show that pathogen identification in ascitic fluid is possible by means of Raman microspectroscopy and chemometrical evaluation with the advantage of strongly increased speed. Therefore, a Raman database containing more than 10000 single-cell Raman spectra of 34 bacterial strains out of 13 different species was built up. The performance of the used statistical model was validated with independent bacterial strains, which were grown in ascitic fluid.

Application of next-generation sequencing to study ascitic microbiome in cirrhotic patients with or without spontaneous bacterial peritonitis

BACKGROUND

Spontaneous bacterial peritonitis is an important cause of morbidity and mortality in cirrhotic patients with ascites. The key step in the pathogenesis of spontaneous bacterial peritonitis is bacterial translocation from intestinal lumen to mesenteric lymph nodes, and from there to the systemic circulation and ascitic fluid. We aimed to study the ascitic microbiota of cirrhotic patients with or without spontaneous bacterial peritonitis.

METHODS

Both the 16S polymerase chain reaction approach and the whole genome shotgun approach were adopted for the next-generation sequencing technology. We compared the results derived from the two methods.

RESULTS

The bacterial culture-negative ascites in cirrhotic patients, which even failed for amplification of 16S ribosomal DNA, were found to contain much less bacterial DNA than the culture-positive ones, indicating that the paucity of bacteria, instead of the difficulty of bacterial culture, was possibly the main reason for negative culture result of the ascites. Escherichia coli was the predominant species in all samples, and the bacteria of low abundance were also identified by the next-generation sequencing technology.

CONCLUSION

Whole genome shotgun-based next-generation sequencing is an appropriate method for depicting the microbiome of ascites or of other specimens with a low abundance of bacterial DNA.

Diagnosis of spontaneous bacterial peritonitis and an in situ hybridization approach to detect an "unidentified" pathogen

Spontaneous bacterial peritonitis (SBP) is a frequent and severe complication in cirrhotic patients with ascites. Although identifying the pathogen(s) plays a major role in the management of infectious diseases, ascitic fluid cultures often show negative results in patients with clinical signs and symptoms of SBP, and ascitic fluid cell analyses are the gold standard method for diagnosing SBP. SBP is generally diagnosed based on an increased number of polymorphonuclear neutrophils in the ascitic fluid (>250/mm(3)), and the identification of the causal pathogen may not be given consideration. We newly developed an in situ hybridization (ISH) method to provide early and direct evidence of bacterial infection in ascites in patients with SBP. This paper will review the diagnosis of SBP, including our novel approach with ISH method to detect bacterial DNA in SBP ascitic fluid.

Risk factors and outcome of bacterial infections in cirrhosis

Viable and non-viable pathological bacterial translocation promote a self-perpetuating circle of dysfunctional immune activation and systemic inflammation facilitating infections and organ failure in advanced cirrhosis. Bacterial infections and sepsis are now recognized as a distinct stage in the natural progression of chronic liver disease as they accelerate organ failure and contribute to the high mortality observed in decompensated cirrhosis. The increasing knowledge of structural, immunological and hemodynamic pathophysiology in advanced cirrhosis has not yet translated into significantly improved outcomes of bacterial infections over the last decades. Therefore, early identification of patients at the highest risk for developing infections and infection-related complications is required to tailor the currently available measures of surveillance, prophylaxis and therapy to the patients in need in order to improve the detrimental outcome of bacterial infections in cirrhosis.

Application of qualitative and quantitative real-time PCR, direct sequencing, and terminal restriction fragment length polymorphism analysis for detection and identification of polymicrobial 16S rRNA genes in ascites

Qualitative and quantitative 16S rRNA gene-based real-time PCR and direct sequencing were applied for rapid detection and identification of bacterial DNA (bactDNA) in 356 ascites samples. bactDNA was detected in 35% of samples, with a mean of 3.24 log copies ml(-1). Direct sequencing of PCR products revealed 62% mixed chromatograms predominantly belonging to Gram-positive bacteria. Terminal restriction fragment length polymorphism (T-RFLP) results of a sample subset confirmed sequence data showing polymicrobial DNA contents in 67% of bactDNA-positive ascites samples.

Ascites and spontaneous bacterial peritonitis: recommendations from two United States centers

Cirrhosis affects millions of people throughout the world. Two of the most serious complications of liver cirrhosis are ascites and spontaneous bacterial peritonitis (SBP). The development of ascites is related to the severity of portal hypertension and is an indicator of increased mortality. Although sodium restriction and diuretic therapy have proven effective, some patients may not respond appropriately or develop adverse reactions to diuretic therapy. In such cases, interventions such as transjugular intrahepatic portosystemic shunt (TIPS) placement are warranted. SBP is a complication of ascites that confers a very high mortality rate. Recognition and prompt treatment of this condition is essential to prevent serious morbidity and mortality. Initiation of prophylaxis in SBP remains controversial. Given the burden of liver cirrhosis on the health care system, ascites and SBP will continue to provide challenges for the primary care provider, hospitalist, internist, and gastroenterologist alike.

Diagnosis of spontaneous bacterial peritonitis and an in situ hybridization approach to detect an "unidentified" pathogen

Spontaneous bacterial peritonitis (SBP) is a frequent and severe complication in cirrhotic patients with ascites. Although identifying the pathogen(s) plays a major role in the management of infectious diseases, ascitic fluid cultures often show negative results in patients with clinical signs and symptoms of SBP, and ascitic fluid cell analyses are the gold standard method for diagnosing SBP. SBP is generally diagnosed based on an increased number of polymorphonuclear neutrophils in the ascitic fluid (>250/mm(3)), and the identification of the causal pathogen may not be given consideration. We newly developed an in situ hybridization (ISH) method to provide early and direct evidence of bacterial infection in ascites in patients with SBP. This paper will review the diagnosis of SBP, including our novel approach with ISH method to detect bacterial DNA in SBP ascitic fluid.

Bacteria-derived DNA fragment in peritoneal dialysis effluent as a predictor of relapsing peritonitis

BACKGROUND AND OBJECTIVES

Relapsing and recurrent peritonitis episodes are important causes of treatment failure in patients undergoing peritoneal dialysis (PD). This study explored whether the level of bacteria-derived DNA fragment in PD effluent predicts the development of relapsing or recurrent peritonitis.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

The study included 143 patients with PD peritonitis in a dialysis unit between September 2010 and December 2011. Every 5 days until antibiotic treatment ended, PD effluent was collected to determine bacteria-derived DNA fragment level, which is represented by the number of PCR cycles at which bacterial DNA could be detected. Patients were followed for the development of relapsing or recurrent peritonitis.

RESULTS

Thirty-nine patients were excluded because of immediate treatment failure or incorrect diagnosis. Of the other 104 patients, 15 (14.4%) developed relapsing peritonitis, 3 (2.9%) had recurrent peritonitis, and 5 (4.8%) had repeat episodes. Patients with relapsing or recurrent peritonitis episodes had significantly higher levels of bacterial DNA fragment in PD effluent than those without relapsing or recurrence, both 5 days before (31.9 ± 3.4 versus 34.3 ± 3.0 cycles; P=0.002) and on the day of (32.3 ± 2.6 versus 34.1 ± 1.7 cycles; P<0.001) completion of antibiotics. When bacterial DNA fragment detectable by 34 PCR cycles 5 days before the completion of antibiotics is used as the cutoff, it has a sensitivity of 88.9% and specificity of 60.5% for the prediction of relapsing or recurrent peritonitis.

CONCLUSIONS

Bacterial DNA fragment levels in PD effluent are significantly higher, both 5 days before and on the date of completion of antibiotics, among patients who subsequently develop relapsing or recurrent peritonitis than among those cured by antibiotics. Further studies are needed to validate these results and confirm the clinical utility of dialysate bacterial DNA fragment level.

Ascitic microbiota composition is correlated with clinical severity in cirrhosis with portal hypertension

Identification of pathogenic bacteria in ascites correlates with poor clinical outcomes. Ascites samples are commonly reported culture-negative, even where frank infection is indicated. Culture-independent methods have previously reported bacterial DNA in ascites, however, whether this represents viable bacterial populations has not been determined. We report the first application of 16S rRNA gene pyrosequencing and quantitative PCR in conjunction with propidium monoazide sample treatment to characterise the viable bacterial composition of ascites. Twenty five cirrhotic patients undergoing paracentesis provided ascites. Samples were treated with propidium monoazide to exclude non-viable bacterial DNA. Total bacterial load was quantified by 16S rRNA Q-PCR with species identity and relative abundance determined by 16S rRNA gene pyrosequencing. Correlation of molecular microbiology data with clinical measures and diagnostic microbiology was performed. Viable bacterial signal was obtained in 84% of ascites samples, both by Q-PCR and pyrosequencing. Approximately 190,000 ribosomal pyrosequences were obtained, representing 236 species, including both gut and non gut-associated species. Substantial variation in the species detected was observed between patients. Statistically significant relationships were identified between the bacterial community similarity and clinical measures, including ascitic polymorphonuclear leukocyte count and Child-Pugh class. Viable bacteria are present in the ascites of a majority of patients with cirrhosis including those with no clinical signs of infection. Microbiota composition significantly correlates with clinical measures. Entry of bacteria into ascites is unlikely to be limited to translocation from the gut, raising fundamental questions about the processes that underlie the development of spontaneous bacterial peritonitis.

Soluble urokinase plasminogen activator receptor is compartmentally regulated in decompensated cirrhosis and indicates immune activation and short-term mortality

OBJECTIVE

Patients with decompensated cirrhosis are susceptible to bacterial infections, which are associated with organ failure and a high mortality rate. Reliable biomarkers are needed to identify patients who require intensified treatment. Our objective was to study the regulation and prognostic relevance of elevated concentrations of soluble urokinase plasminogen activator receptor (suPAR) in patients with advanced cirrhosis.

DESIGN, SETTING AND PARTICIPANTS

We examined the associations between serum and ascitic fluid (AF) suPAR and liver function, bacterial infection, and short-term mortality in 162 consecutive patients with decompensated cirrhosis undergoing diagnostic paracentesis in a tertiary health care centre in Germany.

MAIN OUTCOME MEASURE

Twenty-eight-day mortality.

RESULTS

Circulating suPAR levels were increased in patients with decompensated cirrhosis and correlated with the severity of liver dysfunction and systemic inflammation but were not indicative of bacterial infection. Circulating suPAR levels >14.4 ng mL(-1) predicted 28-day mortality, even after adjustment for liver function and confounders [HR = 3.05 (1.35-6.90); P = 0.0076] equal to the MELD score (AUC = 0.71; 95% CI = 0.61-0.81; P < 0.001). Cut-off levels derived from cohorts without liver disease were not applicable due to the low specificity. AF suPAR levels were elevated during spontaneous bacterial peritonitis (SBP), but not during episodes in which bacteria or bacterial DNA was translocated into the ascites. AF suPAR levels correlated poorly with systemic suPAR but were associated with a more severe course of SBP and a worse outcome. In vitro experiments revealed that monocytes, and to a lesser extent neutrophils, secrete suPAR after Toll-like-receptor ligation, which led to rapid urokinase plasminogen activator receptor cleavage followed by increased synthesis.

CONCLUSION

Blood and ascitic suPAR levels provide distinct, but relevant prognostic information on the severity of complications in patients with end-stage liver disease.

Pathological bacterial translocation in cirrhosis: pathophysiology, diagnosis and clinical implications

Bacterial translocation (BT) is defined by the passage of viable indigenous bacteria from the intestinal lumen to mesenteric lymph nodes (MLNs) and other territories, and its diagnostic criteria rely on the isolation of viable bacteria in MLNs. Small intestinal overgrowth, increased intestinal permeability and immunological alterations are the main factors involved in its pathogenesis. BT is obviously difficult to identify in patients with cirrhosis, and alternative methods have been proposed instead. Bacterial DNA detection and species identification in serum or ascitic fluid has been proposed as a reliable marker of BT. Bacterial products, such as endotoxin, or bacterial DNA can translocate to extra-intestinal sites and promote an immunological response similar to that produced by viable bacteria. Therefore, pathological BT plays an important role in the pathogenesis of the complications of cirrhosis, not only in infections, but by exerting a profound inflammatory state and exacerbating the haemodynamic derangement. This may promote in turn the development of hepatorenal syndrome, hepatic encephalopathy and other portal hypertension-related complications. Therapeutic approaches for the prevention of BT in experimental and human cirrhosis are summarized. Finally, new investigations are needed to better understand the pathogenesis and consequences of translocation by viable bacteria (able to grow in culture), or non-viable BT (detection of bacterial fragments with negative culture) and open new therapeutic avenues in patients with cirrhosis.

Identification of bacterial pathogens in ascitic fluids from patients with suspected spontaneous bacterial peritonitis by use of broad-range PCR (16S PCR) coupled with high-resolution melt analysis

Spontaneous bacterial peritonitis (SBP) can be a severe complication occurring in patients with cirrhosis and ascites, with associated mortality often as high as 40%. Traditional diagnostics for SBP rely on culture techniques for proper diagnosis, although recent reports suggest that the presence of bacterial DNA in peritoneal fluid in patients with cirrhosis and ascites is an indicator of SBP. A previously published broad-range PCR (16S PCR) coupled with high-resolution melt analysis (HRMA) was compared with standard culture techniques for diagnosis of SBP in 106 peritoneal fluid samples from patients with suspected SBP. The sensitivity and specificity for 16S PCR for detecting eubacterial DNA compared with those of standard culture techniques were 100% (17/17) and 91.5% (85/89), respectively. Overall, HRMA concordance with species identification was 70.6% (12/17), although the 5 samples that were discordant at the species level were SBP resulting from a polymicrobial infection, and species-level identification for polymicrobial infections is outside the capability of HRMA. Both the broad-range 16S PCR and HRMA analysis provide useful diagnostic adjunctive assays for clinicians in detecting and identifying pathogens responsible for SBP.

NOD2 gene variants are a risk factor for culture-positive spontaneous bacterial peritonitis and monomicrobial bacterascites in cirrhosis

BACKGROUND

Spontaneous bacterial peritonitis (SBP) is considered as result of bacterial translocation from the gastrointestinal lumen to the mesenteric lymph nodes and subsequent circulation. Variants of the NOD2 gene contribute to bacterial translocation and were associated with SBP in a recent study.

METHODS

We determined common NOD2 variants by TaqMan polymerase chain reaction and analysed the ascitic fluid neutrophil count and bacterial culture results in 175 prospectively characterized hospitalized patients with decompensated cirrhosis who underwent diagnostic paracentesis in two German centres.

RESULTS

Ten patients presented with culture-positive SBP, 19 with culture-negative SBP and six had bacterascites. Minor allele frequencies for R702W, G908R and 1007fs in subjects with sterile non-neutrocytic ascites were 3.2, 2.5 and 2.5% respectively. Patients with SBP [odds ratio (OR) 2.7; P=0.036], culture-positive SBP (OR 6.0; P=0.012) and bacterascites (OR 6.0; P=0.050) were more often carriers of NOD2 variants than patients with sterile non-neutrocytic ascites. The mutations 1007fs and G908R were associated with culture-positive SBP (P ≤ 0.005) and R702W with bacterascites (P=0.014). There was no significant association of NOD2 variants with culture-negative SBP (OR 1.6; P=0.493). In logistic regression, previous SBP, a higher model for end-stage liver disease (MELD) score and the presence of a NOD2 variant were independent predictors of ascitic fluid infection. The median survival was insignificantly shorter in patients with NOD2 variants (268 vs. 339 days; P=0.386). In patients without hepatocellular carcinoma at study entry (N=148), NOD2 was a predictor of survival after adjustment for the MELD score and age (hazard ratio 1.89; P=0.045).

CONCLUSION

NOD2 variants increase the risk for culture-positive SBP and bacterascites in cirrhosis and may affect survival.

Homozygous carrier of the NOD2 1007fs frame-shift mutation presenting with refractory community-acquired spontaneous bacterial peritonitis and developing fatal pulmonary mucormycosis: A case report

Genetic variants of the innate immune system contribute to episodes of spontaneous bacterial peritonitis (SBP) in patients with cirrhosis. We herein report the case of a patient with the homozygous nucleotide-binding oligomerization domain containing 2 (NOD2) frame-shift mutation 1007fs presenting with sepsis and community-acquired SBP by Escherichia coli. Secondary peritonitis, pancreatic ascites and malignant causes were excluded by extensive diagnostic work-up. First-line treatment with ceftriaxone was not successful despite in vitro sensitivity of the isolated strain. Despite prolonged second-line treatment with imipenem/cilastatin and intermittent ascites drainage, the ascitic fluid neutrophil count remained markedly elevated in this patient. In the course of the disease the patient developed pneumonia with identification of the typical hyphae of mucormycosis in the bronchoalveolar lavage and died of sepsis with multi-organ failure. On the basis of this observation, variants of the innate immunity have to be considered in therapy-refractory SBP, even when they are community-acquired and caused by cephalosporin-sensitive Enterobacteriaceae.

Immune dysfunction and infections in patients with cirrhosis

Patients with cirrhosis are immunocompromised and susceptible to infections. Although detection and treatment of spontaneous bacterial peritonitis (SBP) have improved, overall survival rates have not increased greatly in recent decades-infection still increases mortality 4-fold among patients with cirrhosis. Hospitalized patients with cirrhosis have the highest risk of developing infections, especially patients with gastrointestinal (GI) hemorrhage. Bacterial infections occur in 32% to 34% of patients with cirrhosis who are admitted to the hospital and 45% of patients with GI hemorrhage. These rates are much higher than the overall rate of infection in hospitalized patients (5%-7%). The most common are SBP (25% of infections), urinary tract infection (20%), and pneumonia (15%). Bacterial overgrowth and translocation from the GI tract are important steps in the pathogenesis of SBP and bacteremia-these processes increase levels of endotoxins and cytokines that induce the inflammatory response and can lead to septic shock, multiorgan dysfunction, and death. A number of other bacterial and fungal pathogens are more common and virulent in patients with cirrhosis than in the overall population. We review the pathogenesis of infections in these patients, along with diagnostic and management strategies.

Detection of ascitic fluid infections in patients with liver cirrhosis and ascites

BACKGROUND AND STUDY AIMS

Ascitic fluid infections (AFIs) are the frequent complications of advanced liver disease. Bacterial translocation is considered a key step in the pathogenesis of gut-derived bacterial infections; mainly spontaneous bacterial peritonitis (SBP) in cirrhotic patients. Bacterial DNA (bactDNA) in ascitic fluid and serum has been suggested as a surrogate marker for bacterial translocation. We attempted at the isolation and identification of bacteria in ascitic fluid in cirrhotic patients and the assessment of polymerase chain reaction (PCR) in ascitic fluid and serum.

PATIENTS AND METHODS

Fifty cirrhotic patients having ascites with no signs of infection were included. Ascitic fluid cultures were obtained from patients. Ascitic fluid and serum were subjected to DNA extraction and PCR for the universal amplification of a region of the 16S ribosomal RNA (16S rRNA) gene to detect bactDNA.

RESULTS

Bacteria were isolated from 9 (18%) of the ascitic fluid samples, and were mainly Gram-positive bacteria. BactDNA was detected simultaneously in the ascitic fluid and serum of 17 (34%) patients and in the ascitic fluid of only 2 patients. In a single patient with positive ascitic fluid culture no bactDNA was detected in ascitic fluid or serum. By considering AFIs as a positive ascitic fluid culture and/or the presence of bactDNA in the ascitic fluid and/or serum, ascitic fluid culture could detect 9 out of 20 patients with AFIs (45%), PCR of ascitic fluid could detect 19 out of 20 (95%) while PCR of serum could detect 17 out of 20 (85%). In 10 patients with culture negative non-neutrocytic ascites (CNNNA) bactDNA could be detected in serum and ascitic fluid.

CONCLUSION

AFI can be caused by Gram positive as well as Gram negative organisms. A substantial percentage of cases with CNNNA show bactDNA in serum and ascitic fluid. PCR of ascitic fluid should, therefore, be used in the diagnostic workup of suspected cases of ascitic fluid infections.

Performance of the LightCycler SeptiFast test Mgrade in detecting microbial pathogens in purulent fluids

The performance of the LightCycler SeptiFast (SF) assay was compared to that of culture methods in the detection of microorganisms in 43 purulent fluids from patients with pyogenic infections. The SF assay was more sensitive than the culture methods (86% versus 61%, respectively), irrespective of whether the infections were mono- or polymicrobial.

Detection of bacterial DNA in serum and ascitic fluid of asymptomatic outpatients with cirrhosis and non-neutrocytic ascites

BACKGROUND AND AIMS

Bacterial DNA (bactDNA) has been found in serum and ascitic fluid (AF) of 30-40% of hospitalized patients with cirrhosis and non-neutrocytic ascites, but its prevalence in outpatients is unknown. The aim of this prospective study was to investigate the presence of bactDNA in AF and serum among cirrhotic outpatients with non-neutrocytic ascites.

METHODS

Thirty-one consecutive patients with cirrhosis and non-neutrocytic ascites, who underwent therapeutic paracentesis in our outpatient clinic, were enrolled over a 13-week period. Of these patients, 13 had a single paracentesis and 18 patients had several consecutive paracenteses (2-10) over the study period. Overall, 98 serum and non-neutrocytic AF specimens were obtained and tested for the presence of bactDNA by polymerase chain reaction amplification of the 16S ribosomal RNA gene.

RESULTS

The main causes of cirrhosis were alcohol (53.5%) and hepatitis C (30%). The median MELD score was 16 and there were 54.8% Child-Pugh C patients. BactDNA was negative in all samples from 28 of the 31 patients, including 15 patients with several paracentesis. One patient had a single AF sample culture positive and bactDNA positive for Streptococcus mitis, whereas the simultaneous blood sample was negative. For each of the last two patients, DNA from Lactococcus lactis was detected in a single blood sample but not in the simultaneous AF sample.

CONCLUSIONS

In contrast to that reported previously in hospitalized patients, bactDNA is rarely detected in serum and AF of outpatients with cirrhosis and non-neutrocytic ascites.

The augmented neutrophil respiratory burst in response to Escherichia coli is reduced in liver cirrhosis during infection

Several functional abnormalities in phagocytes from patients with liver cirrhosis contribute to an increased risk of infection. An increased resting respiratory burst has been observed in neutrophils from cirrhotic patients. We investigated whether an infection in cirrhosis affects the respiratory burst capacity of neutrophils and monocytes in response to Escherichia coli. This study included 45 hospitalized patients with liver cirrhosis and clinical signs of infection, 39 patients with liver cirrhosis in the absence of infection and 29 healthy subjects. Respiratory burst, lipopolysaccharide-binding protein (LBP), and immunoglobulin (Ig)G-autoantibodies against oxidized low-density lipoproteins (ab-oxLDL) were measured. The fraction of neutrophils spontaneously producing reactive oxygen species (ROS) was elevated in liver cirrhosis (P < 0·01). The neutrophil resting burst increased with Child-Pugh stage (P = 0·02) and correlated with augmented ROS release in response to opsonized E. coli (P < 0·05). Although LBP was increased in patients with cirrhosis (P < 0·01), higher LBP levels correlated with a lower resting burst in neutrophils (r(s)  = -0·395; P < 0·01). In the presence of infection, the resting burst was unaltered. However, neutrophil ROS release in response to E. coli was reduced markedly (P = 0·01), and it decreased as serum C-reactive protein (CRP) concentration rose (r(s)  = -0·437; P < 0·01), indicating the development of a sepsis-like immune paralysis. A positive correlation between ab-oxLDL and ROS release was observed (P < 0·01). In conclusion, the respiratory burst increases with severity of liver cirrhosis but is restrained by increasing LBP levels. Augmented ROS release in response to E. coli is accompanied by elevated markers of oxidative damage and becomes exhausted in the presence of infection.

Bacterial DNA in the diagnosis of spontaneous bacterial peritonitis

BACKGROUND

Despite inoculation into blood culture bottles, ascitic fluid culture is negative in 50% of cases of spontaneous bacterial peritonitis (SBP).

AIM

To determine whether 16S rDNA gene detection by real-time polymerase chain reaction (PCR) and sequencing increases the efficacy of culture in microbiological diagnosis of spontaneous bacterial peritonitis.

METHODS

We prospectively included 55 consecutive spontaneous bacterial peritonitis episodes in cirrhotic patients, 20 cirrhotic patients with sterile ascites and 27 patients with neoplasic ascites. Ascitic fluid was inoculated into blood culture bottles at the bedside and tested for bacterial DNA by real-time PCR and sequencing of 16S rDNA gene.

RESULTS

Bacterial DNA was detected in 23/25 (92%) culture-positive SBP, 16/30 (53%) culture-negative SBP (P = 0.002 with respect to culture-positive SBP), 12/20 (60%) sterile ascites (P = 0.01 with respect to culture-positive SBP) and 0/27 neoplasic ascites (P < 0.001 with respect to other groups). Sequencing identified to genus or species level 12 culture-positive SBP, six culture-negative SBP and six sterile ascites. In the remaining cases with positive PCR, sequencing did not yield a definitive bacterial identification.

CONCLUSIONS

Bacterial DNA was not detected in almost half the culture-negative spontaneous bacterial peritonitis episodes. Methodology used in the present study did not always allow identification of amplified bacterial DNA.

Pathogen-specific DNA enrichment does not increase sensitivity of PCR for diagnosis of invasive aspergillosis in neutropenic patients

PCR assays designed for the diagnosis of invasive aspergillosis (IA) in high-risk patients have to detect minute amounts of target DNA to reach sufficient analytical sensitivity to be of clinical use. This prospective study assessed the use of a novel strategy for selective pathogen DNA enrichment for enhancing the performance of diagnostic PCR in a direct comparison with a highly sensitive in-house quantitative PCR (qPCR) assay and the galactomannan enzyme-linked immunosorbent assay (ELISA). Surprisingly, and in contrast to experience with other patient groups, the novel protocol for selective pathogen DNA enrichment did not enhance but instead significantly impaired sensitivity. This could be explained by the small amounts of host DNA in the specimens, which were derived mostly from severely neutropenic patients. In the qPCR assay, positive samples required an average of 43.5 amplification cycles (range, 39.2 to 50) for detection in the in-house PCR. Repetitive testing of selected samples showed test positivity to be variable, most likely due to the small amounts of target DNA. Despite this, the in-house protocol proved helpful in the diagnosis of IA, detecting 2 out of 3 patients with probable IA and 10 out of 19 patients with possible IA. Our results underline the necessity for diagnostic PCR protocols that help diagnose IA to be highly sensitive and show that selective pathogen DNA enrichment using affinity purification may not be useful in severely neutropenic patients.

Identification of bacterial DNA in noninfectious pleural fluid with a highly sensitive PCR method

BACKGROUND

Bacterial DNA due to bacterial translocation has been identified in noninfectious ascitic fluid samples.

OBJECTIVE

This study investigated the possible presence of bacterial DNA in the pleural fluid of patients with pleural effusions of noninfectious origin, using a highly sensitive PCR-based method.

METHODS

Pleural fluid samples from 175 patients (average age ± SD: 69 ± 14 years) with noninfectious pleural effusion (62 transudates, 113 exudates) were analyzed. Bacterial DNA was detected using nested PCR with amplification of a fragment of the gene r16S, with 2 amplification protocols, i.e. low sensitivity (10 and 40 cycles) and high sensitivity (40 and 40 cycles).

RESULTS

With the less sensitive amplification process, only 1 sample was positive (Haemophilus parainfluenzae in a patient with hepatic hydrothorax). With the highly sensitive nested PCR method, bacterial DNA was identified in the pleural fluid, of both transudative and exudative origin, of 75 of the 175 patients (43%). In cases of isolation of a single bacterium, the more frequent were Escherichia coli, Salmonella enterica and Streptococcus pneumoniae.

CONCLUSIONS

Regardless of its origin, bacterial DNA can be identified in almost half of noninfectious pleural effusions by using a highly sensitive PCR-based method. The possible clinical significance or prognostic value of these findings deserves to be evaluated.

Is detection of bacterial DNA in ascitic fluid of clinical relevance?

BACKGROUND

In patients with cirrhosis, bacterial DNA has been found in ascites reflecting bacterial translocation. However, the clinical relevance of this finding is ill-defined especially compared with the standard diagnostics for detection of spontaneous bacterial peritonitis (SBP). Furthermore, other DNA tests have not been sufficiently evaluated.

PATIENTS AND METHODS

We prospectively included 151 patients with cirrhosis and ascites admitted to our department. The patients were evaluated for diagnosis of SBP (polymorphonuclear count > 250 cells/mm) or finding of bacterascites, defined by positive bacterial culture from ascites. To detect bacterial species of bacterial DNA fragments in ascites, broad-range polymerase chain reaction and nucleotide sequencing analysis with the LightCycler SeptiFast Kit Mgrade were performed. Routine parameters were correlated with these findings.

RESULTS

Eighteen of 151 patients (12%) had SBP according to the classic definition. Bacterial DNA was detected in five of these 18 patients (3%), whereas in 13 patients (9%), bacterial DNA was detected without standard SBP. Seven patients (5%) had culture-positive SBP, only in two of them bacterial DNA was detected. In multivariate analysis, C-reactive protein (P = 0.000), white blood cell count (P = 0.019), and lactic acid dehydrogenase in ascites (P = 0.000) were independently associated with SBP. In the DNA-positive ascites group, none of the assessed parameters was significantly associated with the bacterial DNA positivity.

CONCLUSION

We found no correlation between detection of bacterial DNA in ascites and SBP (polymorphonuclear count > 250/mm). In contrast to the patients with bacterial DNA in ascites, patients with SBP showed clinical signs of infection. This study provides no evidence that detection of bacterial DNA in ascites of patients with liver cirrhosis is of clinical or diagnostic relevance when using the panel of LightCycler SeptiFast Kit Mgrade.

Nucleotide-binding oligomerization domain containing 2 (NOD2) variants are genetic risk factors for death and spontaneous bacterial peritonitis in liver cirrhosis

Spontaneous bacterial peritonitis (SBP), a severe complication in patients with advanced liver cirrhosis, has been attributed to bacterial translocation from the intestine. Variants of the NOD2 (nucleotide-binding oligomerization domain containing 2) gene have been associated with impaired mucosal barrier function in Crohn disease. We hypothesized that the risk of acquiring SBP is increased in patients with cirrhosis carrying NOD2 variants. We recruited 150 nonselected patients with liver cirrhosis and ascites admitted to our unit, monitored survival, and recorded the development of SBP prospectively and retrospectively. SBP was defined as the presence of polymorphonuclear neutrophil (PMN) cells >250 per microL of ascitic fluid. Patients were genotyped for the NOD2 variants p.R702W, p.G908R, and c.3020insC. During a median follow-up of 155 days, 54 patients (36%) died and SBP was diagnosed in 30 patients (20%). The occurrence of SBP was increased significantly (P = 0.008) in carriers of NOD2 variants (odds ratio [OR] = 3.06). Retrospectively, SBP was observed in 22 additional patients, and the combined prospective and retrospective analysis substantiated the association between NOD2 and SBP (P = 0.004; OR = 2.98). Of note, carriers of NOD2 risk alleles showed a significantly (P = 0.007) reduced mean survival time (274 days) in comparison to patients with wildtype genotypes (395 days).

CONCLUSION

Common NOD2 variants linked previously to impaired mucosal barrier function may be genetic risk factors for death and SBP. These findings might serve to identify patients with cirrhotic ascites eligible for preemptive antibiotic treatment.