Role of serum complement, immunoglobulins, and cell-mediated immune system in the pathogenesis of spontaneous bacterial peritonitis (SBP)

Lipid peroxidation and liver damage in double and simple common bile duct ligation models in male Sprague-Dawley rats

AIMS

Bacterial translocation, defined as the presence of living bacteria or bacterial fragments in both mesenteric lymph nodes or systemic circulation, can cause a severe inflammatory reaction in patients with cirrhosis. This study aimed to compare lipid peroxidation associated with liver damage in different experimental models of bile duct ligation: proximal double ligation and transection versus proximal simple ligation versus sham.

MATERIALS AND METHODS

Sixty-two male rats underwent one of three bile duct surgical interventions: proximal double ligation and transection (n = 22); proximal simple ligation (n = 19); or sham operation (n = 21). We performed microbiological culture of mesenteric lymph nodes; portal and cava blood, spleen and liver cultures; and histological analysis of liver parenchyma. Samples of blood and liver were obtained at laparotomy for malondialdehyde quantification.

KEY FINDINGS

Serum malondialdehyde levels were significantly higher in simple ligature animals (3.7 nmol/mg, standard deviation [SD] 2.1) compared to controls (1.6 nmol/mg SD 0.5; p = 0.001) or double ligature (0.3 nmol/mg SD 0.3; p = 0.001). Liver malondialdehyde levels were significantly higher in animals subjected to double ligation vs controls (9.0 nmol/mg SD 2.8 vs. 1.7 nmol/mg SD 1.0; p = 0.0007) and simple ligature (2.9 nmol/mg SD 2.0; p = 0.0001). Overall incidence of bacterial translocation was similar in simple and double ligatures (22.2 % and 21 % respectively), and significantly higher than in controls.

SIGNIFICANCE

the type of bile duct ligation influences the type and localization of lipid peroxidation, but does not influence the development of bacterial translocation.

Proton pump inhibitor therapy and its association with spontaneous bacterial peritonitis incidence and mortality: A meta-analysis

BACKGROUND

Previous meta-analyses reported proton pump inhibitor (PPI) therapy is associated with increased incidence of spontaneous bacterial peritonitis (SBP) in cirrhotic patients. However, this conclusion was based on case-control studies. Moreover, the association between PPI use and mortality of SBP has not yet been confirmed.

AIMS

To evaluate the association between PPI use and SBP incidence and mortality using case-control and cohort studies.

METHODS

We searched Medline, Embase and Web of Knowledge for relevant articles published up to January 2015. Pooled odds ratios (ORs) with 95% confidence intervals (CIs) were calculated using a random-effects model.

RESULTS

A total of 10 case-control and six cohort studies involving 8145 patients were analyzed. The overall analysis indicated that PPI use was associated with SBP (OR=2.11, 95% CI: 1.46-3.06). The association was limited in case-control studies (OR=2.97, 95% CI: 2.06-4.26) but not in cohort studies (OR=1.18, 95% CI: 0.99-1.14). PPI therapy was not associated with mortality during hospitalization or within 30 days after SBP (OR=1.54, 95% CI: 0.92-2.59).

CONCLUSIONS

We could not establish causality that PPI use increases the incidence or mortality of SBP.

Systematic review and meta-analysis of the possible association between pharmacological gastric acid suppression and spontaneous bacterial peritonitis

BACKGROUND

Observational studies have presented conflicting results with regard to an association between gastric acid suppression and spontaneous bacterial peritonitis (SBP). Our aim was to carry out a meta-analysis investigating the possible association between the use of proton pump inhibitors or H2-receptor antagonists and SBP.

METHODS

We searched several databases from inception through 15 December 2014 to identify observational studies that provided data on the association of gastric acid suppression with SBP as their primary outcome, and carried out random effects meta-analyses.

RESULTS

Fourteen observational studies (six case-control and eight cohort) evaluating the association between proton pump inhibitors and SBP revealed a pooled odds ratio (OR) of 2.32 [95% confidence interval (CI) 1.57-3.42, I(2)=82%]. The subgroup analysis based on study design revealed a pooled OR of 2.52 (95% CI 1.71-3.71, I(2)=16%) for case-control studies, and a pooled OR of 2.18 (95% CI 1.24-3.82, I(2)=89%) for cohort studies. Sensitivity analysis including only the peer-reviewed publications in the cohort subgroup revealed a pooled OR of 1.49 (95% CI 1.15-1.95, I(2)=27%). The subgroup analysis for high-quality studies revealed a pooled OR of 1.49 (95% CI 1.19-1.88, I(2)=21%). The pooled OR for H2-receptor antagonists and SBP was 1.93 (95% CI 1.15-3.24, I(2)=0%).

CONCLUSIONS

There appear to be statistically significant, but quantitatively small, associations between gastric acid suppression and SBP. However, the magnitude of the possible association diminished when analysis focused on higher quality data that were more robust. Furthermore, the quality evidence in support of the association, as per the GRADE framework, was very low.

Mortality associated with proton pump inhibitors in cirrhotic patients with spontaneous bacterial peritonitis

BACKGROUND AND AIM

The aims of this study were to investigate whether acid suppressive therapy increases the risk of spontaneous bacterial peritonitis (SBP) and to define factors associated with mortality in cirrhotic patients with SBP.

METHODS

Cirrhotic patients who had undergone paracentesis after hospitalization were included. Those patients were divided into two groups according to the presence or absence of SBP. Factors associated with the development of SBP were analyzed. Mortality rates during hospitalization or within 30 days after SBP and the factors associated with mortality were also analyzed.

RESULTS

A total of 1140 patients (median age, 62; men, 75%; model for end-stage liver disease [MELD] score, 17) were included. Five hundred thirty-three patients were identified as having SBP. In the logistic regression, the use of histamine-2 receptor antagonists, the use of proton pump inhibitors (PPIs), a high admission MELD score, and old age were associated with the development of SBP. The use of PPIs within 30 days (adjusted odds ratio [aOR] 1.960; 95% confidence interval [CI] 1.190-3.227; P = 0.008), a higher admission MELD score (aOR 1.054; 95% CI 1.032-1.076; P < 0.001), and hepatocellular carcinoma (aOR 1.852; 95% CI 1.256-2.730; P = 0.002) were associated with mortality after SBP.

CONCLUSIONS

Acid suppressive therapy is associated with the development of SBP in cirrhotic patients with ascites. The use of PPIs is associated with mortality after SBP independent of the severity of the underlying liver disease in our retrospective cohort study.

Evaluation and management of end-stage liver disease in children

End-stage liver disease in children presents a challenging array of medical and psychosocial problems for the health care delivery team. Many of these problems are similar to those encountered by caregivers of adults with end-stage liver disease, such as the development of complications of cirrhosis, including ascites, spontaneous bacterial peritonitis, and esophageal variceal hemorrhage. However, the natural history of disease progression in children and their responses to medical therapy can differ significantly from that of their adult counterparts. Children with end-stage liver disease are especially vulnerable to nutritional compromise; if not effectively managed, this can seriously impact long-term outcomes and survival both before and after liver transplantation. Moreover, close attention must be given to vaccination status and the clinical setting at which health care is delivered to optimize outcomes and the delivery of high-quality pediatric health care. In this review, we address important components of the evaluation and management of children with chronic end-stage liver disease.

Validation of automated blood cell counter for the determination of polymorphonuclear cell count in the ascitic fluid of cirrhotic patients with or without spontaneous bacterial peritonitis

OBJECTIVES

Polymorphonuclear (PMN) cell count in ascitic fluid is the most useful test for the diagnosis of spontaneous bacterial peritonitis (SBP). We evaluated the validity of an automated blood cell counter for the PMN determination in ascitic fluid by comparing it with the traditional hematologic method with a light microscope in a manual counting chamber.

METHODS

A total of 130 ascitic fluid samples were collected from 74 consecutive cirrhotics. The agreement between the two techniques was assessed according to Bland and Altman's method. The sensitivity, specificity, and positive and negative predictive values of the automated blood cell counter were calculated by considering the diagnosis of SBP as a PMN count > or = 250 cells/mm(3), determined by the manual method as the "gold standard."

RESULTS

The mean PMN counts assessed by the manual method and the automated blood cell counter were 124 +/- 301 cells/mm(3) and 130 +/- 339 cells/mm(3), respectively (p = 0.89, ns). The mean +/- SD of the difference between manual and automated measurements was 6 +/- 61 cells/mm(3), whereas the limits of agreement were +127 cells/mm(3) (95% CI = +108 to +147) and -115 cells/mm(3) (95%CI = -96 to -135). SBP was diagnosed in 11 patients. All but one were correctly identified with the automated blood cell counter, with a sensitivity of 94% and a specificity of 100%; positive and negative predictive values were 100% and 99.1%, respectively.

CONCLUSIONS

The manual method and the automated blood cell counter have a good agreement in the PMN determination in ascitic fluid, and the automated blood cell counter is a reliable tool for rapid diagnosis of SBP.

Spontaneous bacterial peritonitis associated with experimental cirrhosis: Comparative effect of different therapeutic options on endotoxinemia and hemodynamic derangement

OBJECTIVE:  The aim of this investigation was to assess the role of different therapeutic options aimed at modifying the gut microecology in experimental liver cirrhosis in view of the cytokine cascade and splanchnic and systemic hemodynamics.

METHODS:  Cirrhosis was induced in male Sprague‐Dawley rats by carbon tetrachloride (CCL4). After the 6th week of CCL4 administration rats were divided into 5 groups for the remaining 6 weeks: (A) saline b.i.d; (B) lactulose 0.5 g b.i.d.; (C) rifaximine 1 mg b.i.d; (D) 2 mL b.i.d of a probiotic mixture and (E) 1 week of rifaximine followed by 5 weeks of probiotic.

RESULTS:  Rats with cirrhosis and ascites showed a significantly high concentration of either portal, splanchnic and systemic endotoxin, as well as plasma TNF‐α concentration (P < 0.05). Rifaximine alone, rifaximine plus probiotic or probiotic alone significantly decreased the plasma endotoxin concentration at each of the three tested sites, as well as the plasma concentration of TNF‐α (P < 0.01). Total Gram‐negative aerobic bacteria count in the stool markedly decreased together with a significant increase of the enterococcal population in the rifaximine plus probiotic group and, to a lesser extent, in the other treatment groups. Treated rats showed a significantly decreased occurrence of bacterial peritonitis and the rifaximine plus probiotic treatment was the most effective regimen. Each of the treatments significantly reduced the percentage of positive culture of either mesenteric lymph node or portal vein samples, rifaximine plus probiotic being the most effective. As compared with healthy control rats, those with cirrhosis showed a significantly lower mean arterial pressure and systemic vascular resistance, but a higher cardiac index and portal pressure. Spontaneous bacterial peritonitis further worsened the systemic vascular resistance, but this was partly improved by the rifaximine plus probiotic treatment.

CONCLUSION:  These data suggest that the association of a nonabsorbable antibiotic with a probiotic beneficially affects the abnormal systemic vasodilatory response in the course of severe liver cirrhosis, probably through the effects on endotoxin and indirect inhibition of TNF−α release.

Effect of Lactobacillus-fermented diets on bacterial translocation and intestinal flora in experimental prehepatic portal hypertension

Spontaneous bacterial infections in cirrhosis and portal hypertension have been attributed to translocation of gut-derived bacteria, a process promoted by intestinal bacterial overgrowth and disruption of the gut mucosal barrier. Bacteriotherapy with Lactobacillus has been reported to correct bacterial overgrowth, stabilize mucosal barrier function, and decrease bacterial translocation in rat models of acute liver injury and failure. In this study we investigated the effect of Lactobacillus-supplemented diets on intestinal flora and on bacterial translocation rate in portal vein ligated rats. Lactobacillus-fermented milk (yogurt) containing at least 2 x 10(9) colony forming units/ml or placebo (water) was adminstrated by gavage twice daily (2 ml) for 9 days. Portal vein ligation was performed on day 7 of treatment. Bacterial translocation to mesenteric lymph nodes and quantification of intestinal flora was assessed by standard bacteriological cultures. Bacterial translocation was not significantly different between animals that received yogurt (82%) and those that received placebo (75%). Yogurt did not induce any significant changes in intestinal flora, whether it was produced with Lactobacillus acidophilus or Lactobacillus GG. In conclusion, in acute prehepatic portal hypertension, bacteriotherapy with Lactobacillus was unable to induce changes in bacterial translocation probably because it was unable to induce changes in bacterial flora.

Association between hepatitis C infection and other infectious diseases: a case for targeted screening?

OBJECTIVE

Hepatitis C virus (HCV) shares risk factors and routes of transmission with several other infectious agents. However, the prevalence of comorbid infectious disorders among HCV-infected patients remains unknown. To analyze the association between HCV and several categories of infectious disorders, we carried out a case-control study using information from 172 hospitals contained in the computerized databases of the Department of Veterans Affairs.

METHODS

We identified all HCV-infected patients who were hospitalized during 1992-1999. For each case, four control subjects without HCV were randomly chosen from hospitalized patients and were matched with cases on the year of admission. The frequencies of several predefined infectious disease diagnoses were compared between cases and control subjects, and the strength of these associations were assessed in multivariable logistic regression analyses.

RESULTS

We identified 34,204 HCV-infected patients (cases) and 136,816 control subjects without HCV. Patients in the case group were younger (48.4 yr vs 59.8 yr), were more frequently nonwhite (38.5% vs 26.5%), and were more likely to have served in Vietnam (68.1% vs 33.0%); all p < 0.0001. Compared with control subjects, patients with HCV had a significantly higher prevalence of other blood-borne virus infections, including HIV (14.1% vs 3.0%) and hepatitis B (22.4% vs 0.7%); immunodeficiency-related infections, including cytomegalovirus (0.6% vs 0.2%), toxoplasmosis (0.3% vs 0.1%), cryptococcosis (0.4% vs 0.1%), and tuberculosis (3.3% vs 1.3%); sexually transmitted diseases, including gonococcus (0.5% vs 0.1%), chlamydia (1.6% vs 0.7%), syphilis (2.0% vs 0.6%), and genital herpes (1.0% vs 0.3%); and bacterial infection, including peritonitis, sepsis, endocarditis, cellulitis, and carbuncles (all p < 0.0001). After excluding potentially immunocompromised patients, including those with HIV, organ transplant, and cirrhosis, HCV remained significantly associated with CMV, cryptococcus, tuberculosis, and sexually transmitted diseases. Similar results were obtained when the analyses were restricted to Vietnam-era veterans.

CONCLUSIONS

Several infectious diseases are more common among HCV-infected patients compared with those without HCV infection. These findings support an approach of targeted screening for HCV among patients with these infectious diseases.

Why do bacteria reach ascitic fluid?

Spontaneous bacterial peritonitis (SBP) is the most common and serious infection that develops in cirrhotic patients. Translocation of bacteria from their intestinal origin, alterations in immune defence mechanisms and deficiencies in the ascitic fluid antimicrobial activity seem to represent the main steps in the pathogenesis of SBP in cirrhosis. Among the factors determining the development of bacterial translocation, intestinal bacterial overgrowth (mainly related to decreased intestinal motility) and changes in the intestinal barrier appear to play an outstanding role. In conclusion, greater understanding of the pathogenesis of SBP will allow better identification of patients at high risk of developing this complication and contribute to the search for new strategies for its prevention.

Pathophysiology of renal disease associated with liver disorders: implications for liver transplantation. Part I

Renal and hepatic function are often intertwined through both the existence of associated primary organ diseases and hemodynamic interrelationships. This connection occasionally results in the chronic failure of both organs, necessitating combined liver-kidney transplantation (LKT). Since 1988, more than 850 patients in the United States have received such transplants, with patient survival somewhat less than that for patients receiving either organ alone. Patients with renal failure caused by acute injury or hepatorenal syndrome have classically not been included as candidates for combined transplantation because of the reversibility of renal dysfunction after liver transplantation. However, the rate and duration of renal failure before liver transplantation is increasing in association with prolonged waiting list times. Thus, the issue of acquired permanent renal damage in the setting of hepatic failure continues to confront the transplant community. The following article and its sequel (Part II, to be published in vol 8, no 3 of this journal) attempt to review the problem of primary and secondary renal disease in patients with end-stage liver disease, elements involved in renal disease progression and recovery, the impact of renal disease on liver transplant outcome, and results of combined LKT; outline the steps in the pretransplantation renal evaluation; and provide the beginnings of an algorithm for making the decision for combined LKT.

Influence of ascites on the chemotaxis of granulocytes in patients with cirrhosis

Spontaneous bacterial peritonitis is a specific infectious complication in liver cirrhosis. The reasons for the preferred location of infection on the peritoneum are not clear. The aims of the present study were to ascertain whether hepatogenic ascites fluid is chemotactically effective, what part is played by complement factor C3 and whether there are inhibitors of chemotaxis in ascites. Chemotaxis of granulocytes in serum and ascites fluid was measured in 18 patients with cirrhosis and ascites and in 18 healthy individuals using the Boyden chamber method. In the patients, the chemotactic effect of serum was reduced significantly. Ascites fluid had lower chemotactic activity than autologous serum (P < 0.01), directly correlated to C3 levels (P < 0.025). There was a significant correlation between chemotaxis in serum and in ascites fluid (P < 0.005). Adding ascites fluid to serum led to reduction of chemotactic activity only in the patients (P < 0.025). In conclusion, the chemotactic effect of ascites fluid is considerably lower than that of serum and is proportional to local concentrations of C3. Chemotaxis-inhibiting factors can also be identified in ascites fluid, their pathogenetic relevance being limited.

Bacterial translocation in cirrhotic rats. Its role in the development of spontaneous bacterial peritonitis

Bacterial translocation occurs in ascitic cirrhotic rats, but its association with ascites infection is unknown. The aim of this study was to assess the relation between bacterial translocation and ascites infection in cirrhotic rats. Male Sprague-Dawley rats were induced to cirrhosis with intragastric CCl4. Ascitic fluid, portal and peripheral blood, mesenteric lymph nodes, liver and spleen samples were cultured before death in those cirrhotic rats with less (group A) or more (group B) than 250 polymorphonuclear neutrophils/mm3 in ascitic fluid, as well as in healthy control rats. Histological examination of jejunum, ileum, and caecum was also performed. Bacterial translocation occurred in 45% of ascitic rats (without differences between groups A and B), but in 0% controls (p = 0.01). Bacterial translocation was associated with positive ascitic fluid culture in 60% of the cases. In all of them the same bacterial species was isolated in both mesenteric lymph node and ascitic fluid. Submucosal caecal oedema (100%), ileal lymphangiectasia (41%), and caecal inflammatory infiltrate (41%) occurred in ascitic rats, the last being associated with ascitic fluid positive culture (p = 0.04). These results suggests that bacterial translocation occurs frequently in ascitic cirrhotic rats, and may play a permissive, but not unique, part in a number of ascites infections. Whether histological changes seen in cirrhotic ascitic rats favour bacterial translocation remains to be elucidated.