Detection of bacterial DNA by in situ hybridization in patients with decompensated liver cirrhosis

The gut-liver axis in hepatobiliary diseases

Recent advances in the analysis of intestinal bacteria have led to reports of variations in intestinal bacterial levels among hepatobiliary diseases. The mechanisms behind the changes in intestinal bacteria in various hepatobiliary diseases include the abnormal composition of intestinal bacteria, weakening of the intestinal barrier, and bacterial translocation outside the intestinal tract, along with their metabolites, but many aspects remain unresolved. Further research employing clinical studies and animal models is expected to clarify the direct relationship between intestinal bacteria and hepatobiliary diseases and to validate the utility of intestinal bacteria as a diagnostic biomarker and potential therapeutic target. This review summarizes the involvement of the microbiota in the pathogenesis of hepatobiliary diseases via the gut-liver axis.

New Paradigms for Familiar Diseases: Lessons Learned on Circulatory Bacterial Signatures in Cardiometabolic Diseases

Despite the strongly accumulating evidence for microbial signatures in metabolic tissues, including the blood, suggesting a novel paradigm for metabolic disease development, the notion of a core blood bacterial signature in health and disease remains a contentious concept. Recent studies clearly demonstrate that under a strict contamination-free environment, methods such as 16 S rRNA gene sequencing, fluorescence in-situ hybridization, transmission electron microscopy, and several more, allied with advanced bioinformatics tools, allow unambiguous detection and quantification of bacteria and bacterial DNA in human tissues. Bacterial load and compositional changes in the blood have been reported for numerous disease states, suggesting that bacteria and their components may partially induce systemic inflammation in cardiometabolic disease. This concept has been so far primarily based on measurements of surrogate parameters. It is now highly desirable to translate the current knowledge into diagnostic, prognostic, and therapeutic approaches.This review addresses the potential clinical relevance of a blood bacterial signature pertinent to cardiometabolic diseases and outcomes and new avenues for translational approaches. It discusses pitfalls related to research in low bacterial biomass while proposing mitigation strategies for future research and application approaches.

The Diagnostic Value of CD11b Expression on Peripheral Blood Neutrophils for Detection of Spontaneous Bacterial Peritonitis

Background: Spontaneous bacterial peritonitis (SBP) is associated with the highest mortality among end-stage cirrhotic liver disease patients. Neutrophil CD11b expression increases on the neutrophil surface within 5 min of exposure to bacteria. Paracentesis remains the only accepted method for accurate evaluation of patients, with many drawbacks; hence, a diagnostic noninvasive marker with a very high sensitivity and high diagnostic accuracy is very necessary. Aim of the study: to evaluate the neutrophil CD11b as a non-invasive biomarker for the diagnosis of SBP, comparing its sensitivity and specificity to other traditional methods. Patients and Methods: 200 patients who had liver cirrhosis with ascites were recruited to the Hepatology department inpatient wards of the National Liver Institute, Menoufia University. They were divided into Group I: 100 patients with SBP and Group II: 100 patients with non SBP ascites. All studied patients were subjected to full clinical examination, abdominal ultrasound, paracentesis, and laboratory investigations including ascetic fluid (AF) examinations. The CD11b expression and its mean fluorescence intensity (MFI) were assessed on peripheral blood neutrophils by flowcytometry. Results: There was a significant increase in the MFI of CD11b in the SBP group compared to the non SBP group. At cut off >20 for MFI of CD11b with a sensitivity of 100% and specificity of 100% can discriminate between SBP and non SBP cases followed by ascetic fluid TLC examination at a cut off 0.26 (×103) with a sensitivity of 92%, and specificity of 96%, then, AF neutrophil count at cut off 0.25 (×103) with a sensitivity of 80%, specificity of 100%, and AF culture examination with a sensitivity of 56% and specificity of 100%. Conclusion: The measurement of CD11b MFI on peripheral blood neutrophils is a useful non-invasive marker with high sensitivity and specificity to predict SBP compared with other methods. Further large-scale studies are needed to study the value of CD11b MFI level in the SBP follow-up therapy.

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.

Designing a new biosensor "DNA ELISA" to detect Escherichia coli using genomic DNA and comparison of this method to PCR-ELISA

In this experiment, DNA-ELISA biosensor was introduced, bearing the ability to detect specific bacteria in about 4 h. This is a more rapid system in comparison to conventional methods, like colony counting method. Moreover, this method does not require any amplification and directly detects genomic DNA of bacteria, giving a lower limit to the sensitivity of 40,000 bacteria. In this study, two specific probes capture (biotin labelled) and detector (dig labelled), were used against special regions of 16s rRNA gene of Escherichia coli ATCC 25922. The capture probe has the ability to trap the target bacterial DNA from a pool of other kinds of bacteria under specific conditions. The detector probe then was used to hybridize to the genome of trapped bacteria. The detection proceeds by adding HRP-anti dig enzyme and its substrate, ABTS to emit light. Light absorbance is measured for verifying the detection.

Spontaneous bacterial and fungal peritonitis in patients with liver cirrhosis: A literature review

Spontaneous bacterial (SBP) and spontaneous fungal peritonitis (SFP) can be a life-threatening infection in patients with liver cirrhosis (LC) and ascites. One of the possible mechanisms of developing SBP is bacterial translocation. Although the number of polymorphonuclear cells in the culture of ascitic fluid is diagnostic for SBP, secondary bacterial peritonitis is necessary to exclude. The severity of underlying liver dysfunction is predictive of developing SBP; moreover, renal impairment and infections caused by multidrug-resistant (MDR) organism are associated with a fatal prognosis of SBP. SBP is treated by antimicrobials, but initial empirical treatment may not succeed because of the presence of MDR organisms, particularly in nosocomial infections. Antibiotic prophylaxis is recommended for patients with LC at a high risk of developing SBP, gastrointestinal bleeding, or a previous episode of SBP, but the increase in the risk of developing an infection caused by MDR organisms is a serious concern globally. Less is known about SFP in patients with LC, but the severity of underlying liver dysfunction may increase the hospital mortality. SFP mortality has been reported to be higher than that of SBP partially because the difficulty of early differentiation between SFP and SBP induces delayed antifungal therapy for SFP.