Rapid detection of sepsis complicating acute necrotizing pancreatitis using polymerase chain reaction

Microbiome changes associated with acute and chronic pancreatitis: A systematic review

BACKGROUND

Altered intestinal microbiota has been reported in pancreatic disorders, however, it remains unclear whether these changes alter the course of disease in patients with acute (AP) and chronic pancreatitis (CP), or whether these disease states alter the environment to enable pathogenic microbial composition changes to occur. We undertook a systematic review to characterize the gut microbiome in pancreatitis patients.

METHODS

MEDLINE and EMBASE were searched for studies on microbiota in pancreatitis published from January 1, 2000 to June 5, 2020. Animal studies, reviews, case reports, and non-English articles were excluded. A frequency analysis was performed for outcomes reported in ≥2 studies and studies were analyzed for risk of bias and quality of evidence.

RESULTS

22 papers met inclusion criteria; 15 included AP, 7 included CP. No studies were appropriately designed to assess whether alterations in the gut microbiome exacerbate pancreatitis or develop as a result of pancreatitis. We did identify several patterns of microbiome changes that are associated with pancreatitis. The gut microbiome demonstrated decreased alpha diversity in 3/3 A P studies and 3/3 C P studies. Beta diversity analysis revealed differences in bacterial community composition in the gut microbiome in 2/2 A P studies and 3/3 C P studies. Functionally, gut microbiome changes were associated with infectious pathways in AP and CP. Several studies suffered from high risk of bias and inadequate quality.

CONCLUSIONS

Detecting differences in microbial composition associated with AP and CP may represent a diagnostic tool. Appropriately controlled longitudinal studies are needed to determine whether microbiome changes are causative or reactive in pancreatitis.

Meta-analysis of gut barrier dysfunction in patients with acute pancreatitis

BACKGROUND

The gut is implicated in the pathogenesis of acute pancreatitis but there is discrepancy between individual studies regarding the prevalence of gut barrier dysfunction in patients with acute pancreatitis. The aim of this study was to determine the prevalence of gut barrier dysfunction in acute pancreatitis, the effect of different co-variables, and changes in gut barrier function associated with the use of various therapeutic modalities.

METHODS

A literature search was performed using PRISMA and MOOSE guidelines. Summary estimates were presented as pooled prevalence of gut barrier dysfunction and the associated 95 per cent c.i.

RESULTS

A total of 44 prospective clinical studies were included in the systematic review, of which 18 studies were subjected to meta-analysis. The pooled prevalence of gut barrier dysfunction was 59 (95 per cent c.i. 48 to 70) per cent; the prevalence was not significantly affected by disease severity, timing of assessment after hospital admission or type of test used, but showed a statistically significant association with age. Overall, nine of 13 randomized clinical trials reported a significant improvement in gut barrier function following intervention compared with the control group, but only three of six studies that used standard enteral nutrition reported a statistically significant improvement in gut barrier function after intervention.

CONCLUSION

Gut barrier dysfunction is present in three of five patients with acute pancreatitis, and the prevalence is affected by patient age but not by disease severity. Clinical studies are needed to evaluate the effect of enteral nutrition on gut function in acute pancreatitis.

Bacteremia in patients with acute pancreatitis as revealed by 16S ribosomal RNA gene-based techniques*

OBJECTIVES

To define the characteristic of bacteremia in patients with acute pancreatitis and determine its possible association with the disease severity.

DESIGN

A prospective controlled study.

SETTING

ICU of Jinling Hospital, China.

PATIENTS

A total of 48 patients with mild or severe acute pancreatitis were enrolled in the study.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Samples of peripheral blood were collected from the patients at 4 or 5 and 9 or 10 days after acute pancreatitis was definitely diagnosed. Resulting DNA from the blood was analyzed using denaturing gradient gel electrophoresis, and separated fragments were sequenced for identification of bacterial species. Bacterial DNA was detected in peripheral blood from 68.8% of patients with acute pancreatitis, and more than half (60.4%) of the patients encountered polymicrobial flora. Translocated bacteria in patients with acute pancreatitis were primarily constituted of opportunistic pathogens derived from the gut, including Escherichia coli, Shigella flexneri, Enterobacteriaceae bacterium, Acinetobacter lwoffii, Bacillus coagulans, and Enterococcus faecium. The species of circulating bacteria shifted remarkably among the patients with different severity. The presence of the bacteremia correlated positively with the Acute Physiology and Chronic Health Evaluation-II scores of patients with acute pancreatitis (r = 0.7918, p < 0.0001).

CONCLUSIONS

This study provides a detailed description on the prevalence of bacteremia and characteristic of bacterial species in patients with acute pancreatitis. We demonstrate an association between the bacteremia and the disease severity, which enables us to better understand a potential role of bacterial translocation in the pathogenesis of septic complication in acute pancreatitis.

Insulin-like growth factor-1 levels contribute to the development of bacterial translocation in sepsis

RATIONALE

Many lines of evidence point toward the gastrointestinal (GI) tract in the pathophysiology of organ dysfunction in sepsis. Splanchnic hypoperfusion during sepsis leads to enterocyte apoptosis, diminished barrier function, and release of bacterial products. Sepsis lowers levels of insulin-like growth factor (IGF)-1, a known antiapoptotic factor. We recently demonstrated that treatment with IGF-1 is protective in murine sepsis.

OBJECTIVES

We hypothesize that decreased IGF-1 levels in sepsis contributes to the development of bacterial translocation.

METHODS

Sepsis was induced in C57BL/6 mice via intratracheal instillation of Pseudomonas aeruginosa. Human subjects with sepsis were enrolled if they had a documented positive blood culture with a nonenteric organism. Bacterial translocation was measured in serum by quantitative real-time polymerase chain reaction with primers specific for enteric bacteria. Serum IGF-1 was measured by ELISA. Apoptosis of the GI epithelium was assessed via immunohistochemistry.

MEASUREMENTS AND MAIN RESULTS

We found that mice with severe sepsis had evidence of bacterial translocation by 24 hours. Enteric bacterial load correlated inversely with levels of serum IGF-1. If we treated mice with IGF-1, bacterial translocation was significantly decreased. In addition, we found increased GI epithelial cell apoptosis after sepsis, which was significantly decreased after IGF-1 treatment. Human subjects with nonenteric sepsis developed progressive enteric bacteremia over 3 days. The degree of enteric bacteremia correlated inversely with serum IGF-1 levels.

CONCLUSIONS

These data support the hypothesis that sepsis-induced reductions in IGF-1 levels contribute to the development of bacterial translocation in both a murine model and human subjects.

[Automatic detection of bacterial and fungal infections in blood]

La sepsis es una de las principales causas de mortalidad y morbilidad en los hospitales. La detección temprana de los patógenos mediante técnicas basadas en ácidos nucleicos puede facilitar el diagnóstico rápido de la bacteriemia y/o fungemia, la rápida adecuación del tratamiento antibiótico, reducir el uso de antibióticos innecesarios y disminuir la mortalidad. Se describen 2 técnicas disponibles comercialmente que ayudan, en un tiempo reducido, a identificar distintas bacterias y hongos productores de sepsis: LightCycler^® SeptiFast Test Mgrade (Roche Diagnostic SL) y GenoType Blood Culture (Hain Lifescience). De estas 2 técnicas, mostramos los resultados de un estudio inicial propio con el LightCycler^® SeptiFast Test Mgrade. El estudio se realizó con 50 muestras correspondientes a 28 pacientes (1-3 muestras por paciente) con síndrome séptico ingresados en la unidad de cuidados intensivos, comparando la nueva técnica con el hemocultivo convencional. La concordancia entre los resultados del hemocultivo y el SeptiFast fue buena, 79% en el primer ensayo, y 89% en el segundo, después de corregir defectos técnicos. Inicialmente se observó inhibición importante de los controles internos para los bacilos gramnegativos, por la presencia de heparina en la sangre empleada y un exceso de ácido desoxirribonucleico (ADN) debido al número de leucocitos. Con la finalidad de disminuir las inhibiciones, en otro estudio posterior se trabajó con 24 muestras a la mitad de volumen original, llevando el ácido nucleico extraído a dilución 1:4. Con estas modificaciones, se apreciaron reducciones importantes de las inhibiciones. En comparación con el hemocultivo, el SeptiFast diferencia mejor las contaminaciones por estafilococos coagulasa-negativa y especies de estreptococos.

Using the polymerase chain reaction coupled with denaturing gradient gel electrophoresis to investigate the association between bacterial translocation and systemic inflammatory response syndrome in predicted acute severe pancreatitis

AIM

To investigate the use of PCR and DGGE to investigate the association between bacterial translocation and systemic inflammatory response syndrome in predicted severe AP.

METHODS

Patients with biochemical and clinical evidence of acute pancreatitis and an APACHE II score > or = 8 were enrolled. PCR and DGGE were employed to detect bacterial translocation in blood samples collected on d 1, 3, and 8 after the admission. Standard microbial blood cultures were taken when there was clinical evidence of sepsis or when felt to be clinically indicated by the supervising team.

RESULTS

Six patients were included. Of all the patients investigated, only one developed septic complications; the others had uneventful illness. Bacteria were detected using PCR in 4 of the 17 collected blood samples. The patient with sepsis was PCR-positive in two samples (taken on d 1 and 3), despite three negative blood cultures. Using DGGE and specific primers, the bacteria in all blood specimens which tested positive for the presence of bacterial DNA were identified as E coli.

CONCLUSION

Our study confirmed that unlike traditional microbiological techniques, PCR can detect the presence of bacteria in the blood of patients with severe AP. Therefore, this latter method in conjunction with DGGE is potentially an extremely useful tool in predicting septic morbidity and evaluating patients with the disease. Further research using increased numbers of patients, in particular those patients with necrosis and sepsis, is required to assess the reliability of PCR and DGGE in the rapid diagnosis of infection in AP.

Effects of antioxidant on NF-κB and iNOS in rats with acute necrotizing pancreatitis

AIM: To observe the influence of antioxidant N-acetylcysteine (NAC) on nuclear factor-kappa B (NF-κB) and inducible nitric oxide synthase (iNOS) in pancreatic tissue of rats with acute necrotizing pancreatitis (ANP).

METHODS: A total of 95 Spraque-Dawley (SD) male rats were randomly divided into control group (group C, n = 25), acute pancreatitis group (group A, n = 35) and NAC intervention group (group N, n = 35). In group A, SD rats were injected twice intraperitoneally with 8 g/L L-arginine (2×1.2 mg/g) in an interval of 1 hour for ANP. In group C, SD rats received the same amount of saline at the same time. In group N, 0.5 mol/L NAC (0.05 mg/g) was administered intraperitoneally 1 hour before the start of L-arginine injection. Animals were killed at 6, 12, 24, 36, and 48 hours after the first L-arginine injection. The concentration of NF-κB and the activity of iNOS in rat's pancreatic tissue of each group were assayed.

RESULTS: The concentration of NF-κB in pancreatic tissue in group N significantly decreased in earlier period than that in group A (10.4±2.3 vs 89.7±6.4, 6.8±3.2 vs 21.5±3.5, 7.9±3.4 vs 32.5±4.5, 5.4±2.7 vs 14.7±5.2, and 5.0±3.7 vs 11.1±2.3, P < 0.05 or P < 0.01). iNOS activity increased in group A, whereas it significantly decreased in group N (15.2± 4.0 vs 24.2±3.8, 28.3±8.0 vs 36.8±6.0, 25.2±3.8 vs 30.5±3.5 , 21.2±3.7 vs 28.7±7.2, and 18.8±5.5 vs 28.2±4.2, P < 0.05 or P < 0.01).

CONCLUSION: Antioxidants may decrease the activity of iNOS through the inhibition of NF-κB activation.

A mouse model of severe acute pancreatitis induced with caerulein and lipopolysaccharide

AIM: To establish a non-traumatic, easy to induce and reproducible mouse model of severe acute pancreatitis (SAP) induced with caerulein and lipopolyasccharide (LPS).

METHODS: Thirty-two healthy mature NIH female mice were selected and divided at random into four groups (each of 8 mice), i.e., the control group (NS group), the caerulein group (Cn group), the lipopolysaccharide group (LPS group), and the caerulein+LPS group (Cn + LPS group). Mice were injected intraperitoneally with caerulein only, or LPS only, and caerulein and LPS in combination. All the animals were then killed by neck dislocation three hours after the last intraperitoneal injection. The pancreas and exo-pancreatic organs were then carefully removed for microscopic examination. And the pancreatic acinus was further observed under transmission electron microscope (TEM). Pancreatic weight, serum amylase, serum nitric oxide (NO) concentration, superoxide dismutase (SOD) and malondialdehyde (MDA) concentration of the pancreas were assayed respectively.

RESULTS: (1) NS animals displayed normal pancreatic structure both in the exocrine and endocrine. In the LPS group, the pancreas was slightly edematous, with the infiltration of a few inflammatory cells and the necrosis of the adjacent fat tissues. All the animals of the Cn group showed distinct signs of a mild edematous pancreatitis characterized by interstitial edema, infiltration of neutrophil and mononuclear cells, but without obvious parenchyma necrosis and hemorrhage. In contrast, the Cn + LPS group showed more diffuse focal areas of nonviable pancreatic and hemorrhage as well as systemic organ dysfunction. According to Schmidt’s criteria, the pancreatic histologic score showed that there existed significant difference in the Cn + LPS group in the interstitial edema, inflammatory infiltration, parenchyma necrosis and parenchyma homorrhage in comparison with those of the Cn group, LPS group and NS group (P < 0.01 or P < 0.05). (2) The ultrasturcture of acinar cells was seriously damaged in the Cn + LPS group. Chromatin margination of nuclei was present, the number and volume of vacuoles greatly increased. Zymogen granules (ZGs) were greatly decreased in number and endoplasmic reticulum exhibited whorls. The swollen mitochondria appeared, the crista of which was decreased in number or disappeared. (3) Pancreatic weight and serum amylase levels in the Cn +LPS was significantly higher than those of the NS group and the LPS group respectively (P < 0.01 or P < 0.05). However, the pancreatic wet weight and serum amylase concentration showed no significant difference between the Cn + LPS group and the Cn group. (4) NO concentration in the Cn + LPS group was significantly higher than that of NS group, LPS group and Cn group(P < 0.05 or P < 0.01). 5) The SOD and MDA concentration of the pancreas in the Cn + LPS group were significantly higher than those of NS, LPS and Cn groups (P < 0.05 or P < 0.01).

CONCLUSION: The mouse model of severe acute pancreatitis could be induced with caerulein and LPS, which could be non-traumatic and easy to induce, reproducible with the same pathological characteristics as those of SAP in human, and could be used in the research on the mechanism of human SAP.

Pancreatic microcirculatory impairment in experimental acute pancreatitis in rats

AIM: To study the feature of pancreatic microcirculatory impairment, especially the initial changes, in caerulein-induced experimental acute pancreatitis (AP).

METHODS: The pancreatic microcirculation of caerulein-induced AP model was studied by intravital fluorescence microscopy with FITC-labeled erythrocytes (FITC-RBC), scanning electron microscopy of vascular corrosion casts, and light microscopy of Chinese ink-injected/cleared tissues.

RESULTS: Animals in caerulein-treated group showed hyperamylemia (× 2), pancreatic oedema, infiltration of inflammatory cells in pancreas. Constrictions of intralobular arteriolar sphincters, presence of vacuoles in all layers of sphincter, and gross irregularity in capillary network of acini were found in the AP specimens. The decrease of pancreatic capillary blood flow (0.34 ± 0.10 nL·min^-1vs 0.91 ± 0.06 nL·min^-1 of control, P < 0.001), reduction of functional capillary density (277 ± 13 cm^-1vs 349 ± 8 cm^-1 of control, P < 0.001), and irregular intermittent perfusion were observed in caerulein-induced groups.

CONCLUSION: Impairment and constriction of pancreatic intralobular arteriolar sphincter are the initial microcirculatory lesions in the early phase of acute pancreatitis, and play a key role in the pancreatic ischaemia and pancreatic microvascular failure in acute pancreatitis.

Rapid diagnosis of fungal infection in patients with acute necrotizing pancreatitis by polymerase chain reaction

OBJECTIVE

This study was conducted to assess the rapid diagnosis of fungal infections in patients with acute necrotizing pancreatitis by polymerase chain reaction [PCR] using universal primers targeting the 18S rRNA gene.

METHODS

In this study, a PCR assay was developed to identify clinically isolated fungi, and both PCR technique and conventional culture were used to detect fungi in 37 samples from patients with acute necrotizing pancreatitis.

RESULTS

A 197-bp fragment was amplified by PCR from all the clinically isolated fungal strains. This fragment was not isolated from gram-positive, gram-negative bacteria or human leucocytes. Thirty-seven samples of necrotic tissue or peripancreatic fluid from 11 patients were also analyzed, and eight samples were positive for fungi by PCR, six of which were also positive by conventional culture. The whole PCR procedure was completed within 7 hours.

CONCLUSION

PCR can be used to diagnose fungal infection secondary to acute necrotizing pancreatitis rapidly and sensitively.

Relationship between cytokine mRNA expression and organ damage following cecal ligation and puncture

AIM: To investigate the role of cytokine gene expression in organ damage at different tissue sites during sepsis.

METHODS: Male NIH mice were subjected to cecal ligation and puncture (CLP) or sham operation (Sham). Pro-inflammatory cytokine (TNFα, IL-1β and IL-6) and anti-inflammatory cytokine (IL-4) gene expression in the liver and lung tissue were assessed by RT-PCR. The permeability of microvascular and water content in the lungs and liver were also examined.

RESULTS: Significant increase in TNFα, IL-1β and IL-6 gene expression was observed at 3 and 12 h after CLP both in the liver and lungs (P < 0.01).The level of IL-4 gene expression was not changed after CLP in the lungs, but increased at 12 h after CLP (P < 0.01) in the liver tissue. Both the liver and lungs showed a significant increase in microcirculatory permeability at 12 h after CLP(P < 0.01), and the increase in the lungs was higher than that in the liver. The water mass fractions in the liver (P < 0.05) and lungs (P < 0.01) were increased after CLP, and the increase in the lungs happened earlier and more severely than that in the liver.

CONCLUSION: The inflammatory response in the liver and lungs was different during sepsis. At the early stage of sepsis, pro-inflammatory reaction dominates both in the liver and lungs. But at the later stage of sepsis, induction of compensatory anti-inflammatory response was seen in the liver but not in the lungs. This difference in situ activity may contribute to the different vulnerability of organ damage during sepsis. The strategy of systemic administration of anti-inflammatory drugs to sepsis should be reconsidered.

Early diagnosis and treatment of severe acute cholangitis

AIM: To investigate the diagnostic standard for early identification of severe acute cholangitis in order to lower the incidence of morbidity and mortality rate.

METHODS: A diagnostic standard was proposed in this study as follows: documented biliary duct obstruction by ultrasound or computerized tomography or other imaging tools with the manifestation of systemic inflammatory response syndrome (SIRS). The surgical procedures included emergency common bile duct exploration with T tube insertion or cholecystostomy with secondary common bile duct exploration. And incidence of postoperative multiple organ dysfunction syndrome (MODS), duration of systemic inflammatory response and hospital mortality were analyzed.

RESULTS: Fourty-three patients conforming to the diagnostic standard described above were employed in this study. 1 patient was admitted in acutely ill condition and complicated with acute relapse of chronic bronchitis, cholecystostomy procedure was performed but the patient was complicated with postoperative acute lung injury which was treated by assisted mechanical ventilation for 5 d; 2 wk later, two-stage common bile duct Exploration and T tube insertion were performed. The remaining 42 patients underwent primary common bile duct exploration and T tube insertion, 1 developed acute lung injury and recovered 3 d later, 2 patients developed acute renal dysfunction, 1 of which recovered 2 d later and the other died on d 4. For all patients, the postoperative systemic inflammatory response persisted for 2 to 8 d with median of 3 d.

CONCLUSION: Early diagnosis of severe acute cholangitis can be made using this diagnostic standard, further development of systemic inflammatory response could be prevented and incidence of MODS as well as hospital mortality decreased.

Relationship between plasma D(-)-lactate and intestinal damage after severe injuries in rats

AIM: To explore the kinetic changes in plasma D(-)-lactate and lipopolysaccharide (LPS) levels, and investigate whether D(-)-lactate could be used as a marker of intestinal injury in rats following gut ischemia/reperfusion, burn, and acute necrotizing pancreatitis (ANP).

METHODS: Three models were developed in rats: ① gut ischemia/reperfusion obtained by one hour of superior mesenteric artery occlusion followed by reperfusion; ② severe burn injury created by 30% of total body surface area (TBSA) full-thickness scald burn; and ③ ANP induced by continuous inverse infusion of sodium taurocholate and trypsin into main pancreatic duct. Plasma levels of D(-)-lactate in systemic circulation and LPS in portal circulation were measured by enzymatic-spectrophotometric method and limulus amebocyte lysate (LAL) test kit, respectively. Tissue samples of intestine were taken for histological analysis.

RESULTS: One hour gut ischemia followed by reperfusion injuries resulted in a significant elevation in plasma D(-)-lactate and LPS levels, and there was a significant correlation between the plasma D(-)-lactate and LPS (r = 0.719, P < 0.05). The plasma concentrations of D(-)-lactate and LPS increased significantly at 6 h postburn, and there was also a remarkable correlation between them (r = 0.877, P < 0.01). D(-)-lactate and LPS levels elevated significantly at 2 h after ANP, with a similar significant correlation between the two levels (r = 0.798, P < 0.01). The desquamation of intestine villi and infiltration of inflammatory cells in the lamina propria were observed in all groups.

CONCLUSION: The changes of plasma D(-)-lactate levels in systemic blood paralleled with LPS levels in the portal vein blood. The measurement of plasma D(-)-lactate level may be a useful marker to assess the intestinal injury and to monitor an increase of intestinal permeability and endotoxemia following severe injuries in early stage.