Role of host and bacterial virulence factors in Escherichia coli spontaneous bacterial peritonitis

Treatment of Hospital-Acquired Infections in Patients with Cirrhosis - New Challenges

Background

Hospital acquired infections (HAI) in the cirrhotic patients contribute to hepatic decompensation. With emergence of bacterial drug resistance, designing the treatment protocol of HA infection has become the foremost challenge.

Purpose

To analyze the resistance pattern of organisms isolated from hospital-acquired (HA) infections and determine appropriate antibiotics treatment protocols for these infections.

Study Design

A prospective hospital based observational study was undertaken.

Patients and Methods

The present study was conducted over 18 months at Kasturba Medical College, Mangalore, Karnataka, India. Patients with suspected HA infections were subjected to clinical, hematological and microbiological evaluation. Antibiotic sensitivity evaluation was undertaken for the bacteria isolated from these patients.

Results

During the study period, 398 patients with cirrhosis were 472 times admitted to the hospital for treatment. Out of these patients, 40 patients were diagnosed with 50 HA infections. Fifty five different organisms were isolated from these infections. It was found that these 55 bacteria isolates comprised 30 (54.54%) gram-negative (GN) and 25 (45.45%) gram-positive (GP) bacteria. Quite seriously, extended-spectrum beta-lactamase (ESBL) producers and methicillin-resistant Staphylococcus aureus (MRSA) were detected in 40% and 58% of GN and GP infections respectively. A total of 36 (65.4%) and (14.5%) 8 out of 55 isolated organisms exhibited multi–drug resistance (MDR) and extensive drug resistance (XDR) behavior, respectively.

Conclusion

Cirrhosis patients with HA infection possess higher prevalence of MDR and XDR infections. In such sick patients, cephalosporin and quinolones are not the appropriate empirical antibiotics. Herein, we propose a tigecycline with carbapenem like meropenem and vancomycin based empirical antibiotics protocol to be prescribed for such patients. De-escalation is advised after the culture sensitivity report is obtained.

Evaluation of the health and healthcare system burden due to antimicrobial-resistant Escherichia coli infections in humans: a systematic review and meta-analysis

BACKGROUND

Assessment of the burden of disease due to antimicrobial-resistant Escherichia coli infections facilitates understanding the scale of the problem and potential impacts, and comparison to other diseases, which allows prioritization of research, surveillance, and funding. Using systematic review and meta-analysis methodology, the objectives were to evaluate whether humans with antimicrobial-resistant E. coli infections experience increases in measures of health or healthcare system burden when compared to susceptible E. coli infections.

METHODS

Comprehensive literature searches were performed in four primary and seven grey literature databases. Analytic observational studies of human E. coli infections that assessed the impact of resistance to third/fourth/fifth-generation cephalosporins, resistance to quinolones, and/or multidrug resistance on mortality, treatment failure, length of hospital stay and/or healthcare costs were included. Two researchers independently performed screening, data extraction, and risk of bias assessment. When possible, random effect meta-analyses followed by assessment of the confidence in the cumulative evidence were performed for mortality and length of hospital stay outcomes, and narrative syntheses were performed for treatment failure and healthcare costs.

RESULTS

Literature searches identified 14,759 de-duplicated records and 76 articles were included. Based on 30-day and all-cause mortality meta-analyses, regardless of the type of resistance, there was a significant increase in the odds of dying with resistant E. coli infections compared to susceptible infections. A summary mean difference was not presented for total length of hospital stay meta-analyses due to substantial to considerable heterogeneity. Since small numbers of studies contributed to meta-analyses for bacterium-attributable mortality and post-infection length of hospital stay, the summary results should be considered with caution. Studies contributing results for treatment failure and healthcare costs had considerable variability in definitions and reporting.

CONCLUSIONS

Overall, resistant E. coli infections were associated with significant 30-day and all-cause mortality burden. More research and/or improved reporting are necessary to facilitate quantitative syntheses of bacterium-attributable mortality, length of hospital stay, and hospital costs. Protocol Registration PROSPERO CRD42018111197.

Bacterial infections and hepatic encephalopathy in liver cirrhosis-prophylaxis and treatment

Infections are common among patients with liver cirrhosis. They occur more often in cirrhotic patient groups than in the general population and result in higher mortality. One reason for this phenomenon is bacterial translocation from the intestinal lumen that occurs as a consequence of intestinal bacterial overgrowth, increased permeability and decreased motility. The most common infections in cirrhotic patients are spontaneous bacterial peritonitis and urinary tract infections, followed by pneumonia, skin and soft tissue infections. Intestinal bacterial overgrowth is also responsible for hyperammonemia, which leads to hepatic encephalopathy. All of these complications make this group of patients at high risk for mortality. The role of antibiotics in liver cirrhosis is to treat and in some cases to prevent the development of infectious complications. Based on our current knowledge, antibiotic prophylaxis should be administered to patients with gastrointestinal hemorrhage, low ascitic fluid protein concentration combined with liver or renal failure, and spontaneous bacterial peritonitis as a secondary prophylaxis, as well as after hepatic encephalopathy episodes (also as a secondary prophylaxis). In some cases, the use of non-antibiotic prophylaxis can also be considered. Current knowledge of the treatment of infections allows the choice of a preferred antibiotic for empiric therapy depending on the infection location and whether the source of the disease is nosocomial or community-acquired.

Population Phylogenomics of Extraintestinal Pathogenic Escherichia coli

The emergence of genomics over the last 10 years has provided new insights into the evolution and virulence of extraintestinal Escherichia coli. By combining population genetics and phylogenetic approaches to analyze whole-genome sequences, it became possible to link genomic features to specific phenotypes, such as the ability to cause urinary tract infections. An E. coli chromosome can vary extensively in length, ranging from 4.3 to 6.2 Mb, encoding 4,084 to 6,453 proteins. This huge diversity is structured as a set of less than 2,000 genes (core genome) that are conserved between all the strains and a set of variable genes. Based on the core genome, the history of the species can be reliably reconstructed, revealing the recent emergence of phylogenetic groups A and B1 and the more ancient groups B2, F, and D. Urovirulence is most often observed in B2/F/D group strains and is a multigenic process involving numerous combinations of genes and specific alleles with epistatic interactions, all leading down multiple evolutionary paths. The genes involved mainly code for adhesins, toxins, iron capture systems, and protectins, as well as metabolic pathways and mutation-rate-control systems. However, the barrier between commensal and uropathogenic E. coli strains is difficult to draw as the factors that are responsible for virulence have probably also been selected to allow survival of E. coli as a commensal in the intestinal tract. Genomic studies have also demonstrated that infections are not the result of a unique and stable isolate, but rather often involve several isolates with variable levels of diversity that dynamically changes over time.

Opposing roles of IL-10 in acute bacterial infection

Interleukin-10 (IL-10) is recognized as an anti-inflammatory cytokine that downmodulates inflammatory immune responses at multiple levels. In innate cells, production of this cytokine is usually triggered after pathogen recognition receptor (PRR) engagement by pathogen-associated molecular patterns (PAMPs) or damage-associated molecular patters (DAMPs), as well as by other soluble factors. Importantly, IL-10 is frequently secreted during acute bacterial infections and has been described to play a key role in infection resolution, although its effects can significantly vary depending on the infecting bacterium. While the production of IL-10 might favor host survival in some cases, it may also result harmful for the host in other circumstances, as it can prevent appropriate bacterial clearance. In this review we discuss the role of IL-10 in bacterial clearance and propose that this cytokine is required to recover from infection caused by extracellular or highly pro-inflammatory bacteria. Altogether, we propose that IL-10 drives excessive suppression of the immune response upon infection with intracellular bacteria or in non-inflammatory bacterial infections, which ultimately favors bacterial persistence and dissemination within the host. Thus, the nature of the bacterium causing infection is an important factor that needs to be taken into account when considering new immunotherapies that consist on the modulation of inflammation, such as IL-10. Indeed, induction of this cytokine may significantly improve the host's immune response to certain bacteria when antibiotics are not completely effective.

PREVALENCE OF BACTERIAL RESISTANCE IN HOSPITALIZED CIRRHOTIC PATIENTS IN SOUTHERN BRAZIL: A NEW CHALLENGE

BACKGROUND & AIMS

An increased frequency of infections by multiresistant bacteria has been described in hospitalized patients. The aim of this study was to evaluate the bacterial resistance profile in cirrhotic patients.

METHODS

This is a retrospective observational study. We assessed the antimicrobial susceptibility of 5,839 bacterial isolates from patients with and without cirrhosis. Regarding the multidrug resistance, we evaluated 4,505 bacterial isolates from 2,180 patients.

RESULTS

Two hundred and fifty-one patients had cirrhosis (mean age 57.6 ± 11 years; 61.8% were male, 47.8% of cases associated with hepatitis C virus). Of the isolates of patients with and without cirrhosis, 174/464 (37.5%) and 1,783/4,041 (44.1%) were multiresistant, respectively (p = 0.007). E. coli was the most common multiresistant bacteria in both groups. Approximately 20% of E. coli and Klebsiella sp. isolates were ESBL-producers and 44% of S. aureus isolates were methicillin-resistant in cirrhotic patients. In cirrhotic patients admitted to the emergency department, hospital ward, and intensive care unit, 28.3%, 50% and 40% had multiresistant isolates, respectively. In patients with and without cirrhosis, 36.2% and 33.5% of isolates were resistant to third-generation cephalosporins, respectively.

CONCLUSIONS

The empirical treatment of infections in hospitalized patients using broad-spectrum antibiotics should consider the observed pattern of bacterial resistance.

Extensively drug-resistant bacteria are an independent predictive factor of mortality in 130 patients with spontaneous bacterial peritonitis or spontaneous bacteremia

AIM: To evaluate the epidemiology and outcomes of culture-positive spontaneous bacterial peritonitis (SBP) and spontaneous bacteremia (SB) in decompensated cirrhosis.

METHODS: We prospectively collected clinical, laboratory characteristics, type of administered antibiotic, susceptibility and resistance of bacteria to antibiotics in one hundred thirty cases (68.5% males) with positive ascitic fluid and/or blood cultures during the period from January 1, 2012 to May 30, 2014. All patients with SBP had polymorphonuclear cell count in ascitic fluid > 250/mm³. In patients with SB a thorough study did not reveal any other cause of bacteremia. The patients were followed-up for a 30-d period following diagnosis of the infection. The final outcome of the patients was recorded in the end of follow-up and comparison among 3 groups of patients according to the pattern of drug resistance was performed.

RESULTS: Gram-positive-cocci (GPC) were found in half of the cases. The most prevalent organisms in a descending order were Escherichia coli (33), Enterococcus spp (30), Streptococcus spp (25), Klebsiella pneumonia (16), S. aureus (8), Pseudomanas aeruginosa (5), other Gram-negative-bacteria (GNB) (11) and anaerobes (2). Overall, 20.8% of isolates were multidrug-resistant (MDR) and 10% extensively drug-resistant (XDR). Health-care-associated (HCA) and/or nosocomial infections were present in 100% of MDR/XDR and in 65.5% of non-DR cases. Meropenem was the empirically prescribed antibiotic in HCA/nosocomial infections showing a drug-resistance rate of 30.7% while third generation cephalosporins of 43.8%. Meropenem was ineffective on both XDR bacteria and Enterococcus faecium (E. faecium). All but one XDR were susceptible to colistin while all GPC (including E. faecium) and the 86% of GNB to tigecycline. Overall 30-d mortality was 37.7% (69.2% for XDR and 34.2% for the rest of the patients) (log rank, P = 0.015). In multivariate analysis, factors adversely affecting outcome included XDR infection (HR = 2.263, 95%CI: 1.005-5.095, P = 0.049), creatinine (HR = 1.125, 95%CI: 1.024-1.236, P = 0.015) and INR (HR =1.553, 95%CI: 1.106-2.180, P = 0.011).

CONCLUSION: XDR bacteria are an independent life-threatening factor in SBP/SB. Strategies aiming at restricting antibiotic overuse and rapid identification of the responsible bacteria could help improve survival.

Bacterial infections in cirrhosis: a position statement based on the EASL Special Conference 2013

Bacterial infections are very common and represent one of the most important reasons of progression of liver failure, development of liver-related complications, and mortality in patients with cirrhosis. In fact, bacterial infections may be a triggering factor for the occurrence of gastrointestinal bleeding, hypervolemic hyponatremia, hepatic encephalopathy, kidney failure, and development of acute-on-chronic liver failure. Moreover, infections are a very common cause of repeated hospitalizations, impaired health-related quality of life, and increased healthcare costs in cirrhosis. Bacterial infections develop as a consequence of immune dysfunction that occurs progressively during the course of cirrhosis. In a significant proportion of patients, infections are caused by gram-negative bacteria from intestinal origin, yet gram-positive bacteria are a frequent cause of infection, particularly in hospitalized patients. In recent years, infections caused by multidrug-resistant bacteria are becoming an important clinical problem in many countries. The reduction of the negative clinical impact of infections in patients with cirrhosis may be achieved by a combination of prophylactic measures, such as administration of antibiotics, to reduce the occurrence of infections in high-risk groups together with early identification and management of infection once it has developed. Investigation on the mechanisms of altered gut microflora, translocation of bacteria, and immune dysfunction may help develop more effective and safe methods of prevention compared to those that are currently available. Moreover, research on biomarkers of early infection may be useful in early diagnosis and treatment of infections. The current manuscript reports an in-depth review and a position statement on bacterial infections in cirrhosis.

Diagnosis and management of bacterial infections in decompensated cirrhosis

Bacterial infections are one of the most frequent complications in cirrhosis and result in high mortality rates. Patients with cirrhosis have altered and impaired immunity, which favours bacterial translocation. Episodes of infections are more frequent in patients with decompensated cirrhosis than those with compensated liver disease. The most common and life-threatening infection in cirrhosis is spontaneous bacterial peritonitis followed by urinary tract infections, pneumonia, endocarditis and skin and soft-tissue infections. Patients with decompensated cirrhosis have increased risk of developing sepsis, multiple organ failure and death. Risk factors associated with the development of infections are severe liver failure, variceal bleeding, low ascitic protein level and prior episodes of spontaneous bacterial peritonitis (SBP). The prognosis of these patients is closely related to a prompt and accurate diagnosis. An appropriate treatment decreases the mortality rates. Preventive strategies are the mainstay of the management of these patients. Empirical antibiotics should be started immediately following the diagnosis of SBP and the first-line antibiotic treatment is third-generation cephalosporins. However, the efficacy of currently recommended empirical antibiotic therapy is very low in nosocomial infections including SBP, compared to community-acquired episodes. This may be associated with the emergence of infections caused by Enterococcus faecium and extended-spectrum β-lactamase-producing Enterobacteriaceae, which are resistant to the first line antimicrobial agents used for treatment. The emergence of resistant bacteria, underlines the need to restrict the use of prophylactic antibiotics to patients with the greatest risk of infections. Nosocomial infections should be treated with wide spectrum antibiotics. Further studies of early diagnosis, prevention and treatment are needed to improve the outcomes in patients with decompensated cirrhosis.

Persistent spontaneous bacterial peritonitis: a common complication in patients with spontaneous bacterial peritonitis and a high score in the model for end-stage liver disease

OBJECTIVES

Spontaneous bacterial peritonitis (SBP) is associated with a high mortality rate. After antibiotic therapy, improvement in fluid polymorphonuclear (PMN) cell count is expected within 2 days. However, our institution recognized cases unresponsive to standard treatment.

METHODS

To study these recalcitrant cases, we completed a retrospective chart review of patients admitted for SBP to the University of Chicago from 2002 to 2007. SBP was defined by an ascitic PMN cell count ≥250/ml.

RESULTS

Of 55 patients with SBP, 15 did not show improvement in fluid PMN cell count to below 250/ml with standard treatment, leading to a prevalence of 27%. The patients with persistent SBP were younger than those with nonpersistent SBP [mean (SD) 51.80 (9.84) compared with 58.13 (8.79); p = 0.0253]. Persistent SBP had a higher serum ascites albumin gradient (SAAG) [median (Q1, Q3) 1.85 (1.50, 2.41) compared with 1.10 (0.60, 1.60)] and a higher score in the model for end-stage liver disease (MELD) [mean (SD) 27.98 (8.09) compared with 22.22 (8.10)] than nonpersistent SBP patients; p = 0.027 and p = 0.023, respectively. In addition, persistent SBP patients were more likely to have a positive ascitic fluid culture than nonpersistent SBP patients [odds ratio (OR) (95% CI) 4.33 (1.21, 15.47); p = 0.024]. Importantly, in-hospital mortality in the persistent SBP group was 40%, compared with 22.5% in the nonpersistent SBP group [OR = 2.30 (0.64, 8.19); p = 0.20].

CONCLUSIONS

The risk of persistent SBP is nearly 40% in patients with MELD score >25, SAAG >1.5 or positive ascitic fluid culture. Furthermore, patients who develop persistent SBP tend to experience a higher mortality rate. This study underscores the importance of further examination of this vulnerable population.

The new epidemiology of nosocomial bacterial infections in cirrhosis: therapeutical implications

Cirrhotic patients are at increased risk of developing infection, sepsis and death. Enterobacteriaceae and nonenterococcal streptococci are the main bacteria responsible for spontaneous and urinary infections in this population. Prompt and appropriate treatment is basic in the management of cirrhotic patients with infection. Third-generation cephalosporins continue to be the gold-standard antibiotic treatment of the majority of infections acquired in the community because responsible strains are usually susceptible to β-lactams. By contrary, nosocomial infections are nowadays frequently caused by multiresistant bacteria (extended-spectrum β-lactamase-producing Enterobacteriaceae, Pseudomonas aeruginosa, methicillin-resistant Staphylococcus aureus, and vancomycin-resistant enterococci among others) that are nonsusceptible to the main antibiotics. Treatment of these infections requires the use of broader spectrum antibiotics (carbapenems) or of antibiotics that are active against specific resistant bacteria (glycopeptides, linezolid, daptomycin, amikacin and colistin). Empirical antibiotic schedules must be adapted to the local epidemiological pattern of antibiotic resistance. Careful restriction of antibiotic prophylaxis to the high-risk population is also mandatory to reduce the spread of multiresistant bacteria in cirrhosis.

Management of bacterial infections in cirrhosis

Bacterial infections are very frequent in advanced cirrhosis and become the first cause of death of these patients. Despite numerous experimental data and significant advances in the understanding of the pathogenesis of sepsis in cirrhosis, the outcome remains poor. Classical diagnostic parameters such as C-reactive protein and SIRS criteria have less diagnostic capacity in the cirrhotic population, often delaying the diagnosis and the management of bacterial infection. Prompt and appropriate empirical antibiotic treatment of infection and early resuscitation of patients with severe sepsis or septic shock are essential in determining patient's outcome. A strategy of careful restriction of prophylactic antibiotics to the high-risk populations could reduce the spread of multidrug resistant bacteria. This review is focused on the currently recommended diagnostic, therapeutic and prophylactic strategies for bacterial infections in the cirrhotic population.

Prevalence and risk factors of infections by multiresistant bacteria in cirrhosis: a prospective study

Epidemiology, risk factors, and clinical effect of infections by multiresistant bacteria in cirrhosis are poorly known. This work was a prospective evaluation in two series of cirrhotic patients admitted with infection or developing infection during hospitalization. The first series was studied between 2005 and 2007 (507 bacterial infections in 223 patients) and the second between 2010 and 2011 (162 bacterial infections in 110 patients). In the first series, 32% of infections were community acquired (CA), 32% healthcare associated (HCA), and 36% nosocomial. Multiresistant bacteria (92 infections; 18%) were isolated in 4%, 14%, and 35% of these infections, respectively (P < 0.001). Extended-spectrum β-lactamase-producing Enterobacteriaceae (ESBL-E; n = 43) was the main multiresistant organism identified, followed by Pseudomonas aeruginosa (n = 17), methicillin-resistant Staphylococcus aureus (n = 14), and Enterococcus faecium (n = 14). The efficacy of currently recommended empirical antibiotic therapy was very low in nosocomial infections (40%), compared to HCA and CA episodes (73% and 83%, respectively; P < 0.0001), particularly in spontaneous bacterial peritonitis, urinary tract infection, and pneumonia (26%, 29%, and 44%, respectively). Septic shock (26% versus 10%; P < 0.0001) and mortality rate (25% versus 12%; P = 0.001) were significantly higher in infections caused by multiresistant strains. Nosocomial origin of infection (hazard ratio [HR], 4.43), long-term norfloxacin prophylaxis (HR, 2.69), recent infection by multiresistant bacteria (HR, 2.45), and recent use of β-lactams (HR, 2.39) were independently associated with the development of multiresistant infections. Results in the second series were similar to those observed in the first series.

CONCLUSIONS

Multiresistant bacteria, especially ESBL-producing Enterobacteriaceae, are frequently isolated in nosocomial and, to a lesser extent, HCA infections in cirrhosis, rendering third-generation cephalosporins clinically ineffective. New antibiotic strategies tailored according to the local epidemiological patterns are needed for the empirical treatment of nosocomial infections in cirrhosis.

Care of the liver transplant candidate

Care of the liver transplant candidate is one of the most challenging, yet rewarding aspects of hepatology. Anticipation and intervention for the major complications of advanced liver disease increase the likelihood of survival until transplant.

Renal dysfunction is the most important independent predictor of mortality in cirrhotic patients with spontaneous bacterial peritonitis

BACKGROUND & AIMS

Spontaneous bacterial peritonitis (SBP) is the most common infection among patients with cirrhosis. To improve stratification of patient care, we performed a systematic review to identify the most robust predictors of mortality in cirrhotic patients with SBP.

METHODS

We reviewed prognostic studies (English language only) of adult patients with SBP, defined as a polymorphonuclear ascitic fluid cell count of 250 cells/mm(3) or more, with or without positive results from culture of ascitic fluid. We reviewed only studies that performed survival and multivariate analyses and reported in-hospital or mortalities within 30 days.

RESULTS

Of 2008 available references, 18 were included in the study (median, 115 patients per trial). The median age of patients was 56 years (68% male). The most common predictors of death were renal dysfunction, lack of SBP resolution, immunosuppressive factors, and hospital-acquired SBP. Sensitivity analysis using the 12 best-quality studies identified renal dysfunction and levels of blood urea nitrogen and creatinine as the most important variables. The mortality rate among patients with renal dysfunction was 67%, compared with only 11% of patients who maintained normal renal function.

CONCLUSIONS

Renal dysfunction is the main prognostic factor for cirrhotic patients with SBP, followed by the MELD score. Further studies are needed to determine whether these factors identified retain prognostic value in high-risk patients who receive albumin. Risk stratification might be used to select additional treatments, such as early vasoconstrictor therapy, for the highest-risk group.

Infections in patients with cirrhosis increase mortality four-fold and should be used in determining prognosis

BACKGROUND & AIMS

A staged prognostic model of cirrhosis based on varices, ascites, and bleeding has been proposed. We analyzed data on infections in patients with cirrhosis to determine whether it is also a prognostic factor.

METHODS

Studies were identified by MEDLINE, EMBASE, COCHRANE, and ISI Web of Science searches (1978-2009); search terms included sepsis, infection, mortality, and cirrhosis. Studies (n = 178) reporting more than 10 patients and mortality data were evaluated (225 cohorts, 11,987 patients). Mortality after 1, 3, and 12 months was compared with severity, site, microbial cause of infection, etiology of cirrhosis, and publication year. Pooled odds ratio of death was compared for infected versus noninfected groups (18 cohorts, 2317 patients).

RESULTS

Overall median mortality of infected patients was 38%: 30.3% at 1 month and 63% at 12 months. Pooled odds ratio for death of infected versus noninfected patients was 3.75 (95% confidence interval, 2.12-4.23). In 101 studies that reported spontaneous bacterial peritonitis (7062 patients), the median mortality was 43.7%: 31.5% at 1 month and 66.2% at 12 months. In 30 studies that reported bacteremia (1437 patients), the median mortality rate was 42.2%. Mortality before 2000 was 47.7% and after 2000 was 32.3% (P = .023); mortality was reduced only at 30 days after spontaneous bacterial peritonitis (49% vs 31.5%; P = .005).

CONCLUSIONS

In patients with cirrhosis, infections increase mortality 4-fold; 30% of patients die within 1 month after infection and another 30% die by 1 year. Prospective studies with prolonged follow-up evaluation and to evaluate preventative strategies are needed.