Intra-abdominal infections in solid organ transplant recipients: Guidelines from the American Society of Transplantation Infectious Diseases Community of Practice

Simultaneous determination of piperacillin, metronidazole, and tazobactam in plasma by UPLC-MS/MS and application to a pharmacokinetic study in pediatric liver transplant patients

Piperacillin/tazobactam and metronidazole are two commonly antimicrobials used to prevent and treat infections after liver transplantation in pediatric patients. However, under the recommended dose, it may lead to insufficient antimicrobial treatment and poor efficacy. To achieve antimicrobial therapy based on pharmacokinetic strategies, a rapid and highly sensitive ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed to measure the plasma concentrations of piperacillin, tazobactam, and metronidazole in pediatric liver transplant recipients. Sample separation was achieved using an Acquity UPLC CSH C18 column (2.1 × 50 mm, 1.7 μm) with gradient elution. The mobile phase consisted of ammonia solution-formic acid-water (0.5:1:1000, v/v/v) and methanol-acetonitrile (1:1, v/v). The plasma concentration range was 0.20-100.00 μg/mL, with good linear range. The intra- and inter-day precisions were less than 13.4 %, and the accuracy ranged from 90.0 % to 109.0 %. The selectivity, carryover, dilution integrity, matrix effect, recovery, and stability met the requirements of the relevant guidelines. The established UPLC-MS/MS method was successfully applied to measure the concentrations of piperacillin, tazobactam, and metronidazole in the plasma of pediatric liver transplant patients. The results showed that according to the recommended dosing regimen, piperacillin/tazobactam reached the effective therapeutic target of 50 %T > MIC in only 4 h. The maximum plasma concentration (Cmax) of metronidazole ranged from 9.46 to 28 μg/mL, with an average Cmax of 16.59 μg/mL, which did not achieve the ideal Cmax/MIC ratio of 8-10.

The Therapeutic Effect of Contezolid in Complex Intra-Abdominal Infections

Purpose

In this paper, we observed the use of contezolid in patients with complex intra-abdominal infections in the intensive care unit of the Hepatobiliary Surgery department at the Chinese PLA General Hospital.

Patients and Methods

The study collected data on complex intra-abdominal infections patients who received the antibiotic contezolid between January 2022 and April 2023.

Results

Contezolid was administered to 12 patients, including 8 with severe acute pancreatitis, 3 with intra-abdominal infections following abdominal surgery, and 1 with complicated intra-abdominal infection after trauma. Gram-positive bacteria, such as Enterococcus faecium, Enterococcus casseliflavus, Staphylococcus capitis, and Staphylococcus haemo-lytica, were detected in 11 patients. All patients who received contezolid had previously been treated with other anti-Gram-positive agents, including linezolid for 9 patients, teicoplanin for 6 patients, and vancomycin for 3 patients. The treatment with contezolid began 20.0 (15.0, 34.5) days after admission and lasted for 8.0 (6.0, 10.0) days. At the end of the treatment, the patients' body temperature showed a significant decrease. After concomitant therapy, IL-6 levels decreased, and platelet count increased.

Conclusion

Contezolid has shown potential in treating complex intra-abdominal infections caused by Gram-positive bacteria by reducing fever and inflammatory response.

Early Intra-Abdominal Bacterial Infections after Orthotopic Liver Transplantation: A Narrative Review for Clinicians

Despite recent advances in the transplant field, infectious complications after orthotopic liver transplantation (OLT) are major causes of morbidity and mortality. Bacterial intra-abdominal infections (IAIs) are predominant during the first month post-transplantation and affect patient and graft survival. Recently, the emergence of multidrug resistant bacteria has generated great concern in OLT patients. We performed this narrative review of the literature in order to propose a "ready-to-use" flowchart for reasoned empirical antibiotic therapy in the case of suspected post-OLT IAIs. The review was ultimately organized into four sections: "Epidemiology and predisposing factors for IAI"; "Surgical-site infections and perioperative prophylaxis"; "MDRO colonization and infections"; and "Reasoned-empirical antibiotic therapy in early intra-abdominal infections post OLT and source control". Multidisciplinary teamwork is warranted to individualize strategies for the prevention and treatment of IAIs in OLT recipients, taking into account each patient's risk factors, the surgical characteristics, and the local bacterial epidemiology.

Impact of Invasive Pulmonary Aspergillosis in Critically Ill Surgical Patients with or without Solid Organ Transplantation

BACKGROUND

Critically ill patients, especially those who have undergone solid organ transplantation (SOT), are at risk of invasive pulmonary aspergillosis (IPA). The outcome relevance of adequately treated putative IPA (pIPA) is a matter of debate. The aim of this study is to assess the outcome relevance of pIPA in a cohort of critically ill patients with and without SOT.

METHODS

Data from 121 surgical critically ill patients with pIPA (n = 30) or non-pIPA (n = 91) were included. Cox regression analysis was used to identify risk factors for mortality and unfavourable outcomes after 28 and 90 days.

RESULTS

Mortality rates at 28 days were similar across the whole cohort of patients (pIPA: 31% vs. non-pIPA: 27%) and did not differ in the subgroup of patients after SOT (pIPA: 17% vs. non-pIPA: 22%). A higher Sequential Organ Failure Assessment (SOFA) score and evidence of bacteraemia were identified as risk factors for mortality and unfavourable outcome, whereas pIPA itself was not identified as an independent predictor for poor outcomes.

CONCLUSIONS

Adequately treated pIPA did not increase the risk of death or an unfavourable outcome in this mixed cohort of critically ill patients with or without SOT, whereas higher disease severity and bacteraemia negatively affected the outcome.

Pyogenic liver abscesses in liver transplant recipients versus non-transplant population. Outcome and risk factors of patient survival

Pyogenic liver abscess (PLA) is a life-threatening infection in both liver transplant (LT) and non-LT patients. Several risk factors, such as benign and malignant hepatopancreatobiliary diseases and colorectal tumors have been associated with PLA in the non-LT population, and hepatic artery stricture/thrombosis, biliary stricture, and hepaticojejunostomy in the LT patients. The objective of this study is to compare the outcomes of patients with PLA in LT and non-LT patients and to determine the risk factors associated with patient survival. From January 2000 to November 2020, a total of 296 adult patients were diagnosed of PLA in our institution, of whom 26 patients had previously undergone liver transplantation (LTA group), whereas 263 patients corresponded to the non-LTA population. Seven patients with PLA who had undergone previous kidney transplantation were excluded from this retrospective study. Twenty-six patients out of 1503 LT developed PLA (incidence of 1.7%). Median age was significantly higher in non-LTA patients (p = .001). No significant differences were observed in therapy. PLA recurrence was significantly higher in LTA than in non-LTA (34.6% vs. 14.8%; p = .008). In-hospital mortality was greater in the LT group than in the non-LT group (19.2% vs. 9.1% p = .10) and was identified in multivariable analysis as a risk factor for mortality (p = .027). Mortality rate during follow-up did not show significant differences between the groups: 34.6% in LTA patients versus 26.2% in non-LTA patients (p = .10). The most common causes of mortality during follow-up were malignancies, Covid-19 infection, and neurologic disease. 1-, 3-, and 5-year actuarial patient survival rates were 87.0%, 64.1%, and 50.4%, respectively, in patients of LTA group, and 84.5%, 66.5%, and 51.0%, respectively, in patients with liver abscesses in non-LTA population (p = .53). In conclusion, LT was a risk factor for in hospital mortality, but not during long-term follow-up.

Korean Guidelines for Use of Antibiotics for Intra-abdominal Infections in Adults

The guidelines are intended to provide practical information for the correct use of antibiotics for intra-abdominal infections in Korea. With the aim of realizing evidence-based treatment, these guidelines for the use of antibiotics were written to help clinicians find answers to key clinical questions that arise in the course of patient care, using the latest research results based on systematic literature review. The guidelines were prepared in consideration of the data on the causative pathogens of intra-abdominal infections in Korea, the antibiotic susceptibility of the causative pathogens, and the antibiotics available in Korea.

Shorter durations of antibiotic therapy in organ transplant

PURPOSE OF REVIEW

Recent evidence supports shorter courses of antibiotics for several common infections and prophylactic indications. Unfortunately, solid organ transplant patients are often underrepresented or excluded from these studies. As a result, prolonged antibiotic durations are often used in clinical practice despite a lack of demonstrable benefit. This paper reviews recent publications addressing antibiotic duration of therapy in SOT recipients.

RECENT FINDINGS

Although largely limited to observational studies, longer courses of antibiotics for surgical prophylaxis, urinary tract infections, and bloodstream infections have not demonstrated benefit compared to shorter courses. In some instances, longer courses of therapy have been associated with harm (i.e., adverse drug events and development of resistance).

SUMMARY

Although the data remains limited, findings from retrospective studies evaluating shorter courses of antibiotics in SOT patients is encouraging. More robust research is desperately needed to define the optimal duration of antibiotics for common infections in SOT patients.

Ventriculoperitoneal shunt management in children undergoing liver transplantation

There is a lack of data to guide neurosurgeons on the management of ventriculoperitoneal shunts (VPS) in patients undergoing abdominal transplant operations. We present the cases of two pediatric patients with VPS undergoing liver transplantation who were successfully managed with externalization of the VPS at time of transplantation, with subsequent re-internalization once cleared by the transplant surgery team. We present this as an effective management strategy in patients undergoing liver transplantation.

Therapeutic Drug Monitoring of Amphotericin-B in Plasma and Peritoneal Fluid of Pediatric Patients after Liver Transplantation: A Case Series

Fungal infections represent a serious complication during the post-liver transplantation period. Abdominal infections can occur following pre-existing colonization, surgical procedures, and permanence of abdominal tubes. In our center, liposomal amphotericin-B is used as antifungal prophylaxis in pediatric patients undergoing liver transplantation. The aim of this study is to evaluate peritoneal levels of amphotericin-B following intravenous administration. Six liver recipients received liposomal amphotericin-B. Three of them were treated as prophylaxis; meanwhile, three patients received liposomal amphotericin-B to treat Candida albicans infection. Plasma and peritoneal amphotericin-B levels were measured by LC-MS/MS in two consecutive samplings. Cmin (pre-dose) and Cmax (2 h after the end of infusion) were evaluated as drug exposure parameters for both plasma and peritoneum. Our results showed that peritoneal amphotericin-B levels were significantly lower than plasma and that the correlation coefficient was 0.72 (p = 0.03) between plasma and peritoneal Cmin. Moreover, although peritoneal levels were within the therapeutic range, they never reached the PK/PD target (Cmax/MIC > 4.5). In conclusion, PK exposure parameters could be differently used to analyze amphotericin-B concentrations in plasma and peritoneum. However, liposomal amphotericin-B should be preferred in these patients as prophylactic rather than therapeutic treatment for fungal infections.

Artificial Intelligence May Predict Early Sepsis After Liver Transplantation

Background: Sepsis, post-liver transplantation, is a frequent challenge that impacts patient outcomes. We aimed to develop an artificial intelligence method to predict the onset of post-operative sepsis earlier. Methods: This pilot study aimed to identify "physiomarkers" in continuous minute-by-minute physiologic data streams, such as heart rate, respiratory rate, oxygen saturation (SpO2), and blood pressure, to predict the onset of sepsis. The model was derived from a cohort of 5,748 transplant and non-transplant patients across intensive care units (ICUs) over 36 months, with 92 post-liver transplant patients who developed sepsis. Results: Using an alert timestamp generated with the Third International Consensus Definition of Sepsis (Sepsis-3) definition as a reference point, we studied up to 24 h of continuous physiologic data prior to the event, totaling to 8.35 million data points. One hundred fifty-five features were generated using signal processing and statistical methods. Feature selection identified 52 highly ranked features, many of which included blood pressures. An eXtreme Gradient Boost (XGB) classifier was then trained on the ranked features by 5-fold cross validation on all patients (n = 5,748). We identified that the average sensitivity, specificity, positive predictive value (PPV), and area under the receiver-operator curve (AUC) of the model after 100 iterations was 0.94 ± 0.02, 0.9 ± 0.02, 0.89 ± 0.01, respectively, and 0.97 ± 0.01 for predicting sepsis 12 h before meeting criteria. Conclusion: The data suggest that machine learning/deep learning can be applied to continuous streaming data in the transplant ICU to monitor patients and possibly predict sepsis.

The failing kidney allograft: A review and recommendations for the care and management of a complex group of patients

The return to dialysis after allograft failure is associated with increased morbidity and mortality. This transition is made more complex by the rising numbers of patients who seek repeat transplantation and therefore may have indications for remaining on low levels of immunosuppression, despite the potential increased morbidity. Management strategies vary across providers, driven by limited data on how to transition off immunosuppression as the allograft fails and a paucity of randomized controlled trials to support one approach over another. In this review, we summarize the current data available for management and care of the failing allograft. Additionally, we discuss a suggested plan for immunosuppression weaning based upon the availability of re-transplantation and residual allograft function. We propose a shared-care model in which there is improved coordination between transplant providers and general nephrologists so that immunosuppression management and preparation for renal replacement therapy and/or repeat transplantation can be conducted with the goal of improved outcomes and decreased morbidity in this vulnerable patient group.

Peritoneal Dialysis After Liver Transplantation: A Systematic Review

Background:

Chronic kidney disease following liver transplantation is a major long-term complication. Most liver transplant recipients with kidney failure will be treated with dialysis instead of kidney transplantation due to noneligibility and shortage in organ availability. In this population, the role of peritoneal dialysis (PD) as a modality of kidney replacement therapy (KRT) remains unclear.

Objective:

To determine the feasibility regarding safety, technique survival, and dialysis efficiency of PD in liver transplant recipients requiring KRT for maintenance dialysis.

Design:

Systematic review.

Setting:

Interventional and observational studies reporting the use of PD after liver transplantation.

Patients:

Adult liver transplant recipients with kidney failure treated with maintenance KRT.

Measurements:

Extracted data included eligibility criteria, study design, demographics, and PD modality. The following outcomes of interest were extracted: rate of peritonitis and microorganisms involved, noninfectious peritoneal complications, technique survival, and kidney transplantation-censored technique survival. Non-PD complications included overall survival, liver graft dysfunction, and hospitalization rate.

Methods:

The following databases were searched until July 2020: MedLine/PubMed, EMBASE, CINAHL, and Cochrane Library. Two reviewers independently screening all titles and abstracts of all identified articles. Due to the limited sample size, observational designs and study heterogeneity expected, no meta-analysis was pre-planned. Descriptive statistics were used to report all results.

Results:

From the 5263 identified studies, 4 were included in the analysis as they reported at least 1 outcome of interest on a total of 21 liver transplant recipients, with an overall follow-up duration on PD of 19.0 (Interquartile range [IQR]: 9.5-29.5) months. Fifteen episodes of peritonitis occurred in a total cumulative PD follow-up of 514 patient-months, representing an incidence rate of 0.35 per year. These episodes did not result in PD technique failure, mortality, or impairment of liver graft function.

Limitations:

Limitations include the paucity of studies in the field and the small number of patients included in each report, a risk of publication bias and the impossibility to directly compare hemodialysis to PD in this population. These results, therefore, must be interpreted with caution.

Conclusions:

Based on limited data reporting the feasibility of PD in liver transplant recipients with kidney failure, no signal was associated with an increased risk of infectious complications. Long-term studies evaluating this modality need to be performed.

Registration (PROSPERO):

CRD42020218374.

Carbapenemase-producing Enterobacteriaceae in transplant patients

Carbapenemase-producing Enterobacteriaceae (CPE) are a serious public health concern and represent a major threat to immunocompromised hosts, including solid organ (SOT) and stem cell transplant (HSCT) recipients. Transplant patients are at particular risk of developing CPE colonization and/or infection due to their frequent exposure to prolonged courses of broad-spectrum antibiotics, altered immunocompetence and exposure to invasive procedures and immunosuppressive drugs. Gut colonization with CPE, in particular carbapenem-resistant Klebsiella pneumoniae, may occur before or after SOT in 2%-27% of patients and among 2%-9% of HSCT and has been associated with increased risk of developing CPE infections. In endemic areas, CPE infections occur in up to 18% of SOT, and HSCT patients can account for 5%-18% of all patients with CPE bacteraemia. Mortality rates up to 70% have been associated with CPE infections in both patient populations. The rapid initiation of an active therapy against CPE is advocated in these infections. Therapeutic options, however, are limited by the paucity of novel compounds that are currently available and by potential antibiotic-associated toxicities. Therefore, a multidisciplinary approach involving infection control and antimicrobial stewardship programmes still represents the mainstay for the management of CPE infections among transplant patients. The evidence for the use of prevention strategies such as CPE-targeted perioperative prophylaxis or gut decolonization is still scarce. Large, multicentre trials are required to better define prevention strategies and to guide the management of CPE infections in the transplant setting.

Solid organ transplant-specific antibiogram in a tertiary pediatric hospital in Canada

SOT recipients are more vulnerable to infections with antimicrobial-resistant organisms, and therefore, it may be useful for transplant centers to create transplant-specific antibiograms to direct empirical antimicrobial regimens and monitor trends in antimicrobial resistance. SOT-specific antibiograms were created using antimicrobial susceptibility data on isolates from 2012 to 2018 at The Hospital for Sick Children, Toronto, Ontario, Canada. The CLSI guidelines were followed to generate the antibiograms except that results from 2 years of data were pooled on a rolling basis to achieve larger sample sizes. The 3 most frequent organisms in one analysis period of the SOT antibiogram were Escherichia coli (average sample size ±standard deviation; n = 28.7 ± 3.8), Staphylococcus aureus (n = 27.8 ± 5.0), and Pseudomonas aeruginosa (non-CF) (n = 19.8 ± 8.8). For E.coli, susceptibilities in the SOT antibiogram were significantly lower than those in the hospital-wide antibiogram in 2017-2018 for ampicillin (27% vs 47%; p = .014), piperacillin/tazobactam (55% vs 88%; p < .001), cefotaxime (59% vs 89%; p < .001), ciprofloxacin (71% vs 88%; p = .007), and trimethoprim-sulfamethoxazole (41% vs 69%; p = .001), but not significantly different for aminoglycosides and meropenem. In the SOT antibiogram of E. coli, decreased susceptibility trend was confirmed in some antibiotics, including piperacillin/tazobactam (83% in 2012-2013 vs 55% in 2017-2018). At our center, the solid organ transplant-specific antibiogram revealed important differences in E. coli susceptibilities and trends in antimicrobial resistance. Developing a SOT antibiogram will assist in revising and improving empiric treatment guidelines as well as monitoring antimicrobial resistance in this population.

Does vancomycin resistance increase mortality in Enterococcus faecium bacteraemia after orthotopic liver transplantation? A retrospective study

BACKGROUND

The relevance of vancomycin resistance in enterococcal blood stream infections (BSI) is still controversial. Aim of this study was to outline the effect of vancomycin resistance of Enterococcus faecium on the outcome of patients with BSI after orthotopic liver transplantation (OLT).

METHODS

The outcome of OLT recipients developing BSI with vancomycin-resistant (VRE) versus vancomycin-susceptible Enterococcus faecium (VSE) was compared based on data extraction from medical records. Multivariate regression analyses identified risk factors for mortality and unfavourable outcomes (defined as death or prolonged intensive care stay) after 30 and 90 days.

RESULTS

Mortality was similar between VRE- (n = 39) and VSE- (n = 138) group after 30 (p = 0.44) or 90 days (p = 0.39). Comparable results occurred regarding unfavourable outcomes. Mean SOFA_Non-GCS score during the 7-day-period before BSI onset was the independent predictor for mortality at both timepoints (HR 1.32; CI 1.14-1.53; and HR 1.18; CI 1.08-1.28). Timely appropriate antibiotic therapy, recent ICU stay and vancomycin resistance did not affect outcome after adjusting for confounders.

CONCLUSION

Vancomycin resistance did not influence outcome among patients with Enterococcus faecium bacteraemia after OLT. Only underlying severity of disease predicted poor outcome among this homogenous patient population.

TRIAL REGISTRATION

This study was registered at the German clinical trials register (DRKS-ID: DRKS00013285).

Management of Antimicrobial Agents in Abdominal Organ Transplant Patients in Intensive Care Unit

PURPOSE OF REVIEW

Early diagnosis of infections and immediate initiation of appropriate antimicrobials are crucial in the management of patients before and after organ transplantation. We reviewed the most recent literature and guidelines in this field and organized the current recommendations for healthcare professionals caring for critically ill organ transplant recipients.

RECENT FINDINGS

The incidence of multidrug-resistant organisms is increasing. Multidrug-resistant Gram-negative bacteria comprise about 14% of organisms. Vancomycin-resistant enterococci bloodstream infections are also on the rise, as 20.5% of nosocomial enterococci are now vancomycin-resistant, changing empiric antibiotic selection. Fluconazole-resistant Candida species comprise up to 46% of cases of candidemia in hospitalized patients. Consequently, new guidelines recommend primary use of echinocandins in patients with candidemia who have moderate-to-severe disease. Finally, the incidence of emergence of ganciclovir-resistant cytomegalovirus infection in patients is 5-12%, requiring early recognition and change to alternative regimens in the case of poor response to therapy.

SUMMARY

Bloodstream infections are a major cause of mortality and morbidity in solid organ transplantation. Mortality as high as 24% and 50% have been reported with sepsis and septic shock respectively. As such, bloodstream infections should be diagnosed rapidly and intravenous antibiotics should be started immediately. Appropriate resuscitation should be initiated and the number and/or dose of immunosuppressive drugs should be reduced. Proper source control must also be achieved with radiologic drainage or surgical intervention as appropriate. Initial antibiotic treatment of these patients should cover both Gram-positive organisms, especially in the presence of intravascular catheters, and Gram-negative bacteria. Echinocandins like caspofungin should also be considered especially in critically ill patients, particularly if a patient has been on total parenteral nutrition or broad-spectrum antibiotics.