Pneumonia after liver transplantation

Clinical Application of Metagenomic Next-Generation Sequencing (mNGS) in Patients with Early Pulmonary Infection After Liver Transplantation

Purpose

To examine the clinical utility of metagenomic next-generation sequencing (mNGS) in individuals with early pulmonary infection following liver transplantation.

Patients and Methods

mNGS and traditional detection results were retrospectively collected from 99 patients with pulmonary infection within one week following liver transplantation. These patients were admitted to the Department of Critical Liver Diseases at Beijing Friendship Hospital from February 2022 to February 2024, along with their general clinical data.

Results

mNGS exhibited a significantly higher detection rate than traditional methods (92.93% vs 54.55%, P < 0.05) and was more effective in identifying mixed infections (67.68% vs 14.81%, P < 0.05). mNGS identified 303 pathogens in 92 patients, with Enterococcus faecium, Pneumocystis jirovecii, and human herpesvirus types 5 and 7 being the most prevalent bacteria, fungi, and viruses. A total of 26 positive cases were identified through traditional culture methods (sputum and bronchoalveolar lavage fluid), with 18 cases consistent with mNGS detection results, representing 69.23% consistency. Among the three drug-resistant bacteria that showed positivity in mNGS and traditional culture, the presence of drug-resistance genes-mecA in Staphylococcus aureus; KPC-2, KPC-9, KPC-18, KPC-26, OXA27, OXA423 in Klebsiella pneumoniae; and OXA488 and NDM6 in Pseudomonas aeruginosa-reliably predicted drug-resistance phenotype. The treatment regimen for 76 of the 92 patients with positive mNGS relied on these results; 74 exhibited significant symptom improvement, yielding a 97.37% recovery rate. The overall prognosis was favorable.

Conclusion

mNGS offers rapid detection, a high positivity rate, insensitivity to antibiotics, and a superior ability to detect mixed infections in patients with early post-transplant pulmonary infections. Additionally, mNGS shows good consistency with traditional culture and can predict drug-resistant phenotypes to guide targeted antibiotic therapy for early-stage post-transplant pulmonary infection after liver transplantation. Patients whose antibiotic therapy is based on mNGS results have experienced decreased mortality rates and overall improved prognosis.

Thrombocytopenia Predicts Poor Prognosis of Liver Transplantation

BACKGROUND/AIM

Platelets not only participate in physiological hemostasis but also play a major role in liver ischemia-reperfusion injury, liver damage, tissue repair, and liver regeneration. A decrease in platelet count can lead to spontaneous bleeding, infection, and other complications that can seriously impact patient prognosis. Thrombocytopenia has been associated with increased complications after partial hepatectomy, although the effects of thrombocytopenia on patient outcomes remain unclear. Therefore, this study aimed to examine the impact of thrombocytopenia on short- and long-term prognosis following liver transplantation (LT).

METHODS

This was a retrospective analysis comprising 234 adult liver transplant recipients and conducted from January 2019 to June 2022. Preoperative and postoperative daily platelet counts were recorded up to the 30th postoperative day (POD). We defined people with platelet counts <70 × 109/L as the low platelet group, and people with platelet counts >70 × 109/L as the high platelet group. Multivariate analysis was carried out to determine whether low perioperative platelet count was a risk factor for postoperative complications, graft failure, and patient survival.

RESULTS

Of the 234 patients analyzed in this study, approximately half (n = 112, 47.9%) developed persistent thrombocytopenia after LT. The most substantial decrease in platelet levels occurred on POD7. The cumulative survival rates at 1, 2, and 3 years in the high platelet group were higher than those in the low platelet group, 94%, 87%, and 85%, respectively, while those of the low platelet group were 84%, 78%, and 70% (P = .0014). In addition, the high platelet group had a lower incidence of biliary complications compared with the low platelet group (8% vs 19%, P = .020). At the same time, the high platelet group had a lower incidence of posttransplant lung infection (55% vs 75%, P = .040).

CONCLUSIONS

Thrombocytopenia is a common complication of LT. It indicates the severity of the postoperative course and is closely associated with patient survival. In particular, patients who undergo orthotopic liver transplantation (OLT) and have a platelet count <70 × 109/L on the POD7 have significant negative prognostic implications and should be further investigated.

Predictive performance of Metagenomic Next Generation Sequencing in early detection of post-liver transplantation infections

Objective

To evaluate the predictive performance of metagenomic next-generation sequencing (mNGS) in identifying and predicting pulmonary infections following liver transplantation and to investigate its association with patient outcomes within the initial four-week post-transplantation period.

Methods

We retrospectively analyzed 41 liver transplant patients with suspected pulmonary infections from August 2022 to May 2023. Bronchoalveolar lavage fluid (BALF) samples were collected on the first postoperative day for metagenomic next generation sequencing (mNGS) and culture. The predictive capability of mNGS for subsequent infections was assessed by monitoring inflammatory biomarkers and comparing the detection rates with culture methods. Real-time Polymerase Chain Reaction (Rt-PCR) was used to monitor Human betaherpesvirus 5 (CMV) and Human parvovirus B19 (B19) weekly during a four-week postoperative period. Inflammatory biomarkers and blood coagulation function were evaluated on specific days throughout the first, third, fifth, and during four weeks following surgery. The study was conducted until August 2023 to evaluate the patients' prognostic survival outcome, classifying them into groups based on the mortality and survival.

Results

The analysis included a total of 41 patients, comprising 32 males and 9 females, with an average age of 52 (47, 63) years. Within one week after liver transplantation, there were 7 cases of bacterial infections, 5 cases of fungal infections, 19 cases of mixed infections, 8 cases without any infection, and 2 cases with unidentified pathogen-associated infections. mNGS successfully predicted 39 (72 %) strains of pathogens, while culture-based methods only detected 28 (52 %) strains. Among the 8 patients diagnosed as non-infected, culture methods identified positive results in 4 cases (50 %), whereas mNGS yielded positive results in 7 cases (87.5 %). The detection rates of CMV and B19 by Rt-PCR within 4 weeks after liver transplantation were 61 % and 17 %, respectively (25/41, 7/41) among the patients. During the study period, a total of 9 patients succumbed while 32 patients survived. The death group and the survival group exhibited significant differences in CRP, HGB, and INR levels at specific monitoring time points. The proportion of CMV detection in blood was significantly higher in the death group compared to the surviving group. Elevated CRP level was identified as a prognostic risk factor.

Conclusions

Despite the presence of false positives, mNGS still presents a potential advantage in predicting pulmonary infection pathogens following liver transplantation. Furthermore, the levels of CRP and CMV carrier status within four weeks post-surgery exhibit significant associations with patient survival and prognosis.

Role of a Real-Time TDM-Based Expert Clinical Pharmacological Advice Program in Optimizing the Early Pharmacokinetic/Pharmacodynamic Target Attainment of Continuous Infusion Beta-Lactams among Orthotopic Liver Transplant Recipients with Documented or Suspected Gram-Negative Infections

(1) Objectives: To describe the attainment of optimal pharmacokinetic/pharmacodynamic (PK/PD) targets in orthotopic liver transplant (OLT) recipients treated with continuous infusion (CI) beta-lactams optimized using a real-time therapeutic drug monitoring (TDM)-guided expert clinical pharmacological advice (ECPA) program during the early post-surgical period. (2) Methods: OLT recipients admitted to the post-transplant intensive care unit over the period of July 2021-September 2023, receiving empirical or targeted therapy with CI meropenem, piperacillin-tazobactam, meropenem-vaborbactam, or ceftazidime-avibactam optimized using a real-time TDM-guided ECPA program, were retrospectively retrieved. Steady-state beta-lactam (BL) and/or beta-lactamase inhibitor (BLI) plasma concentrations (Css) were measured, and the Css/MIC ratio was selected as the best PK/PD target for beta-lactam efficacy. The PK/PD target of meropenem was defined as being optimal when attaining a fCss/MIC ratio > 4. The joint PK/PD target of the BL/BLI combinations (namely piperacillin-tazobactam, ceftazidime-avibactam, and meropenem-vaborbactam) was defined as being optimal when the fCss/MIC ratio > 4 of the BL and the fCss/target concentration (CT) ratio > 1 of tazobactam or avibactam, or the fAUC/CT ratio > 24 of vaborbactam were simultaneously attained. Multivariate logistic regression analysis was performed for testing potential variables that were associated with a failure in attaining early (i.e., at first TDM assessment) optimal PK/PD targets. (3) Results: Overall, 77 critically ill OLT recipients (median age, 57 years; male, 63.6%; median MELD score at transplantation, 17 points) receiving a total of 100 beta-lactam treatment courses, were included. Beta-lactam therapy was targeted in 43% of cases. Beta-lactam dosing adjustments were provided in 76 out of 100 first TDM assessments (76.0%; 69.0% decreases and 7.0% increases), and overall, in 134 out of 245 total ECPAs (54.7%). Optimal PK/PD target was attained early in 88% of treatment courses, and throughout beta-lactam therapy in 89% of cases. Augmented renal clearance (ARC; OR 7.64; 95%CI 1.32-44.13) and MIC values above the EUCAST clinical breakpoint (OR 91.55; 95%CI 7.12-1177.12) emerged as independent predictors of failure in attaining early optimal beta-lactam PK/PD targets. (4) Conclusion: A real-time TDM-guided ECPA program allowed for the attainment of optimal beta-lactam PK/PD targets in approximately 90% of critically ill OLT recipients treated with CI beta-lactams during the early post-transplant period. OLT recipients having ARC or being affected by pathogens with MIC values above the EUCAST clinical breakpoint were at high risk for failure in attaining early optimal beta-lactam PK/PD targets. Larger prospective studies are warranted for confirming our findings.

Intracerebral opportunistic infections caused by immunosuppressants after orthotopic liver transplantation: Report of two cases and literature review

Central nervous system (CNS) infections in adults are rare because of normal immunity and the existence of the blood brain barrier, which prevents the invasion of pathogenic microorganisms. Liver transplant recipients are at an increased risk of opportunistic infections (OI) due to immunosuppressive therapy compared to those with normal immunity. Early diagnosis and timely implementation of treatment are critical for the successful treatment of these infections. We present two cases of intracerebral OI after orthotopic liver transplantation (OLT), with different clinical presentations. Patient 1 presented with epileptic seizures, mainly manifested as unresponsiveness, unconsciousness, and coma complicated with involuntary limb twitching. Patient 2 presented with a consciousness disorder, mainly manifested as unclear consciousness content, poor orientation, calculation power, and logical ability. Next-generation sequencing (NGS) examination of the cerebrospinal fluid confirmed human herpesvirus 6 B (HHV-6B) infection in patient 1 and intracranial Aspergillus infection in patient 2. Intracranial OI has insidious onset and atypical clinical manifestations. NGS can allow for the proper diagnosis and monitoring of the effects of treatment.

Infection in Living Donor Liver Transplantation Leads to Increased Risk of Adverse Renal Outcomes

(1) Background: Little is known about the subsequent renal function change following incident infectious diseases in living-donor liver transplant (LT) recipients. (2) Methods: We studied patients who underwent living-donor LT from January 2003 to January 2019 to evaluate the association of incident hospitalization with major infections or pneumonia with adverse renal outcomes, including a sustained 40% reduction in estimated glomerular filtration rate (eGFR) and renal composite outcome (a 40% decline in eGFR, end-stage renal disease, or death.). Multivariable-adjusted time-dependent Cox models with infection as a time-varying exposure were used to estimate hazard ratio (HR) with 95% confidence interval (CI) for study outcomes. (3) Results: We identified 435 patients (mean age 54.6 ± 8.4 years and 76.3% men), of whom 102 had hospitalization with major infections during follow-up; the most common cause of infection was pneumonia (38.2%). In multiple Cox models, hospitalization with a major infection was associated with an increased risk of eGFR decline > 40% (HR, 3.32; 95% CI 2.13−5.16) and renal composite outcome (HR, 3.41; 95% CI 2.40−5.24). Likewise, pneumonia was also associated with an increased risk of eGFR decline > 40% (HR, 2.47; 95% CI 1.10−5.56) and renal composite outcome (HR, 4.37; 95% CI 2.39−8.02). (4) Conclusions: Our results illustrated the impact of a single infection episode on the future risk of adverse renal events in LT recipients. Whether preventive and prophylactic care bundles against infection and judicious modification of the immunosuppressive regimen benefit renal outcomes may deserve further study.

Diagnostic Value and Clinical Application of mNGS for Post-Liver Transplantation Infection: A Cross-Sectional Study With Case Reports

Liver transplantation is widely acknowledged as the only effective treatment for end-stage liver disease, and infection is reportedly an important cause of postoperative death. Clinical use of metagenomic next-generation sequencing (mNGS) to diagnose postoperative infection and successfully guide drug therapy remains rare. This study included patients with infectious complications after liver transplantation from July 2019 to December 2020 and was divided into three groups: pneumonia, unknown fever, and others (including hepatic failure, kidney failure, cirrhosis after LT, and other postoperative complications that predispose to infection). The mNGS sequencing was used to detect microorganisms, and the results were compared with traditional culture. We found that mNGS yielded improved sensitivity over culture (85.19 vs. 22.22%; p<0.0001) but lower specificity (35.71 vs. 89.28%; p<0.0001). Among the 48 kinds of pathogens detected, the Torque teno virus 22 (15/122) was the most common, followed by Primate erythroparvovirus 1 (13/122). The top four bacteria included Klebsiella pneumoniae (n = 8), Enterococcus faecium (n = 5), Stenotrophomonas maltophilia (n = 4), and Escherichia coli (n = 4). Aspergillus fumigatus was the most common fungus. The bronchoalveolar lavage fluid (BALF) exhibited the highest proportion of positive findings among sample types, with viral, fungal, and bacterial mixed infection being the most common (n = 6, 19.35%). Besides, using mNGS for early diagnosis of infection after liver transplantation may effectively prolong patient survival. This is the first study to explore the application value of mNGS and its comparison with traditional culture in pneumonia and other infections in post-liver transplantation patients. The simultaneous application of these two methods suggested that the Torque teno virus 22, Klebsiella pneumoniae, and the Aspergillus fumigatus are the most common pathogens of viruses, bacteria, and fungi after LT, suggesting that these pathogens may be associated with postoperative pathogen infection and patient prognosis. The mNGS technique showed distinct advantages in detecting mixed, viral, and parasitic infections in this patient population. Further studies are warranted to systematically elucidate the dynamic evolution and molecular characteristics of infection after liver transplantation.

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.

Predictors of Mortality During Initial Liver Transplant Hospitalization and Investigation of Causes of Death

Background

Liver transplant (LT) remains a life-saving procedure with a high mortality rate. The present study investigated the causes of death and sought to identify predictive factors of mortality during the initial LT hospitalization.

Material/Methods

We retrieved data on first-time adult recipients who underwent LT between November 2017 and October 2019 receiving grafts from donation after citizen’s death. The risk factors for mortality during the initial LT hospitalization were confirmed by univariate analysis. We also analyzed the causes of death.

Results

We enrolled 103 recipients, including 86 males and 17 females, with a mean age of 47.7 years. Thirty-eight (36.9%) recipients were labeled as non-cholestatic cirrhosis-related indications. Approximately 8% of all recipients had diabetes prior to LT. Induction therapy was used in 11 (10.7%) recipients, along with maintenance therapy. The median model for end-stage liver disease score at LT was 32.4 (21.4–38.4). The in-hospital mortality rate of LT recipients was 6.8% (7/103), and infections were responsible for most of the deaths (6/7). The 1 remaining death resulted from primary graft failure. Univariate analysis showed recipients with postoperative pneumonia (p<0.05), acute hepatic necrosis, and intensive care unit (ICU) stay ≥7 days (both p<0.01), postoperative bacteremia, creatinine on day 3 after LT>2 mg/dL, and alanine transaminase on day 1 after LT >1800 μmol/L (all P<0.001) were much more likely to die.

Conclusions

In-hospital mortality of LT recipients was high, due in large part to infections. Acute hepatic necrosis, prolonged post-transplant ICU stays, certain types of postoperative infections, and postoperative liver and kidney dysfunction were potential risk factors for in-hospital mortality of LT recipients.

Effects of Multidrug-resistant Bacteria in Donor Lower Respiratory Tract on Early Posttransplant Pneumonia in Lung Transplant Recipients Without Pretransplant Infection

BACKGROUND

Multidrug-resistant (MDR) bacteria in the lower respiratory tracts of allografts may be risk factors for early posttransplant pneumonia (PTP) that causes detrimental outcomes in lung transplant recipients (LTRs). We evaluated the effects of immediate changes in MDR bacteria in allografts on early PTP and mortality rates in LTRs.

METHODS

We reviewed 90 adult bilateral LTRs without pretransplant infections who underwent lung transplantation between October 2012 and May 2018. Quantitative cultures were performed with the bronchoalveolar lavage fluids of the allografts preanastomosis and within 3 days posttransplant. The International Society for Heart and Lung Transplantation consensus defines early PTP as pneumonia acquired within 30 days posttransplant and not associated with acute rejection.

RESULTS

MDR Acinetobacter baumannii (11/34, 32.4%) and Staphylococcus aureus (9/34, 26.5%) were identified in 24.4% (22/90) of the preanastomosis allografts. Four LTRs had the same MDR bacteria in allografts preanastomosis and posttransplant. Allograft MDR bacteria disappeared in 50% of the LTRs within 3 days posttransplant. Early PTP and all-cause in-hospital mortality rates were not different between LTRs with and without preanastomosis MDR bacteria (P = 0.75 and 0.93, respectively). MDR bacteria ≥10 CFU/mL in the lungs within 3 days posttransplant was associated with early PTP (odds ratio, 5.8; 95% confidence interval, 1.3-27.0; P = 0.03).

CONCLUSIONS

High levels of preexisting MDR bacteria in allografts did not increase early PTP and mortality rates in LTRs. Despite the small and highly selective study population, lung allografts with MDR bacteria may be safely transplanted with appropriate posttransplant antibiotic therapy.

Controversies in Perioperative Antimicrobial Prophylaxis

Although clinical guidelines for antibiotic prophylaxis across a wide array of surgical procedures have been proposed by multidisciplinary groups of physicians and pharmacists, clinicians often deviate from recommendations. This is particularly true when recommendations are based on weak data or expert opinion. The goal of this review is to highlight certain common but controversial topics in perioperative prophylaxis and to focus on the data that does exist for the recommendations being made.

Predictors of Outcomes After Thoracic Surgery in Orthotopic Liver Transplant Recipients With Pleural Disease

Orthotopic liver transplant (OLT) recipients are at high risk for postoperative pulmonary complications. We aim to determine factors associated with morbidity and mortality in OLT recipients that required thoracic surgery for pleural space complications. A retrospective review was performed of 42 patients who underwent thoracic surgery after OLT between 2005 and 2015. Preoperative data and postoperative outcomes were reviewed. Time to mortality was summarized using Kaplan-Meier curves. Outcomes associated with 30-day morbidity and mortality as well as long-term mortality were analyzed with univariate analysis. Between 2005 and 2015, 1735 OLTs were performed at our institution. We identified 42 patients who required thoracic surgery. Of these 42 OLT recipients, 33 patients required thoracic surgery for pleural space complications. The median interval between OLT and thoracic surgery for pleural space complications was 5.7 months (interquartile range 2.2-14.1). The most common surgical indications were chronic pleural effusion (n = 12, 36.4%) and empyema (n = 10, 30.3%). The most common thoracic operations were decortication and empyema evacuation. The 30-day morbidity was 69.7%. Bilirubin and empyema were significantly associated with 30-day morbidity (odds ratio [OR] = 2.3, P = 0.023; OR = 16.3, P = 0.015). The 30-day, 1-year, and 5-year mortality rates were 15.2%, 57.6%, and 70.2%, respectively. Vasopressor requirement was significantly associated with 30-day mortality (OR = 10.2, P = 0.031). The development of pleural space complications requiring surgery in OLT recipients suggests a poor prognosis. Hyperbilirubinemia and pleural space infections were associated with high postoperative morbidity in OLT recipients requiring thoracic surgery for pleural space complications.

A Targeted Swallow Screen for the Detection of Postoperative Dysphagia in Liver Transplant Patients

Introduction:

Postoperative dysphagia leads to aspiration pneumonia, prolonged hospital stay, and is associated with increased mortality. We have demonstrated the validity of a bedside targeted swallow evaluation following cardiac surgery. Since dysphagia following liver transplantation is not well examined, we evaluated the efficacy of this swallow screen method in postoperative liver transplant patients.

Methods:

This was a prospective trial involving adult patients who underwent liver transplant surgery at our institution over a 5-month period. Within 24 hours of extubation and prior to the initiation of oral intake, all patients were evaluated using the targeted swallow screen, which is a direct assessment of mental status and laryngeal sensation/elevation upon swallowing of progressively larger amounts of water. A fiberoptic endoscopic evaluation of swallowing was requested for failed screenings.

Results:

During the study, 50 patients were screened. Twenty (40%) failed the targeted swallow screen, while 18 (90%)/20 failed the subsequent fiberoptic endoscopic examination (overall dysphagia incidence = 40%). Patients with dysphagia were older and had significantly longer intensive care unit and hospital stays. The screening test had a 90% sensitivity and a specificity of 83% for detecting dysphagia.

Conclusion:

The true incidence of dysphagia following liver transplantation appears to be significantly higher than previously recognized. A simple bedside swallow screen can efficiently screen these patients for dysphagia. Our findings require further validation and may support programs for reduction and early detection of dysphagia.