Bacterial infections in lung transplantation

Lung transplant: A clinical overview

Lung transplant is a recognised treatment option for end-stage respiratory failure. It is, however, a complex process and involves careful patient selection, comprehensive work-up followed by a technically challenging surgical procedure and a rigorous follow-up. In this article we provide an overview of the process, condensed down to the important facts for physicians with limited experience with transplant patients or medicine. Our aim is to take the reader through the journey from patient selection to post-transplant care and attempt to address commonly faced issues with such a niche cohort of patients.

Increasing risk of postlung transplant hospitalizations for infection: An analysis of recent trends

Background

Despite advancements in lung transplantation (LT), infection remains a major cause of morbidity and mortality following LT. We examined trends in hospitalizations for infection in the first year after LT.

Methods

We identified adult LT recipients in the United States (March 1, 2018-March 9, 2023) using the Organ Procurement and Transplantation Network database. We categorized transplants into 3 eras to account for the Composite Allocation Score allocation policy change and coronavirus disease 2019: March 2018 to March 2020, March 2020 to March 2022, and March 2022 to March 9, 2023. One-year post-LT survival was compared using Kaplan-Meier survival analysis and Cox proportional hazards regression. Hospitalizations for infection were compared using multivariable logistic regression, adjusted for era and donor and recipient characteristics.

Results

Of 12,388 LT recipients (median age = 62, male = 61.2%), hospitalization for infection in the first-year post transplant was 5.2% for patients transplanted from March 2018 to March 2020 (N = 5,031), 7.6% from March 2020 to March 2022 (N = 4,659), and 13.2% post-March 2022 (N = 3,640) (p < 0.001). Compared to March 2018 to March 2020, patients transplanted from March 2020 to March 2022 (adjusted aoods ratio [aOR] = 1.50, 95% confidence interval [CI] = 1.26-1.79) and post-March 2022 (aOR = 2.89, 95% CI = 2.29-3.65) were more likely to be hospitalized for an infection. After adjustment, we found no significant difference in risk of death following LT for recipients transplanted between March 2020 and March 2022 (aHR = 1.09, 95% CI = 0.96-1.23, p = 0.175) compared to March 2018 and March 2020. Post-March 2022 risk of death was elevated (aHR = 1.21, 95% CI = 1.04, 1.40, p = 0.014).

Conclusions

Odds of hospitalization for infection in the first year after LT performed between March 2020 and March 2022 and post-March 2022 were 1.50 and 2.89 times as high, respectively, as LT performed between March 2018 and March 2020.

IRB NUMBERS

IRB00352819.

When to Remove Tracheal Intubation During ECMO Support in Lung Transplant Patients With Idiopathic Pulmonary Fibrosis

BACKGROUND

Lung transplantation is the optimal treatment choice, while extracorporeal membrane oxygenation (ECMO) provides cardiopulmonary support during the perioperative period of lung transplantation. Currently, there is no reported research on the ECMO withdrawal and duration of mechanical ventilation (MV) in idiopathic pulmonary fibrosis (IPF) patients undergoing lung transplantation. Therefore, this study aims to evaluate the impact of ECMO duration on prolonged mechanical ventilation (PMV) time in patients, attempting to explore the relationship between the two.

METHODS

This study included 170 patients with IPF who underwent lung transplantation under ECMO technology. The patients were divided into normal and delayed groups based on the ECMO application time of 72 hours. A multifactor logistic regression analysis was conducted to explore the independent risk factors for PMV time, and restricted cubic spline (RCS) was used to investigate the relationship between ECMO application time and MV time. Receptor operating characteristics (ROC) were further used to find the cut-off value of ECMO application time to predict PMV time.

RESULTS

In the normal group, there were 135 cases, of which 79.25% (107 cases) were males and 20.74% (28 cases) were females, whereas in the delayed group, there were 35 cases, of which 57.14% (20 cases) were males and 42.86% (15 cases) were females. In the RCS curves, there was a nonlinear correlation between the duration of ECMO application and the duration of MV, which tended to increase as the duration of ECMO application increased. According to univariate and multivariate logistic analyses, ECMO application time was an influential factor in the occurrence of PMV time, in which the OR of PMV time was 2.02 (95% CI 1.11,1.63, P = .001) when ECMO application time was ≥ 52.01 hours.

CONCLUSION

After lung transplantation, there is a nonlinear relationship between the application time of ECMO and MV time in patients with IPF. The application time of ECMO can predict well the extension of MV in patients during ICU stay. Therefore, clinicians can assess the duration of MV in patients with IPF based on the application time of ECMO, further avoiding complications related to MV.

Exploring the Association Between Torquetenovirus Viral Load and Immunosuppressive Drug Exposure in Lung Transplantation

To improve lung transplant recipient (LungTx) outcome, it would be of great interest to measure the net state of immunosuppression to avoid both infection and rejection. Measurement of Torquetenovirus load (TTV load) has been proposed as a biomarker to monitor solid organ transplantation, but its relationship with immunosuppressive drugs, particularly mycophenolic acid (MPA), is not well understood. We performed a prospective study of 53 LungTx, measuring TTV load before transplantation, at week 3, and at month 3. Tacrolimus and MPA doses and levels were recorded, and an area under the MPA curve (AUC-MPA) was calculated at the third month. LungTx in the fourth quartile of TTV load at the third week and the third month exhibited a low risk of acute rejection (OR 0.113, 95% CI 0.013-0.953, p = 0.045) and a high risk of opportunistic infection from month 3 to 6 (OR 15.200, 95% CI 1.525-151.511, p = 0.020), respectively. TTV load was weakly related to tacrolimus trough level at month 3 (rho = 0.283, p = 0.040). Neither MPA blood levels nor AUC-MPA were related to TTV load, although only patients with a reduction in MPA dose from month 1 to 3 showed a smaller increase in TTV load (0.86, IQR 2.58 log10 copies/mL vs. 2.26, IQR 3.02 log10 copies/mL, p = 0.026). In conclusion, TTV load in LungTx is only partially related to exposure to immunosuppressive drugs. Other variables, such as inflammation, immunosenescence, and frailty, may influence the overall level of immunosuppression and TTV load.

Mycobacteroides abscessus outbreak and mitigation in a cardiothoracic transplant population: the problem with tap water

BACKGROUND

Hospital outbreaks caused by Mycobacteroides abscessus complex are a major cause for concern in vulnerable patients such as the cardiothoracic transplant population.

AIM

To describe the outbreak investigation and mitigation steps undertaken to address an increase in healthcare-associated M. abscessus complex cases in an inpatient cardiothoracic transplant population.

METHODS

We extracted clinical characteristics from patients with M. abscessus pre-outbreak (March 2018 to December 2020) and during the outbreak (January 2021 to June 2022) from the electronic medical record. A multi-disciplinary team conducted the outbreak investigation and devised a mitigation strategy to implement at our institution.

FINDINGS

The baseline incidence of healthcare-associated M. abscessus was 0.11 cases per 10,000 patient-days; this increased to 0.24 cases per 10,000 patient-days during the outbreak. There were 1/9 (11%) cardiothoracic transplant patients in the pre-outbreak group compared with 7/12 (58%) during the outbreak, and respiratory specimen types compromised 6/9 (67%) of M. abscessus results in the pre-outbreak group compared with 10/12 (83%) during the outbreak. Among the clinical care activities involving water, a variety of water sources were utilized, including filtered and tap water. The incidence of healthcare-associated M. abscessus subsequently decreased to 0.06 cases per 10,000 patient-days after implementing an outbreak-mitigation strategy of sterile water precautions.

CONCLUSIONS

Robust educational efforts from a multi-disciplinary team on eliminating exposure to tap water were effective measures to reduce healthcare-associated M. abscessus incidence at our institution. Non-tuberculous mycobacteria infection surveillance, targeted education, and water mitigation strategies may be beneficial preventative strategies for other lung transplant centres facing similar issues.

Epidemiology and pathogen characteristics of infections following solid organ transplantation

Solid organ transplantation (SOT) recipients have a heightened risk for infection due to prolonged immunosuppressive drug use following transplant procedures. The occurrence of post-transplant infections is influenced not only by the transplanted organ type but also by varied factors. The kidney is the most common organ in SOT, followed by the liver, heart, and lung. This review aims to provide a comprehensive overview of the current epidemiological characteristics of infections after kidney, liver, heart, and lung transplantation, focusing on bacterial, fungal, and viral infections. The incidence and infection types demonstrated significant variability across different SOTs. Furthermore, this review attempts to elucidate the clinical characteristics of infections across patients following different SOTs and contribute to the development of individualized prevention strategies according to infection incidence, ultimately enhancing the quality of life of transplant recipients.

Successful Medical Management of Pulmonary Gangrene in a Transplanted Lung

Pulmonary gangrene (PG) is a potentially devastating complication of necrotizing pneumonia. We describe successful nonsurgical management of PG in a lung transplant recipient. The patient presented with symptoms and imaging consistent with pneumonia. Bronchoalveolar lavage cultures demonstrated polymicrobial growth and antibiotic treatments were tailored. Imaging demonstrated a large cavitary lesion with intracavitary lung tissue consistent with PG. Prolonged antibiotic therapy resulted in clinical improvement and radiographic resolution.

Pulmonary bacterial infection after lung transplantation: risk factors and impact on short-term mortality

OBJECTIVE

To explore the risk factors for pulmonary bacterial infection (PBI) after lung transplantation (LTX) and to evaluate the impact of PBI on short-term postoperative mortality.

METHODS

We retrospectively analyzed data on 549 recipients who underwent LTX at the Affiliated Wuxi People's Hospital of Nanjing Medical University, China, between January 2018 and December 2021. The risk factors for PBI after LTX were explored by univariate analysis and multivariate logistic regression. Cox proportional hazards regression models were used to estimate the hazard ratios (HR) and 95% confidence intervals (CI) of one-, two-, and three-year mortality. Subgroup analysis was performed by the time of postoperative PBI (≤7 days or 8-30 day after surgery).

RESULTS

The incidence of postoperative PBI in 549 recipients was 82.70% (454/549). Preoperative history of infections with multidrug-resistant bacteria (OR 12.34, 95% CI 1.69-1572.39), Acinetobacter baumannii infection in donor (OR 3.08, 95% CI 1.26-9.66), and longer cold ischemia time (OR 1.16, 95% CI 1.03-1.32) were risk factors for postoperative PBI. Postoperative PBI was associated with one-year (HR 1.80, 95% CI 1.09-2.96), two-year (HR 1.91, 95% CI 1.20-3.04), and three-year mortality (HR 2.03, 95% CI 1.29-3.19). Subgroup analysis showed that PBI within 7 days after surgery was associated with one-year (HR 1.86, 95% CI 1.12-3.08), two-year (HR 1.99, 95% CI 1.25-3.17), and three-year mortality (HR 2.13, 95% CI 1.35-3.36), while PBI at 8-30 days after surgery was not associated with short-term mortality (one-year: HR 1.36, 95% CI 0.69-2.69; two-year: HR 1.48, 95% CI 0.80-2.76; three-year: HR 1.51, 95% CI 0.82-2.77).

CONCLUSIONS

Donor-recipient and surgical factors are risk factors for PBI after LTX. Active prevention and treatment of PBI within the first 7 days after surgery may improve short-term survival.

Analysis of Perioperative Factors Leading to Postoperative Pulmonary Complications, Graft Injury and Increased Postoperative Mortality in Lung Transplantation

OBJECTIVES

Postoperative complications such as postoperative pulmonary complications (PPCs) and other organ complications are associated with increased morbidity and mortality after successful lung transplantation and have a detrimental effect on patient recovery. The aim of this study was to investigate perioperative risk factors for in-hospital mortality and postoperative complications with a focus on PPC and graft injury in patients undergoing lung transplantation DESIGN: Single-center retrospective cohort study of 173 patients undergoing lung transplantation SETTING: University Hospital, Medical Center Freiburg.

MAIN RESULTS

In the stepwise multivariate regression analysis, donor age >60 years (odds ratio [OR], 1.85; 95% confidence interval [CI], 1.27-2.81), intraoperative extracorporeal membrane oxygenation (OR, 2.4; 95% CI, 1.7-3.3), transfusion of >4 red blood cell concentrates (OR, 3.1; 95% CI, 1.82-5.1), mean pulmonary artery pressure of >30 mmHg at the end of surgery (OR, 3.5; 95% CI, 2-6.3), the occurrence of postoperative graft injury (OR, 4.1; 95% CI, 2.8-5.9), PPCs (OR, 2.1; 95% CI, 1.7-2.6), sepsis (OR, 4.5; 95% CI, 2.8-7.3), and Kidney disease Improving Outcome grading system stage 3 acute renal failure (OR, 4.3; 95% CI, 2.4-7.7) were associated with increased in hospital mortality, whereas patients with chronic obstructive pulmonary disease had a lower in-hospital mortality (OR, 1.6; 95% CI, 1.4-1.9). The frequency and number of PPCs correlated with postoperative mortality.

CONCLUSIONS

Clinical management and risk stratification focusing on the underlying identified factors that could help to improve patient outcomes.

Analysis of high-risk factors for early pulmonary bacterial infection after lung transplantation and their correlation with long-term mortality

OBJECTIVE

To investigate the high-risk factors for early pulmonary bacterial infection following lung transplantation and their association with long-term mortality.

METHODS

A retrospective analysis was conducted on 142 lung transplant recipients treated at Wuxi People's Hospital between January 2018 and July 2022. After applying predefined inclusion and exclusion criteria, 111 cases were analyzed. Univariate and multivariate logistic regression analyses were performed to identify independent risk factors for early pulmonary infection post-transplantation. Additionally, univariate and multivariate Cox regression analyses were used to identify independent prognostic factors affecting one-year survival post-transplantation.

RESULTS

Univariate analysis identified age, bacterial infection in donor lungs, and operation duration as risk factors for early pulmonary infection (all P < 0.05). Multivariate analysis was confirmatory for these as independent risk factors (all P < 0.05). Univariate analysis also showed that intraoperative blood loss and oxygenation index impacted one-year survival (P < 0.05). Multivariate analysis was confirmatory for these as independent risk factors (P < 0.05).

CONCLUSION

Early pulmonary bacterial infection was not found to be an independent factor affecting 1-year survival. However, substantial intraoperative blood loss and a reduced oxygenation index were identified as independent risk factors associated with increased mortality within 1 year post-transplantation.

Immunopathology of lung transplantation: from infection to rejection and vice versa

Lung transplantation offers a lifesaving option for patients with end-stage lung disease, but it is marred by a high risk of post-transplant infections, particularly involving multidrug-resistant bacteria, Cytomegalovirus, and fungal pathogens. This elevated infection rate, the highest among solid organ transplants, poses a significant challenge for clinicians, particularly within the first year post-transplantation, where infections are the leading cause of mortality. The direct exposure of lung allografts to the external environment exacerbates this vulnerability leading to constant immune stimulation and consequently to an elevated risk of triggering alloimmune responses to the lung allograft. The necessity of prolonged immunosuppression to prevent allograft rejection further complicates patient management by increasing susceptibility to infections and neoplasms, and complicating the differentiation between rejection and infection, which require diametrically opposed management strategies. This review explores the intricate balance between preventing allograft rejection and managing the heightened infection risk in lung transplant recipients.

The application of ERAS in the perioperative period management of patients for lung transplantation

Objective

To explore the application of enhanced recovery after surgery (ERAS) in the perioperative period of lung transplantation.

Methods

We retrospectively collected the clinical data of 27 lung transplant patients who underwent ERAS during the perioperative period, while 12 lung transplant patients receiving routine treatment served as controls. General information was collected, including the specific implementation plan of ERAS, the incidence of complications and survival rate during the perioperative period (<30 d), postoperative hospitalization indicators, the postoperative length of stay, and numerical rating scale (NRS) scores.

Results

Comparison of postoperative hospitalization indicators, the ERAS group compared with the control group, there were significant differences in postoperative ICU stay time (2.0(2.0,4.0) vs 4.5(3.0,6.0), p = 0.005), postoperative hospital stay time (18(15,26) vs 24(19.5,32.75), p = 0.016), duration of nasogastric tube (3(2,3) vs 4(2.25,4.75), p = 0.023), and first ambulation time (4(3,5) vs 5.8(4.5,7.5), p = 0.004). There was no significant difference in postoperative invasive mechanical ventilation time, time to eat after surgery, duration of urinary catheter and duration of chest tube between the ERAS group and the control group (p>0.05). The perioperative survival of the ERAS group was 81.5%, which was higher than the control group (66.7%), but there is no statistically significant difference. Comparison of post-extubation NRS scores, the ERAS group had lower NRS scores at 12 h (5.30 ± 0.14 vs 6.25 ± 0.75), 24 h (3.44 ± 0.64 vs 5.58 ± 0.9), 48 h (2.74 ± 0.66 vs 4.08 ± 0.79) and 72 h (1.11 ± 0.80 vs 2.33 ± 0.49) than the control group, the difference was statistically significant (p<0.01). Intra-group comparison, post-extubation 12 h comparison post-extubation 24 h, 48 h, 72 h, the NRS scores showed a gradual downward trend, the difference was statistically significant (p<0.01). In the comparison of perioperative complications, the ERAS group had a lower postoperative infection incidence than the control group, the difference was statistically significant (44.4% vs 83.3%, p = 0.037). The ERAS group had lower postoperative delirium incidence than the control group, the difference was statistically significant (11.1% vs 50%, p = 0.014). There was no significant difference in the incidence of acute rejection, primary graft loss (PGD), gastrointestinal (GI) complications and airway complications between two groups (p>0.05).

Conclusion

The ERAS can be applied to lung transplant patients to relieve postoperative pain, shorten postoperative tube time, and shorten postoperative stay. Perioperative pulmonary rehabilitation exercises are beneficial to reducing the occurrence of postoperative pulmonary complications.

Antibiotic Prophylaxis in Patients Undergoing Lung Transplant: Single-Center Cohort Study

Perioperative antibiotic prophylaxis (PAP) in lung transplant recipients (LuTRs) has high heterogeneity between centers. Our aim was to investigate retrospectively the approach to PAP in our center over a 20-year period (2002-2023), and its impact on early post-operative infections (EPOIs) after lung transplantation (LuT). Primary endpoint was diagnosis of EPOI, defined as any bacterial infection including donor-derived events diagnosed within 30 days from LuT. Main exposure variables were type of PAP (combination vs. monotherapy) and PAP duration. We enrolled 111 LuTRs. PAP consisted of single-agent or combination regimens in 26 (25.2%) and 85 (74.8%) LuTR. Median PAP duration was 10 days (IQR 6-13) days. Piperacillin/tazobactam was the most common agent used either as monotherapy (n = 21, 80.7%) or as combination with levofloxacin (n = 79, 92.9%). EPOIs were diagnosed in 30 (27%) patients. At multivariable analysis no advantages were found for combination regimens compared to single-agent PAP in preventing EPOI (OR: 1.57, 95% CI: 0.488-5.068, p:0.448). The impact of PAP duration on EPOIs development was investigated including duration of PAP ≤6 days as main exposure variables, without finding a significantly impact (OR:2.165, 95% CI: 0.596-7.863, p: 0.240). Our results suggest no advantages for combination regimens PAP in preventing EPOI in LuTR.

Lung transplantation, case anecdotes reconstruction for inadequate left atrial cuff on the donor side by aortic arch: A feasible case report

Abnormalities in pulmonary vasculature or technical issues during lung procurement can lead to an insufficient left atrial (LA) cuff in donors. However, surgeons frequently need to reconfigure these less-than-ideal lungs for transplantation. This case report introduces a novel technique for such reconstruction. The patient was a 35-year-old male diagnosed with pneumoconiosis for over a year. Due to progressive worsening dyspnoea leading to respiratory failure on multiple occasions, he was deemed a candidate for lung transplantation. While obtaining the donor's lung, an inadvertent short cut of the LA cuff around the left inferior pulmonary vein orifice resulted in the residual vein retracting into the pulmonary hilum. To overcome this, we employed the aortic arch for reconstruction, enabling the successful completion of the lung transplantation. On post-transplantation day 2, extracorporeal membrane oxygenation was no longer required. Mechanical ventilation ceased after 13 days, with the subsequent removal of a tracheostomy. The patient spent 35 days in the intensive care unit and 58 days in the hospital. Post-transplantation complications included primary graft dysfunction, acute kidney failure, pneumothorax in the transplanted lung, the clots in the inferior vena cava, and pneumonia. Remarkably, over a year of follow-up (19 months after lung transplantation), the patient reported no adverse events and had successfully returned to work. In this case, the aortic arch is an alternative for reconstructing an insufficient LA cuff.

Dramatic increase in antimicrobial resistance in ESKAPE clinical isolates over the 2010-2020 decade in India

RATIONALE AND OBJECTIVES

ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species) constitute a threat to humans worldwide. India is now the most populous country. The goal was to investigate the evolution of the rates of antimicrobial resistance in ESKAPE pathogens across India over the 2010-20 decade.

METHODS

The data (89 studies) were retrieved from the Medline PubMed repository using specific keywords.

RESULTS

The study of 20 177 ESKAPE isolates showed that A. baumannii isolates were the most represented (35.9%, n = 7238), followed by P. aeruginosa (25.3%, n = 5113), K. pneumoniae (19.5%, n = 3934), S. aureus (16.3%, n = 3286), E. faecium (2.6%, n = 517) and Enterobacter spp. (0.4%, n = 89). A notable increase in the resistance rates to antimicrobial agents occurred over the 2010-20 decade. The most important levels of resistance were observed in 2016-20 for A. baumannii (90% of resistance to the amoxicillin-clavulanate combination) and K. pneumoniae (81.6% of resistance to gentamycin). The rise in β-lactamase activities was correlated with an increase in the positivity of Gram-negative isolates for β-lactamase genes.

CONCLUSIONS

This review highlighted that, in contrast to developed countries that kept resistance levels under control, a considerable increase in resistance to various classes of antibiotics occurred in ESKAPE pathogens in India over the 2010-2020 decade.

Bacterial infections in solid organ transplant recipients

PURPOSE OF REVIEW

Bacteria are the leading cause of infections in solid organ transplant (SOT) recipients, significantly impacting patient outcome. Recently detailed and comprehensive epidemiological data have been published.

RECENT FINDING

This literature review aims to provide an overview of bacterial infections affecting different types of SOT recipients, emphasizing underlying risk factors and pathophysiological mechanisms.

SUMMARY

Lung transplantation connects two microbiotas: one derived from the donor's lower respiratory tract with one from the recipient's upper respiratory tract. Similarly, liver transplantation involves a connection to the digestive tract and its microbiota through the bile ducts. For heart transplant recipients, specific factors are related to the management strategies for end-stage heart failure based with different circulatory support tools. Kidney and kidney-pancreas transplant recipients commonly experience asymptomatic bacteriuria, but recent studies have suggested the absence of benefice of routine treatment. Bloodstream infections (BSI) are frequent and affect all SOT recipients. Nonorgan-related risk factors as age, comorbidity index score, and leukopenia contribute to BSI development. Bacterial opportunistic infections have become rare in the presence of efficient prophylaxis. Understanding the epidemiology, risk factors, and pathophysiology of bacterial infections in SOT recipients is crucial for effective management and improved patient outcomes.

Unique Changes in the Lung Microbiome following the Development of Chronic Lung Allograft Dysfunction

The importance of lung microbiome changes in developing chronic lung allograft dysfunction (CLAD) after lung transplantation is poorly understood. The lung microbiome-immune interaction may be critical in developing CLAD. In this context, examining alterations in the microbiome and immune cells of the lungs following CLAD, in comparison to the lung condition immediately after transplantation, can offer valuable insights. Four adult patients who underwent lung retransplantation between January 2019 and June 2020 were included in this study. Lung tissues were collected from the same four individuals at two different time points: at the time of the first transplant and at the time of the explantation of CLAD lungs at retransplantation due to CLAD. We analyzed whole-genome sequencing using the Kraken2 algorithm and quantified the cell fractionation from the bulk tissue gene expression profile for each lung tissue. Finally, we compared the differences in lung microbiome and immune cells between the lung tissues of these two time points. The median age of the recipients was 57 years, and most (75%) had undergone lung transplants for idiopathic pulmonary fibrosis. All patients were administered basiliximab for induction therapy and were maintained on three immunosuppressants. The median CLAD-free survival term was 693.5 days, and the median time to redo the lung transplant was 843.5 days. Bacterial diversity was significantly lower in the CLAD lungs than at transplantation. Bacterial diversity tended to decrease according to the severity of the CLAD. Aerococcus, Caldiericum, Croceibacter, Leptolyngbya, and Pulveribacter genera were uniquely identified in CLAD, whereas no taxa were identified in lungs at transplantation. In particular, six taxa, including Croceibacter atlanticus, Caldiserium exile, Dolichospermum compactum, Stappia sp. ES.058, Kinetoplastibacterium sorsogonicusi, and Pulveribacter suum were uniquely detected in CLAD. Among immune cells, CD8+ T cells were significantly increased, while neutrophils were decreased in the CLAD lung. In conclusion, unique changes in lung microbiome and immune cell composition were confirmed in lung tissue after CLAD compared to at transplantation.

Treatment of Staphylococcus aureus infection with sphingosine in ex vivo perfused and ventilated lungs

BACKGROUND

Ex vivo lung perfusion (EVLP) has expanded the donor pool for lung transplantation. Pulmonary Staphylococcus aureus infection, especially that caused by multidrug-resistant strains, is a severe threat to posttransplantation outcomes. Sphingosine is a lipid compound that exhibits broad-spectrum antibacterial activity. Therefore, we aimed to evaluate the effects of S aureus infection on EVLP and whether sphingosine administration during EVLP prevents infection with S aureus.

METHODS

Eighteen pigs were randomly assigned to 3 groups: uninfected, infected with S aureus with NaCl treatment, or infected with sphingosine treatment. Bacterial numbers were determined before and after treatment. Sphingosine concentrations in the lung tissues were determined using biochemical assays. Lung histology, lung physiological parameters, perfusate content, lung weight, and cell death were measured to analyze the effects of infection and sphingosine administration on EVLP.

RESULTS

Sphingosine administration significantly reduced the bacterial load. The concentration of sphingosine in the bronchial epithelium was elevated after sphingosine administration. S aureus infection increased pulmonary artery pressure and pulmonary vascular resistance. Lung edema, histology scores, lactate and lactate dehydrogenase levels in the perfusate, ΔPO2 in the perfusate, static lung compliance, and lung peak airway pressure did not differ among the groups.

CONCLUSIONS

Infection of S aureus did not affect the lung function during EVLP but induced higher pulmonary artery pressure and pulmonary vascular resistance. Administration of sphingosine effectively eliminated S aureus without side effects in isolated, perfused, and ventilated pig lungs.

Diagnostic difficulties in non-tuberculous mycobacterial infection in lung transplant recipients

Despite antimicrobial prophylaxis, 34% to 59% of lung transplant recipients experience severe life-threatening opportunistic infections, sometimes caused by Nontuberculous Mycobacteria (NTM) and Nocardia. Although differentiating these infections is of utmost importance for effective treatment, it can be challenging as they share morphological and growth characteristics. Therefore, culture remains the gold standard for laboratory confirmation. With the aid of novel molecular methods performed on the cultured organisms, diagnosis may be accomplished rapidly and precisely. We present a case of a lung transplant recipient with a pulmonary infection where long, thin, beaded, branching filamentous organisms were seen with Acid-Fast Bacilli (AFB) and Modified Gomori's Methenamine Silver (GMS) stains in bronchoalveolar lavage sample. Cytological characteristics led to the suspicion of a Nocardia species infection. However, culture and the PCR-restriction fragment length polymorphism analysis (PRA) identified M. fortuitum. Additionally, antibiotic resistance was detected, which aided in choosing the appropriate treatment. Therefore, to overcome such diagnostic difficulties to differentiate NTM and Nocardia, a multidisciplinary approach including culture, molecular methods, and cytology is needed to enhance clinical outcomes.

Etiologic characteristics revealed by mNGS-mediated ultra-early and early microbiological identification in airway secretions from lung transplant recipients

Background

Post-operative etiological studies are critical for infection prevention in lung transplant recipients within the first year. In this study, mNGS combined with microbial culture was applied to reveal the etiological characteristics within one week (ultra-early) and one month (early) in lung transplant recipients, and the epidemiology of infection occurred within one month.

Methods

In 38 lung transplant recipients, deep airway secretions were collected through bronchofiberscope within two hours after the operation and were subjected to microbial identification by mNGS and microbial culture. The etiologic characteristics of lung transplant recipients were explored. Within one month, the infection status of recipients was monitored. The microbial species detected by mNGS were compared with the etiological agents causing infection within one month.

Results

The detection rate of mNGS in the 38 airway secretions specimens was significantly higher than that of the microbial culture (P<0.0001). MNGS identified 143 kinds of pathogenic microorganisms; bacterial pathogens account for more than half (72.73%), with gram-positive and -negative bacteria occupying large proportions. Fungi such as Candida are also frequently detected. 5 (50%) microbial species identified by microbial culture had multiple drug resistance (MDR). Within one month, 26 (68.42%) recipients got infected (with a median time of 9 days), among which 10 (38.46%) cases were infected within one week. In the infected recipients, causative agents were detected in advance by mNGS in 9 (34.62%) cases, and most of them (6, 66.67%) were infected within one week (ultra-early). In the infection that occurred after one week, the consistency between mNGS results and the etiological agents was decreased.

Conclusion

Based on the mNGS-reported pathogens in airway secretions samples collected within two hours, the initial empirical anti-infection regimes covering the bacteria and fungi are reasonable. The existence of bacteria with MDR forecasts the high risk of infection within 48 hours after transplant, reminding us of the necessity to adjust the antimicrobial strategy. The predictive role of mNGS performed within two hours in etiological agents is time-limited, suggesting continuous pathogenic identification is needed after lung transplant.

Multidrug-Resistant and Extended-Spectrum β-Lactamase Gram-Negative Bacteria in Bilateral Lung Transplant Recipients: Incidence, Risk Factors, and In-Hospital Mortality

BACKGROUND

In recent decades, the incidence of multidrug-resistant (MDR) and extended-spectrum β-lactamase (ESBL) gram-negative (GN) bacteria has increased progressively among lung transplantation (LT) recipients. A prompt diagnosis, prevention, and management of these pathogens remain the cornerstone for successful organ transplantation.

RESEARCH QUESTION

What are the incidence of MDR and ESBL GN bacteria within the first 30 days after LT and related risk of in-hospital mortality? What are the potential clinical predictors of isolation of MDR and ESBL GN bacteria?

STUDY DESIGN AND METHODS

All consecutive LT recipients admitted to the ICU of the University Hospital of Padua (February 2016-December 2021) were screened retrospectively. Only adult patients undergoing the first bilateral LT and not requiring invasive mechanical ventilation, extracorporeal membrane oxygenation, or both before surgery were included. MDR and ESBL GN bacteria were identified using in vitro susceptibility tests and were isolated from the respiratory tract, blood, urine, rectal swab, or surgical wound or drainage according to a routine protocol.

RESULTS

One hundred fifty-three LT recipients were screened, and 132 were considered for analysis. Median age was 52 years (interquartile range, 41-60 years) and 46 patients (35%) were women. MDR and ESBL GN bacteria were identified in 45 patients (34%), and 60% of patients demonstrated clinically relevant infection. Pseudomonas aeruginosa (n = 22 [49%]) and Klebsiella pneumoniae (n = 17 [38%]) were frequently isolated after LT from the respiratory tract (n = 21 [47%]) and multiple sites (n = 18 [40%]). Previous recipient-related colonization (hazard ratio [HR], 2.48 [95% CI, 1.04-5.90]; P = .04) and empirical exposure to broad-spectrum antibiotics (HR, 6.94 [95% CI, 2.93-16.46]; P < .01) were independent predictors of isolation of MDR and ESBL GN bacteria. In-hospital mortality of the MDR and ESBL group was 27% (HR, 6.38 [95% CI, 1.98-20.63]; P < .01).

INTERPRETATION

The incidence of MDR and ESBL GN bacteria after LT was 34%, and in-hospital mortality was six times greater. Previous recipient-related colonization and empirical exposure to broad-spectrum antibiotics were clinical predictors of isolation of MDR and ESBL GN bacteria.

Microbiosis in lung allotransplantation and xenotransplantation: State of the art and future perspective

The respiratory tract is known to harbor a microbial community including bacteria, viruses, and fungi. New techniques contribute enormously to the identification of unknown or culture-independent species and reveal the interaction of the community with the host immune system. The existing respiratory microbiome and substantial equilibrium of the transplanted microbiome from donor lung grafts provide an extreme bloom of dynamic changes in the microenvironment in lung transplantation (LT) recipients. Dysbiosis in grafts are not only related to the modified microbial components but also involve the kinetics of the host-graft "talk," which signifies the destination of graft allograft injury, acute rejection, infection, and chronic allograft dysfunction development in short- and long-term survival. Microbiome-derived factors may contribute to lung xenograft survival when using genetically multimodified pig-derived organs. Here, we review the most advanced knowledge of the dynamics and resilience of microbial communities in transplanted lungs with various pretransplant indications. Conceptual and analytical points of view have been illustrated along the time series, gaining insight into the microbiome and lung grafts. Future endeavors on precise tools, sophisticated models, and novel targeted regimens are needed to improve the long-term survival in these patients.

Risk factors of wound infection after lung transplantation: a narrative review

Background and Objective

The incidence of incision infection after lung transplantation is prominently high which affect the prognosis. Summarizing the risk factors related to incision infection after lung transplantation contribute to the control of incision infection by pre-controlling the risk factors. The objective is to summarize risk factors related to wound infection after lung transplantation.

Methods

PubMed was used to research the literature relating to the risk factors to incision infection after lung transplantation through 1990 to 2022. The retrieval strategy were Medical Subject Heading (MeSH) terms combined entry terms. Two researchers conducted the literature retrieval independently. Two researchers independently evaluate the quality of the literature and summarize the indicators.

Key Content and Findings

A total of 98 researches were collected from PubMed and 8 articles described the related risk factors of incision infection after lung transplantation. All of the 8 articles were retrospective studies, of which 4 articles were grouped by the delayed chest closure (DCC) execution and the other 4 articles were grouped by the surgical site infection (SSI) occurred. Two articles performed multivariate regression analysis to determine the independent risk factors of SSI after lung transplantation and the other 6 articles compared the SSI rate in different patients population. The integrated results showed that bronchoalveolar lavages (BALs), smoking status, body mass index (BMI), diabetes, operation duration, thoracic drainage tube placement time and DCC were related to the SSI after lung transplantation.

Conclusions

BALs, smoking status, BMI, diabetes, operation duration, thoracic drainage tube placement time and DCC were related to the SSI after lung transplantation.

Antibiotic Therapy for Difficult-to-Treat Infections in Lung Transplant Recipients: A Practical Approach

Lung transplant recipients are at higher risk to develop infectious diseases due to multi-drug resistant pathogens, which often chronically colonize the respiratory tract before transplantation. The emergence of these difficult-to-treat infections is a therapeutic challenge, and it may represent a contraindication to lung transplantation. New antibiotic options are currently available, but data on their efficacy and safety in the transplant population are limited, and clinical evidence for choosing the most appropriate antibiotic therapy is often lacking. In this review, we provide a summary of the best evidence available in terms of choice of antibiotic and duration of therapy for MDR/XDR P. aeruginosa, Burkholderia cepacia complex, Mycobacterium abscessus complex and Nocardia spp. infections in lung transplant candidates and recipients.