Multidrug-resistant organisms in lung transplant: a narrative review

Optimizing patient outcomes in interstitial lung disease through pre- and post-transplant management strategies

Interstitial lung diseases (ILD) encompass a diverse group of over 200 chronic pulmonary disorders characterized by varying degrees of inflammation and fibrosis, which can lead to severe respiratory impairment. Lung transplantation offers a crucial therapeutic option for patients with advanced ILD, extending survival and improving quality of life. This review explores optimal management strategies in both the pre- and post-transplant phases to enhance patient outcomes. Comprehensive pre-transplant evaluation, including pulmonary function testing, imaging, and comorbidity assessment, is critical for determining transplant eligibility and timing. Post-transplant care must focus on preventing complications such as primary graft dysfunction and chronic lung allograft dysfunction, managed through tailored immunosuppression and proactive monitoring. Recent advancements in diagnostic techniques and therapeutic approaches, including emerging technologies like ex vivo lung perfusion and precision medicine, promise to further improve outcomes. The ultimate goal is to establish an evidence-based, multidisciplinary framework for optimizing ILD management and lung transplantation.

Characteristics of upper and lower respiratory tract microbiota after lung transplantation

BACKGROUND

The composition and characteristics of airway microbiota offer critical insights for clinical decision-making. Current research on chronic lung diseases shows differences in the composition and characteristics of upper and lower respiratory tract microbiota compared with healthy individuals. However, the temporal changes of these microbial communities in lung transplant recipients remain poorly characterized.

METHODS

This is a longitudinal prospective study. Respiratory specimens were collected regularly from lung transplant recipients for testing and analysis. A total of 150 bronchoalveolar lavage fluid (BALF) samples, 150 throat swab samples, 51 sputum samples, and 36 lung tissue samples were collected from the recipients, at 7 days, 14 days, 1 month, 2 months, 3 months, and 6 months post-transplant for 16S rRNA gene sequencing and analysis.

RESULTS

Our study showed that there were significant differences in α-diversity and β-diversity among lung tissue, throat swab, and sputum samples, although α-diversity did not show a significant difference between lung tissue and BALF. Most amplicon sequence variants (ASVs) belonged to the families Enterobacteriaceae, Pseudomonadaceae, and Stenotrophomonas in BALF, while most ASVs belonged to the genera Streptococcus, Pseudomonadaceae, and Stenotrophomonas in sputum samples. Regarding dynamic changes, Corynebacterium and Staphylococcus were more prevalent in the early post-operative period but gradually decreased by 7 days post-operatively, while the common microbiota found in healthy populations based on literature became the most abundant ASVs at 6 months post-operatively in our study participants. Pseudomonadaceae and Stenotrophomonas contributed to the similarity in the composition of upper and lower respiratory microbiota.

CONCLUSIONS

This study demonstrates that lung transplant recipients exhibit unique characteristics in their upper and lower respiratory tract microbiota, which are distinct ecological profiles, and both undergo significant changes within 6 months post-operatively. The similarity between upper and lower respiratory tract microbiota is associated with microbial diversity and taxonomic dominance.

CLINICAL TRIAL

The clinical trial was registered at Chinese Clinical Trial Registry (ChiCTR2200056908) in February 2022.

Risk factors for survival after lung transplantation in cystic fibrosis: impact of colonization with multidrug-resistant strains of Pseudomonas aeruginosa

BACKGROUND

Lung transplantation is the ultimate treatment option for patients with advanced cystic fibrosis. Chronic colonization of these recipients with multidrug-resistant (MDR) pathogens may constitute a risk factor for an adverse outcome. We sought to analyze whether colonization with MDR pathogens, as outlined in the German classification of multiresistant Gram-negative bacteria (MRGN), was associated with the success of lung transplantation.

METHODS

We performed a monocentric retrospective analysis of 361 lung transplantations performed in Homburg, Germany, between 1995 and 2020. All recipients with a main diagnosis of cystic fibrosis (n = 69) were stratified into two groups based on colonization with Pseudomonas aeruginosa in view of MRGN before transplantation: no colonization and colonization without (n = 23) or with (n = 46) resistance to three or four antibiotic groups (3MRGN/4MRGN). Multivariable analyses were performed including various clinical parameters (preoperative data, postoperative data).

RESULTS

CF patients colonized with multidrug-resistant pathogens (Pseudomonas aeruginosa) classified as 3MRGN/4MRGN had poorer survival (median survival 16 years (without MRGN) versus 8 years (with MRGN), P = 0.048). Extracorporeal support (P = 0.014, HR = 2.929), re-transplantation (P = 0.023, HR = 2.303), female sex (P = 0.019, HR = 2.244) and 3MRGN/4MRGN (P = 0.036, HR = 2.376) were predictors of poor outcomes in the multivariate analysis. Co-colonization with the mold Aspergillus fumigatus was further associated with mortality risk in the 3MRGN/4MRGN group (P = 0.037, HR = 2.150).

CONCLUSION

Patients with cystic fibrosis and MDR colonization (Pseudomonas aeruginosa) are risk candidates for lung transplantation, targeted diagnostics and tailored anti-infective strategies are essential for survival after surgery. MDR colonization as expressed by MRGN may help to identify patients at increased risk to improve the organ allocation process.

Clinical characteristics, risk factor analysis and peripheral blood cell changes for early warning of multidrug-resistant bacteria (MDR) infection in elderly patients

OBJECTIVE

To explore peripheral blood indicators that may serve as early indicators for multidrug-resistant bacteria (MDR) infections in this demographic, with the goal of providing reference suggestions for the clinical prevention of MDR infections in elderly inpatients.

METHODS

Clinical data of patients were divided into the MDR-infected group (n = 488) and the MDR-uninfected group (n = 233) according to the results of drug sensitivity experiments, risk factors for MDR infection, and peripheral blood indicators related to MDR infections were analyzed using univariate and multivariate logistic regression in conjunction with the construction of a Chi-squared automatic interaction detector (CHAID) decision tree model, considering statistical significance at p < .05.

RESULTS

Of 721 patients, 488 multidrug-resistant strains were identified. Among them, with Staphylococcus spp. the most prevalent in 148 strains. The most frequent detection of MDR occurred in puncture fluid samples (167 cases). Univariate and multivariate regression analyses revealed that prolonged hospitalization, use of antibiotics preadmission, duration of antibiotics, invasive procedures or recent surgery, and coexisting lung disease were independent risk factors for contracting MDR. Subsequent analysis comparing the aforementioned influences with peripheral blood cells revealed associations between the number of antibiotic treatment days and increased neutrophil-to-lymphocyte ratio (NLR), platelet count-to-lymphocyte ratio (PLR), neutrophils, decreased lymphocytes, and increased eosinophils; preadmission antibiotic use correlated with increased PLR, NLR, neutrophils, and decreased lymphocytes; and invasive manipulation or surgery correlated with increased PLR and NLR.

CONCLUSIONS

Elevated NLR, PLR, neutrophils, lowered lymphocytes, and eosinophils may serve as early indicators of MDR infections in elderly hospitalized patients.

Gram-negative bacterial colonizations before bilateral lung transplant. The impact of 'targeted' versus 'standard' surgical prophylaxis

BACKGROUND

Infections are one of the most common causes of death after lung transplant (LT). However, the benefit of 'targeted' prophylaxis in LT recipients pre-colonized by Gram-negative (GN) bacteria is still unclear.

METHODS

All consecutive bilateral LT recipients admitted to the Intensive Care Unit of the University Hospital of Padua (February 2016-2023) were retrospectively screened. Only patients with pre-existing GN bacterial isolations were enrolled and analyzed according to the antimicrobial surgical prophylaxis ('standard' vs. 'targeted' on the preoperative bacterial isolation).

RESULTS

One hundred eighty-one LT recipients were screened, 46 enrolled. Twenty-two (48%) recipients were exposed to 'targeted' prophylaxis, while 24 (52%) to 'standard' prophylaxis. Overall prevalence of postoperative multi-drug resistant (MDR) GN bacteria isolation was 65%, with no differences between the two surgical prophylaxis (p = 0.364). Eleven (79%) patients treated with 'standard' prophylaxis and twelve (75%) with 'targeted' therapy reconfirmed the preoperative GN pathogen (p = 0.999). The prevalence of postoperative infections due to MDR GN bacteria was 50%. Of these recipients, 4 belonged to the 'standard' and 11 to the 'targeted' prophylaxis (p = 0.027).

CONCLUSIONS

The administration of a 'targeted' prophylaxis in LT pre-colonized recipients seemed not to prevent the occurrence of postoperative MDR GN infections.

The effect of infectious diseases on lung transplantation in Japan

Lung transplantation in Japan is an increasingly accessible treatment option for end-stage lung disease; however, the lack of donor organs is a persisting challenge. Five- and 10-year survival rates of lung transplant recipients in Japan are comparable, if not superior, to international standards. The outcomes of lung transplantation in Japan are likely affected by multiple factors. Infectious disease complications are a significant burden to transplant recipients and account for approximately 30% of recipient mortality in Japan, presenting a major challenge in peri-transplant management. Herein, we explore the current status of infectious disease epidemiology, available evidence surrounding infectious diseases in lung transplantation, and potentially influential factors pertinent to lung transplantation outcomes in Japan. Although infection remains the major cause of morbidity and mortality associated with lung transplantation in Japan, there is limited data and evidence. Despite some uncertainties, publicly available data suggests a low rate of antimicrobial resistance in Gram-negative bacteria and a distinct set of endemic pathogens that recipients may encounter. As a countermeasure against the burden of infectious diseases, 8 out of 10 transplant centers in Japan have a dedicated infectious diseases department. Despite these efforts, specific surveillance, prevention, and management are indispensable to improving post-transplantation infectious disease management. We accordingly lay out potential areas for improving infectious disease-related outcomes among lung transplant recipients in Japan.

Fungal Infections and Colonization after Bilateral Lung Transplant: A Six-Year Single-Center Experience

Fungal infections (FIs) are one of the leading causes of morbidity and mortality within the first year of lung transplant (LT) in LT recipients (LTRs). Their prompt identification and treatment are crucial for a favorable LTR outcome. The objectives of our study were to assess (i) the FI incidence and colonization during the first year after a bilateral LT, (ii) the risk factors associated with FI and colonization, and (iii) the differences in fungal incidence according to the different prophylactic strategies. All bilateral LTRs admitted to the intensive care unit of Padua University Hospital were retrospectively screened, excluding patients <18 years of age, those who had been re-transplanted, and those who had received ventilation and/or extracorporeal membrane oxygenation before LT. Overall, 157 patients were included. A total of 13 (8%) patients developed FI, and 36 (23%) developed colonization, which was mostly due to Aspergillus spp. We did not identify independent risk factors for FI. Groups of patients receiving different prophylactic strategies reported a similar incidence of both FI and colonization. The incidence of FI and fungal colonization was 8% and 23%, respectively, with no differences between different antifungal prophylaxes or identified predisposing factors. Further studies with larger numbers are needed to confirm our results.

An Emerging Issue: Carbapenem-Resistant Enterobacteriaceae in Solid-Organ Transplantation

OBJECTIVES

Bloodstream infections caused by carbapenem-resistant bacteria have increased globally. Solid-organ transplant recipients are more prone to these infections. This study aimed to compare the clinical courses of carbapenem-susceptible and carbapenem-resistant Enterobacteriaceae bloodstream infections and to identify risk factors for carbapenem resistance in solid-organ transplant recipients.

MATERIALS AND METHODS

For this retrospective descriptive study, data for solid-organ transplant recipients (age ≥18) treated from 2015 to 2022 were obtained from medical records. Enterobacteriaceaepositive blood culture was screened from laboratory data.

RESULTS

Among 72 patients, there were 100 bacteremia episodes. Patients included 40 kidney (55.6%), 21 liver (29.2%), 7 heart (9.7%), and 4 combined liver and kidney (5.6%) transplant recipients. Fifty-seven bacteremia episodes were recorded between 2015 and 2020, and 43 bacteremia episodes were recorded between 2020 and 2022. Carbapenem resistance was reported in 15.8% of patients before 2020, whereas this rate increased to 39.5% after 2020 (P = .007). Pitt bacteremia score ≥4 (P < .001), Charlson comorbidity index ≥4 (P = .021), chronic liver disease (P = .015), septic shock at admission (P = .001), hypotension at admission (P = .006), bacteremia episodes 48 hours after hospitalization (P = .004), hospitalization in the past 3 months (P = .004), and prior invasive procedure (P = .043) were significant factors for carbapenem resistance. Logistic regression analysis showed that bacteremia 48 hours after hospitalization (P = .002) and hospitalization in the past 3 months (P = .006) were independent risk factors.

CONCLUSIONS

Carbapenem resistance increased significantly over the years. Bacteremia 48 hours after hospitalization and hospitalization within the past 3 months were determined to be risk factors for carbapenem resistance. Carbapenem-resistant infections are still nosocomial infections. Patients should be hospitalized for as a short time as possible, and both patients and their physicians should follow infection control and prevention methods.