Mediastinitis in heart and lung transplantation: 15 years experience

Infections in Heart and Lung Transplant Recipients

Infections in heart and lung transplant recipients are complex and heterogeneous. This article reviews the epidemiology, risk factors, specific clinical syndromes, and most frequent opportunistic infections in heart and/or lung transplant recipients that will be encountered in the intensive care unit and will provide a practical approach of empirical management.

Bacterial infections in lung transplantation

Lung transplantation has lower survival rates compared to other than other solid organ transplants (SOT) due to higher rates of infection and rejection-related complications, and bacterial infections (BI) are the most frequent infectious complications. Excess morbidity and mortality are not only a direct consequence of these BI, but so are subsequent loss of allograft tolerance, rejection, and chronic lung allograft dysfunction due to bronchiolitis obliterans syndrome (BOS). A wide variety of pathogens can cause infections in lung transplant recipients (LTRs), including a number of nosocomial pathogens and other multidrug-resistant (MDR) pathogens. Although pneumonia and intrathoracic infections predominate, LTRs are at risk of a number of types of infections. Risk factors include altered anatomy and function of airways, impaired immunity, the microbial flora of the donor and recipient, underlying medical conditions, and genetic factors. Further work on immune monitoring has the potential to improve outcomes. The infecting agents can be derived from the donor lung, pre-existing recipient flora, or acquired from the environment over time. Certain infections may preclude lung transplantation, but this varies from center to center, and more recent studies suggest fewer patients should be disqualified. New molecular methods allow microbiome studies of the lung, gut, and other sites that may further our knowledge of how airway colonization can result in infection and allograft loss. Surveillance, early diagnosis, and aggressive antimicrobial therapy of BI is critical in LTRs. Antibiotic resistance is a major barrier to successful management of these infections. The availability of new agents for MDR Gram-negatives may improve outcomes. Other new therapies, such as bacteriophage therapy, show promise for the future. Finally, it is important to prevent infections through peri-transplant prophylaxis, vaccination, and infection control measures.

Case Report on Sternal Osteomyelitis by Trichosporon inkin Complicating Lung Transplantation: Effective Treatment With Vacuum-Assisted Closure and Surgical Reconstruction

Sternal osteomyelitis is a serious complication that significantly increases morbidity and mortality after thoracic surgery. We describe a case of sternal osteomyelitis by Trichosporon inkin following lung transplantation and the excellent results achieved with vacuum-assisted closure therapy.

Complications of Lung Transplantation: Update on Imaging Manifestations and Management

As lung transplantation has become the most effective definitive treatment option for end-stage chronic respiratory diseases, yearly rates of this surgery have been steadily increasing. Despite improvement in surgical techniques and medical management of transplant recipients, complications from lung transplantation are a major cause of morbidity and mortality. Some of these complications can be classified on the basis of the time they typically occur after lung transplantation, while others may occur at any time. Imaging studies, in conjunction with clinical and laboratory evaluation, are key components in diagnosing and monitoring these conditions. Therefore, radiologists play a critical role in recognizing and communicating findings suggestive of lung transplantation complications. A description of imaging features of the most common lung transplantation complications, including surgical, medical, immunologic, and infectious complications, as well as an update on their management, will be reviewed here. Keywords: Pulmonary, Thorax, Surgery, Transplantation Supplemental material is available for this article. © RSNA, 2021.

Management and prophylaxis of bacterial and mycobacterial infections among lung transplant recipients

Bacterial and mycobacterial infections are associated with morbidity and mortality in lung transplant recipients. Infectious complications are categorized by timing post-transplant: <1, 1–6, and >6 months. The first month post-transplant is associated with the highest risk of infection. During this period, infections are most commonly healthcare-associated, and include infections related to surgical complications. The lungs and bloodstream are common sites of infections. Common healthcare-associated organisms include methicillin-resistant Staphylococcus aureus (MRSA), Gram-negative bacilli such as Pseudomonas aeruginosa, and Clostridioides difficile. More than 1-month post-transplant, opportunistic infections can occur. Tuberculosis occurs in 0.8–10% of lung transplant recipients which reflects variation in background prevalence. The majority of post-transplant tuberculosis stems from reactivation of untreated or undiagnosed latent tuberculosis. Most post-transplant tuberculosis occurs in the lungs and develops within a year of transplant. Non-tuberculous mycobacteria commonly colonize the lungs of lung transplant candidates and are often hard to eradicate even with prolonged courses of antimycobacterial agents. Drug interactions between antimycobacterial agents and calcineurin and mTOR inhibitors also complicates treatment post-transplant. Given that infection adversely impacts outcomes after lung transplant, and that anti-infective therapy is often less effective after transplant, infection prevention is key to long-term success. A comprehensive approach that includes pre-transplant evaluation, perioperative prophylaxis, long-term antimicrobial prophylaxis, immunization, and safer living at home and in the community, should be employed to minimize the risk of infection.

Surgical site infections: Guidelines from the American Society of Transplantation Infectious Diseases Community of Practice

These guidelines from the Infectious Diseases Community of Practice of the American Society of Transplantation review the diagnosis, prevention, and management of post-operative surgical site infections (SSIs) in solid organ transplantation. SSIs are a significant cause of morbidity and mortality in SOT recipients. Depending on the organ transplanted, SSIs occur in 3%-53% of patients, with the highest rates observed in small bowel/multivisceral, liver, and pancreas transplant recipients. These infections are classified by increasing invasiveness as superficial incisional, deep incisional, or organ/space SSIs. The spectrum of organisms implicated in SSIs in SOT recipients is more diverse than the general population due to other important factors such as the underlying end-stage organ failure, immunosuppression, prolonged hospitalizations, organ transportation/preservation, and previous exposures to antibiotics in donors and recipients that could predispose to infections with multidrug-resistant organisms. In this guideline, we describe the epidemiology, clinical presentation, differential diagnosis, potential pathogens, and management. We also provide recommendations for the selection, dosing, and duration of peri-operative antibiotic prophylaxis to minimize post-operative SSIs.

Infections in Heart, Lung, and Heart-Lung Transplantation

Half a century has passed since the first orthotopic heart transplant took place. Surgical innovations allowed for heart, lung, and heart-lung transplantation to save lives of patients with incurable chronic cardiopulmonary conditions. The complexity of the surgical interventions, chronic host health conditions, and antirejection immunosuppressive medications makes infectious complications common. Infections have remained one of the main barriers for successful transplantation and a source of significant morbidity and mortality. Recognition of infections and its management in this setting require outstanding clinical skills since transplant recipients may not exhibit classic signs or symptoms of disease, and laboratory work has some pitfalls. The prevention, identification, and management of infectious diseases complications in this population are a priority to undertake to improve the medical outcomes of transplantation. Herein, we reviewed the historical aspects, epidemiology, and prophylaxis of infections in heart, lung, and heart-lung transplantation. We also discuss the most prevalent organisms affecting the host and the organ systems involved.

Infections in Heart and Lung Transplant Recipients

Infections in heart and lung transplant recipients are complex and heterogeneous. This article reviews the epidemiology, risk factors, specific clinical syndromes, and most frequent opportunistic infections in heart and/or lung transplant recipients that will be encountered in the intensive care unit and will provide a practical approach of empirical management.

Severe infections in critically ill solid organ transplant recipients

BACKGROUND

Severe infections are among the most common causes of death in immunocompromised patients admitted to the intensive care unit. The epidemiology, diagnosis and treatment of these infections has evolved in the last decade.

AIMS

We aim to provide a comprehensive review of these severe infections in this population.

SOURCES

Review of the literature pertaining to severe infections in critically ill solid organ transplant recipients. PubMed and Embase databases were searched for documents published since database inception until November 2017.

CONTENT

The epidemiology of severe infections has changed in the immunocompromised patients. This population is presenting to the intensive care unit with specific transplantation procedure-related infections, device-associated infections, a multitude of opportunistic viral infections, an increasing number of nosocomial infections and bacterial diseases with a more limited therapeutic armamentarium. Both molecular diagnostics and imaging techniques have had substantial progress in the last decade, which will, we hope, translate into faster and more precise diagnoses, as well as more optimal empirical treatment de-escalation.

IMPLICATIONS

The key clinical elements to improve the outcome of critically ill solid organ transplant recipients depend on the knowledge of geographic epidemiology, specific surgical procedures, net state of immunosuppression, hospital microbial ecology, aggressive diagnostic strategy and search for source control, rapid initiation of antimicrobials and minimization of iatrogenic immunosuppression.

Infections in pediatric solid-organ transplant recipients

Solid-organ transplantation in pediatrics can be a life-saving procedure, but it cannot be accomplished without risk of infection-related morbidity and mortality. Evaluation of the recipient during candidacy and donor during evaluation can assist with identification of risk. Further, risk of infection from the surgical procedure can be mitigated through careful planning and attention to infection prevention processes. Finally, early recognition of infection posttransplant can limit the impact of these events.

Sepsis and Challenging Infections in the Immunosuppressed Patient in the Intensive Care Unit

In 2017, most intensive care units (ICUs) worldwide are admitting a growing population of immunosuppressed patients. The most common causes of pre-ICU immunosuppression are solid organ transplantation, hematopoietic stem cell transplantation, and infection due to human immunodeficiency virus. In this article, the authors review the most frequent infections that cause critical care illness in each of these 3 immunosuppressed patient populations.

Fungal Infections After Lung Transplantation

Infection remains a significant source of morbidity and mortality after lung transplant, including fungal infection. Various antifungal prophylactic agents are administered for a variable duration after transplant with the goal of preventing invasive fungal infections. Alternatively, some programs target the use of antifungal agents only in those colonized with Aspergillus spp. Despite prophylaxis or preemptive therapy, a significant number of invasive fungal infections occur after lung transplant. Risk factors for fungal infections include single lung transplant, pretransplant Aspergillus colonization, environmental risks, structural lung disease such as cystic fibrosis, augmented immunosuppression, sinus disease, and use of indwelling airway stents.

Novel Method of Infection Prophylaxis in Heart Transplantation by Retrosternal Gentamycin Sponge Application

BACKGROUND

Surgical wound infections are more frequent in patients undergoing heart transplantation than in other heart surgery patients. There is a wide spread of sternal wound infection incidence in transplant patients ranging from 4% to 40%. It is first study describing local gentamicin sponge application during heart transplantation procedure.

MATERIALS AND METHODS

We enrolled 75 patients in a retrospective, single-center study, including 25 patients who underwent orthotopic heart transplantation (heart transplant group) and 50 in the cardiac surgery group. They were in mean age of 49 ± 12 years and 51 ± 13 years in heart transplantation and cardiac surgery group, respectively. A gentamicin sponge was inserted intraoperatively between sternal borders before chest closure in all heart transplantation patients.

RESULTS

There was 1 early death (4%) on postoperative day 7 owing to Clostridium difficile infection in the heart transplant group. There was 1 death (2%) in the cardiac surgery group owing to multiorgan failure secondary to perioperative heart ischemia. There was neither bacterial sternal wound infection nor sternal instability in the heart transplant group. None of the patients who had gentamicin sponge applied had wound healing problems. Two patients (4%) had a deep sternal wound infection in the cardiac surgery group, who had no sponge application; 1 (2%) was treated by surgical debridement and active drainage and 1 (2%) by vacuum therapy. There were 11 patients (44%) discharged on insulin therapy in the heart transplant group and 21 (21%) in the cardiac surgery group. Mean overall postoperative hospital stay was 35 ± 19 days in the heart transplant group and 10 ± 4 days in the cardiac surgery group.

CONCLUSIONS

Gentamicin sponge is an effective local infection prophylaxis in heart transplant patients.

[Nosocomial infection in patients receiving a solid organ transplant or haematopoietic stem cell transplant]

Bacterial infections are the most common infections in solid organ transplant recipients. These infections occur mainly in the first month after transplantation and are hospital-acquired. Nosocomial infections cause significant morbidity and are the most common cause of mortality in this early period of transplantation. These infections are caused by multi-drug resistant (MDR) microorganisms, mainly Gram-negative enterobacteria, non-fermentative Gram-negative bacilli, enterococci, and staphylococci. The patients at risk of developing nosocomial bacterial infections are those previously colonized with MDR bacteria while on the transplant waiting list. Intravascular catheters, the urinary tract, the lungs, and surgical wounds are the most frequent sources of infection. Preventive measures are the same as those applied in non-immunocompromised, hospitalized patients except in patients at high risk for developing fungal infection. These patients need antifungal therapy during their hospitalization, and for preventing some bacterial infections in the early transplant period, patients need vaccinations on the waiting list according to the current recommendations. Although morbidity and mortality related to infectious diseases have decreased during the last few years in haematopoietic stem cell transplant recipients, they are still one of the most important complications in this population. Furthermore, as occurs in the general population, the incidence of nosocomial infections has increased during the different phases of transplantation. It is difficult to establish general preventive measures in these patients, as there are many risk factors conditioning these infections. Firstly, they undergo multiple antibiotic treatments and interventions; secondly, there is a wide variability in the degree of neutropenia and immunosuppression among patients, and finally they combine hospital and home stay during the transplant process. However, some simple measures could be implemented to improve the current situation.

Multidrug-resistant bacterial infection in solid organ transplant recipients

The most frequent complication from infection after solid organ transplantation is bacterial infection. This complication is more frequent in organ transplantation involving the abdominal cavity, such as liver or pancreas transplantation, and less frequent in heart transplant recipients. The sources, clinical characteristics, antibiotic resistance and clinical outcomes vary according to the time of onset after transplantation. Most bacterial infections during the first month post-transplantation are hospital acquired, and there is usually a high incidence of multidrug-resistant bacterial infections. The higher incidence of complications from bacterial infection in the first month post-transplantation may be associated with high morbidity. Of special interest due to their frequency are infections by S. aureus, enterococci, Gram-negative enteric and non-fermentative bacilli. Opportunistic bacterial infections may occur at any time on the posttransplant timeline, but are more frequent between months two and six, the period in which immunosuppression is higher. The most frequent bacterial species causing opportunistic infections in organ transplant recipients are Listeria monocytogenes and Nocardia spp. After month six, posttransplantation solid organ transplant patients usually develop conventional community-acquired bacterial infections, especially urinary tract infections by E. coli and S. pneumoniae pneumonia. In this article we review the clinical characteristics, epidemiology, diagnosis and prognosis of bacterial infections in solid organ transplant patients.

Surgical wound complications after heart transplantation

Surgical wound complications are more frequent in patients undergoing heart transplantation than in other heart surgery patients. This is probably attributed to the presence of additional risk factors in these patients, such as immunosuppression, mechanical support through assist devices and generally poor health. Analyses of wound infections in heart transplantation are based on smaller patient population than those for general heart surgery, and the reported incidences vary largely. The identification of specific risk factors in heart transplant recipients to date is mainly based on retrospective case-control studies in small patient cohorts, the results are controversial, and the comparability of data is limited because of the lack of application of consistent definitions. The impact of immunosuppression and especially immunosuppression with mammalian target of rapamycin (mTOR) inhibitors on the development of surgical wound complications has been widely discussed following reports of increased occurrence with sirolimus. However, nonheart-transplant specific risk factors should also be considered to develop risk profiles and treatment algorithms for individual patients. Data on surgical wound complications in general heart surgery patients and in heart transplant recipients are compared, the impact of modern immunosuppression reviewed, and areas for further investigation discussed.

[Medical complications of lung transplantation]

In 2010, lung transplantation is a valuable therapeutic option for a number of patients suffering from of end-stage non-neoplastic pulmonary diseases. The patients frequently regain a very good quality of life, however, long-term survival is often hampered by the development of complications such as the bronchiolitis obliterans syndrome, metabolic and infectious complications. As the bronchiolitis obliterans syndrome is the first cause of death in the medium and long term, an intense immunosuppressive treatment is maintained for life in order to prevent or stabilize this complication. The immunosuppression on the other hand induces a number of potentially severe complications including metabolic complications, infections and malignancies. The most frequent metabolic complications are arterial hypertension, chronic renal insufficiency, diabetes, hyperlipidemia and osteoporosis. Bacterial, viral and fungal infections are the second cause of mortality. They are to be considered as medical emergencies and require urgent assessment and targeted therapy after microbiologic specimens have been obtained. They should not, under any circumstances, be treated empirically and it has also to be kept in mind that the lung transplant recipient may present several concomitant infections. The most frequent malignancies are skin cancers, the post-transplant lymphoproliferative disorders, Kaposi's sarcoma and some types of bronchogenic carcinomas, head/neck and digestive cancers. Lung transplantation is no longer an exceptional procedure; thus, the pulmonologist will be confronted with such patients and should be able to recognize the symptoms and signs of the principal non-surgical complications. The goal of this review is to give a general overview of the most frequently encountered complications. Their assessment and treatment, though, will most often require the input of other specialists and a multidisciplinary and transversal approach.

Preliminary report of the safety and efficacy of hyperbaric oxygen therapy for specific complications of lung transplantation

BACKGROUND

Lung transplantation (LTx) is a complex therapy requiring immunosuppression and is associated with significant infective morbidity and mortality. Hyperbaric oxygen (HBO) therapy has been used successfully in the treatment of specific serious infections, ischemic injuries and cerebral arterial gas embolism. The purpose of this study was to evaluate the efficacy and safety of HBO therapy after LTx, generally as indicated for refractory infectious complications.

METHODS

This investigation was a retrospective study of all lung transplant recipients treated with HBO therapy at the Alfred Hospital between March 1990 and August 2005.

RESULTS

In this study we describe 9 patients (1.7%) from a total of 544 overall lung transplants performed over the period. Indications included: sternal osteomyelitis (n = 4); refractory cellulitis (n = 2); refractory septic arthritis (n = 1); ischemic toes (n = 1); and cerebral arterial gas embolism (n = 1). The patients received 1 to 25 HBO treatments at 100% Fio(2) and 100 to 180 kPa for 100 minutes per treatment. The treatment was generally well tolerated, although 2 patients ceased therapy prematurely due to a seizure and ear barotrauma (n = 1 each). Five patients had complete resolution of these life-threatening complications. Long-term survival and graft function were excellent, although graft function temporarily fell.

CONCLUSIONS

HBO is a safe therapy for traditional HBO indications after LTx and appears useful, particularly in the management of infectious complications, whereas other therapies have failed or are contraindicated.

Acinetobacter mediastinitis in a heart transplant patient

We report a 56-year-old who underwent orthotopic heart transplantation following left ventricular assist device bridge to transplantation. His postoperative course was complicated by severe sternal wound infection with Acinetobacter species requiring extensive debridement and reconstruction with a pectoralis major flap. This was followed by a total sternectomy, pectoralis flap debridement, and vacuum-assisted dressing.

Investigation of mediastinitis due to coagulase-negative staphylococci after cardiothoracic surgery

Six cases of coagulase-negative staphylococcal mediastinitis were identified in the latter half of 1999. A new preoperative cleansing solution was suspected by hospital staff to be a factor in the outbreak. We evaluated this possible risk factor along with other known and suspected surgical site infection risk factors in this case-control study.

The Use of Vacuum-Assisted Closure in the Treatment of Post-transplant Wound Infections: A Case Series

We present 6 cases of the successful use of vacuum-assisted closure dressings as the primary treatment of wound infection after thoracic organ transplantation. In a series of 160 successive transplant operations, deep wound infections developed in 6 patients (3.7%). These all fully resolved over 3 to 29 days with the use of vacuum dressings. We believe vacuum-assisted closure therapy in the context of heart and lung transplantation is effective, well tolerated, and avoids the need for repeated surgical debridement and reconstruction.

De Novo Immunosuppression With Sirolimus and Tacrolimus in Heart Transplant Recipients Compared With Cyclosporine and Mycophenolate Mofetil: A One-Year Follow-Up Analysis

BACKGROUND

Limited data exist regarding the safety and efficacy of sirolimus in combination with a calcineurin inhibitor in heart transplant recipients.

METHODS

From January 2001 to June 2002, 31 de novo heart transplant recipients (treatment group) received a combination of sirolimus, tacrolimus, low-dose rabbit antithymocyte globulin, and glucocorticoids. Outcomes, such as actuarial survival, rate of rejection, incidence of infection, probability of developing diabetes mellitus, renal function, platelet and white blood cell counts, and incidence of coronary artery disease at 1 year, were compared with a cohort of 25 patients (control group) who underwent transplantation primarily in 2000 and in early 2002 treated with cyclosporine, mycophenolate mofetil, and glucocorticoids. All patients were followed up for at least 12 months.

RESULTS

Kaplan-Meier actuarial 1-year survival rates were equivalent between groups (97% for the treatment group and 88% for the control group), as was freedom from allograft rejection (48% and 42% for treatment and control groups, respectively). No cases of transplant arteriopathy were noted within the first posttransplantation year. Renal function was not significantly affected in either group. There was a striking increased incidence of mediastinitis in the treatment group (19%) versus 0% in the control group (P = .02). Tacrolimus-sirolimus therapy was associated with a nearly 11-fold increased incidence of new-onset diabetes mellitus as well (P = .004).

CONCLUSION

Tacrolimus, sirolimus, and steroids (following low-dose rabbit antithymocyte globulin) were associated with an increased incidence of mediastinitis and posttransplantation diabetes mellitus. No obvious long-term benefit on survival, arteriopathy, or renal function was noted.

Postoperative mediastinitis in children: epidemiology, microbiology and risk factors for Gram-negative pathogens

BACKGROUND

Mediastinitis, although an infrequent complication of median sternotomy, represents a significant source of morbidity and mortality.

OBJECTIVE

To determine the incidence and describe the epidemiology and microbiology of mediastinitis in children after cardiac surgery and to identify risk factors for the development of Gram-negative mediastinitis.

STUDY DESIGN

This was a retrospective case-control study nested within the cohort of children, birth to 18 years of age, undergoing median sternotomy between January 1, 1995 and December 31, 2003.

RESULTS

Forty-three cases of mediastinitis were identified. The incidence of mediastinitis was 1.4%. Median patient age at time of inciting sternotomy was 32 days (interquartile range, 5 days-9 months). Twenty-three (54%) cases occurred in girls. Median time to onset of infection after surgery was 11 days (range, 4-34 days). Overall Gram-positive organisms were present in 29 (67%) cases, and Gram-negative organisms were present in 13 (30%) cases. The organisms most commonly isolated from mediastinal culture were Staphylococcus aureus (46%), coagulase-negative staphylococci (17%) and Pseudomonas aeruginosa (17%). The rate of concurrent bacteremia was 53% (95% confidence interval, 38-69%). In multivariable analysis, delayed sternal closure was an independent risk factor for the development of Gram-negative mediastinitis (odds ratio, 9.3; 95% confidence interval, 1.5-56.8; P = 0.016).

CONCLUSIONS

Although Gram-positive organisms were the most common cause of infection, Gram-negative organisms accounted for one-third of all isolates. More than one-half of patients with mediastinitis had concurrent bacteremia. Delayed sternal closure was an independent risk factor for Gram-negative mediastinitis.

Lung transplantation for emphysema

Great strides have been made in lung transplantation in the past two decades. Changes in technique, immunosuppression regimens, and treatment of infectious complications have led to improvements in survival and functional results. Current areas of discussion concern the use of single lung transplantation versus bilateral sequential lung transplantation and the criteria for allocating donor lungs. This article reviews the current state of lung transplantation for emphysema and provides insight from more than one decade of experience with Washington University's lung transplant program.