Microbiologic features and outcome of pneumonia in transplanted patients

Epidemiology and Management of Infections in Liver Transplant Recipients

Background: Improvements in liver transplant (LT) outcomes are attributed to advances in surgical techniques, use of potent immunosuppressants, and rigorous pre-LT testing. Despite these improvements, post-LT infections remain the most common complication in this population. Bacteria constitute the most common infectious agents, while fungal and viral infections are also frequently encountered. Multi-drug-resistant bacterial infections develop because of polymicrobial overuse and prolonged hospital stays. Immediate post-LT infections are commonly caused by viruses. Conclusions: Appropriate vaccination, screening of both donor and recipients before LT and antiviral prophylaxis in high-risk individuals are recommended. Antimicrobial drug resistance is common in high-risk LT and associated with poor outcomes; epidemiology and management of these cases is discussed. Additionally, we also discuss the effect of coronavirus disease 2019 (COVID-19) infection and monkeypox in the LT population.

Aetiology, management, and outcome of lower respiratory tract infection in renal allograft recipients - A report from a tropical country

Introduction

Lower respiratory tract infections (LRTIs) among renal transplant recipients (RTRs) are a significant cause of morbidity and mortality. This study aimed to analyse the aetiology, outcome, and risk factors associated with mortality.

Methods

We analysed baseline transplant characteristics, symptoms, hospital course, laboratory, serological and microbial results, and their association with the outcome of all RTRs between January 2011 and December 2019.

Results

A total of 206 LRTI patients out of 1051 RTRs were analysed. The incidence proportion was nearly 22 episodes per 1000 patients per year. The mean age was 39.3 years, with male predominance. Bacterial was the most common aetiology (53%), and staphylococcus was the most common species. Among the fungal causes (14%), 68% had aspergillus infection. More than one-third RTRs died during the hospital course mainly because of bacterial causes (42.6%). The aspergillus infection was the most common fungus associated with 50% mortality. On multi-variate analysis, sepsis, septic shock, and the need for mechanical ventilation independently predicted mortality.

Conclusion

Bacterial aetiology was the most common cause; though the fungal aetiology was seen less, it was associated with higher mortality. Mortality in RTR with LRTI was associated with sepsis, septic shock, and the need for mechanical ventilation.

Bacterial and Viral Infection and Sepsis in Kidney Transplanted Patients

Kidney transplanted patients are a unique population with intrinsic susceptibility to viral and bacterial infections, mainly (but not exclusively) due to continuous immunosuppression. In this setting, infectious episodes remain among the most important causes of death, with different risks according to the degree of immunosuppression, time after transplantation, type of infection, and patient conditions. Prevention, early diagnosis, and appropriate therapy are the goals of infective management, taking into account that some specific characteristics of transplanted patients may cause a delay (the absence of fever or inflammatory symptoms, the negativity of serological tests commonly adopted for the general population, or the atypical anatomical presentation depending on the surgical site and graft implantation). This review considers the recent available findings of the most common viral and bacterial infection in kidney transplanted patients and explores risk factors and outcomes in septic evolution.

Posttransplant Pneumonia Among Solid Organ Transplant Recipients Followed in Intensive Care Unit

OBJECTIVES

Pneumonia is a significant cause of morbidity and mortality in solid-organ transplant recipients. We studied the demographic characteristics, respiratory management, and outcomes of solid-organ transplant recipients with pneumonia in an intensive care unit.

MATERIALS AND METHODS

There have been 2857 kidney, 687 liver, and 142 heart transplants performed between October 16, 1985, and February 28, 2021, at our center. We retrospectively analyzed records for 51 of 193 recipients with pneumonia during the posttransplant period between January 1, 2016, and December 31, 2018.

RESULTS

Fifty-one of 193 recipients were followed in the intensive care unit. Mean age was 45.4 ± 16.6 years among 42 male (82.4%) and 9 female (17.6%) recipients. Twenty-six patients (51%) underwent kidney transplant, 14 (27.5%) liver transplant, 7 (13.7%) heart transplant, and 4 (7.8%) combined kidney and liver transplant. Most pneumonia episodes occurred 6 months after transplant (70.6%) with acute hypoxemic respiratory failure. Mean Acute Physiology and Chronic Health Evaluation System II score was 18.9 ± 7.7, and the Sequential Organ Failure Assessment score was 8.5 ± 3.9 at intensive care unit admission. Whereas 66.7% of pneumonia cases were nosocomial acquired, 33.3% were community acquired. The intensive care unit and 28-day mortality rates were 39.2% and 64.7%, respectively.

CONCLUSIONS

Solid-organ transplant recipients with pneumonia have been associated with poor prognosis. Our cohort followed in the intensive care unit comprised mostly patients with nosocomial pneumonia with acute hypoxemic respiratory failure, hospitalized 6 months after transplant with high Acute Physiology and Chronic Health Evaluation System II scores predictive of mortality. In this high-risk patient group, careful follow-up, early discovery of warning signs, and rapid treatment initiation could improve the outcomes in the intensive care unit.

Pneumococcal pneumonia in adult hospitalised solid organ transplant recipients: Nationwide, population-based surveillance

BACKGROUND

Pneumococcal disease poses a burden to the community in high risk population. Most early studies focused on invasive pneumococcal disease. However, the epidemiology of pneumococcal pneumonia (PP) requiring hospitalisation in solid organ transplant recipients (SOTRs) is poorly defined.

METHODS

We conducted a retrospective cohort study (January 1, 2000 and December 31, 2012) to evaluate the risk of PP requiring hospitalisation in SOTRs. SOTRs and non-SOT cohorts, propensity score-matched at a 1:1 ratio for age, sex, index date and underlying comorbidities, were identified from the National Health Insurance Research Database.

RESULTS

Each cohort consisted of 7507 patients. In the SOT cohort, 26 episodes of PP requiring hospitalisation were identified (incidence rate of 52.4 per 100,000 person-years). The risk of PP requiring hospitalisation in the SOT cohort was 1.50 times greater than in the non-SOT cohort [adjusted hazard ratio: 1.50, 95% confidence interval = 1.31-1.71, P < .001]. The nested case control study identified older age, kidney transplant, and concomitant chronic obstructive pulmonary disease, chronic kidney disease and heart failure as predictors of PP requiring hospitalisation in the SOT cohort. The highest risk period for PP requiring hospitalisation occurred within the first year of transplantation (36.47 per 1000 patients). Amongst kidney transplant recipients, patients with PP requiring hospitalisation exhibited higher cumulative incidences of graft failure than those without PP (log-rank test: P value = .004).

CONCLUSIONS

SOTRs are at risk of PP requiring hospitalisation with its attendant morbidity. Strategies to reduce risk of PP requiring hospitalisation using preventive vaccinations warrant further study.

Machine learning for the prediction of severe pneumonia during posttransplant hospitalization in recipients of a deceased-donor kidney transplant

Background

Pneumonia accounts for the majority of infection-related deaths after kidney transplantation. We aimed to build a predictive model based on machine learning for severe pneumonia in recipients of deceased-donor transplants within the perioperative period after surgery.

Methods

We collected the features of kidney transplant recipients and used a tree-based ensemble classification algorithm (Random Forest or AdaBoost) and a nonensemble classifier (support vector machine, Naïve Bayes, or logistic regression) to build the predictive models. We used the area under the precision-recall curve (AUPRC) and the area under the receiver operating characteristic curve (AUROC) to evaluate the predictive performance via ten-fold cross validation.

Results

Five hundred nineteen patients who underwent transplantation from January 2015 to December 2018 were included. Forty-three severe pneumonia episodes (8.3%) occurred during hospitalization after surgery. Significant differences in the recipients' age, diabetes status, HBsAg level, operation time, reoperation, usage of anti-fungal drugs, preoperative albumin and immunoglobulin levels, preoperative pulmonary lesions, and delayed graft function, as well as donor age, were observed between patients with and without severe pneumonia (P<0.05). We screened eight important features correlated with severe pneumonia using the recursive feature elimination method and then constructed a predictive model based on these features. The top three features were preoperative pulmonary lesions, reoperation and recipient age (with importance scores of 0.194, 0.124 and 0.078, respectively). Among the machine learning algorithms described above, the Random Forest algorithm displayed better predictive performance, with a sensitivity of 0.67, specificity of 0.97, positive likelihood ratio of 22.33, negative likelihood ratio of 0.34, AUROC of 0.91, and AUPRC of 0.72.

Conclusions

The Random Forest model is potentially useful for predicting severe pneumonia in kidney transplant recipients. Recipients with a potential preoperative potential pulmonary infection, who are of older age and who require reoperation should be monitored carefully to prevent the occurrence of severe pneumonia.

Pneumonia in solid organ transplantation: Guidelines from the American Society of Transplantation Infectious Diseases Community of Practice

These guidelines from the AST Infectious Diseases Community of Practice review the diagnosis and management of pneumonia in the post-transplant period. Clinical presentations and differential diagnosis for pneumonia in the solid organ transplant recipient are reviewed. A two-tier approach is proposed based on the net state of immunosuppression and the severity of presentation. With a lower risk of opportunistic, hospital-acquired, or exposure-specific pathogens and a non-severe presentation, empirical therapy may be initiated under close clinical observation. In all other patients, or those not responding to the initial therapy, a more aggressive diagnostic approach including sampling of tissue for microbiological and pathological testing is warranted. Given the broad range of potential pathogens, a microbiological diagnosis is often key for optimal care. Given the limited literature comparatively evaluating diagnostic approaches to pneumonia in the solid organ transplant recipient, much of the proposed diagnostic algorithm reflects clinical experience rather than evidence-based data. It should serve as a template which may be modified according to local needs. The same holds true for the suggested empiric therapies, which need to be adapted to the local resistance patterns. Further study is needed to comparatively evaluate diagnostic and empiric treatment strategies in SOT recipients.

Is hospital-acquired pneumonia different in transplant recipients?

Hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP) are serious complications in transplant patients. The aim of this review is to summarize the evidence regarding nosocomial pneumonia in transplant recipients, including HAP in non-ventilated patients and VAP, and to identify future directions for improvement.A comprehensive literature search in the PubMed/MEDLINE database was performed. Articles written in English and published between 1990 and November 2018 were included. HAP/VAP in transplant patients usually occurs early post-transplant, particularly during neutropenia in haematopoietic stem cell transplant recipients. Bacteria are the leading cause of nosocomial pneumonia for both immunocompetent and transplant recipients, being Gram negative organisms, and especially Pseudomonas aeruginosa, highly prevalent. Multidrug-resistant bacteria are of special concern. Pneumonia in the transplant setting may be caused by opportunistic pathogens, and the differential diagnosis needs to be extended to other non-infectious complications. The most relevant opportunistic pathogens are Aspergillus fumigatus, Pneumocystis jirovecii and cytomegalovirus. Nevertheless, they are an exceptional cause of nosocomial pneumonia, and usually occur in severely immunosuppressed patients not receiving antimicrobial prophylaxis. Performing bronchoalveolar lavage may improve the rate of aetiological diagnosis, leading to a change in therapeutic management and improved outcomes. The optimal length of antibiotic therapy for bacterial HAP/VAP has not been well defined, but it should perhaps be longer than in the general population. Mortality associated with HAP/VAP is high. HAP/VAP in transplant patients is frequent and is associated with increased mortality. There is room for improvement in gaining knowledge about the management of HAP/VAP in this population.

Infections in Liver Transplantation

Liver transplantation has become an important treatment modality for patients with end-stage liver disease/cirrhosis, acute liver failure, and hepatocellular carcinoma. Although surgical techniques and immunosuppressive regimens for liver transplantation have improved significantly over the past 20 years, infectious complications continue to contribute to the morbidity and mortality in this patient population. The use of standardized screening protocols for both donors and recipients, coupled with targeted prophylaxis against specific pathogens, has helped to mitigate the risk of infection in liver transplant recipients. Patients with chronic liver disease and cirrhosis have immunological deficits that place them at increased risk for infection while awaiting liver transplantation. The patient undergoing liver transplantation is prone to develop healthcare-acquired infections due to multidrug-resistant organisms that could potentially affect patient outcomes after transplantation. The complex nature of liver transplant surgery that involves multiple vascular and hepatobiliary anastomoses further increases the risk of infection after liver transplantation. During the early post-transplantation period, healthcare-acquired bacterial and fungal infections are the most common types of infection encountered in liver transplant recipients. The period of maximal immunosuppression that occurs at 1–6 months after transplantation can be complicated by opportunistic infections due to both primary infection and reactivation of latent infection. Severe community-acquired infections can complicate the course of liver transplantation beyond 12 months after transplant surgery. This chapter provides an overview of liver transplantation including indications, donor-recipient selection criteria, surgical procedures, and immunosuppressive therapies. A focus on infections in patients with chronic liver disease/cirrhosis and an overview of the specific infectious complications in liver transplant recipients are presented.

Early Bacterial Pneumonia After Hepatic Transplantation: Epidemiologic Profile

BACKGROUND

Postoperative pulmonary complications are major cause of morbidity and mortality in patients receiving liver transplantation (LT), particularly bacterial pneumonia occurring within the first 100 days after transplantation. Our aim in this study was to determine the incidence, microorganisms involved, associated factors, and morbidity of bacterial pneumonia presenting in the first 100 days posttransplant.

METHODS

We performed a cohort study in which patients receiving liver transplantation were included prospectively in our national database (Database of Infections in Transplantation of Solid Organs). The study period was from July 14, 2009 to July 24, 2015.

RESULTS

One hundred six patients were transplanted during the 6-year period. We documented 9 bacterial pneumonia cases with an incidence of 8.5 per 100 patients; 2 patients had hospital-acquired pneumonia (HAP) and 7 had ventilator-associated pneumonia (VAP). In 4 of the 9 bacterial pneumonia cases, patients presented with bacteremia. Eleven microorganisms were isolated these 9 patients. Microbiologic diagnosis methods included 5 cases of alveolar bronchoalveolar lavage (BAL), 1 case of BAL and pleural fluid puncture, 1 case of pleural fluid puncture, and 1 case through sputum study. Of the 11 isolated organisms, 9 corresponded to Gram-negative bacilli (GNB): Klebsiella spp, n = 3; Acinetobacter baumannii, n = 4; Morganella morganii, n = 1; and Pseudomonas aeruginosa, n = 1. Regarding the resistance profile, 7 presented with a multiresistance profile (MDR) and extreme resistance (XDR). Univariate analysis identified the Model for End-Stage Liver Disease (MELD) pretransplant score as a factor associated with developing pneumonia (P < .001, 95% confidence interval [CI] 2.872-10.167), and early extubation, before 8 hours posttransplant, as a protective factor (P = .008; relative risk [RR] 0.124; 95% CI 0 .041-0.377). Hospital stay was longer in patients with pneumonia compared to those without pneumonia (P < .0001, 95% CI 17.79-43.11 days). There was also an increased risk of death in patients with pneumonia (RR 17.963; 95% CI 5106-63,195).

CONCLUSIONS

Early bacterial pneumonia after hepatic transplantation is associated with higher morbidity and mortality. At our center, 4 of 9 patients had bacteremia. GNB cases with MDR and XDR profiles are predominant. Early extubation is a protective factor.

Pneumonia in Renal Transplant Recipients: A Single-Center Study

OBJECTIVES

Pulmonary infections are a significant cause of morbidity and mortality in solid-organ transplant recipients despite enhanced facilities for perioperative care. The aim of this study was to evaluate the demographic characteristics, clinical course, and outcomes of renal transplant recipients with pneumonia.

MATERIALS AND METHODS

The medical records of all renal transplant recipients from January 2010 to December 2014 were retrospectively reviewed, and patients diagnosed with pneumonia according to Centers for Disease Control and Prevention criteria were evaluated. Pneumonia was classified as community acquired or nosocomial. Patient demographics, microbiologic findings, need for intensive care/mechanical ventilation over the course of treatment, and information about clinical follow-up and mortality were all recorded.

RESULTS

Eighteen (13.4%) of 134 renal transplant recipients had 25 pneumonia episodes within the study period. More than half (56%) of the pneumonia episodes developed within the first 6 months of transplant, whereas 44% developed after 6 months (all > 1 year). Eight cases (32%) were considered nosocomial pneumonia, and 17 (68%) were considered community-acquired pneumonia. Bacteria were the most common cause of pneumonia (28%), and fungi ranked second (8%). No viral or mycobacterial agents were detected. No patients required prolonged mechanical ventilation. No statistically significant difference was found in the need for intensive care or regarding mortality between patients with nosocomial and community-acquired pneumonia. Two patients (11%) died, and all remaining patients recovered.

CONCLUSIONS

The present study confirmed that pneumonia after renal transplant is not a rare complication but a significant cause of morbidity. Long-term and close follow-up for pneumonia is necessary after renal transplant.

Prevalence of Pulmonary Infections Caused by Atypical Pathogens in non-HIV Immunocompromised Patients

Although atypical bacteria are important causes of lower airway infections, data on their role in immunocompromised patients are scarce. The aim of the study was to evaluate the prevalence of atypical pulmonary infections in patients with various types of immunosuppression, and to analyze clinical characteristics of these infections. Eighty non-HIV immunocompromised patients with different underlying diseases and clinical and radiological signs of pulmonary infection were enrolled. Due to incomplete data on eight patients, 72 patients were eligible for final analysis (median age 58 years). All patients underwent fiberoptic bronchoscopy and bronchoalveolar lavage. Bronchoalveolar lavage fluid (BALF) fluid samples were sent for direct microscopy, cultures, and fungal antigen detection, when appropriate. Commercial qualitative amplification assay (PNEUMOTRIS oligomix Alert Kit(®)), based on nested PCR method, was used to detect specific DNA sequences of L. pneumophila, C. pneumoniae, and M. pneumoniae in BALF. There were 61 (84.7 %) patients with hematologic diseases, 3 (4.2 %) after solid organ transplantation, and 8 (11.1 %) with miscellaneous diseases affecting immune status. Specific sequences of M. pneumoniae, C. pneumoniae, and L. pneumophila DNA were found in 7 (9.7 %), 2 (2.8 %), and 0 patients, respectively. In 8 of these patients co-infections with different microorganisms were demonstrated. Co-infection with A. baumanii and P. aeruginosa was diagnosed in three patients who died. We conclude that atypical lower airway infections are uncommon in immunocompromised patients. The majority of these infections are co-infections rather than single pathogen infections.

The Distribution and Resistance of Pathogens Among Solid Organ Transplant Recipients with Pseudomonas aeruginosa Infections

Background

Pseudomonas aeruginosa infection remains a life-threatening complication after solid organ transplantation (SOT). We aimed to investigate the distribution and drug susceptibility of pathogens, and clinical characteristics of SOT recipients with Pseudomonas aeruginosa infections.

Material/Methods

A total of 55 SOT recipients who developed 61 episodes of Pseudomonas aeruginosa infections between January 1, 2003 and July 31, 2015 were retrospectively analyzed. The distribution and the drug susceptibility of Pseudomonas aeruginosa were reviewed.

Results

The most common site from which 61 Pseudomonas aeruginosa rods were isolated were the lungs (57.4%, n=37), followed by the blood (27.9%, n=17). There were 35, 18, and 9 recipients accompanied with a serum creatinine level of >1.5 mg/dL, lymphocyte count of <300/mm³, and a serum albumin level of <30 g/L, respectively. Seven patients each presented with white blood cell count of >15 000/mm³ and platelet count of <50 000/mm³. There were 6 (10.9%) cases of septic shocks and 18 (32.7%) deaths. Antibiotic resistance rate of all Pseudomonas aeruginosa to 4 of 10 antibiotics investigated was more than 50%. Of these 61 Pseudomonas aeruginosa isolates, 47.5% were carbapenem-resistant. The rods were relatively sensitive to piperacillin-tazobactam, levofloxacin, amikacin, and cefoperazone-sulbactam (resistance rate <40%).

Conclusions

The clinical presentation of Pseudomonas aeruginosa infections included high body temperature, decreased platelet count, elevated white blood cell count, a high nosocomial origin and mortality, and onset in the late period after transplantation. According to our findings, piperacillin-tazobactam, levofloxacin, amikacin, and cefoperazone-sulbactam, alone or combination, are recommended to treat SOT recipients with Pseudomonas aeruginosa infections.

An Approach to a Pulmonary Infiltrate in Solid Organ Transplant Recipients

The onset of a pulmonary infiltrate in a solid organ transplant (SOT) recipient is both a challenging diagnostic and therapeutic challenge. We outline the potential aetiologies of a pulmonary infiltrate in a SOT recipient, with particular attention paid to fungal pathogens. A diagnostic and empirical therapy approach to a pulmonary infiltrate, especially invasive fungal disease (IFD) in SOT recipients, is provided.

Pneumococcal disease in adult solid organ transplantation recipients

In solid organ transplant (SOT) recipients, Streptococcus pneumoniae can cause substantial morbidity and mortality ranging from non-invasive to invasive diseases, including pneumonia, bacteremia, and meningitis, with a risk of invasive pneumococcal disease 12 times higher than that observed in non-immunocompromised patients. Moreover, pneumococcal infection has been related to graft dysfunction. Several factors have been involved in the risk of pneumococcal disease in SOT recipients, such as type of transplant, time since transplantation, influenza activity, and nasopharyngeal colonization. Pneumococcal vaccination is recommended for all SOT recipients with 23-valent pneumococcal polysaccharides vaccine. Although immunological rate response is appropriate, it is lower than in the rest of the population, decreases with time, and its clinical efficacy is variable. Booster strategy with 7-valent pneumococcal conjugate vaccine has not shown benefit in this population. Despite its relevance, there are few studies focused on invasive pneumococcal disease in SOT recipients. Further studies addressing clinical, microbiological, and epidemiological data of pneumococcal disease in the transplant setting as well as new strategies for improving the protection of SOT recipients are warranted.

[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 infections after liver transplantation: An ever-growing challenge

Bacterial infections are a leading cause of morbidity and mortality among solid organ transplant recipients. Over the last two decades, various multidrug-resistant (MDR) pathogens have emerged as relevant causes of infection in this population. Although this fact reflects the spread of MDR pathogens in health care facilities worldwide, several factors relating to the care of transplant donor candidates and recipients render these patients particularly prone to the acquisition of MDR bacteria and increase the likelihood of MDR infectious outbreaks in transplant units. The awareness of this high vulnerability of transplant recipients to infection leads to the more frequent use of broad-spectrum empiric antibiotic therapy, which further contributes to the selection of drug resistance. This vicious cycle is difficult to avoid and leads to a scenario of increased complexity and narrowed therapeutic options. Infection by MDR pathogens is more frequently associated with a failure to start appropriate empiric antimicrobial therapy. The lack of appropriate treatment may contribute to the high mortality occurring in transplant recipients with MDR infections. Furthermore, high therapeutic failure rates have been observed in patients infected with extensively-resistant pathogens, such as carbapenem-resistant Enterobacteriaceae, for which optimal treatment remains undefined. In such a context, the careful implementation of preventive strategies is of utmost importance to minimize the negative impact that MDR infections may have on the outcome of liver transplant recipients. This article reviews the current literature regarding the incidence and outcome of MDR infections in liver transplant recipients, and summarizes current preventive and therapeutic recommendations.

Nosocomial infections within the first month of solid organ transplantation

Infections remain a common complication of solid organ transplantation. Early postoperative infections remain a significant cause of morbidity and mortality in solid organ transplant (SOT) recipients. Although significant effort has been made to understand the epidemiology and risk factors for early nosocomial infections in other surgical populations, data in SOT recipients are limited. A literature review was performed to summarize the current understanding of pneumonia, urinary tract infection, surgical-site infection, bloodstream infection, and Clostridium difficult colitis, occurring within the first 30 days after transplantation.

Early respiratory complications after liver transplantation

The poor clinical conditions associated with end-stage cirrhosis, pre-existing pulmonary abnormalities, and high comorbidity rates in patients with high Model for End-Stage Liver Disease scores are all well-recognized factors that increase the risk of pulmonary complications after orthotopic liver transplantation (OLT) surgery. Many intraoperative and postoperative events, such as fluid overload, massive transfusion of blood products, hemodynamic instability, unexpected coagulation abnormalities, renal dysfunction, and serious adverse effects of reperfusion syndrome, are other factors that predispose an individual to postoperative respiratory disorders. Despite advances in surgical techniques and anesthesiological management, the lung may still suffer throughout the perioperative period from various types of injury and ventilatory impairment, with different clinical outcomes. Pulmonary complications after OLT can be classified as infectious or non-infectious. Pleural effusion, atelectasis, pulmonary edema, respiratory distress syndrome, and pneumonia may contribute considerably to early morbidity and mortality in liver transplant patients. It is of paramount importance to accurately identify lung disorders because infectious pulmonary complications warrant speedy and aggressive treatment to prevent diffuse lung injury and the risk of evolution into multisystem organ failure. This review discusses the most common perioperative factors that predispose an individual to postoperative pulmonary complications and these complications’ early clinical manifestations after OLT and influence on patient outcome.

Infections in transplant patients

Recipients of solid organ transplants (SOT) need primary care providers (PCPs) who are familiar with their unique needs and understand the lifelong infectious risks faced by SOT patients because of their need for lifelong immunosuppressive medications. SOT recipients can present with atypical and muted manifestations of infections, for which the knowledgable PCP will initiate a comprehensive evaluation. The goal of this article is to familiarize PCPs with the infectious challenges facing SOT patients. General concepts are reviewed, and a series of patient cases described that illustrate the specific learning points based on common presenting clinical symptoms.

Opportunistic pulmonary infections in solid organ transplant recipients

BACKGROUND

Opportunistic pulmonary infections (OPI) represent common life-threatening complications after solid organ transplantation. Our objective was to describe pulmonary infections caused by opportunistic pathogens in solid-organ transplant patients.

METHODS

We analyzed all adult solid organ recipients (liver, heart, kidney, and pancreas) between July 2003 and June 2010, reporting all episodes of pulmonary opportunistic infection.

RESULTS

During the study period, 1656 solid organ transplants were performed and 188 opportunistic infections were diagnosed in 163 patients (incidence 10%). In 40 cases, the site of infection was the lung (21%) with 57.5% occurring between the first and sixth month posttransplantation. The most frequently isolated microorganism was Aspergillus spp (n = 25, 63%), followed by Pneumocystis jirovecii (n = 6 cs, 15%). Twenty-five patients with an opportunistic pulmonary infections died during the follow-up including, 16 related to the infection (40%). The causative organism responsible for the highest mortality was Aspergillus spp (n = 12; 48%). Twenty-one patients with an opportunistic nonrespiratory infection died, five of them related to it (4%). Opportunistic pulmonary infection was associated with an increased mortality rate (P < .001). There was a trend toward a higher mortality among patients who developed OPI during the first 6 months after transplantation.

CONCLUSIONS

Opportunistic pulmonary infections after solid organ transplantation are not infrequent. The period of risk for developing this infectious complications goes beyond the first 6 months posttransplantation. Mortality due to these infections was high in comparison to that of opportunistic nonrespiratory infections. It is important to keep a high index of suspicion for infectious complications during all posttransplant periods, as this is the first step toward a rapid diagnosis and adequate treatment.

Pulmonary infections in transplant recipients

PURPOSE OF REVIEW

Hematopoietic stem cell as well as solid-organ transplantation is being carried out with increasing frequency throughout the world. Lower respiratory tract infections (LRTIs) remain a common life-threatening complication faced by the transplant recipients. The purpose of this review is to provide up-to-date information on pulmonary infections among the transplant recipients, especially emphasizing the endemicity of microorganisms, epidemiology, work-up of infections, and principles of their management.

RECENT FINDINGS

A lower respiratory tract infection such as pneumonia is the most frequent of all the infections and is associated with high morbidity and mortality. Factors increasing the risk of pulmonary infections include surgical techniques, immune status, chemoradiotherapy, alloimmune mechanisms between the host and the graft, and the environment. A high degree of suspicion, computed tomography (CT) scan of the chest, and flexible bronchoscopy are required in most to establish the diagnosis.

SUMMARY

Proper management of LRTI in transplant recipients requires a high degree of suspicion, thorough knowledge of the epidemiology and endemicity of the suspected organisms, CT scan of the chest, and expertise at bronchoscopy. Utmost teamwork among transplant physicians, infectious disease specialist, and bronchoscopist is essential.

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.

Epidemiology and outcome of infections in human immunodeficiency virus/hepatitis C virus-coinfected liver transplant recipients: a FIPSE/GESIDA prospective cohort study

Information about infections unrelated to acquired immunodeficiency syndrome (AIDS) in human immunodeficiency virus (HIV)-infected liver recipients is scarce. The aims of this study were to describe the prevalence, clinical characteristics, time of onset, and outcomes of bacterial, viral, and fungal infections in HIV/hepatitis C virus (HCV)-coinfected orthotopic liver transplant recipients and to identify risk factors for developing severe infections. We studied 84 consecutive HIV/HCV-coinfected patients who underwent liver transplantation at 17 sites in Spain between 2002 and 2006 and were followed until December 2009. The median age was 42 years, and 76% were men. The median follow-up was 2.6 years (interquartile range = 1.25-3.53 years), and 54 recipients (64%) developed at least 1 infection. Thirty-eight (45%) patients had bacterial infections, 21 (25%) had cytomegalovirus (CMV) infections (2 had CMV disease), 13 (15%) had herpes simplex virus infections, and 16 (19%) had fungal infections (7 cases were invasive). Nine patients (11%) developed 10 opportunistic infections with a 44% mortality rate. Forty-three of 119 infectious episodes (36%) occurred in the first month after transplantation, and 53 (45%) occurred after the sixth month. Thirty-six patients (43%) had severe infections. Overall, 36 patients (43%) died, and the deaths were related to severe infections in 7 cases (19%). Severe infections increased the mortality rate almost 3-fold [hazard ratio (HR) = 2.9, 95% confidence interval (CI) = 1.5-5.8]. Independent factors for severe infections included a pretransplant Model for End-Stage Liver Disease (MELD) score >15 (HR = 3.5, 95% CI = 1.70-7.1), a history of AIDS-defining events before transplantation (HR = 4.0, 95% CI = 1.9-8.6), and non-tacrolimus-based immunosuppression (HR = 2.5, 95% CI = 1.3-4.8). In conclusion, the rates of severe and opportunistic infections are high in HIV/HCV-coinfected liver recipients and especially in those with a history of AIDS, a high MELD score, or non-tacrolimus-based immunosuppression.

Epidemiology of pneumonia in kidney transplantation

BACKGROUND

Pneumonia remains an important cause of morbidity among solid organ transplant recipients.

METHODS

We prospectively evaluated all renal transplant patients at our center from July 2003 to December 2008 who had pneumonia that required hospitalization. We gathered data regarding underlying diseases as well as pretransplant, transplant, and posttransplant characteristics. Pneumonia defined according to the Centers for Disease Control and Prevention criteria was classified depending on its origin as community acquired or nosocomial. In all patients, microbiologic samples of respiratory secretions and blood were collected at the physician's discretion. The indication to perform a fiberoptic bronchoscopy was the presence of multiple, bilateral, or diffuse pulmonary infiltrates or the absence of a clinical or radiologic response after 3 days of antimicrobial therapy.

RESULTS

Among 610 kidney transplant recipients, we diagnosed 60 episodes of pneumonia in 54 patients (8.8%), of which 23 had a nosocomial origin (38%) and 37 community acquired (62%). Bacterial infection was the most frequent etiology (44%), followed by fungal in 4 (7%) and viral in 2 (3.5%). The most commonly isolated microorganism in nosocomial pneumonia was Pseudomonas aeruginosa (26%, among which 50% was multidrug resistant). In 34% there was no microbiologic isolation. The most common pathogen among community-acquired pneumonias was Strepococcus pneumoniae (11%). In 54% of cases there was no microbiologic confirmation of disease. The overall accuracy of bronchoalveolar lavage was 72%. A total of 21 patients with pneumonia (35%) were admitted to the intensive care unit; of these, 14 had a nosocomial origin (60%) and 9 (15%) died due to the infection (8 [88%] of whom had nosocomial pneumonia; P=.001).

CONCLUSIONS

Our data confirmed that nosocomial pulmonary infections are associated with considerable morbidity and mortality in renal transplant recipients. The performance of invasive procedures is useful for the diagnosis of pneumonia.

Clinical implications of respiratory virus infections in solid organ transplant recipients: a prospective study

BACKGROUND

There is limited information about clinical consequences of respiratory virus infections (RVI) in solid organ transplant recipients. No prospective epidemiological study has been published previously.

METHODS

We selected a cohort of 152 transplant recipients (cardiac, hepatic and renal transplant recipients). Median time from transplantation was 17 months (range 1-50). They were prospectively followed-up for RVI during 7 months (October to April). Clinical and microbiological evaluation (cell culture, shell vial and polymerase chain reaction technique) of each RVI episode was made.

RESULTS

We detected 81 RVI (0.91 episodes/patient/year). Complications were detected in 15/81 episodes (18.5%): acute bronchitis (10 cases), pneumonia (three cases; 3.7% of RVI episodes) and bacterial sinusitis (2 cases). In 4 of 81 episodes (5%), patients needed hospitalization. A respiratory virus was isolated in 17 of 68 nasopharyngeal samples (six respiratory syncytial virus, six influenza, four picornavirus, one adenovirus). Fever presented an 83% positive predictive value for the diagnosis of influenza virus infection among those with a positive microbiological isolation. There were no episodes of acute rejection coincidentally with RVI. Only 54% of the subjects had been previously vaccinated against influenza.

CONCLUSIONS

Incidence of RVI among solid organ transplant recipients is similar to general population but complications are higher. A relationship between RVI and rejection was not detected. The rate of influenza vaccination was lower than expected. The presence of fever in a transplant recipient with RVI strongly suggests influenza infection.

Infecciones en el paciente con trasplante renal y pancreático

Infection can lead to graft loss and death in patients undergoing kidney and double kidney-pancreas transplantation. In this review, the prophylactic measures, the post-transplant timeline for the development of infections, and the most frequent infectious complications in patients with kidney and pancreas transplantation are described. Although great advances have been achieved in the prevention of infections, new problems have developed. Nosocomial bacterial infection with multidrug-resistant bacteria is an emerging complication. Cytomegalovirus is still the most frequent viral infection despite the advances in prevention measures. Moreover, in recent years polyomavirus type BK infection has been recognized as a major cause of renal graft loss. Knowledge of the infectious complications associated with these transplants and the risk factors for their occurrence will allow optimal therapeutic management of this patient population.