The diagnosis of pneumonia in renal transplant recipients using invasive and noninvasive procedures

Analysis of clinical characteristics and prognostic factors of ARDS caused by community-acquired pneumonia in people with different immune status

BACKGROUND

The purpose of this study is to describe the clinical characteristics and prognostic risk factors of acute respiratory distress syndrome (ARDS) caused by community-acquired pneumonia under different immune states.

METHODS

The patients were divided into immunocompetent and immunocompromised groups according to their immune status. The basic clinical data of the two groups were collected and statistically analyzed, and the clinical characteristics and prognostic factors of ARDS caused by community-acquired pneumonia under different immune states were summarized.

RESULTS

128 patients with ARDS caused by community-acquired pneumonia were enrolled. The chest High-Resolution Computed Tomography (HRCT) scores of patients with immunosuppression were higher (236.0 ± 55.0 vs. 207.5 ± 49.6, p < 0.05) and the score of APACHE II was higher (17.3 ± 4.8 vs. 15.1 ± 5.4, p < 0.05). The 28-day intensive care unit (ICU) mortality was higher in the immunocompromised group (54.5% vs. 34.7%, p = 0.045). The 28-day in-hospital mortality in the immunocompetent group was mainly related to NLR and the oxygenation index. The 28-day in-hospital mortality in the immunocompromised group was mainly related to LDH and APACHE II.

CONCLUSION

There are differences in clinical characteristics and mortality of ARDS patients caused by community-acquired pneumonia under different immune states.

Pulmonary Complications in Renal Transplant Recipients

Background Kidney transplantation recipients are at an increased risk of lung complications due to infectious or non-infectious reasons. We aimed to determine the lung complications after transplantation and what we could do to prevent the complications during the follow-up, retrospectively. Material and Methods The 296 patients who underwent kidney transplantation surgery in our centre between the years 1999 to 2006 were included in the study. Results 75% of the patients were male (n: 222). 77% of the patients (n: 228) had a living-related donor. The mean hospitalisation duration in the post-transplantation period was 13.3±9.07 days. During the follow-up, 37.2% of the patients (n: 110) had rejection, and pulse steroid treatments were given to the 74.5% of these patients. In our study, the lung complication development ratio was 16.2%, and 84% of these complications were due to infections. A specific aetiology was not identified in 63.5% of patients. The patients with a living-related donor had more lung complications due to infection (p

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.

Successful pulsed methylprednisolone and convalescent plasma treatment in a case of a renal transplant recipient with COVID-19 positive pneumonia: a case report

Coronavirus 2019 disease (COVID-19) is a deadly disease that was first seen in Wuhan, China, and primarily affects the respiratory system, but also has different systemic involvements. It has caused 89 million cases and 1.9 million deaths worldwide. COVID-19 positive renal transplant recipients have a higher mortality rate than COVID-19 patients in the normal population. There is no specific treatment and follow-up protocol for COVID-19 infection in transplant recipients. COVID-19 treatment and immunosuppressive therapy choices are controversial. Recently, pulse steroid therapies have been used in cases with severe COVID-19 pneumonia. Convalescent plasma therapy is used limitedly in COVID-19 patients. Our 49-year-old male patient has been a recipient of a renal transplant from a cadaver for 6 years. We aimed to make an additional contribution by presenting our patient to the literature whose COVID-19 PCR-RT test performed in the emergency department due to the complaints of fever, shortness of breath, and cough for five days was positive and had moderate COVID-19 pneumonia in thorax tomography and had serious clinical and radiological improvement after pulsed methylprednisolone and convalescent plasma therapy in the early period.

Diagnosis of severe respiratory infections in immunocompromised patients

An increasing number of critically ill patients are immunocompromised. Acute hypoxemic respiratory failure (ARF), chiefly due to pulmonary infection, is the leading reason for ICU admission. Identifying the cause of ARF increases the chances of survival, but may be extremely challenging, as the underlying disease, treatments, and infection combine to create complex clinical pictures. In addition, there may be more than one infectious agent, and the pulmonary manifestations may be related to both infectious and non-infectious insults. Clinically or microbiologically documented bacterial pneumonia accounts for one-third of cases of ARF in immunocompromised patients. Early antibiotic therapy is recommended but decreases the chances of identifying the causative organism(s) to about 50%. Viruses are the second most common cause of severe respiratory infections. Positive tests for a virus in respiratory samples do not necessarily indicate a role for the virus in the current acute illness. Invasive fungal infections (Aspergillus, Mucorales, and Pneumocystis jirovecii) account for about 15% of severe respiratory infections, whereas parasites rarely cause severe acute infections in immunocompromised patients. This review focuses on the diagnosis of severe respiratory infections in immunocompromised patients. Special attention is given to newly validated diagnostic tests designed to be used on non-invasive samples or bronchoalveolar lavage fluid and capable of increasing the likelihood of an early etiological diagnosis.

Evaluation of the Renal Transplant Recipient in the Emergency Department

Renal transplants are becoming more and more frequent in the United States and worldwide. Studies demonstrate that these patients inevitably end up visiting an emergency department. In addition to typical medical and surgical problems encountered in the general population, this group of patients has unique problems arising from their immunocompromised state and also due to side effects of the medications required. This article discusses these risks and management decisions that the emergency department physician should be aware of in order to prevent adverse outcomes for the patient and transplanted kidney.

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.

Utility of fiber-optic bronchoscopy in pulmonary infections among abdominal solid-organ transplant patients: A comprehensive review

Pulmonary infections are frequent complications in abdominal solid-organ transplantation (aSOT) which may threaten patient and allograft survival. Accurate diagnosis and treatment of pulmonary infections in this population can be challenging. Immunosuppressive therapy not only increases the risk of acquiring opportunistic and non-opportunistic infections, but it also impairs the inflammatory responses associated with microbial invasion which in an otherwise normal host produce clinical and radiologic responses that allow for early identification of the offending pathogen. Serologic testing is not a reliable diagnostic modality. Direct microbiological sampling is often necessary to make a definitive diagnosis early in the clinical course to optimize timely, targeted therapy while reducing the risk of developing antimicrobial resistance, and minimize adverse effects of therapy, if any. Fiber-optic bronchoscopy (FOB) with bronchoalveolar lavage (BAL) or transbronchial lung biopsy (TBB) offers such diagnostic advantage and possesses a potential therapeutic value too. This comprehensive review discusses the potential benefits of FOB alongside its risks and complications, indications and contraindications, and techniques. Additionally, the essay highlights FOB's utility and yield specifically with regard to type and timing of infections in aSOT patients.

Utility of Mean Platelet Volume to Diagnose Pneumonia in Patients With Solid-Organ Transplant

OBJECTIVES

Despite improved success with solid-organ transplant procedures, recipients remain at risk for infections, including pneumonia, due to their immunosuppressive regimens. In solid-organ transplant patients, clinical findings of pneumonia can be nonspecific, and diagnosis of pneumonia may be difficult as several conditions (drug lung, hypervolemia, infections, hemorrhage) can led to pulmonary infiltrates, mimicking pneumonia in these patients. The role of mean platelet volume, a predictor of inflammatory disease, with elevated values inversely correlated with inflammatory problems, in the diagnosis of pneumonia has not yet been investigated in solid-organ transplant patients. Here, we retrospectively investigated mean platelet volume in diagnosis of pneumonia in transplant patients.

MATERIALS AND METHODS

Medical records of solid-organ transplant patients from 2011 to 2016 were reviewed for demographic, clinical, radiographic, laboratory, and microbiology data. Transplant type, immunosuppressive drugs, and clinical outcomes were noted. Pneumonia diagnosis was based on clinical respiratory symptoms and signs, imaging findings, positive microbiological tests, pathologic findings, laboratory findings, or effective clinical treatment trials.

RESULTS

Our study included 70 patients (47 male/23 female; mean age of 46 ± 14 years), comprising 26 liver and 44 renal transplant recipients. Pneumonia was diagnosed radiologically in 30 patients (42.9%), with procalcitonin positive in 11 patients (36.7%), C-reactive protein elevated in 29 patients (96.7%), and leukocytes increased in 6 patients (20%). When laboratory measurements were compared with mean platelet volume, mean platelet volume values were significantly lower in patients with pneumonia who had elevated procalcitonin levels (P = .038).

CONCLUSIONS

We found that mean platelet volume for diagnosis of pneumonia in solid-organ transplant patients was not a promising tool. Considering the difficulties in caring for transplant patients with pulmonary infiltrates, clinical decisions should be based on clinical, laboratory, microbiological, and radiologic findings.

Causes of Hemoptysis in Renal Transplant Patients

OBJECTIVES

Hemoptysis is a symptom that can be caused by airway disease, pulmonary parenchymal disease, or pulmonary vascular disease, or it can be idiopathic. Infection is the most common cause of hemoptysis, accounting for 60% to 70% of cases. Hemoptysis is also an initial symptom of diffuse alveolar hemorrhage syndrome, although it may be absent at presentation in one-third of patients. Diffuse alveolar hemorrhage is characterized by disruption of the alveolar-capillary basement membranes because of either injury or inflammation of the arterioles, venules, or capillaries, resulting in bleeding in alveolar spaces. To date, no study in the literature has investigated the cause of hemoptysis in renal transplant patients. In this retrospective study, we aimed to investigate the causes of hemoptysis in renal recipients.

MATERIALS AND METHODS

The data included in this study were obtained from 352 renal transplant patients who were consulted by the pulmonology department regarding hemoptysis between 2011 and 2017 at Baskent University. Patient medical records were reviewed for demographic, clinical, radiographic, bronchoscopic features, and microbiology data. Immunosuppressive drugs and clinical outcome data were also noted.

RESULTS

This study included 352 renal transplant patients (139 male patients with mean age of 34.9 ± 7 years and 113 female patients with mean age of 31.1 ± 5 years). Hemoptysis was detected in 17 patients (4.8%),with 3 (0.85%) having massive hemoptysis as a result of diffuse alveolar hemorrhage syndrome. Fourteen of our patient group (4%) had pneumonia, and Aspergillus species was detected in 5 patients (1.4%). The only reason for diffuse alveolar hemorrhage was immunosuppressive agents, including sirolimus and mycophenolate mofetil.

CONCLUSIONS

Hemoptysis is an important respiratory symptom in renal transplant patients. Although community- or hospital-acquired pneumonia may result in hemoptysis, drug-induced diffuse alveolar hemorrhage and Aspergillus infection should be considered for causes in renal transplant patients.

Lower Respiratory Tract Infections

This review will focus on the infectious etiologies and more common noninfectious causes of lower respiratory tract syndromes among major immunosuppressed populations. The changing epidemiology of infections in the era of highly active antiretroviral therapy (HAART) in the case of HIV-positive patients and the impacts of both newer immune-suppressant therapies and anti-infective prophylaxis for other immunocompromised hosts will be discussed, with emphasis on diagnostic approaches and practice algorithms.

Bacteria Isolated From Respiratory Tract Specimens of Renal Recipients With Acute Respiratory Distress Syndrome Due to Pneumonia: Epidemiology and Susceptibility of the Strains

OBJECTIVE

We estimated species distribution and frequency of antimicrobial resistance among bacterial pathogens isolated from respiratory tract specimens of renal recipients with acute respiratory distress syndrome (ARDS) due to pneumonia.

METHODS

We retrospectively collected patient demographics and clinical characteristics and microbiologic culture data with the use of standard microbiologic procedures and commercially available tests.

RESULTS

From January 2001 to August 2014, 320 respiratory tract specimens were obtained from 94 renal recipients with ARDS. Bacterial cultures were positive in 134 specimens from 68 recipients (72.3%), yielding 139 bacterial strains. The most commonly isolated species were gram-negative bacteria (111 isolates) with dominance of Acinetobacter baumanii (29.7%) and Pseudomonas aeruginosa (18.0%). The gram-negative bacteria were relatively resistant to 1st- and 2nd-generation cephalosporin and monocyclic beta-lactam and relatively sensitive to levofloxacin and meropenem, with rates of resistance of 80.2%, 76.6%, 73.9%, 36.0%, and 44.1%, respectively. The gram-positive bacteria, excluding Streptococcus uberis, were sensitive to glycopeptides and oxazolidone.

CONCLUSIONS

Gram-negative bacteria predominated as 79.9% of isolates from respiratory tract specimens of renal recipients with ARDS. The gram-negative bacteria were relatively sensitive to levofloxacin and meropenem and the gram-positive bacteria were sensitive to glycopeptides and oxazolidone.

Bacterial and fungal infections in the early post-transplant period after kidney transplantation: etiological agents and their susceptibility

BACKGROUND

Infections remain serious complications in solid-organ transplant recipients, despite professional medical care, the introduction of new immunosuppressive drugs, and treatment that decreases the risk of infections.

METHODS

The study covered 295 adult patients undergoing kidney transplantation (KTx) between September 2001 and December 2007. All the patients were followed prospectively for infections from the KTx date and during the first 4 weeks after surgery. Samples of clinical materials were investigated for microbiological cultures. The microorganisms were cultured and identified in accordance with standard bacteriological procedures. Susceptibility testing was carried out through the use of Clinical and Laboratory Standards Institute procedures.

RESULTS

From 295 KTx recipients, 1073 clinical samples were taken for microbiological examination. Positive cultures were 26.9% (n = 289) of all samples tested; 525 strains were collected. Gram-positive bacteria were isolated in 52.2% (n = 274), Gram-negative bacteria were isolated in 40.8% (n = 214), and fungal strains were isolated in 7% (n = 37). Urine specimens (n = 582) were obtained from 84.5% of 245 recipients during the first month after transplantation. Among the isolated bacterial strains (n = 291), the most common were Gram-negative bacteria (56.4%). Gram-positive bacteria comprised 35.7%; fungal strains were found in 23 cases (7.9%). In surgical site specimens (n = 309), Gram-positive bacteria (72.1%) were the most common. Gram-negative bacteria comprised 24.4%. In blood specimens (n = 138), Gram-positive bacteria (81.6%) were the most common. Gram-negative bacteria comprised 15.8%; fungi were isolated in 2.6%. In respiratory tract specimens (n = 13), among the isolated bacterial strains (n = 8), the most common were Gram-positive bacteria (57.1%). Gram-negative bacteria comprised 14.3%; fungi were isolated in 28.6%.

CONCLUSIONS

Urine samples were predominantly positive after KTx. Our study showed Gram-positive bacteria in 52.2% after kidney transplantation. The proportion of isolates of multi-drug-resistant bacterial strains (MRCNS, vancomycin-resistant strains, high-level aminoglycoside-resistant strains, extended-spectrum beta-lactamase producers, and high-level aminoglycoside-resistant strains) was increased. These data indicate the need for strict adherence to infection control procedures in these patients.

Pleural effusion as the initial clinical presentation in disseminated cryptococcosis and fungaemia: an unusual manifestation and a literature review

BACKGROUND

Cryptococcus neoformans infection usually presents as chronic meningitis and is increasingly being recognized in immunocompromised patients. Presentation with pleural effusion is rare in cryptococcal disease; in fact, only 4 cases of pleural effusion as the initial clinical presentation in cryptococcosis have been reported in English-language literature to date. We report the first case of pleural effusion as the initial clinical presentation in a renal transplant recipient who was initially misdiagnosed with tuberculous pleuritis but who then developed fungaemia and disseminated cryptococcosis. The examination of this rare manifestation and the accompanying literature review will contribute to increased recognition of the disease and a reduction in misdiagnoses.

CASE PRESENTATION

We describe a 63-year-old male renal transplant recipient on an immunosuppressive regimen who was admitted for left pleural effusion and fever. Cytological examinations and pleural fluid culture were nonspecific and negative. Thoracoscopy only found chronic, nonspecific inflammation with fibrosis in the pleura. After empirical anti-tuberculous therapy, the patient developed an elevated temperature, a severe headache and vomiting and fainted in the ward. Cryptococci were specifically found in the cerebrospinal fluid following lumbar puncture. Blood cultures were twice positive for C. neoformans one week later. He was transferred to the respiratory intensive care unit (RICU) immediately and was placed on non-invasive ventilation for respiratory failure for 2 days. He developed meningoencephalitis and fungaemia with C. neoformans during hospitalization. He was given amphotericin B liposome combined with 5-flucytosine and voriconazole for first 11 days, then amphotericin B liposome combined with 5-flucytosine sustained to 8 weeks, after that changed to fluconazole for maintenance. His condition improved after antifungal treatment, non-invasive ventilation and other support. Further pathological consultation and periodic acid-Schiff staining revealed Cryptococcus organisms in pleural sections, providing reliable evidence for cryptococcal pleuritis.

CONCLUSION

Pleural effusion is an unusual manifestation of cryptococcosis. Cryptococcal infection must be considered in the case of patients on immunosuppressives, especially solid-organ transplant recipients, who present with pleural effusion, even if pleural fluid culture is negative. Close communication between the pathologist and the clinician, multiple special biopsy section stains and careful review are important and may contribute to decreasing misdiagnosis.

[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.

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.

Diagnostic bronchoscopy in solid-organ and hematopoietic stem cell transplantation

Fiberoptic bronchoscopy is a valuable diagnostic tool in solid-organ and hematopoietic stem cell transplant recipients presenting with a range of pulmonary complications. This article provides a comprehensive overview of the utility and potential adverse effects of diagnostic bronchoscopy for transplant recipients. Recommendations are offered on the selection of patients, the timing of bronchoscopy, and the samples to be obtained across the spectrum of suspected pulmonary complications of transplantation. Based on review of the literature, the authors recommend early diagnostic bronchoscopy over empiric treatment in transplant recipients with evidence of certain acute, subacute, or chronic pulmonary processes. This approach may be most critical when an underlying infectious etiology is suspected. In the absence of prompt diagnostic information on which to base effective treatment, the risks associated with empiric antimicrobial therapy, including medication side effects and the development of antibiotic resistance, compound the potential harm of delaying targeted management.

Radiological spectrum of pulmonary infections in patients post solid organ transplantation

Pneumonia remains an important source of morbidity and mortality in transplant recipients. Since clinical findings are nonspecific and cultures may be time-consuming, imaging plays an important role in establishing the probable etiology of pneumonia. Plain films are used as an initial study. However, they have a limited capacity in differentiating the causative factors. HRCT is used as a problem-solving tool in patients with unclear plain film findings and/or no response to treatment. The main advantage of HRCT is a very detailed depiction of the lung parenchyma. Even though HRCT findings are not always specific, there are several sings that are more common in certain types of pneumonia. The aim of the article is to present radiological findings suggestive of a particular causative microorganism and show how they can narrow the differential diagnosis when coupled with clinical data.

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.

A model for diagnosis of pulmonary infections in solid-organ transplant recipients

BACKGROUND

Opportunistic pulmonary infections are a major cause of morbidity and mortality among solid organ transplant recipients. The diagnosis of these infections is challenging because of the broad spectrum of bacteria, fungi and viruses affecting these patients and the lack of specific signs and symptoms. Treatment directed at the offending organism started as soon as possible improves survival.

OBJECTIVE

To develop a decision support system for the diagnosis of pulmonary infections in solid-organ transplant recipients. The model's goal is to improve the accuracy of the diagnosis and thus the appropriateness of empirical treatment.

DESIGN

The model is built using a Bayesian network (also known as causal probabilistic network). The network is based on pathogen segments which are the main building blocks of the model. Segments share common risk factors, such as time after transplantation, latent infections of donor/recipient and organ transplanted. The segments are linked at symptoms, signs and diagnostic tests common to all pathogens. The outputs of the model are predicted probabilities of infectious pathogens. To populate the model with data we have mainly abstracted data from the literature, using a systematic approach. The structure of the model and its adaptation for decision support will be presented.

EVALUATION

The first evaluation phase assessed the model's diagnosis in a series of 20 representative cases of opportunistic infections. A match between the case's diagnosis and the model's prediction was achieved in 17/20 of cases. The next evaluation phase will consist of a prospective observational study comparing the accuracy of the model's diagnosis vs. that of the physician within 24h of episode onset, as compared with a gold-standard diagnosis ascribed to the patients at the end of the infectious episode by two independent experts. Data for this phase are currently collected prospectively.

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.

Lung and renal transplantation

Renal transplantation is the most common type of solid organ transplantation and kidney transplant recipients are susceptible to pulmonary complications of immunosuppressive therapy, which are a diagnostic and therapeutic challenge.

AIM

To evaluate patients admitted to the Renal Transplant Unit (RTU) of Hospital de S. João with respiratory disease.

SUBJECT AND METHODS

We performed a retrospective study of all patients admitted to RTU with respiratory disease during a period of 12 months.

RESULTS

Thirty-six patients were included. Mean age 55.2 (+/-13.4) years; 61.1% male. Immunosuppressive agents most frequently used were prednisolone and mycophenolate mofetil associated with ciclosporin (38.9%) or tacrolimus (22.2%) or rapamycin (13.9%). Thirty-one patients (86.1%) presented infectious respiratory disease. In this group the main diagnoses were 23 (74.2%) pneumonias, 5 (16.1%) opportunistic infections, 2 (6.5%) tracheobronchitis, and 1 case (3.2%) of lung abscesses. Microbiological agent was identified in 7 cases (22.6%). Five patients (13.9%) presented rapamycin-induced lung disease. Fibreoptic bronchoscopy was performed in 15 patients (41.7%), diagnostic in 10 cases (66.7%). Mean hospital stay was 17.1 (+/-18.5) days and no related death was observed.

CONCLUSION

Respiratory infections were the main complications in these patients. Drug-induced lung disease implies recognition of its features and a rigorous monitoring of drug serum levels. A more invasive diagnostic approach was determinant in the choice of an early and more specific therapy.

Infection frequency and profile in different age groups of kidney transplant recipients

BACKGROUND

Older transplant recipients have been shown to be at greater risk for infectious death than younger adults, but no study to date has looked at relative risk of infection and infection profile differences for children versus adults, which may be very different from one another.

METHODS

Data from primary Medicare renal transplant recipients between 1991 and 1998 (n=64,751), as reported in the United States Renal Data System (USRDS), were analyzed for Medicare claims (both inpatient and outpatient) for infection and type of infection in the first year posttransplant. Cox regression was used to model adjusted hazard ratios (AHR) for infection.

RESULTS

Total infections among renal transplant recipients increased significantly in more recent years. Patients transplanted in or after 1995 had a significantly higher adjusted risk for infection compared to those transplanted earlier (AHR 1.34, 95% CI=1.29-1.39). Older adults > or = 51 years of age had the highest percentage of experiencing infection, as compared to adults between 18-50 years and children < or = 17 years (P<0.001). Children were at highest risk of viral infection prior to 1995 but at lowest risk of viral infection after 1995, whereas elderly adults were at highest risk of bacterial infection throughout the study. Children experienced more claims for viral infections, whereas older transplant recipients experienced more claims for bacterial infections.

CONCLUSIONS

The two extremes of transplant recipient age display very different risks for infection claim frequency and profile.

Persistent Mediastinal and Axillary Lymph Node Tuberculosis in a Renal Transplant Patient With Successful Outcome

Tuberculosis is an opportunistic infection that carries substantial morbidity and mortality in renal transplant recipients. We report here about a 21 year-old man with a living related renal transplant from his mother who developed persistent extra-pulmonary tuberculosis. The disease showed aggressive invasion to the axillary and mediastinal regions with abscess formations, despite standard antituberculosis treatment. During the course of the disease, immunosuppressive therapy was stopped, and the patient received extraordinary doses of multiple antituberculosis drugs. The patient then showed an uneventful course with good clinical and radiological responses.

An aggressive systematic strategy for acute respiratory distress syndrome caused by severe pneumonia after renal transplantation

Acute respiratory distress syndrome (ARDS) caused by pneumonia after renal transplantation was usually associated with overimmunosuppression and high mortality rate. We evaluated the efficacy of an aggressive systemic protocol including strategies improving body's immune function. Twenty-one recipients were enrolled in this study. Patients were subjected to a protocol including (i) withdrawal of most immunosuppressants, (ii) early use of immunoenhancers and continuous renal replacement therapy (CRRT), (iii) reasonable administration of antibiotic regimen, (iv) prompt mechanical ventilating strategy, and (v) adequate nutrition. Immunosuppressants were adjusted according to the value of CD4+, CD8+T lymphocytes in peripheral blood. CRRT was conducted at once when patients were admitted to the intensive care unit (ICU), regardless the graft function. Thirteen (62%) survived and eight died finally. This is a high survival rate for this kind of patients. Eighteen patients had received thymosin treatment. All patients who survived experienced renal allograft dysfunction during CRRT, but when CRRT stopped, the function of all grafts gradually recovered. No acute rejection episodes were documented during the treatment. The aggressive systemic protocol including strategies improving the body's immune function and CRRT can improve the outcome of patients with ARDS after renal transplantation. The count of CD4+, CD8+T lymphocytes of peripheral blood is useful in the adjustment of immunosuppressants and the prediction of patient outcome.

Microbiologic features and outcome of pneumonia in transplanted patients

We prospectively evaluated lower respiratory tract infections in solid organ transplantation (SOT) patients to determine the microbiologic diagnosis and clinical outcomes. We diagnosed 83 cases of pneumonia, 38 of which were community acquired and 45 were nosocomial. Those with bilateral infiltrates or absence of improvement after 3 days of treatment underwent fiberoptic bronchoscopy. Bacterial pneumonia was the most frequent diagnosis and mixed infection predominated in the nosocomial group (11/45 nosocomial versus 1/38 community). Fiberoptic bronchoscopy with bronchoalveolar lavage had higher diagnostic yield in nosocomial pneumonia (77% versus 47%). Mortality differences between the 2 groups were 58% nosocomial versus 8% community-acquired infections (P < 0.001). SOT patients with nosocomial pneumonia, or those who needed mechanical ventilation, had a high mortality rate and benefits from the fiberoptic diagnostic techniques.

The incidence and costs of sepsis and pneumonia before and after renal transplantation in the United States

We compared the graft survival and accumulative costs associated with sepsis and pneumonia pre- and post-transplantation. We analyzed 44 916 first kidney transplants from 1995 to 2001 USRDS where Medicare was the primary payer. We drew five cohorts for each disease from the baseline population: patients who had a disease onset in the first or second years pre-transplantation (cohorts 1 and 2) or post-transplantation (cohorts 3 and 4) and patients who were disease-free (cohort 5). For each cohort, we calculated graft survival and average accumulated Medicare payments (AAMPs) for the two pre- and post-transplantation years. Graft survival: new-onset sepsis and pneumonia both significantly (p <0.01) lowered graft survival during the year of onset. AAMPs: the AAMPs incurred by sepsis- (pneumonia-) free patients during the first and second years post-transplantation were dollar 50,000 and 13,000 (dollar 51,100 and 13,500), respectively. Patients with a sepsis (pneumonia) onset post-transplantation cost on average dollar 48,400 (dollar 38,400) extra (p<0.01). Episodes of sepsis and pneumonia have a strong and independent impact on graft survival and costs.

Bacterial and Mycobacterial Pneumonia in Transplant Recipients

Bacteria and myobacteria are important pulmonary pathogens in transplant recipients and are the focus of this article. Although considerable overlap exists, there are significant differences in the epidemiology and clinical presentation of these organisms in solid organ transplant (SOT) and hematopoietic stem cell transplant (HSCT) recipients. The first section of this article focuses on infections in SOT recipients (predominantly heart, liver, lung, and kidney transplant recipients), and the latter addresses these infections in HSCT recipients.

Pneumonia in the solid organ transplant patient

As the field of solid organ transplantation has grown, so has the importance of infectious complications in this select group of patients. Chronic immunosuppression compromises the natural host defenses that typically prevent lower respiratory tract infections and makes the solid organ transplant recipient especially susceptible to pneumonia. Evaluation of pneumonia in this population differs owing to the potential for opportunistic infections. Lung transplant recipients are particularly susceptible to pneumonia and pose unique diagnostic dilemmas. An understanding of the time line for the different key pathogens after transplantation aids the initial evaluation and management.