Pneumocystis pneumonia in solid organ transplant recipients

Lesson learnt from 60 years of liver transplantation: Advancements, challenges, and future directions

Over the past six decades, liver transplantation (LT) has evolved from an experimental procedure into a standardized and life-saving intervention, reshaping the landscape of organ transplantation. Driven by pioneering breakthroughs, technological advancements, and a deepened understanding of immunology, LT has seen remarkable progress. Some of the most notable breakthroughs in the field include advances in immunosuppression, a revised model for end-stage liver disease, and artificial intelligence (AI)-integrated imaging modalities serving diagnostic and therapeutic roles in LT, paired with ever-evolving technological advances. Additionally, the refinement of transplantation procedures, resulting in the introduction of alternative transplantation methods, such as living donor LT, split LT, and the use of marginal grafts, has addressed the challenge of organ shortage. Moreover, precision medicine, guiding personalized immunosuppressive strategies, has significantly improved patient and graft survival rates while addressing emergent issues, such as short-term complications and early allograft dysfunction, leading to a more refined strategy and enhanced post-operative recovery. Looking ahead, ongoing research explores regenerative medicine, diagnostic tools, and AI to optimize organ allocation and post-transplantation car. In summary, the past six decades have marked a transformative journey in LT with a commitment to advancing science, medicine, and patient-centered care, offering hope and extending life to individuals worldwide.

Complications in Post-Liver Transplant Patients

Liver transplantation (LT) is the treatment of choice for liver failure and selected cases of malignancies. Transplantation activity has increased over the years, and indications for LT have been widened, leading to organ shortage. To face this condition, a high selection of recipients with prioritizing systems and an enlargement of the donor pool were necessary. Several authors published their case series reporting the results obtained with the use of marginal donors, which seem to have progressively improved over the years. The introduction of in situ and ex situ machine perfusion, although still strongly debated, and better knowledge and treatment of the complications may have a role in achieving better results. With longer survival rates, a significant number of patients will suffer from long-term complications. An extensive review of the literature concerning short- and long-term outcomes is reported trying to highlight the most recent findings. The heterogeneity of the behaviors within the different centers is evident, leading to a difficult comparison of the results and making explicit the need to obtain more consent from experts.

Preliminary Study on the Combination Effect of Clindamycin and Low Dose Trimethoprim-Sulfamethoxazole on Severe Pneumocystis Pneumonia After Renal Transplantation

Objective

Evaluate the effect of the combination of clindamycin with low-dose trimethoprim-sulfamethoxazole (TMP/SMX) regimen on sever Pneumocystis pneumonia (PCP) after renal transplantation.

Method

20 severe PCP patients after renal transplantation were included in this historical-control, retrospective study. A 10 patients were treated with the standard dose of TMP/SMX (T group), the other 10 patients were treated with the combination of clindamycin and low dose TMP/SMX (CT group).

Results

Although there was no significant difference in the hospital survival between the two groups, the CT protocol improved the PaO2/FiO2 ratio more significantly and rapidly after the 6th ICU day (1.51 vs. 0.38, P = 0.014). CT protocol also ameliorated the pulmonary infiltration and the lactate dehydrogenase level more effectively. Moreover, the CT protocol reduced the incidence of pneumomediastinum (0 vs. 50%, P = 0.008), the length of hospital staying (26.5 vs. 39.0 days, P = 0.011) and ICU staying (12.5 vs. 22.5 days, P = 0.008). Furthermore, more thrombocytopenia (9/10 vs. 3/10, P = 0.020) was emerged in the T group than in the CT group. The total adverse reaction rate was much lower in the CT group than in the T group (8/80 vs. 27/80, P < 0.001). Consequently, the dosage of TMP/SMX was reduced in 8 patients, while only 2 patients in the CT group received TMP/SMX decrement (P = 0.023).

Conclusion

The current study proposed that clindamycin combined with low-dose TMP/SMX was more effective and safer the than single use of TMP/SMX for severe PCP patients after renal transplantation (NCT04328688).

Fungal pneumonia in kidney transplant recipients

Fungal pneumonia is a dreaded complication encountered after kidney transplantation, complicated by increased mortality and often associated with graft failure. Diagnosis can be challenging because the clinical presentation is non-specific and diagnostic tools have limited sensitivity and specificity in kidney transplant recipients and must be interpreted in the context of the clinical setting. Management is difficult due to the increased risk of dissemination and severity, multiple comorbidities, drug interactions and reduced immunosuppression which should be applied as an important adjunct to therapy. This review will focus on the main causes of fungal pneumonia in kidney transplant recipients including Pneumocystis, Aspergillus, Cryptococcus, mucormycetes and Histoplasma. Epidemiology, clinical presentation, laboratory and radiographic features, specific characteristics will be discussed with an update on diagnostic procedures and treatment.

Care of Pediatric Solid Organ Transplant Recipients: An Overview for Primary Care Providers

As the number of living pediatric solid organ transplant (SOT) recipients continues to grow, there is an increased likelihood that primary care providers (PCPs) will encounter pediatric SOT recipients in their practices. In addition, as end-stage organ failure is replaced with chronic medical conditions in transplant recipients, there is a need for a comprehensive approach to their management. PCPs can significantly enhance the care of immunosuppressed hosts by advising parents of safety considerations and avoiding adverse drug interactions. Together with subspecialty providers, PCPs are responsible for ensuring that appropriate vaccinations are given and can play an important role in the diagnosis of infections. Through early recognition of rejection and posttransplant complications, PCPs can minimize morbidity. Growth and development can be optimized through frequent assessments and timely referrals. Adherence to immunosuppressive regimens can be greatly improved through reinforcement at every encounter, particularly among adolescents. PCPs can also improve long-term outcomes by easing the transition of pediatric SOT recipients to adult providers. Although guidelines exist for the primary care management of adult SOT recipients, comprehensive guidance is lacking for pediatric providers. In this evidence-based overview, we outline the main issues affecting pediatric SOT recipients and provide guidance for PCPs regarding their management from the first encounter after the transplant to the main challenges that arise in childhood and adolescence. Overall, PCPs can and should use their expertise and serve as an additional layer of support in conjunction with the transplant center for families that are caring for a pediatric SOT recipient.

Recent Advances in the Diagnosis and Management of Pneumocystis Pneumonia

In human immunodeficiency virus (HIV)-infected patients, Pneumocystis jirovecii pneumonia (PCP) is a wellk-nown opportunistic infection and its management has been established. However, PCP is an emerging threat to immunocompromised patients without HIV infection, such as those receiving novel immunosuppressive therapeutics for malignancy, organ transplantation, or connective tissue diseases. Clinical manifestations of PCP are quite different between patients with and without HIV infections. In patients without HIV infection, PCP rapidly progresses, is difficult to diagnose correctly, and causes severe respiratory failure with a poor prognosis. High-resolution computed tomography findings are different between PCP patients with HIV infection and those without. These differences in clinical and radiological features are due to severe or dysregulated inflammatory responses that are evoked by a relatively small number of Pneumocystis organisms in patients without HIV infection. In recent years, the usefulness of polymerase chain reaction and serum β-D-glucan assay for rapid and non-invasive diagnosis of PCP has been revealed. Although corticosteroid adjunctive to anti-Pneumocystis agents has been shown to be beneficial in some populations, the optimal dose and duration remain to be determined. Recent investigations revealed that Pneumocystis colonization is prevalent and that asymptomatic carriers are at risk for developing PCP and can serve as the reservoir for the spread of Pneumocystis by airborne transmission. These findings suggest the need for chemoprophylaxis in immunocompromised patients as well as infection control measures, although the indications remain controversial. Because a variety of novel immunosuppressive therapeutics have been emerging in medical practice, further innovations in the diagnosis and treatment of PCP are needed.

One-year Outcome of Everolimus With Standard-dose Tacrolimus Immunosuppression in De Novo ABO-incompatible Living Donor Kidney Transplantation: A Retrospective, Single-center, Propensity Score Matching Comparison With Mycophenolate in 42 Transplants

Background.

Despite improvement in immunosuppressive therapy, long-term kidney allograft survival remains a major challenge. The outcomes of therapy with everolimus (EVR) and standard-dose tacrolimus (Tac) have not been compared with those of mycophenolate mofetil (MMF) and standard-dose Tac in recipients of de novo ABO-incompatible (ABOi) living donor kidney transplantation (LDKT).

Methods.

This retrospective, observational, single-center, propensity score matching (PSM) study compared the outcomes of EVR and standard-dose Tac with those of MMF and standard-dose Tac following de novo ABOi LDKT. In total, 153 recipients of ABOi LDKT between January 2008 and March 2018 were screened for inclusion in the study. The variables considered for PSM were: recipient age/sex, duration of dialysis, cytomegalovirus mismatch (seronegative recipient and seropositive donor), cause of kidney disease, donor age/sex, and numbers of mismatches (HLA-A, HLA-B, and HLA-DR). After PSM, there were 21 patients in each group (n = 42 overall).

Results.

Four patients in the EVR group and 1 patient in the MMF group were withdrawn because of adverse effects. There were no significant differences between the 2 groups in 1-year outcomes regarding patient death, graft loss, delayed graft function, biopsy-proven acute rejection, infection requiring hospital admission, or estimated glomerular filtration rate. The 1-year protocol biopsy showed that the severity of interstitial fibrosis/tubular atrophy was significantly milder in the EVR group than in the MMF group.

Conclusions.

The findings suggest that the renal efficacy and safety of EVR and standard-dose Tac in recipients of de novo ABOi LDKT are comparable with those of MMF and standard-dose Tac.

Life-long antimicrobial therapy: where is the evidence?

The decision to prescribe long-term or 'life-long' antibiotics in patients requires careful consideration by the treating clinician. While several guidelines exist to help assist in this decision, the long-term consequences are yet to be well studied. In this review, we aim to provide a summary of the available evidence for patient populations where long-term antibiotic therapy is currently recommended in clinical practice. We will also discuss the pitfalls of this approach, including medication adverse effects, economic cost and any possible contribution to the emerging epidemic of microbial resistance.

Infection in Kidney Transplant Recipients

In organ transplant recipients, impaired inflammatory responses suppress the clinical and radiologic findings of infection. The possible etiologies of infection are diverse, ranging from common bacterial and viral pathogens that affect the entire community to opportunistic pathogens that cause invasive disease only in immunocompromised hosts. Antimicrobial therapies required to treat established infection are often complex, with accompanying risks for drug toxicities and drug interactions with the immunosuppressive agents used to maintain graft function. Rapid and specific diagnosis is essential for successful therapy. The risk of serious infections in the organ transplant patient is largely determined by the interaction between two factors: the patient’s epidemiologic exposures and the patient’s net state of immunosuppression. The epidemiology of infection includes environmental exposures and nosocomial infections, organisms derived from donor tissues, and latent infections from the recipient activated with immunosuppression. The net state of immune suppression is a conceptual framework that measures those factors contributing to risk for infection: the dose, duration, and temporal sequence of immunosuppressive drugs; the presence of foreign bodies or injuries to mucocutaneous barriers; neutropenia; metabolic abnormalities including diabetes; devitalized tissues, hematomas, or effusions postsurgery; and infection with immunomodulating viruses. Multiple factors are present in each host. A timeline exists to aid in the development of a differential diagnosis for infection. The timeline for each patient is altered by changes in prophylaxis and immunosuppressive drugs. For common infections, new microbiologic assays, often nucleic acid based, are useful in the diagnosis and management of opportunistic infections.

Cytomegalovirus infection and graft rejection as risk factors for pneumocystis pneumonia in solid organ transplant recipients: A systematic review and meta-analysis

A growing number of publications have reported the outbreaks of post-transplant pneumocystis pneumonia (PJP). In most studies, the onset of PJP was beyond 6-12 months of prophylaxis. Cytomegalovirus (CMV) infection and allograft rejection have been repeatedly reported as probable risk factors for post-transplant PJP. In this systematic review and meta-analysis, we determined the pooled effect estimates of these 2 variables as risk factors. Data sources included PUBMED, MEDLINE-OVID, EMBASE-OVID, Cochrane Library, Networked Digital Library of Theses and Dissertations, World Health Organization, and Web of Science. We excluded publications related to hematopoietic stem cell transplantation (HSCT) or Human Immunodeficiency Virus (HIV) patients. Eventually, 15 studies remained for the final stage of screening. Cytomegalovirus infection (OR: 3.30, CI 95%: 2.07-5.26, I² : 57%, P = 0.006) and allograft rejection (OR:2.36, CI95%: 1.54-3.62, I2: 45.5%, P = 0.05) significantly increased the risk of post-transplant PJP. Extended prophylaxis targeting recipients with allograft rejection or CMV infection may reduce the risk of PJP.

Infections after lung transplantation

The good clinical result of lung transplantation is constantly undermined by the high incidence of infection, which negatively impacts on function and survival. Moreover, infections may also have immunological interactions that play a role in the acute rejection and in the development of chronic lung allograft dysfunction. There is a temporal sequence in the types of infection that affects lung allograft: in the first postoperative month bacteria are the most frequent cause of infection; following this phase, cytomegalovirus and Pneumocystis carinii are common. Fungal infections are particularly feared due to their association with bronchial complication and high mortality. Scrupulous postoperative surveillance is mandatory for the successful management of lung transplantation patients with respect to early detection and treatment of infections. This paper is aimed to address clinicians in the management of the major infectious complications that affect the lung transplant population.

Pneumocystis jirovecii pneumonia in HIV-uninfected, rituximab treated non-Hodgkin lymphoma patients

Rituximab is associated with a higher incidence of Pneumocystis jirovecii pneumonia infection. Pneumocystis prophylaxis is advised in many immunocompromised populations treated with rituximab. However, the beneficial effect of pneumocystis prophylaxis in HIV-uninfected, rituximab-treated non-Hodgkin lymphoma (NHL) patients has not been assessed. Thus, we conducted this retrospective study to explore pneumocystis infection in HIV-uninfected NHL patients who received at least three courses of chemotherapy without haematopoietic stem cell transplantation using the Taiwan National Health Insurance Research Database. Patients who had rituximab-based chemotherapy were included in the experimental (rituximab) group, while the rest of the patients who did not receive any rituximab-based chemotherapy throughout the study period formed the control group. The prevalence rate of pneumocystis infection in the rituximab group (N = 7,554) was significantly higher than that in the control group (N = 4,604) (2.95% vs. 1.32%). The onset of pneumocystis infection occurred between 6 and 16 weeks after chemotherapy. Patients who had pneumocystis prophylaxis, whether or not they had a pneumocystis infection later in their treatment course, had significantly better first-year survival rates (73% vs. 38%). Regular pneumocystis prophylaxis should be considered in this group of patients.

Single-center outbreak of Pneumocystis jirovecii pneumonia in heart transplant recipients

BACKGROUND

Pneumocystis jirovecii pneumonia (PJP) outbreaks are described in solid organ transplant recipients. Few reports suggest interhuman transmission with important infection control implications. We described a large PJP outbreak in heart transplant (HTx) recipients.

METHODS

Six cases of PJP occurred in HTx recipients within 10 months in our hospital. Demographics, clinical characteristics, treatment and outcomes were described. To identify contacts among individuals a review of all dates of out-patient visits and patient hospitalizations was performed. Cross exposure was also investigated using genotyping on PJ isolates.

RESULTS

At the time of PJP-related hospitalization, patients' mean age was 49 ± standard deviation 4 years, median time from HTx was 8 (25%-75% interquartile range [Q1-Q3] 5-12) months and none of the cases were on prophylaxis. At PJP-related admission, 5 patients had CMV reactivation, of whom 4 were on antiviral preemptive treatment. Median in-hospital stay was 30 (Q1-Q3, 28-48) days; and 2 cases required intensive care unit admission. All patients survived beyond 2 years. Transmission map analysis suggested interhuman transmission in all cases (presumed incubation period, median 90 [Q1-Q3, 64-91] days). Genotyping was performed in 4 cases, demonstrating the same PJ strain in 3 cases.

CONCLUSIONS

We described a large PJP cluster among HTx recipients, supporting the nosocomial acquisition of PJP through interhuman transmission. Based on this experience, extended prophylaxis for more than 6 months after HTx could be considered in specific settings. Further work is required to understand its optimal duration and timing based on individual risk factor profiles and to define standardized countermeasures to prevent and limit PJP outbreaks.

Switch to atovaquone and subsequent re-challenge with trimethoprim-sulfamethoxazole for Pneumocystis prophylaxis in a kidney transplant population

Kidney transplant recipients who are switched to atovaquone (ATO) from trimethoprim-sulfamethoxazole (TMP/SMX) for Pneumocystis jirovecii pneumonia (PJP) prophylaxis because of adverse events or complications may miss opportunities to be re-challenged with TMP/SMX, the first-line agent. This single-site, retrospective study assessed kidney transplant recipients for documented reasons for switching from TMP/SMX to alternate PJP prophylaxis and outcomes of TMP/SMX re-challenge. Out of 166 patients, 155 initially received TMP/SMX; of these, 31 were switched to ATO for various reasons. Fourteen patients receiving ATO were re-challenged with TMP/SMX; all were successfully re-initiated on TMP/SMX therapy. Most patients switched to ATO post kidney transplant secondary to non-hypersensitivity reasons should be re-challenged with TMP/SMX because of the advantages it provides over other agents.

HIV-related Pneumocystis jirovecii pneumonia managed with caspofungin and veno-venous extracorporeal membrane oxygenation rescue therapy

Patients with pneumocystis pneumonia have a risk of progressing to acute respiratory failure necessitating admission to intensive care. The case described is of a patient with a newly diagnosed HIV infection presenting with pneumocystis pneumonia. Despite initiating the appropriate pharmacological treatment the patient’s clinical condition deteriorated, and required both rescue pharmacological therapy with echinocandins as well as respiratory support with extracorporeal membrane oxygenation therapy. The patient recovered well on ventilator and circulatory support despite a long weaning process complicated by sequelae common to pneumocystis pneumonia. Following initialisation of antiretroviral therapy and step-down from an intensive care setting, the patient required further prolonged hospital stay for rehabilitation and mental health support before being discharged. This case reviews the novel pharmacological therapies and respiratory support strategies used in cases of pneumocystis pneumonia, including the clinical and psychological sequelae that may follow.

High-dose calcineurin inhibitor-free everolimus as a maintenance regimen for heart transplantation may be a risk factor for Pneumocystis pneumonia

BACKGROUND

Everolimus reduces the incidence of cardiac-allograft vasculopathy (CAV) and is less renally toxic than are calcineurin inhibitors (CNIs). We evaluated the safety of CNI-free everolimus for post-heart transplant (HTx) patients.

METHODS

We retrospectively reviewed the records of 36 consecutive patients who had undergone an HTx between January 2006 and December 2013 in National Cheng Kung University Hospital. All patients initially had been treated with the standard tacrolimus regimen. The Study group-12 patients with CAV, renal impairment, or a history of malignancy-were switched from tacrolimus to everolimus. The Control group consisted of 19 patients who remained on the standard regimen. The target everolimus trough concentration was 8-14 ng/mL. The primary outcome was survival, and the secondary outcomes were bacterial, viral, fungal, and other infections; Pneumocystis jirovecii pneumonia (PJP); and rejection (≥2R).

RESULTS

During a 53.3±25.6-month follow-up, the survival rate, rejection rate, and number of infections, except for PJP, were not significantly different between the two groups. In the Study group, 6 patients were diagnosed with PJP 33±18.2 months after switching. None of the Control group patients were diagnosed with PJP during follow-up.

CONCLUSIONS

A high-dose CNI-free everolimus maintenance regimen might yield a higher incidence of post-transplantation PJP.

Risk factors for Pneumocystis jirovecii pneumonia (PJP) in kidney transplantation recipients

Pneumocystis jirovecii pneumonia (PJP) is a potentially life-threatening infection that occurs in immunocompromised patients. The aim of this study was to evaluate risk factors for PJP in kidney transplantation recipients. We conducted a retrospective analysis of patient data from 500 consecutive kidney transplants performed at Severance Hospital between April 2011 and April 2014. Eighteen kidney transplantation recipients (3.6%) were diagnosed with PJP. In the univariate analysis, acute graft rejection, CMV infection, use of medication for diabetes mellitus, and lowest lymphocyte count were associated with PJP. Recipients who experienced acute graft rejection (odds ratio [OR] 11.81, 95% confidence interval [CI] 3.06–45.57, P < 0.001) or developed CMV infection (OR 5.42, 95% CI 1.69–17.39, P = 0.005) had high odds of PJP in multivariate analysis. In the acute graft rejection subgroup, patients treated with anti-thymocyte globulin (ATG) had significantly higher odds of PJP (OR 5.25, 95% CI 1.01–27.36, P = 0.006) than those who were not. Our data suggest that acute graft rejection and CMV infection may be risk factors for PJP in kidney transplant patients. The use of ATG for acute graft rejection may increase the risk of PJP.

Surveillance of life-long antibiotics: a review of antibiotic prescribing practices in an Australian Healthcare Network

Background

The rise of antimicrobial use in the twentieth century has significantly reduced morbidity due to infection, however it has also brought with it the rise of increasing resistance. Some patients are on prolonged, if not “life-long” course of antibiotics. The reasons for this are varied, and include non-infectious indications. We aimed to study the characteristics of this potential source of antibiotic resistance, by exploring the antibiotic dispensing practices and describing the population of patients on long-term antibiotic therapy.

Methods

A retrospective cross-sectional study of antibiotic dispensing records was performed at a large university hospital-based healthcare network in Melbourne, Australia. Outpatient prescriptions were extracted from the hospital pharmacy database over a 6 month period in 2014. Medical records of these patients were reviewed to determine the indication for prescription, including microbiology, the intended duration, and the prescribing unit. A descriptive analysis was performed on this data.

Results

66,127 dispensing episodes were reviewed. 202 patients were found to have been prescribed 1 or more antibiotics with an intended duration of 1 year or longer. 69/202 (34%) of these patients were prescribed prolonged antibiotics for primary prophylaxis in the setting of immunosuppression. 43/202 (21%) patients were prescribed long-term suppressive antibiotics for infections of thought incurable (e.g. vascular graft infections), and 34/43 (79%) were prescribed by Infectious Diseases doctors. 66/202 (33%) patients with cystic fibrosis were prescribed prolonged courses of macrolides or fluoroquinolones, by respiratory physicians. There was great heterogeneity noted in indications for prolonged antibiotic courses, as well as antibiotic agents utilised.

Conclusion

Our study found that that continuous antibiotic therapy represented only a small proportion of overall antibiotic prescribing at our health network. Prolonged courses of antibiotics were used mainly to suppress infections thought incurable, but also as primary and secondary prophylaxis and as anti-inflammatory agents. More research is needed to understand the impact of long-term antibiotic consumption on both patients and microbial ecology.

Structural Basis for the Selective Binding of Inhibitors to 6-Hydroxymethyl-7,8-dihydropterin Pyrophosphokinase from Staphylococcus aureus and Escherichia coli

6-Hydroxymethyl-7,8-dihydropterin pyrophosphokinase (HPPK) is a member of the folate biosynthesis pathway found in prokaryotes and lower eukaryotes that catalyzes the pyrophosphoryl transfer from the ATP cofactor to a 6-hydroxymethyl-7,8-dihydropterin substrate. We report the chemical synthesis of a series of S-functionalized 8-mercaptoguanine (8MG) analogues as substrate site inhibitors of HPPK and quantify binding against the E. coli and S. aureus enzymes (EcHPPK and SaHPPK). The results demonstrate that analogues incorporating acetophenone-based substituents have comparable affinities for both enzymes. Preferential binding of benzyl-substituted 8MG derivatives to SaHPPK was reconciled when a cryptic pocket unique to SaHPPK was revealed by X-ray crystallography. Differential chemical shift perturbation analysis confirmed this to be a common mode of binding for this series to SaHPPK. One compound (41) displayed binding affinities of 120 nM and 1.76 μM for SaHPPK and EcHPPK, respectively, and represents a lead for the development of more potent and selective inhibitors of SaHPPK.

Pentamidine in Pneumocystis jirovecii prophylaxis in heart transplant recipients

Despite advances in transplantation techniques and the quality of post-transplantation care, opportunistic infections remain an important cause of complications. Pneumocystis jirovecii (P. jirovecii) is an opportunistic organism, represents an important cause of infections in heart transplantation patients. Almost 2% to 10% of patients undergoing cardiac transplantation have Pneumocystis pneumonia. Prophylaxis is essential after surgery. Various prophylaxis regimes had been defined in past and have different advantages. Trimethoprim/sulfamethoxazole (TMP/SMX) has a key role in prophylaxis against P. jirovecii. Generally, although TMP/SMX is well tolerated, serious side effects have also been reported during its use. Pentamidine is an alternative prophylaxis agent when TMP/SMX cannot be tolerated by the patient. Structurally, pentamidine is an aromatic diamidine compound with antiprotozoal activity. Since it is not effectively absorbed from the gastrointestinal tract, it is frequently administered via the intravenous route. Pentamidine can alternatively be administered through inhalation at a monthly dose in heart transplant recipients. Although, the efficiency and safety of this drug is well studied in other types of solid organ transplantations, there are only few data about pentamidine usage in heart transplantation. We sought to evaluate evidence-based assessment of the use of pentamidine against P. jirovecii after heart transplantation.

Diagnosis of pneumocystis pneumonia using serum (1-3)-β-D-Glucan: a bivariate meta-analysis and systematic review

BACKGROUND

The (1-3)-β-D-Glucan (BG) assay has been approved for making a diagnosis of invasive fungal disease. However, the role of serum-BG assay for the diagnosis of pneumocystis pneumonia (PCP) is controversial, especially between patients with human immunodeficiency virus (HIV) and non-HIV. We conducted a meta-analysis to determine the difference of the overall accuracy of serum-BG assay for the diagnosis of PCP in immunocompromised patients with and without HIV.

METHODS

After a systematic review of English-language studies and manual researching, sensitivity (Se), specificity (Sp), and other measures of accuracy of serum-BG for the diagnosis of PCP were pooled using random-effects models for bivariate meta-analysis. Summary receiver operating characteristic (SROC) curve was used to summarize overall test performance. Subgroup analyses were performed to explore the heterogeneity in Se and Sp.

RESULTS

Thirteen studies met our inclusion criteria. The summary estimates for serum-BG assay for definite PCP were as follows: Se, 0.91 [95% confidence interval (CI), 0.88-0.93]; Sp, 0.75 (95% CI, 0.68-0.81). As for the patients with and without HIV, the Se and Sp were 0.92 and 0.78, 0.85 and 0.73, respectively. Significant heterogeneity between Se was presented (P=0.04).

CONCLUSIONS

Contrary to the results of the previous meta-analysis, a negative result of serum-BG determination is sufficient for ruling out PCP only in HIV cases. For non-HIV patients, the results should be interpreted in parallel with clinical and radiological findings. Besides, further prospective studies with larger sample size are needed to confirm the diagnosis strategy of BG detection.

Risks and Epidemiology of Infections After Intestinal Transplantation

Intestinal transplantation has become a well-accepted and successful procedure to save the lives of patients suffering from intestinal failure and who have developed life-threatening complications of parenteral nutrition. Advances in all aspects of care, from the role of multidisciplinary intestinal rehabilitation services prior to transplant to the development strategies for early recognition of infectious sequelae and even the increasing availability of preventive strategies, have led to improved outcomes and a dramatic decline in infection-associated morbidity and mortality in children undergoing intestinal transplantation. Improvements in surgical techniques and immunosuppressive regimens have been essential components in these improvements, reducing risk of infection through reduction of technical complications and more optimal immunosuppression regimens. In addition, the development of molecular tools for early recognition of viral pathogens and an understanding of the timing and risks for infection have allowed for earlier and more successful treatments. Despite these improvements, infectious sequelae remain an important problem in this population, and additional efforts are needed to further minimize the risk of infectious sequelae in those children requiring this procedure.

Pneumocystis Pneumonia in Solid-Organ Transplant Recipients

Pneumocystis pneumonia (PCP) is well known and described in AIDS patients. Due to the increasing use of cytotoxic and immunosuppressive therapies, the incidence of this infection has dramatically increased in the last years in patients with other predisposing immunodeficiencies and remains an important cause of morbidity and mortality in solid-organ transplant (SOT) recipients. PCP in HIV-negative patients, such as SOT patients, harbors some specificity compared to AIDS patients, which could change the medical management of these patients. This article summarizes the current knowledge on the epidemiology, risk factors, clinical manifestations, diagnoses, prevention, and treatment of Pneumocystis pneumonia in solid-organ transplant recipients, with a particular focus on the changes caused by the use of post-transplantation prophylaxis.

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.

Infections after orthotopic liver transplantation

Opportunistic infections are a leading cause of morbidity and mortality after orthotopic liver transplantation. Systemic immunosuppression renders the liver recipient susceptible to de novo infection with bacteria, viruses and fungi post-transplantation as well to reactivation of pre-existing, latent disease. Pathogens are also transmissible via the donor organ. The time from transplantation and degree of immunosuppression may guide the differential diagnosis of potential infectious agents. However, typical systemic signs and symptoms of infection are often absent or blunted after transplant and a high index of suspicion is needed. Invasive procedures are often required to procure tissue for culture and guide antimicrobial therapy. Antimicrobial prophylaxis reduces the incidence of opportunistic infections and is routinely employed in the care of patients after liver transplant. In this review, we survey common bacterial, fungal, and viral infections after orthotopic liver transplantation and highlight recent developments in their diagnosis and management.

Structure-based design and development of functionalized Mercaptoguanine derivatives as inhibitors of the folate biosynthesis pathway enzyme 6-hydroxymethyl-7,8-dihydropterin pyrophosphokinase from Staphylococcus aureus

6-Hydroxymethyl-7,8-dihydropterin pyrophosphokinase (HPPK), an enzyme from the folate biosynthesis pathway, catalyzes the pyrophosphoryl transfer from ATP to 6-hydroxymethyl-7,8-dihydropterin and is a yet-to-be-drugged antimicrobial target. Building on our previous discovery that 8-mercaptoguanine (8MG) is an inhibitor of Staphylococcus aureus HPPK (SaHPPK), we have identified and characterized the binding of an S8-functionalized derivative (3). X-ray structures of both the SaHPPK/3/cofactor analogue ternary and the SaHPPK/cofactor analogue binary complexes have provided insight into cofactor recognition and key residues that move over 30 Å upon binding of 3, whereas NMR measurements reveal a partially plastic ternary complex active site. Synthesis and binding analysis of a set of analogues of 3 have identified an advanced new lead compound (11) displaying >20-fold higher affinity for SaHPPK than 8MG. A number of these exhibited low micromolar affinity for dihydropteroate synthase (DHPS), the adjacent, downstream enzyme to HPPK, and may thus represent promising new leads to bienzyme inhibitors.

Therapeutic approach to respiratory infections in lung transplantation

Lung transplant recipients (LTRs) are at life-long risk for infections and disseminated diseases owing to their immunocompromised state. Besides organ failure and sepsis, infection can trigger acute and chronic graft rejection which increases mortality. Medical prophylaxis and treatment are based on comprehensive diagnostic work-up including previous history of infection and airway colonisation to reduce long-term complications and mortality. Common bacterial pathogens include Pseudomonas and Staphylococcus, whilst Aspergillus and Cytomegalovirus (CMV) are respectively the commonest fungal and viral pathogens. Clinical symptoms can be various in lung transplant recipients presenting an asymptomatic to severe progress. Regular control of infection parameters, daily lung function testing and lifelong follow-up in a specialist transplant centre are mandatory for early detection of bacterial, viral and fungal infections.

After transplantation each patient receives intensive training with rules of conduct concerning preventive behaviour and to recognize early signs of post transplant complications. Early detection of infection and complications are important goals to reduce major complications after lung transplantation.

Benefits of sulfamethoxazole-trimethoprim prophylaxis on rates of sepsis after kidney transplant

BACKGROUND

The use of potent immunosuppression increases the risk of infectious complications following kidney transplantation. Sulfamethoxazole-trimethoprim (SMX/TMP) is an inexpensive broad-spectrum antimicrobial agent used in our center as lifelong prophylaxis against Pneumocystis jirovecii, unless contraindicated. This study evaluated the clinical impact of SMX/TMP prophylaxis compared with no prophylaxis with SMX/TMP (NoPPx), but with alternative agents.

METHODS

This was a retrospective cohort analysis of renal transplant recipients (RTR) transplanted from January 2002 through December 2010. Patients were divided into SMX/TMP group and NoPPX group, based on whether they received prophylaxis with SMX/TMP or not, and rates of sepsis were compared between groups. We also analyzed the pathogens and source implicated in these episodes, as well as the dose of SMX/TMP. Rates were compared using multivariate logistic regression.

RESULTS

With a mean follow-up of 4.8 (± 2.5) years, 63 cases of sepsis occurred in 1224 patients (5.1%), and 60% of these cases had a urinary source. The risk of sepsis was significantly reduced with prophylaxis vs. NoPPx (13.3% vs. 4.3% for SMX/TMP, P < 0.001), and this association was maintained through multivariate regression. Sepsis was associated with a numerically increased risk of graft loss and death that was not significantly affected by use of SMX/TMP.

CONCLUSIONS

Prophylaxis with SMX/TMP is an inexpensive way to reduce the incidence of sepsis in RTR.

Update on pulmonary Pneumocystis jirovecii infection in non-HIV patients

Pneumocystis jirovecii is the only fungus of its kind to be pathogenic in humans. It is primarily responsible for pneumonia (PJP). The key to understanding immune defences has focused on T-cells, mainly because of the HIV infection epidemic. Patients presenting with PJP all have a CD4 count below 200/mm(3). The introduction of systematic primary prophylaxis and the use of new anti-retroviral drugs have significantly reduced the incidence of this disease in the HIV-infected population, mainly in developed countries. The increasingly frequent use of corticosteroids, chemotherapy, and other immunosuppressive drugs has led to an outbreak of PJP in patients not infected by HIV. These patients presenting with PJP have more rapid and severe symptoms, sometimes atypical, leading to delay the initiation of a specific anti-infective therapy, sometimes a cause of death. However, the contribution of new diagnostic tools and a better understanding of patients at risk should improve their survival.

Replacing sulfa drugs with novel DHPS inhibitors

More research effort needs to be invested in antimicrobial drug development to address the increasing threat of multidrug-resistant organisms. The enzyme DHPS has been a validated drug target for over 70 years as the target for the highly successful sulfa drugs. The use of sulfa drugs has been compromised by the widespread presence of resistant organisms and the adverse side effects associated with their use. Despite the large amount of structural information available for DHPS, few recent publications address the possibility of using this knowledge for novel drug design. This article reviews the relevant papers and patents that report promising new small-molecule inhibitors of DHPS, and discuss these data in light of new insights into the DHPS catalytic mechanism and recently determined crystal structures of DHPS bound to potent small-molecule inhibitors. This new functional understanding confirms that DHPS deserves further consideration as an antimicrobial drug target.

Infections of the Liver

The portal vein carries blood from the gastrointestinal tract to the liver and in so doing carries microbes as well. The liver may therefore be involved in infections with a myriad number of microbial organisms. While some of these infections most commonly occur in the immunocompromised host, others affect the immune competence. Hepatic infections may be primary in nature or secondary, as part of systemic or contagious disease. The purpose of this chapter is to provide a brief overview of the various infections of the liver in the pediatric patient.

Infectious Complications of Transplantation

Post-transplant infection is a common cause of graft deterioration, morbidity and mortality. It is also responsible for delayed discharge, multiple, often prolonged admissions and thus a significant clinical challenge. Infections can be donor derived, pre-existing in the recipient, nosocomial and opportunistic. For each of these categories, it is often possible to significantly reduce hazard and thus the adverse consequences by first identifying patients at high risk. As always, clinical vigilance is vital, but equally important is the establishment of robust clinical systems for prevention, screening and rapid treatment.

Nocardiosis in transplant recipients

Nocardiosis is a rare opportunistic infection caused by Nocardia spp., an aerobic actinomycete, that mainly affects patients with cell-mediated immunity defects, such as transplant recipients. Despite recent progress regarding Nocardia identification and changes in taxonomic assignment, many challenges remain for the diagnosis or management of nocardiosis. This opportunistic infection affects 0.04 to 3.5 % of patients with solid organ or hematopoietic stem cell transplantation, depending on the organ transplanted, cytomegalovirus (CMV) infection, corticosteroids dose and calcineurin inhibitors level. Nocardiosis diagnosis relies on appropriate clinical, radiological and microbiological workup that includes the sampling of an accessible involved site and molecular microbiology tools. In parallel, extensive clinical and radiological evaluations are mandatory, including brain imaging, even in the absence of neurological signs. In transplanted patients, differential diagnosis is challenging, with co-infections reported in 20 to 64 % of cases. As the antibiotic susceptibility pattern varies among species, the antimicrobial regimen before species identification should rely on the association of antibiotics active on all species of Nocardia. Bactericidal antibiotics are required in cases of severe or disseminated disease. Furthermore, in transplant recipients, combination therapy is difficult to manage because of cumulative toxicity and interactions with immunosuppressive agents. Because of a high recurrence rate, antibiotic therapy should be prescribed for 6 to 12 months.

Life-threatening infection in transplant recipients

Modern post-transplant care pathways commonly encompass periods of critical care support. Infectious events account for many of these interactions making critical care physicians integral members of multidisciplinary transplant teams. Despite continuing advances in clinical care and infection prophylaxis, the morbidity and mortality attributable to infection post-transplant remains considerable. Emerging entities constantly add to the breadth of potential opportunistic pathogens. Individualized risk assessments, rapid and thorough diagnostic evaluation, and prompt initiation of appropriate antimicrobial therapies are essential. The approach to managing transplant recipients with infection in critical care is discussed and common and emerging opportunistic pathogens are reviewed.

Low incidence of Pneumocystis jirovecii pneumonia in an unprophylaxed liver transplant cohort

BACKGROUND

Liver transplant recipients are managed with a range of immunosuppressive regimens that place them at heightened risk of life-threatening opportunistic infections such as Pneumocystis jirovecii pneumonia (PJP). No routine PJP prophylaxis is used at out institution. We reviewed the incidence of PJP in this cohort of unprophylaxed liver transplant recipients.

METHODS

We examined all liver transplants performed between January 2000 and January 2012 in Ireland's National Liver Transplant Centre, St. Vincent's University Hospital, Dublin. Cases were identified through a computerized database and through the histopathology and microbiology registration system. The diagnosis of PJP was confirmed by identification of Pneumocystis cysts in bronchoalveolar lavage (BAL) fluid or on autopsy specimens using Grocott-Gomori methenamine-silver nitrate or modified Wright-Giemsa staining methods.

RESULTS

During the study period, 687 liver transplants were performed. We found 7 cases of PJP with an incidence rate of 0.84 per 1000 person transplant years. Five cases occurred within 12 months of transplant with 2 cases occurring at 56 and 60 months, respectively. Two cases were diagnosed at postmortem; 1 previously had negative cytology from BAL, while the other could not be bronchoscoped because of rapid deterioration in the clinical condition. Three of the 5 treated patients died.

CONCLUSIONS

The incidence of PJP in this cohort was very low, but the case fatality rate was high. Two cases occurred well after the usual recommended period of prophylaxis. In institutions with a very low risk of infection, targeted rather than universal prophylaxis may be reasonable.

Quinolone prophylaxis for the prevention of BK virus infection in kidney transplantation: study protocol for a randomized controlled trial

BACKGROUND

BK virus infection has emerged as a major complication in kidney transplantation leading to a significant reduction in graft survival. There are currently no proven strategies to prevent or treat BK virus infection. Quinolone antibiotics, such as levofloxacin, have demonstrated activity against BK virus. We hypothesize that administration of a quinolone antibiotic, when given early post-transplantation, will prevent the establishment of BK viral replication in the urine and thus prevent systemic BK virus infection.

METHODS/DESIGN

The aim of this pilot trial is to assess the efficacy, safety and feasibility of a 3-month course of levofloxacin in the kidney transplant population. This is a multicenter, randomized, double-blind, placebo-controlled trial with two parallel arms conducted in 11 Canadian kidney transplant centers. A total of 154 patients with end-stage renal disease undergoing kidney transplantation will be randomized to receive a 3-month course of levofloxacin or placebo starting in the early post-transplant period. Levofloxacin will be administered at 500 mg po daily with dose adjustments based on kidney function. The primary outcome will be the time to occurrence of BK viruria within the first year post-transplantation. Secondary outcomes include BK viremia, measures of safety (adverse events, resistant infections,Clostridium difficile-associated diarrhea), measures of feasibility (proportion of transplanted patients recruited into the trial), proportion of patients adherent to the protocol, patient drop-out and loss to follow-up,and use of quinolone antibiotics outside of the trial protocol.

DISCUSSION

Results from this pilot study will provide vital information to design and conduct a large, multicenter trial to determine if quinolone therapy decreases clinically meaningful outcomes in kidney transplantation. If levofloxacin significantly reduces BK viruria and urine viral loads in kidney transplantation, it will provide important justification to progress to the larger trial. If the full trial shows that levofloxacin significantly reduces BK infection and improves outcomes, its use in kidney transplantation will be strongly endorsed given the lack of proven therapies for this condition.

TRIAL REGISTRATION

This trial was funded by the Canadian Institutes of Health Research (grant number:222493) and is registered at ClinicalTrials.gov (NCT01353339).

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.

Increased risk of pneumocystis jiroveci pneumonia among patients with inflammatory bowel disease

OBJECTIVES

Patients with inflammatory bowel disease (IBD) may be at increased risk for pneumocystis jiroveci pneumonia (PCP). Our aims were (1) to determine the incidence and relative risk of PCP in IBD and (2) to describe medication exposures in patients with IBD with PCP.

METHODS

We performed a retrospective cohort study and a case series using administrative data from IMS Health Inc, LifeLink Health Plan Claims Database. In the cohort, patients with IBD were matched to 4 individuals with no IBD claims. PCP risk was evaluated by incidence rate ratio and adjusted Cox proportional hazards modeling. The demographics and medication histories of the 38 cases of PCP in patients with IBD were extracted.

RESULTS

The cohort included 50,932 patients with Crohn's disease, 56,403 patients with ulcerative colitis, and 1269 patients with unspecified IBD; matched to 434,416 individuals without IBD. The crude incidence of PCP was higher in the IBD cohort (10.6/100,000) than in the non-IBD cohort (3.0/100,000). In the adjusted analyses, PCP risk was higher in the IBD versus non-IBD cohort (hazard ratio, 2.96; 95% confidence interval, 1.75-4.29), with the greatest risk in Crohn's disease compared with non-IBD (hazard ratio, 4.01; 95% confidence interval, 1.88-8.56). In the IBD case series of PCP cases (n = 38), the median age was 49 (interquartile range, 43-57). A total of 20 individuals (53%) were on corticosteroids alone or in combination with other immunosuppression.

CONCLUSIONS

Although the overall incidence of PCP is low, patients with IBD are at increased risk. Patients with IBD with PCP are predominantly on corticosteroids alone or in combination before PCP diagnosis.