Nocardiosis in transplant recipients. Eur J Clin Microbiol Infect Dis. 2014;33:689-702. [PMID: 24272063 DOI: 10.1007/s10096-013-2015-5]

Nocardiosis in kidney transplant recipients: A tertiary care center experience

INTRODUCTION

Kidney transplant recipients are at increased risk of opportunistic infections, including Nocardia. The incidence of nocardiosis in kidney transplant recipients is 0.4-1.3%. The data regarding its epidemiology and outcomes is limited.

METHODS

This was a 10-year retrospective observational study from January 2012 to December 2021 at a tertiary care center in northern India, in which all kidney transplant recipients with Nocardia infection were included and followed.

RESULTS

12 (1.1%) patients had a Nocardia infection among the 1108 kidney transplant recipients. All were living donor kidney transplant recipients, and the mean age at diagnosis was 48.67 ± 12.60 years. Nocardia infection occurred at a median of 26 months (range 4-235) post-transplantation, with 4 (33.1%) of the cases occurring within a year of transplant. Breakthrough infection occurred in 7 (58.3%) patients on cotrimoxazole prophylaxis. 41.7% (n = 5) cases had an episode of rejection in the preceding year of Nocardia diagnosis. Concurrent cytomegalovirus (CMV) infection was present in one (8.3%) case. The lung was the most frequently involved organ. Microscopy was positive in all the cases; while culture was positive in 10 cases, and antimicrobial susceptibility testing (AST) were performed for these isolates. The majority (60%) of isolates were resistant to cotrimoxazole. All tested isolates remained susceptible to Amikacin, Imipenem, and Linezolid. No patients experienced Nocardia recurrence after completion of antibiotic therapy. The mortality at 12 months was 66.7% (n = 4), and only one death was Nocardia-related.

CONCLUSION

Nocardia may cause a late-manifesting infection beyond the traditional window. The cotrimoxazole prophylaxis may not be sufficient for Nocardia prevention.

In vitro activity of omadacycline against clinical isolates of Nocardia

Nocardiosis typically requires a prolonged treatment duration of ≥6 months and initial combination therapy with 2-3 antibiotics. First-line regimens for nocardiosis are associated with considerable toxicity; therefore, alternative therapies are needed. Omadacycline is an aminomethylcycline with broad antimicrobial activity whose in vitro activity against Nocardia species has not been formally assessed. The in vitro potency of omadacycline was evaluated against 300 Nocardia clinical isolates by broth microdilution. The most common Nocardia species tested were N. cyriacigeorgica (21%), N. nova (20%), and N. farcinica (12%). The most common specimens were respiratory (178 isolates, 59%) and wound (57 isolates, 19%). Omadacycline minimum inhibitory concentrations (MICs) across all Nocardia species ranged from 0.06 µg/mL to 8 µg/mL, with an MIC50 of 2 µg/mL and MIC90 of 4 µg/mL. The lowest MICs were found among N. paucivorans (MIC50 = 0.25 µg/mL, MIC90 = 0.25 µg/mL), N. asiatica (MIC50 = 0.25 µg/mL, MIC90 = 1 µg/mL), N. abscessus complex (MIC50 = 0.5 µg/mL, MIC90 = 1 µg/mL), N. beijingensis (MIC50 = 0.5 µg/mL, MIC90 = 2 µg/mL), and N. otitidiscaviarum (MIC50 = 1 µg/mL, MIC90 = 2 µg/mL). The highest MICs were found among N. farcinica (MIC50 = 4 µg/mL, MIC90 = 8 µg/mL). In vitro potency differed by species among Nocardia clinical isolates. Further studies are warranted to evaluate the potential clinical utility of omadacycline for nocardiosis.

Successful maintenance treatment of disseminated nocardiosis with cerebral abscess in a severely immunocompromised patient allergic to trimethoprim-sulfamethoxazole using moxifloxacin and high-dose minocycline: A case report

Nocardiosis in patients after allogeneic hematopoietic stem cell transplantation (HSCT) is rare, but is associated with a significant mortality risk. Although trimethoprim-sulfamethoxazole (TMP/SMX) remains the cornerstone of nocardiosis treatment, optimal alternative therapies for patients intolerant to TMP/SMX are not well-established. Herein, we report a case of disseminated nocardiosis with bacteremia and multiple lesions in the lungs and brain caused by Nocardia farcinica, in a 60-year-old man who had previously undergone allogeneic HSCT and was receiving immunosuppressants for severe chronic graft-versus-host disease. The patient received atovaquone for the prophylaxis of Pneumocystis pneumonia because of a previous serious allergic reaction to TMP/SMX. The patient was initially treated with imipenem/cilastatin and amikacin, which were later switched to ceftriaxone and amikacin based on the results of antimicrobial susceptibility testing. After switching to oral levofloxacin and a standard dose of minocycline, the patient experienced a single recurrence of brain abscesses. However, after switching to oral moxifloxacin and high-dose minocycline, the patient did not experience any relapses during the subsequent two years and seven months of treatment. In treating nocardiosis with brain abscesses, it is crucial to select oral antibiotics based on the antimicrobial susceptibility test results and pharmacokinetics, especially when TMP/SMX is contraindicated. A combination of oral moxifloxacin and high-dose minocycline could be a promising alternative therapy.

Microbiological and Molecular Study of Paranasal Sinus Infections of Children with Malignancy and Unknown Origin Fever in Markazi Province, Iran

Background

Children with malignancies are vulnerable to various infections, including sinus infections. Sinusitis is primarily caused by bacterial infections, followed by fungal infections. Due to this, evaluating the occurrence, diversity, and antibiotic susceptibility patterns of bacterial species that cause paranasal sinus infections in children with malignancy and unexplained fever is important.

Objective

To investigate the bacterial species accountable for sinusitis in children with malignancy and unexplained fever, and determine their susceptibility to antibiotics.

Methods

The study involved collecting 90 sinus samples from children aged 5 to 15 years with malignancy in Arak City, Iran. The isolates were identified using a combination of phenotypic, biochemical, and molecular techniques, including specific polymerase chain reaction and 16S ribosomal RNA gene sequencing. Drug susceptibility testing was performed following the Clinical & Laboratory Standards Institute 2021 guidelines.

Results

A total of 36 isolates (40%) were obtained, including 4 isolates of Nocardia (11.12%), 4 isolates of Escherichia coli (11.12%), 3 isolates of Klebsiella pneumoniae (8.33%), 5 isolates of Pseudomonas aeruginosa (13.88%), 3 isolates of Acinetobacter baumannii (8.33%), 4 isolates of Staphylococcus aureus (11.12%), 3 isolates of Staphylococcus epidermidis (8.33%), 5 isolates of Streptococcus agalactiae (13.88%), 2 isolates of Streptococcus pneumoniae (5.55%), and 3 isolates of Enterococcus faecium (8.33%). The isolates showed the most sensitivity to imipenem and trimethoprim-sulfamethoxazole and the least sensitivity to erythromycin and tetracycline.

Conclusions

The findings of the study indicate that sinusitis can contribute to fever of unknown origin in patients with cancer. Therefore, it is recommended to use a combination of molecular and phenotypic methods for accurate identification of isolates. This approach can provide more reliable and precise results, leading to better diagnosis and treatment of sinusitis infections in children with malignancy.

Disseminated Nocardia farcinica Infection in a Renal Transplant Patient: A Case Report

Nocardia farcinica, an aerobic, Gram-positive bacterium belonging to the genus Nocardia, is a challenging opportunistic pathogen, particularly impacting immunocompromised individuals. The prevalence of human disease has witnessed a notable rise over the past two decades, correlating with an expanding population of immunocompromised individuals and advancements in the detection and identification of Nocardia spp. within clinical laboratories. This case is of a 59-year-old male with compromised immunity due to immunosuppressive medication use following a renal transplant who had an array of presentations before confirming a diagnosis of disseminated nocardiosis. The challenges faced in our case provide valuable insights into the complexities associated with diagnosing and managing Nocardia infections in immunocompromised populations, informing future clinical practice and research endeavors.

Disseminated Nocardia nova in a child with relapsed acute lymphoblastic leukemia: a case report

BACKGROUND

Nocardiosis is a rare infection that typically results from inhalation of or inoculation with Nocardia organisms. It may cause invasive disease in immunocompromised patients. This case describes nocardiosis with bacteremia and pulmonary involvement in a child with a hematologic malignancy.

CASE PRESENTATION

A boy with testicular relapsed acute lymphoblastic leukemia with marrow involvement presented with sudden onset of fever, body aches, headaches, chills, and moderate respiratory distress during continuation 2 chemotherapy. Radiographic imaging demonstrated consolidation and ground glass opacities in bilateral lower lungs. Central line blood cultures grew Nocardia nova complex, prompting removal of the central line and initiation of triple therapy with imipenem-cilastatin, linezolid, and trimethoprim-sulfamethoxazole with rapid improvement of symptoms. Antibiotic susceptibilities showed a multidrug-susceptible isolate. The patient is anticipated to remain on trimethoprim-sulfamethoxazole for at least 12 months.

CONCLUSIONS

In an immunocompromised child, blood cultures, chest imaging, and head imaging can aid in the diagnosis of disseminated nocardiosis. Long-term antibiotic therapy is necessary, guided by the organism and simplified with the results of antimicrobial susceptibility testing.

Fifteen years of phenotypic and genotypic surveillance and antibiotic susceptibility pattern of Actinomycetes (Mycobacterium, Nocardia, Rhodococcus, etc.) in clinical and environmental samples of Iran

Actinomycetes, ubiquitous in the natural world, have been known to inflict infections upon both immunocompromised and healthy individuals. Interestingly enough, these species are oftentimes found residing within the microbiota of humans and animals alike. Unfortunately, these infections are frequently misdiagnosed as more sinister ailments such as malignancy or tuberculosis. Due to this issue, this review deals with 15 years of study on clinical and environmental samples to determine Actinomycetes' prevalence, isolation, identification, and antibiotic susceptibility pattern in Iran by Davood Azadi et al. According to the Davood Azadi framework, we searched the following databases: PubMed/MEDLINE, Embase, Scopus, Web of Science, SID, and Google Scholar in the period from 2007 to 2023. This review aimed to provide an overview of the most recent techniques for collecting environmental samples, cultivating them, and identifying the Actinomycetes group's members. The isolation of Actinomycetes from clinical and ecological sources is becoming more prevalent and should be a concern for health authorities in developing countries. Health centers should take action to increase awareness of diagnostic criteria and management guidelines for actinomycete diseases. Improvements in national and regional reference laboratories may also aid in accurately diagnosing these diseases.

Clinical characteristics and treatment strategy of nocardiosis in lung transplant recipients: a single-center experience

Objective

Nocardia are infrequent pathogens that disproportionately afflict organ transplant recipients. The present study aimed to summarize the clinical manifestations, diagnostic approaches, and treatment strategies of nocardiosis in lung transplant recipients.

Methods

This retrospective study reviewed the clinical data of adult lung transplant recipients who were complicated with nocardiosis between January 2018 and December 2021 at the largest lung transplant center in South China.

Results

The incidence of nocardiosis was 4.2% (13/316), including 9 cases of pulmonary nocardiosis and 4 disseminated nocardiosis (blood, pulmonary and intracranial). The accuracy in diagnosing nocardiosis was 77.8% by culture and 100% by metagenomic next-generation sequencing (mNGS). Nocardia farcinica was the most common causative pathogen. Trimethoprim-sulfamethoxazole-based combination therapy was administered initially, followed by a single antibiotic as the maintained therapy, lasting for 4-8 months.

Conclusions

mNGS is more accurate than culture in diagnosing nocardiosis. Most patients responded well to the antibiotic therapy with combined antibiotics at the initial stage followed by a single antibiotic treatment.

Nocardial Infection in the Early Period after Kidney Transplantation

Patients with solid organ transplant have weaker immune system and can develop opportunistic infections. Prophylactic antimicrobials can help lower that risk but do not prevent it completely. High index of suspicion increases the chance of diagnosing rare opportunistic infections in immunocompromised patients and helps early and effective treatment. We present a unique case of a patient who developed pneumonia from Nocardia early after kidney transplant despite being on trimethoprim-sulfamethoxazole (TMP-SMX) prophylaxis. He was diagnosed and treated early which helped improving his outcome. We discuss incidence, risk factors, and treatment of nocardiosis post kidney transplant.

Nocardia Infections in the Immunocompromised Host: A Case Series and Literature Review

Nocardia is primarily considered an opportunistic pathogen and affects patients with impaired immune systems, solid-organ transplant recipients (SOTRs), and patients with haematologic malignancies. We present the cases of six patients diagnosed with nocardiosis at our center in the last two years, describing the various predisposing conditions alongside the clinical manifestation, the diagnostic workup, and the treatment course. Moreover, we propose a brief literature review on Nocardia infections in the immunocompromised host, focusing on SOTRs and haematopoietic stem cell transplantation recipients and highlighting risk factors, clinical presentations, the diagnostic tools available, and current treatment and prophylaxis guidelines.

Immune reconstitution inflammatory syndrome (IRIS) in a patient with neuro pulmonary nocardiosis following hematopoietic cells transplantation (HCT)

Immune reconstitution inflammatory syndrome (IRIS) is increasingly reported in various HIV negative patients with immunosuppression, but the relationship with hematopoietic cell transplantation (HCT) is not well defined. We report a case of IRIS in a patient infected with pulmonary and CNS Nocardiosis following HCT due to primary myelofibrosis.

Central nervous system infections after solid organ transplantation

PURPOSE OF REVIEW

Significant advances to our understanding of several neuroinfectious complications after a solid organ transplant (SOT) have occurred in the last few years. Here, we review the central nervous system (CNS) infections that are relevant to SOT via a syndromic approach with a particular emphasis on recent updates in the field.

RECENT FINDINGS

A few key studies have advanced our understanding of the epidemiology and clinical characteristics of several CNS infections in SOT recipients. Risk factors for poor prognosis and protective effects of standard posttransplant prophylactic strategies have been better elucidated. Newer diagnostic modalities which have broad clinical applications like metagenomic next-generation sequencing, as well as those that help us better understand esoteric concepts of disease pathogenesis have been studied. Finally, several studies have provided newer insights into the treatment of these diseases.

SUMMARY

Recent findings reflect the steady progress in our understanding of CNS infections post SOT. They provide several avenues for improvement in the prevention, early recognition, and therapeutic outcomes of these diseases.

Treatment of disseminated nocardiosis: a host-pathogen approach with adjuvant interferon gamma

Disseminated nocardiosis is a rare, life-threatening disease. Particularly at risk are immunocompromised patients, highlighting the crucial role of host factors. Conventional intensive antibiotic treatment has improved survival rates, but the overall prognosis of patients with disseminated nocardiosis remains unsatisfactory. In this Grand Round, we present a case of severe nocardiosis that did not respond to standard therapy. The patient's condition deteriorated when antibiotic therapy was given alone and improved substantially only after coadministration of interferon gamma. We review the literature relevant to adjuvant interferon gamma therapy of nocardiosis and discuss its potential harms and benefits. Overall, we consider such treatment as beneficial and low risk if the patient is followed-up closely. We conclude that clinicians should consider this regimen in refractory cases of severe Nocardia infection.

Disseminated Nocardia Paucivorans in an immunocompetent patient: A case report and literature review

Nocardia paucivorans can cause disseminated infection in immunocompetent hosts in rare occasions. Nocardia paucivorans is usually susceptible to many antibiotics including Trimethoprim/Sulfamethoxazole. Duration of treatment is usually 6-12 months.

Trimethoprim/sulfamethoxazole for nocardiosis in solid organ transplant recipients: Real-life data from a multicentre retrospective study

BACKGROUND

Little is known regarding the optimal management of nocardiosis among solid organ transplant (SOT) recipients. It is often suggested to avoid trimethoprim/sulfamethoxazole (TMP-SMX) monotherapy in heavily immunocompromised patients (such as SOT recipients) and/or in case of severe or disseminated nocardiosis. Our aim was to report our experience with TMP-SMX monotherapy in SOT recipients with nocardiosis.

METHODS

Using data from a previously published European study, we assessed the incidence of adverse events in SOT recipients receiving TMP-SMX monotherapy and assessed its effectiveness.

RESULTS

Thirty-one SOT recipients with nocardiosis were included, mostly kidney transplant recipients (20/31, 65%). Eleven (36%) had disseminated infection, and four (13%) had brain nocardiosis. Most patients had lung and/or pleural involvement (26/31, 84%). Daily dose of trimethoprim at initiation was 10 [6.4-14.8] mg/kg. The median estimated glomerular filtration rate at time of diagnosis of nocardiosis was 44 [30-62] ml/min/1.73 m². TMP-SMX was discontinued prematurely in one third of the patients (10/31, 32%, mostly for hematological toxicity [n = 3] or increased serum creatinine [n = 3]). Focusing on the 24 (77%) patients who completed at least 30 days of TMP-SMX monotherapy, 4 had late (>30 days) drug discontinuation, 1 experienced treatment failure, and 19 completed planned TMP-SMX monotherapy. Clinical outcome was favorable in these 19 patients, despite the fact that 8 (42%) had disseminated infection and 2 (11%) brain nocardiosis. Overall, all-cause 1-year mortality was 10% (3/31).

CONCLUSIONS

TMP-SMX monotherapy appears to be effective for the treatment of most nocardiosis among SOT recipients. Interventional studies are needed to compare its safety and effectiveness with those of other regimens used to treat posttransplant nocardiosis.

Clarithromycin As an Alternative and Prophylactic Agent in a Hematopoietic Stem Cell Transplantation Patient

Patient: Male, 34-year-old

Final Diagnosis: Nocardia infection

Symptoms: Chest pain

Medication: —

Clinical Procedure: —

Specialty: Infectious Diseases

Molecular identification and antibiotic resistance pattern of actinomycetes isolates among immunocompromised patients in Iran, emerging of new infections

Recent advancements in DNA-based approaches have led to the identification of uncommon and rare bacterial pathogens. In this study, by utilizing a DNA-based approach, a total of 1043 clinical specimens were processed for the identification of actinobacteria targeting the 16S rRNA and gyrB genes. Drug susceptibility testing was also conducted using micro-broth dilution and PCR. Two isolates of Nocardia flavorosea and Rhodococcus erythropolis were reported for the first time in Iran. Also, Nocardiopsis dassonvillei, Streptomyces olivaceus, and Streptomyces griseus were reported for the first time in Asia. Infections caused by Nocardia caishijiensis and Prauserella muralis have also been reported in this study. The first Asian case of pulmonary infection caused by Nocardia ignorata and the first global case of brain abscess caused by Nocardia ninae and Nocardia neocaledoniensis have been reported in this study. Overall 30 isolates belonging to 6 genera (Nocardia, Streptomyces, Rodoccoccus, Nocardiopsis, Rothia, and Prauserella) were detected in 30 patients. All 30 isolates were susceptible to amikacin and linezolid. Three isolates including Nocardia otitidiscaviarum (n = 2) and Nocardia flavorosea (n = 1) were resistant to trimethoprim-sulfamethoxazole which were the first trimethoprim-sulfamethoxazole resistant clinical actinomycetes in Iran. Isolation of rare species of actinomycetes particularly Nocardia spp. requires urgent action before they spread clinically particularly among immunocompromised patients.

Case Report: A Severe and Multi-Site Nocardia farcinica Infection Rapidly and Precisely Identified by Metagenomic Next-Generation Sequencing

Nocardia genus is an aerobic, gram-positive, and opportunistic pathogen, which mainly affects cell-mediated immunosuppressed patients. Early diagnosis and treatment greatly improve prognosis. However, the limitation of golden standard-bacterial culture exists. Here, we report a 61-year-old male with pneumonia, sepsis and intermuscular abscesses induced by Nocardia farcinica. Venous blood culture reported negative results. Former improper diagnosis and treatment did not improve his condition. With the assistant of metagenomic next-generation sequencing, the pathogen was identified as Nocardia farcinica. He was then applied with accurate treatment and had a remarkable clinical and radiological improvement.

Pulmonary alveolar proteinosis complicated with nocardiosis: A case report and review of the literature

BACKGROUND

Pulmonary alveolar proteinosis (PAP) is a pulmonary syndrome wherein large volumes of phospholipid and protein-rich surfactants accumulate within the alveoli. PAP forms include primary (auto-immune PAP), secondary, and congenital. Nocardiosis is a form of suppurative disease induced upon infection with bacteria of the Nocardia genus. Clinically, cases of PAP complicated with Nocardia infections are rare, regardless of form. Unfortunately, as such, they are easily overlooked or misdiagnosed. We describe, here, the case of a patient suffering from simultaneous primary PAP and nocardiosis.

CASE SUMMARY

A 45-year-old Chinese man, without history of relevant disease, was admitted to our hospital on August 8, 2018 to address complaints of activity-related respiratory exertion and cough lasting over 6 mo. Lung computed tomography (CT) revealed diffuse bilateral lung infiltration with local consolidation in the middle right lung lobe. Subsequent transbronchial lung biopsy and CT-guided lung biopsy led to a diagnosis of primary PAP (granulocyte-macrophage colony-stimulating factor antibody-positive) complicated with nocardiosis (periodic acid-Schiff-positive). After a 6 mo course of anti-infective treatment (sul-famethoxazole), the lesion was completely absorbed, such that only fibrous foci remained, and the patient exhibited significant symptom improvement. Follow-up also showed improvement in pulmonary function and the CT imaging findings of PAP. No whole-lung lavage has been conducted to date. This case highlights that active anti-nocardia treatment may effectively improve the symptoms and alleviate PAP in patients with PAP and nocardia, possibly reducing the need for whole-lung lavage.

CONCLUSION

When evaluating patients presenting with PAP and pulmonary infections, the potential for nocardiosis should be considered.

Pulmonary Nocardiosis in Pemphigus Vulgaris Patients from Tehran, Iran

OBJECTIVE

Nocardiosis is an opportunistic infection in individuals who had organ transplants and in patients with immunosuppressive diseases such as pemphigus Vulgaris (PV), diabetes mellitus, and HIV. Nocardiosis rate has not been assessed in Iranian PV patients, and this was the first study to estimate nocardiosis rate in these patients.

METHODS

In this study, 103 patients with PV were examined. BAL samples were obtained and direct smear was prepared and visualized by microscopy after PAS staining. Samples were cultured on antibiotic-containing blood and chocolate agar media. DNA extraction and PCR were performed on positive cultures, and final identification was done by 16S rRNA gene sequencing. Drug susceptibility testing was done by microbroth dilution method.

RESULTS

Four positive cultures (3.88%) were found in the samples (n = 103). According to sequence analysis, 2 isolates were identified as Nocardia cyriacigeorgica and 2 as Nocardia otitidiscaviarum and Nocardia cerradoensis. Nocardia cerradoensis was isolated from an invasive brain infection. Isolated bacteria were susceptible to majority of the tested antibiotics, except for 2 strains of Nocardia cyriacigeorgica and Nocardia cerradoensis. This was the first isolation of Nocardia cerradoensis of human infection in Asia. Patients with PV are susceptible to nocardiosis, similar to other immunocompromised patients.

CONCLUSION

Pemphigus Vulgaris is a severe autoimmune disease which is treated by a high dosage of corticosteroids. Opportunistic infections are one of the greatest challenges of these patients. One of the neglected agents of opportunistic infection in this disorder is Nocardiosis which can cause a high mortality rate in PV patients.

Primary cutaneous nocardiosis caused by Nocardia nova with possible Apremilast contribution

Primary cutaneous nocardiosis accounts for 5-8 % of all nocardiosis cases and represents a diagnostic dilemma among immunocompetent and immunocompromised hosts. Herein, we present a case of a 30-year-old male with history of psoriasis with recent addition of Apremilast. Patient received intralesional triamcinolone injections for psoriatic plaques on the hands and abdomen prior to traveling to warm climate vacation. While on vacation, patient developed hand swelling and painful, red nodules on the dorsal hands and abdomen, sites where he received intralesional injections. Patient was empirically given doxycycline, but continued to develop new nodules. An abdominal lesion was biopsied for H&E and tissue culture. Tissue culture revealed beaded gram-positive rods identified as Nocardia nova by MALDI-TOF. Patient was switched to trimethoprim-sulfamethoxazole with significant improvement. This case represents an atypical primary cutaneous nocardiosis with Nocardia nova most likely in the setting of intralesional steroid injections and possible contribution of Apremilast.

Long-term use of liposomal nebulized amikacin and tedizolid for the treatment of disseminated nocardiosis after allogeneic hematopoietic stem cell transplantation

Nocardiosis is a life-threatening opportunistic infection in immunocompromised patients. Herein, we present successful adjunctive use of liposomal nebulized amikacin and tedizolid in a recipient of allogeneic hematopoietic stem cell transplantation infected with Nocardia nova complex who presented multiple complications to conventional therapeutic options.

Nocardiosis Associated with Primary Immunodeficiencies (Nocar-DIP): an International Retrospective Study and Literature Review

PURPOSE

Nocardiosis is a life-threatening infectious disease. We aimed at describing nocardiosis in patients with primary immunodeficiency diseases (PID).

METHODS

This international retrospective cohort included patients with PID and nocardiosis diagnosed and/or published from Jan 1, 2000, to Dec 31, 2016. To identify nocardiosis cases, we analyzed PID databases from the French National Reference Center for PID (Paris, France) and the National Institute of Health (NIH, United States of America) and we performed a literature review on PubMed.

RESULTS

Forty-nine cases of nocardiosis associated with PID were included: median age at diagnosis of nocardiosis was 19 (0-56) years and most cases were observed among chronic granulomatous disease (CGD) patients (87.8%). Median time from symptoms to diagnosis of Nocardia infection was 20 (2-257) days. Most frequent clinical nocardiosis presentation was pneumonia (86.7%). Twelve-month mortality rate was 4.2%, and 11.9% of patients experienced a possible recurrence of infection. Nocardiosis more frequently led to the diagnosis of PID among non-CGD patients than in CGD patients. Non-CGD patients experienced more cerebral nocardiosis and more disseminated infections, but mortality and recurrence rates were similar. Highest incidences of nocardiosis among PID cohorts were observed among CGD patients (0.0057 and 0.0044 cases/patient-year in the USA and in France, respectively), followed by IL-12p40 deficiency.

CONCLUSIONS

Among 49 cases of nocardiosis associated with PID, most patients had CGD and lung involvement. Both mortality and recurrence rates were low.

Diffuse primary cutaneous infection by Alternaria alternata in a liver transplant recipient with pulmonary nocardiosis: Importance of prompt identification for clinical resolution

Fungal infections are rare in the general population but are an emerging cause of disease in immunosuppressed patients, especially solid organ transplant recipients. Here, we report the case of a female Caucasian liver transplant patient who developed pulmonary nocardiosis two months after an episode of liver rejection. At the time of lung nocardiosis, she was being treated with tacrolimus and corticosteroids and suffered from diffuse papular skin lesions. She was initially suspected of having a cutaneous nocardial infection but culture examination revealed the presence of a dematiaceous fungus; Alternaria alternata. The prompt identification of the fungus and administration of oral Voriconazole resolved the skin infection with complete remission.

Inhibition Activity of Avibactam against Nocardia farcinica β-Lactamase FARIFM10152

Nocardia farcinica, one of the most frequent pathogenic species responsible for nocardiosis, is characterized by frequent brain involvement and resistance to β-lactams mediated by a class A β-lactamase. Kinetic parameters for hydrolysis of various β-lactams by FAR_IFM10152 from strain IFM 10152 were determined by spectrophotometry revealing a high catalytic activity (k _cat/K_m ) for amoxicillin, aztreonam, and nitrocefin. For cephems, k _cat/K_m was lower but remained greater than 10⁴ M^-1 s^-1 A low catalytic activity was observed for meropenem, imipenem, and ceftazidime hydrolysis. FAR_IFM10152 inhibition by avibactam and clavulanate was compared using nitrocefin as a reporter substrate. FAR_IFM10152 was efficaciously inhibited by avibactam with a carbamoylation rate constant (k ₂/K_i ) of (1.7 ± 0.3) × 10⁴ M^-1 s^-1 The 50% effective concentrations (EC₅₀s) of avibactam and clavulanate were 0.060 ± 0.007 μM and 0.28 ± 0.06 μM, respectively. Amoxicillin, cefotaxime, imipenem, and meropenem MICs were measured for ten clinical strains in the presence of avibactam and clavulanate. At 4 μg/ml, avibactam and clavulanate restored amoxicillin susceptibility in all but one of the tested strains but had no effect on the MICs of cefotaxime, imipenem, and meropenem. At 0.4 μg/ml, amoxicillin susceptibility (MIC ≤ 8 μg/ml) was restored for 9 out of 10 strains by avibactam but only for 4 out of 10 strains by clavulanate. Together, these results indicate that avibactam was at least as potent as clavulanate, suggesting that the amoxicillin-avibactam combination could be considered as an option for the rescue treatment of N. farcinica infections if clavulanate cannot be used.

Nocardiosis: 7-year experience at an Australian tertiary hospital

BACKGROUND

Nocardiosis has historically been reported in immunocompromised patients, but Australian epidemiological and antimicrobial susceptibility data are limited.

AIM

To describe the epidemiology, diagnosis and initial treatment of nocardiosis in an Australian tertiary hospital over 7 years.

METHODS

In this retrospective study, all positive cultures for Nocardia species from any site isolated at the Alfred Hospital, Melbourne, between 1 January 2010 and 31 December 2016 were identified, and corresponding laboratory data and medical records reviewed.

RESULTS

Sixty-eight non-duplicate isolates were identified from 67 patients. Common predisposing factors were chronic lung disease (38/67; 57%), organ, particularly lung, transplantation (13/67; 19%) and solid organ malignancy (6/67; 9%); 12% (8/67) of patients had no identifiable systemic risk factors. Seventy-nine percent (53/67) of patients had pulmonary nocardiosis only. Nocardia nova was the most commonly isolated species (20/68; 29%). In 48% (32/67) of patients, Nocardia species were isolated only on specific mycobacterial media. All tested species were susceptible to sulfamethoxazole-trimethoprim and amikacin, with the majority (58/63; 92%) susceptible to imipenem. All-cause mortality rates at 6 and 12 months where data were available were 15% (10/66 patients) and 22% (14/64 patients) respectively.

CONCLUSION

In the largest Australian series in 25 years, nocardiosis predominantly affected patients with chronic lung disease or impaired cell-mediated immunity. A significant proportion of organisms from pulmonary sites were isolated on mycobacterial culture media only, suggesting that its use may improve yield. Isolates remain highly susceptible to sulfamethoxazole-trimethoprim, amikacin and imipenem, while other agents should be used only after confirmation of in vitro susceptibility.

The emergence of rare nocardiosis following allogeneic hematopoietic stem cell transplantation in the era of molecular taxonomy

OBJECTIVE

The purpose of this study was to describe the clinical features of nocardiosis after allogeneic hematopoietic stem cell transplantation (allo-HSCT), focusing on new Nocardia species.

METHODS

We retrospectively reviewed data from patients with nocardiosis after allo-HSCT treated at our hospital and documented cases in the medical literature.

RESULTS

Fifty-seven cases were identified from our institution and the literature review. Although 51 patients (89.5%) responded to initial treatment, 28 (49.1%) patients were switched over to other treatment regimens due to the recurrence of nocardiosis or adverse events of antimicrobials. Nocardiosis-attributed mortality occurred in ten patients (17.5%). Antimicrobial susceptibilities varied among intra- and inter-species except linezolid (LZD). In the present study, five species were newly discovered after 2000, including N. cyriacigeorgica, N. veterana, N. abscessus, N. aobensis, and N. mexicana. All isolates of N. cyriacigeorgica, N. veterana, N. abscessus, and N. aobensis were sensitive to trimethoprim/sulfamethoxazole, amikacin (AMK), imipenem (IPM), and LZD; however, N. mexicana was resistant to AMK and IPM.

CONCLUSION

Newly identified Nocardia species have various antimicrobial susceptibility patterns. Long-term maintenance therapy could be challenging due to the adverse events of antimicrobials, especially in the allo-HSCT setting. Prudent evaluation is crucial for selecting a second-line or further treatment options.

Updates on Nocardia Skin and Soft Tissue Infections in Solid Organ Transplantation

PURPOSE OF REVIEW

Due to their immunocompromised status, solid organ transplant (SOT) recipients are at risk for Nocardia infections. These infections often necessitate early invasive diagnostics alongside prolonged, often combination antimicrobial therapy. This review summarizes the importance of this pathogen in skin and soft tissue infections (SSTIs) in SOT recipients inclusive of recently reported cases in the literature and an update on the epidemiology, diagnostics, and management.

RECENT FINDINGS

Six studies with 13 isolated SSTIs due to Nocardia have been published in the last 5 years in SOT recipients. The most common underlying type of transplant was kidney and time from transplantation to infection varied from 6 months to 16 years. Misdiagnosis was frequent. Available identified species included N. brasiliensis (2), N. farcinica (2), N. flavorosea (1), N. abscessus (1), N. anaemiae (1), N. asteroides (1), N. nova (1), and N. vinacea (1). Treatment choice and duration varied widely, and trimethoprim-sulfamethoxazole was utilized most often with no documented infection relapse. Nocardia SSTIs can occur both in isolation and as a component of a disseminated infection. Overall, isolated Nocardia SSTIs are uncommon in SOT recipients and are often initially misdiagnosed. They present multiple challenges to the clinician including evaluation for potential co-pathogens and/or non-infectious processes and ruling out the presence of disseminated infection. While trimethoprim-sulfamethoxazole remains the agent of choice for management of most isolated SSTIs, therapy must be tailored to the individual patient based on species-specific susceptibility patterns and formal susceptibility testing, site(s) of infection, and patient tolerability.

Altered thymic CD4+ T-cell recovery after allogeneic hematopoietic stem cell transplantation is critical for nocardiosis

PURPOSE OF THE STUDY

Nocardia affects immunocompromised human host exhibiting an altered cell-mediated immunity. Infectious risk after allogeneic hematopoietic cell transplantation (AHCT) is significantly correlated to the recovery status of donor-derived immune system, especially CD4⁺ T-cells reconstitution and thymopoiesis. The purpose of this paper is to highlight a lack of cell-mediated immunity recovery for patients presenting a nocardiosis compared to a control cohort.

PATIENTS AND METHODS

This is a case control retrospective monocentric study. We retrospectively analyzed a monocentric cohort of 15 cases of nocardiosis after AHCT and we explored the degree of patients' immunosuppression by phenotyping circulating lymphoid subpopulations, including NK cells, CD8⁺ T-cells, CD4⁺ T-cells and CD19⁺ B-cells. We focused on CD4⁺ T-cell subsets to appreciate thymic output, especially on naive CD4⁺ T-cells (NTE, CD45RA⁺/RO^- CD4⁺ T-cells) and recent thymic emigrants (RTE, CD4⁺CD45RA⁺/RO^-/CD31⁺). Infected patients were paired with a control cohort of patients with identical transplantation characteristics screened on hematological disease, AHCT conditioning, primary graft-versus-host disease (GHVD) prophylaxis, graft type, sex, age, and season at the AHCT and data concerning immunological reconstitution were compared.

RESULTS

At onset of nocardiosis, circulating lymphocytes and CD4⁺ T-cells means count were respectively 730/μL and 162/μL. CD8⁺ T-cells, CD56⁺ NK cells and CD19⁺ B-cells means count were respectively 362/μL, 160/μL, 112/μL. CD4⁺ T-cells subpopulations, naïve CD4⁺ T-cells production was impaired with NTE and RTE means count at 26/μL and 11/μL respectively. Comparison between nocardiosis cohort and control cohort over time highlight significant lower cellular count for lymphocytes, CD4⁺ T-cells, NTE and RTE with p = 0.001, p < 0.001, p < 0.001, p < 0.001 respectively.

CONCLUSION

Immune recovery monitoring follow-up after AHCT is of particular importance to identify patients susceptible to develop Nocardiosis. Efficient microbiological investigations toward Nocardia such PCR should be used in case of compatible clinical presentation.

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

These updated guidelines from the Infectious Diseases Community of Practice of the American Society of Transplantation review the diagnosis, prevention, and management of Nocardia infections after solid organ transplantation (SOT). Nocardia infections have increased in the last two decades, likely due to improved detection and identification methods and an expanding immunocompromised population. The risk of developing nocardiosis after transplantation varies with the type of organ transplanted and the immunosuppression regimen used. Nocardia infection most commonly involves the lung. Disseminated infection can occur, with spread to the bloodstream, skin, or central nervous system. Early recognition of the infection and initial appropriate treatment is important to achieve good outcomes. Species identification and antimicrobial susceptibility testing are strongly recommended, as inter- and intraspecies susceptibility patterns can vary. Sulfonamide is the first-line treatment of Nocardia infections, and combination therapy with at least two antimicrobial agents should be used initially for disseminated or severe nocardiosis. Trimethoprim-sulfamethoxazole (TMP-SMX) prophylaxis may be helpful in preventing Nocardia infection after SOT.

Manifestations and outcomes of nocardia infections: Comparison of immunocompromised and nonimmunocompromised adult patients

Nocardia is a ubiquitous environmental pathogen that causes infection primarily following inhalation into the lungs. It is generally thought to cause infection primarily in immunocompromised patients, but nonimmunocompromised individuals are also at risk of infection. We sought to compare risk factors, clinical manifestations, diagnostic approach, treatment, and mortality in immunocompromised and nonimmunocompromised adults with nocardiosis.We studied all adults with culture-proven Nocardia infection at a tertiary care hospital from 1994 to 2015 and compared immunocompromised with nonimmunocompromised patients. The immunocompromised group included patients who had a solid organ transplant, hematopoietic cell transplant (HCT), hematological or solid tumor malignancy treated with chemotherapy in the preceding 90 days, inherited immunodeficiency, autoimmune/inflammatory disorders treated with immunosuppressive agents, or high-dose corticosteroid therapy for at least 3 weeks before the diagnosis of nocardiosis.There were 112 patients, mean age 55 ± 17 years; 54 (48%) were women. Sixty-seven (60%) were immunocompromised, and 45 (40%) were nonimmunocompromised. The lung was the site of infection in 54 (81%) immunocompromised and 25 (55%) nonimmunocompromised patients. Pulmonary nocardiosis in immunocompromised patients was associated with high-dose corticosteroids, P = .002 and allogeneic HCT, P = .01, and in nonimmunocompromised patients with cigarette smoking, bronchiectasis, and other chronic lung diseases, P = .002.Cavitation occurred only in the immunocompromised group, P < .001. Disseminated infection was more common in the immunocompromised, P = .01, and was highest in solid organ transplant recipients, P = .007. Eye infection was more common in nonimmunocompromised patients, P = .009. Clinical signs and symptoms did not differ significantly between the 2 groups. The initial treatment for most patients in both groups was trimethoprim-sulfamethoxazole with or without a carbapenem. All-cause 1-year mortality was 19%; 18 (27%) immunocompromised and 3 (7%) nonimmunocompromised patients died, P = .01.Immunocompromised patients with nocardiosis had more severe disease and significantly higher mortality than nonimmunocompromised patients, but clinical presentations did not differ.

Nocardia infections in solid organ and hematopoietic stem cell transplant recipients

PURPOSE OF REVIEW

Nocardia spp. is a gram-positive bacteria that may cause infections in humans. Nocardiosis has been described since the early years of transplantation. This review aims to provide an overview of present knowledge regarding posttransplant nocardiosis, with a focus on recent findings.

RECENT FINDINGS

Nocardiosis is not rare among transplant recipients, especially after thoracic transplantation and/or in case of intense immunosuppressive regimen or use of tacrolimus. Low-dose cotrimoxazole is not effective to prevent nocardiosis. Although lung is the most common site of infection, more than 40% of organ transplant patients have a disseminated infection. As central nervous system involvement is frequent (about 1/3 of the patients) and possibly asymptomatic, brain imaging is mandatory. Diagnosis relies on direct examination and culture; molecular species identification is useful to guide treatment. Although cotrimoxazole is the drug for which we have the strongest clinical experience, other antibiotics such as linezolid, parenteral cephalosporins, carbapenems, and amikacin can be used to treat nocardiosis. Although treatment duration has historically been set to at least 6 months, shorter durations (<120 days) seem associated with a good outcome in selected patients.

SUMMARY

Physicians in charge of transplant patients should be aware of nocardiosis. Diagnosis and management of transplant recipients with nocardiosis require a multidisciplinary approach.

Clinical Assessment of a Nocardia PCR-Based Assay for Diagnosis of Nocardiosis

The diagnosis of nocardiosis, a severe opportunistic infection, is challenging. We assessed the specificity and sensitivity of a 16S rRNA Nocardia PCR-based assay performed on clinical samples. In this multicenter study (January 2014 to April 2015), patients who were admitted to three hospitals and had an underlying condition favoring nocardiosis, clinical and radiological signs consistent with nocardiosis, and a Nocardia PCR assay result for a clinical sample were included. Patients were classified as negative control (NC) (negative Nocardia culture results and proven alternative diagnosis or improvement at 6 months without anti-Nocardia treatment), positive control (PC) (positive Nocardia culture results), or probable nocardiosis (positive Nocardia PCR results, negative Nocardia culture results, and no alternative diagnosis). Sixty-eight patients were included; 47 were classified as NC, 8 as PC, and 13 as probable nocardiosis. PCR results were negative for 35/47 NC patients (74%). For the 12 NC patients with positive PCR results, the PCR assay had been performed with respiratory samples. These NC patients had chronic bronchopulmonary disease more frequently than did the NC patients with negative PCR results (8/12 patients [67%] versus 11/35 patients [31%]; P = 0.044). PCR results were positive for 7/8 PC patients (88%). There were 13 cases of probable nocardiosis, diagnosed solely using the PCR results; 9 of those patients (69%) had lung involvement (consolidation or nodule). Nocardia PCR testing had a specificity of 74% and a sensitivity of 88% for the diagnosis of nocardiosis. Nocardia PCR testing may be helpful for the diagnosis of nocardiosis in immunocompromised patients but interpretation of PCR results from respiratory samples is difficult, because the PCR assay may also detect colonization.

Nocardia infections in the transplanted host

BACKGROUND

Nocardia are uncommon pathogens that disproportionately afflict the immunocompromised host. Epidemiology and outcome data of Nocardia infections in transplant recipients are limited.

METHODS

We performed a retrospective chart review of all patients at Duke University Hospital with a history of solid organ transplant (SOT) or hematopoietic cell transplant (HCT) and at least one positive culture for Nocardia between 1996 and 2013. Our aim was to describe the epidemiology and outcomes of Nocardia infections in the transplanted host.

RESULTS

During the 18-year study period, 51 patients (14 HCT and 37 SOT recipients) had Nocardia infection. Nocardia incidence was stable during the study period in all populations except heart transplants, whose incidence declined. Infection occurred earlier in the HCT group than the SOT group (median time to diagnosis of 153 and 370 days, respectively). In both groups, the most common site involved was the lung. Outcomes were overall poor, especially in the HCT group with a cure rate of 29%. Heart transplant recipients had significantly better overall survival (P < .05) than other patients. Trimethoprim-sulfamethoxazole (TMP-SMX) prophylaxis did not provide complete protection from Nocardia infections, nor did it appear to select for resistant Nocardia isolates.

CONCLUSIONS

Infections with Nocardia are typically a late post-transplant complication. The use of TMP-SMX prophylaxis was not associated with TMP-SMX-resistant Nocardia. Overall outcomes remain poor.

Bacterial pneumonia in kidney transplant recipients

Bacterial pathogens are the most frequent cause of pneumonia after transplantation. Early after transplantation, recipients are at higher risk for nosocomial infections. The most commonly encountered pathogens during this period are gram-negative bacilli (Klebsiella pneumoniae, Escherichia coli, Pseudomonas aeruginosa …), but gram-positive coccus such as Staphylococcus aureus or Streptococcus pneumoniae and anaerobic bacteria can also be found. Empirical antibiotic therapy should be guided by previous colonisation of the recipient and bacterial resistance pattern in the hospital. Six months after transplantation, pneumonias are mostly due to community-acquired bacteria (S. pneumonia, H. influenza, Mycoplasma, Chlamydia and others). Opportunistic pathogens take advantage of the state of immunosuppression which is usually highest from one to six months after transplantation. During this period, but also occurring many years later in the setting of a chronically depressed immune system, bacterial pathogens with low intrinsic virulence can cause pneumonia. The diagnosis of pneumonia caused by opportunistic pathogens can be challenging. The delay in diagnosis preventing the early instauration of adequate treatment in kidney transplant recipients with a depressed immune system, frequently coupled with co-morbid conditions and a state of frailty, will affect prognosis and outcome, increasing morbidity and mortality. This review will focus on the most common opportunistic bacterial pathogens causing pneumonia in kidney transplant recipients: Legionella, Nocardia, Mycobacterium tuberculosis/nontuberculous, and Rhodococcus. Recognition of their specificities in the setting of immunosuppression will allow early diagnosis, crucial for initiation of effective therapy and successful outcome. Interactions with immunosuppressive therapy should be considered as well as reducing immunosuppression if necessary.

Relationship between the duration of trimethoprim/sulfamethoxazole treatment and the clinical outcome of pulmonary nocardiosis

BACKGROUND

Despite treatment, pulmonary nocardiosis, which is a rare opportunistic disease caused by Nocardia species, has poor clinical outcomes including recurrence and death. Currently, the treatment regimen and duration for pulmonary nocardiosis are not fully understood. The present study aimed to clarify the factors related to the clinical outcome of pulmonary nocardiosis.

METHODS

The medical records of 24 patients with pulmonary nocardiosis were retrospectively reviewed. The patients were divided into two groups based on the outcomes within 2 years: patients with controlled disease (n = 14) and patients who developed recurrence or died (n = 10).

RESULTS

Nocardia was identified by 16S ribosomal RNA sequencing in 17 patients (70.8%) and by conventional biochemical test in five patients (20.8%). The patients' characteristics, clinical findings, radiological features, and treatment history were not different between the two groups. Compared with patients who developed recurrence or died, those with controlled disease had significantly longer total duration of treatment with antibiotics, especially trimethoprim/sulfamethoxazole (67.5 ± 111.6 days vs. 9.0 ± 6.5 days; p = 0.01). Pancytopenia was the most frequent adverse effect of trimethoprim/sulfamethoxazole.

CONCLUSIONS

Longer duration of trimethoprim/sulfamethoxazole treatment was significantly associated with better outcomes of pulmonary nocardiosis. In such cases, antibiotics, especially trimethoprim/sulfamethoxazole, should be administered for more than 3 months.

Fulminant Nocardiosis Due to a Multidrug-Resistant Isolate in a 12-Year-Old Immunocompetent Child

Nocardiosis is a rare cause of infection that usually affects immunocompromised adult patients and might not be recognized by pediatricians. We report a fatal case of disseminated nocardiosis in a previously healthy child initially admitted for an abdominal mass with suspicion of a renal malignant tumor. The patient, originating from Mali without any medical history, displayed abdominal pain with progressive altered general status. Laboratory and imaging findings revealed lymphocytic meningitis and disseminated abscesses in the brain and the cerebellum and a large number of cystic lesions of the kidney. Despite being administered wide-spectrum antibiotics and antituberculous and antifungal therapies with an external ventricular drainage for intracranial hypertension, the patient died 6 days after his admission. Nocardia spp was cultured from a renal biopsy and the cerebrospinal fluid. Species identification and antibiotic susceptibility were obtained later, revealing a multidrug-resistant isolate of the Nocardia elegans/aobensis/africana complex. This case reveals the difficulties of diagnosing nocardiosis, in particular in children not known to be immunocompromised, because we face multiple differential diagnoses and the importance of treating nocardiosis appropriately because of intrinsic resistance issues.

Nocardia spp. Pneumonia in a Solid Organ Recipient: Role of Linezolid

We describe a rare infection with Nocardia spp. (N. pseudobrasiliensis species identification based on high-performance liquid chromatography analysis) in a 68-year-old renal transplant recipient. He presented with pneumonia complicated by hypoxic respiratory failure. He was allergic to sulphonamides. He was initially successfully treated with linezolid. However, he suffered severe sensory neuropathy after 4 months of therapy, necessitating linezolid cessation and completion of treatment with azithromycin. He had clinical and radiological resolution of his pneumonia and was disease free at subsequent follow-up 4 years later. This case highlights the need for alternative therapies for nocardiosis for patients that cannot be treated with sulphonamides due to allergies or/and infection with multidrug-resistant pathogens. It also illustrates the treatment limiting side effects of long-term therapy with linezolid.

[Practices in infectious pathology in France in 2015. Results of the national survey]

Pathologists have been, are and will be always implicated in the diagnosis of infectious and tropical diseases. The resurgence of opportunistic infections due to the development of immunosuppressive drugs, the increase of migratory involvements draining tropical infections and the last epidemics spotlight the importance of pathologists in the field of infectious diseases. However, cancer is nowadays the first preoccupation of pathologists, which is constantly subject to evaluate diagnostic and prognostic markers and factors predictive to targeted therapy response or immunotherapy. As tumor pathology, infectious diseases require more sophisticated and rapidly changing complementary techniques, appraisals and perhaps a national network of diagnosis. The infectious pathology club committee carries out here a census of methods used in the diagnosis of infectious diseases in France in 2015 and particularly the different techniques used by laboratories to perform infectious diseases diagnosis. This will lay down the foundation of a future national organization of the infectious pathology in providing efficient services (diagnostic support, complementary tools) for the community of French pathologists in this specific domain of competence.

Syndrome of Inappropriate Antidiuretic Hormone Secretion Complicating Systemic Nocardiosis in a Renal Transplant Recipient: A Case Report

BACKGROUND

Infection by Nocardia species is an uncommon cause of severe clinical syndromes, particularly in immunocompromised patients, and solid-organ transplantation is the most common underlying condition. The syndrome of inappropriate antidiuretic hormone secretion (SIADH) has been described thus far in lung and stem cell transplants with systemic nocardiosis.

CASE REPORT

We report the first case of SIADH in a female elderly renal transplant recipient diagnosed with systemic nocardiosis 2 years after transplantation. The SIADH was managed appropriately, and her immunosuppressive regimen remained unchanged but was adjusted at a lower level. The systemic Nocardia infection was successfully treated with intravenous administration of trimethoprim-sulfamethoxazole and imipenem for 2 weeks followed by oral trimethoprim-sulfamethoxazole for a total of 12 months.

CONCLUSIONS

The SIADH syndrome is a recognizable complication of Nocardia infection in renal transplant recipients. Prompt identification along with proper management and prolonged antimicrobial treatment are essential to improve patients' outcome.