Epidemiology and Antimicrobial Resistance Profiles of the Nocardia Species in China, 2009 to 2021

Disseminated Nocardia cyriacigeorgica Infection Disguised as a Metastatic Adrenal Gland Malignancy in a Healthy Patient

Nocardia, typically recognized as an uncommon opportunistic pathogen affecting immunocompromised individuals, has also been documented in various case reports involving infections in immunocompetent hosts. Transmission occurs through inhalation or inoculation into compromised skin. Subsequently, it can lead to disseminated infection via hematogenous spread, affecting nearly any organ with a particular affinity for the central nervous system. Dissemination to the adrenal glands is extremely rare, with only a few cases reported. In this report, we present a rare case of disseminated Nocardia cyriacigeorgica, initially resembling a metastatic adrenal gland malignancy in an otherwise healthy individual. The patient presented with non-specific symptoms, had multiple sets of negative blood cultures, clinical findings suggestive of an underlying adrenal gland malignancy, and lacked identifiable risk factors for Nocardia, creating a significant diagnostic challenge. Additionally, we review the existing literature on nocardiosis involving the adrenal glands. This case marks the third reported instance of a Nocardia cyriacigeorgica adrenal gland abscess in the literature.

Chronic inflammatory demyelinating polyneuropathy with pulmonary nocardiosis: A case report

RATIONALE

Chronic inflammatory demyelinating polyneuropathy (CIDP) is an immune-mediated motor sensory peripheral neuropathy that is rare in clinical practice. This treatment method aims to suppress potential immunopathology. Nocardiosis is a rare, destructive, opportunistic disease. We report a case of failed treatment of CIDP combined with pulmonary nocardiosis, and for the first time, we link these 2 diseases together.

PATIENT CONCERNS

A 65-year-old man developed symmetrical limb weakness. Four months later, he was diagnosed with CIDP and started receiving glucocorticoid (GC) treatment. The disease progressed slowly and was treated with mycophenolate mofetil (MMF) in combination. He did not follow the doctor requirements for monthly follow-up visits, and the preventive medication for sulfamethoxazole/trimethoprim was not strictly implemented. Two months after the combination therapy, the patient developed fever, coughing and sputum production, as well as fatigue and poor appetite. Based on imaging and etiological results, he was diagnosed with pulmonary nocardiosis.

DIAGNOSES

Chronic inflammatory demyelinating polyneuropathy, pulmonary nocardiosis.

INTERVENTIONS

After treatment with antibiotics, the patient lung infection temporarily improved. However, the patient CIDP condition progressed, limb weakness worsened, respiratory muscle involvement occurred, and intravenous immunoglobulin (IVIG) was administered. However, there was no significant improvement in the condition, and the patient died.

OUTCOMES

In this report, we present a case of a patient with CIDP and pulmonary nocardiosis. It is worth noting that in order to avoid the progression and recurrence of CIDP, we did not stop using related therapeutic drugs during the treatment process, the patient had repeatedly refused to use IVIG. Despite this, the patient condition worsened when lung inflammation improved, leading to persistent respiratory failure and ultimately death. Treatment contradictions, medication issues, and patient compliance issues reflected in this case are worth considering.

LESSONS

For patients with CIDP receiving immunosuppressive therapy, attention should be paid to the occurrence and severity of Nocardia infection. Therefore, early detection and treatment are necessary. We need to pay attention to the compliance of patients with prophylactic use of antibiotics, strengthen the follow-up, and urge them to return to their appointments on time.

Comparison of Clinical Characteristics and Treatment Outcome Between Localized and Disseminated Nocardiosis in a Tertiary Hospital in China

Background

In China, due to the large population, infections caused by Nocardia may not be as rare. Unfortunately, there is still inadequate knowledge of the clinical impact caused by Nocardia. This study aimed to compare the clinical characteristics and treatment of localized and disseminated nocardiosis.

Methods

The clinical and microbiological data of patients diagnosed with nocardiosis in a tertiary hospital in Beijing from July 2011 to July 2021 were collected and retrospectively analyzed.

Results

Among the 54 nocardiosis cases, 34 cases were in the localized infection group, while 20 cases in the disseminated infection group. The proportion of patients with chronic structural lung disease was higher in the localized group (P=0.010). In contrast, patients with disseminated infections were more prone to receive long-term glucocorticoids and/or immunosuppressants (P=0.027). Pulmonary nodules were prominent features of imaging changes in patients with disseminated infections (P=0.027) whereas bronchial dilatation was more common in patients with localized infections (P=0.025). In addition, the disseminated group had longer average hospitalization days relative to the localized group (P=0.016), but there was no significant difference in mortality between them (P=0.942).

Conclusion

There were differences in the clinical profiles between patients with localized and disseminated nocardiosis in terms of clinical presentation, infection site, radiological features, treatment, and prognosis. These findings may provide references for the management and treatment of patients with nocardiosis.

Weathering the storm: diagnosis and treatment of a life-threatening disseminated Nocardia otitidiscaviarum infection

Nocardiosis demonstrates a temporal categorization that includes acute, subacute, and chronic stages alongside distinct typical localizations such as pulmonary, cutaneous, and disseminated forms. Disseminated nocardiosis, commonly caused by Nocardia asteroides, N. brasiliensis, and N. farcinica, continues to result in substantial morbidity and mortality. Herein, we report a life-threatening disseminated nocardiosis caused by Nocardia otitidiscaviarum in a patient with minimal change disease. This study emphasizes the difficulty in the diagnosis and treatment of unknown infections in clinical settings and highlights the important role played by laboratories in solving infectious diseases caused by rare pathogens.

Metagenome next-generation sequencing plays a key role in the diagnosis and selection of effective antibiotics on the treatment of Nocardia pneumonia: a case report

Nocardia disease is an opportunistic infection, the occurrence is rare and mostly occurs in patients with immune deficiency. Even if the patient is immunocompetent, it can still be life-threatening. This case report describes a previously healthy 78-year-old male farmer with lung lesions discovered on a computerized tomography scan. Combined with the patient's history of fever and the results of elevated laboratory markers associated with inflammation, the patient was diagnosed with a lung infection. After escalating empirical broad-spectrum antibiotics, antiviral and antifungal therapy, the patient continued to deteriorate to septic shock. In the meanwhile, the patient's sputum was cultured repeatedly, and no obvious positive pathogenic bacteria were found. Considering the patient was elderly and that these lesions were solid with burr signs, as well as the progression after antimicrobial therapy cancer was considered in the differential diagnosis. Artificial intelligence (YITU, Hangzhou Yitu Medical Technology Limited Company) was also applied, and it also calculated that these lesions were cancerous. The patient received a puncture biopsy of the largest lung lesion. During the puncture pus was withdrawn from largest lung lesion. Culture and metagenome next-generation sequencing (mNGS) detection performed on pus indicated Nocardia otitidiscaviarum. The test report of the mNGS is also attached with a susceptibility report of commonly used clinical antibiotics to this Nocardia spp. Using this result, the patient's disease was quickly controlled after selecting the targeted drug compound sulfamethoxazole and intravenous meropenem for treatment. In view of the high misdiagnosis rate and poor sensitivity of culture for Nocardia spp., this case emphasized mNGS playing a key role in the diagnosis and selection of effective antibiotics for the treatment of Nocardia spp. lung infections.

Nocardia farcinica brain abscess with torque teno virus co-infection: A case report

Background

Brain abscesses caused by Nocardia are rare and difficult to diagnose. Nocardia farcinica is among the most common species; however, the conventional diagnosis of N. farcinica infection consists of cerebrospinal fluid (CSF) and blood culture and Gram staining. These procedures prolong the time to diagnosis and initiating treatment.

Case presentation

A 69-year-old woman with diabetes mellitus presented with headaches and dizziness persisting for 2 weeks, which was initially diagnosed as a brain abscess. Due to the unusual presentation and rapid progression of symptoms, she underwent surgical resection of the brain abscess. No pathogens were detected in blood or CSF cultures. However, metagenomic next-generation sequencing (mNGS) identified N. farcinica and Torque teno virus in pus extracted from the abscesses. The patient received appropriate antibiotic therapy and recovered fully without any residual neurological deficits.

Conclusion

mNGS useful for prompt diagnosis and selection of antibiotic therapy for brain abscesses caused by Nocardia. Surgical intervention is necessary in some cases.

Nocardia species distribution and antimicrobial susceptibility within Australia

BACKGROUND

Nocardia is a ubiquitous saprophyte capable of causing human disease. Disease is primarily respiratory or cutaneous, usually acquired via inhalation or inoculation. Under the influence of environmental and host factors, Nocardia incidence and species distribution demonstrate geographical variation.

AIMS

To examine for differences in Nocardia incidence within Western Australia (WA) and analyse species distribution in the context of prior published studies. To analyse antibiogram data from a nationwide passive antimicrobial resistance surveillance program.

METHODS

Retrospective extraction of laboratory data for Western Australian Nocardia isolates over a 21-year period. Analysis of Nocardia antimicrobial susceptibility testing data submitted to the Australian Passive Antimicrobial Resistance Surveillance (APAS) program between 2005 and 2022.

RESULTS

Nine hundred sixty WA isolates were identified, giving an annual incidence of 3.03 per 100 000 population with apparent latitudinal variation. The four most common species identified within WA and amongst APAS isolates were N. nova, N. cyriacigeorgica, N. brasiliensis and N. farcinica. APAS data demonstrated that all species exhibited high rates of susceptibility to linezolid (100%) and trimethoprim-sulfamethoxazole (98%). Amikacin (>90% susceptibility for all species except N. transvalensis) was the next most active parenteral agent, superior to both carbapenems and third-generation cephalosporins. Susceptibility to oral antimicrobials (other than linezolid) demonstrated significant interspecies variation.

CONCLUSIONS

We demonstrate geographical variation in the distribution of Nocardia incidence. Four species predominate in the Australian setting, and nationwide data confirm a high in vitro susceptibility to trimethoprim-sulphamethoxazole and linezolid, justifying their ongoing role as part of first-line empiric therapy.

Clinical characteristics and drug resistance of Nocardia in Henan, China, 2017-2023

BACKGROUND

The aim of this study was to investigate the clinical features of Nocardia infections, antibiotic resistance profile, choice of antibiotics and treatment outcome, among others. In addition, the study compared the clinical and microbiological characteristics of nocardiosis in bronchiectasis patients and non-bronchiectasis patients.

METHODS

Detailed clinical data were collected from the medical records of 71 non-duplicate nocardiosis patients from 2017 to 2023 at a tertiary hospital in Zhengzhou, China. Nocardia isolates were identified to the species level using MALDI-TOF MS and 16S rRNA PCR sequencing. Clinical data were collected from medical records, and drug susceptibility was determined using the broth microdilution method.

RESULTS

Of the 71 cases of nocardiosis, 70 (98.6%) were diagnosed as pulmonary infections with common underlying diseases including bronchiectasis, tuberculosis, diabetes mellitus and chronic obstructive pulmonary disease (COPD). Thirteen different strains were found in 71 isolates, the most common of which were N. farcinica (26.8%) and N. cyriacigeorgica (18.3%). All Nocardia strains were 100% susceptible to both TMP-SMX and linezolid, and different Nocardia species showed different patterns of drug susceptibility in vitro. Pulmonary nocardiosis is prone to comorbidities such as bronchiectasis, diabetes mellitus, COPD, etc., and Nocardia is also frequently accompanied by co-infection of the body with pathogens such as Mycobacterium and Aspergillus spp. Sixty-one patients underwent a detailed treatment regimen, of whom 32 (52.5%) received single or multi-drug therapy based on TMP-SMX. Bronchiectasis was associated with a higher frequency of Nocardia infections, and there were significant differences between the bronchiectasis and non-bronchiectasis groups in terms of age distribution, clinical characteristics, identification of Nocardia species, and antibiotic susceptibility (P < 0.05).

CONCLUSIONS

Our study contributes to the understanding of the species diversity of Nocardia isolates in Henan, China, and the clinical characteristics of patients with pulmonary nocardiosis infections. Clinical and microbiologic differences between patients with and without bronchiectasis. These findings will contribute to the early diagnosis and treatment of patients.

Brucella infection combined with Nocardia infection: A case report and literature review

Human brucellosis is an infectious disease caused by Brucella and is often misdiagnosed for atypical manifestations including fever of unknown origin, headache, weakness, among else. Nocardiosis is a zoonotic disease caused by the genus Nocardia, which usually spreads through the respiratory tract, skin, and digestive tract. Limited research has documented cases of co-infection involving both Brucella and Nocardia pathogens in patients. A 55-year-old male was admitted to our hospital with intermittent high-grade fever. Following sputum and blood cultures, as well as other laboratory examinations, the patient was diagnosed with concurrent brucellosis and nocardiosis. According to recommendations of previous studies and reports, the patient was successively treated with levofloxacin, doxycycline, piperacillin sodium and sulbactam sodium, trimethoprim-sulfamethoxazole, rifampicin, and tigecycline, after which the patient recovered and was discharged. Brucella and Nocardia are both opportunistic pathogens and simultaneous infection of Brucella and Nocardia is relatively rare. If patients continue to experience persistent fever despite receiving empirical antibiotic therapy, it becomes necessary to conduct examinations to identify potential atypical pathogens, including Brucella and Nocardia. Sputum staining, sputum culture, and blood culture are critical auxiliary examinations during clinical practice. The treatment plan should be selected based on guidelines and the individual patient's condition. Regular reevaluation should be conducted, and antimicrobial agents should be adjusted accordingly.

Nocardia farcinica infection presenting as a solitary bronchial neoplasm in an immunocompetent adult: a case report

Nocardia species are gram-positive, acid-fast, saprophytic, aerobic bacilli, predominantly resulting in opportunistic infections in immunocompromised individuals. Here, we reported a case of Nocardia infection in a 27-year-old woman with normal immunocompetence, who presented as a solitary neoplasm in the left principal bronchus with a chief complaint of postural dyspnea. By electrotomy via bronchoscopy, the neoplasm was successfully removed, and it was further identified as Nocardia farcinica by metagenomic next-generation sequencing.

Invasive Nocardia Infections across Distinct Geographic Regions, United States

We reviewed invasive Nocardia infections in 3 noncontiguous geographic areas in the United States during 2011–2018. Among 268 patients with invasive nocardiosis, 48.2% were from Minnesota, 32.4% from Arizona, and 19.4% from Florida. Predominant species were N. nova complex in Minnesota (33.4%), N. cyriacigeorgica in Arizona (41.4%), and N. brasiliensis in Florida (17.3%). Transplant recipients accounted for 82/268 (30.6%) patients overall: 14 (10.9%) in Minnesota, 35 (40.2%) in Arizona, and 33 (63.5%) in Florida. Manifestations included isolated pulmonary nocardiosis among 73.2% of transplant and 84.4% of non–transplant patients and central nervous system involvement among 12.2% of transplant and 3.2% of non–transplant patients. N. farcinica (20.7%) and N. cyriacigeorgica (19.5%) were the most common isolates among transplant recipients and N. cyriacigeorgica (38.0%), N. nova complex (23.7%), and N. farcinica (16.1%) among non–transplant patients. Overall antimicrobial susceptibilities were similar across the 3 study sites.

Nocardia pseudobrasiliensis infection in a patient with arthritis

Nocardia pseudobrasiliensis is a new taxon constituting an emerging species of human pathogenic Nocardia, which shares morphological features with N. brasiliensis. However, N. pseudobrasiliensis is more invasive and more easily disseminated, and it exhibits distinctive antibiotic susceptibility. Few clinical cases related to N. pseudobrasiliensis infection have been reported, and N. pseudobrasiliensis hydrarthrosis has not been described. Here, we analyzed the case information, diagnostic process, treatment, and prognosis of a patient with N. pseudobrasiliensis hydrarthrosis who received treatment in Zhejiang Provincial People's Hospital. Magnetic resonance imaging showed joint cavity effusion and soft tissue swelling with high signal on proton density-fat saturated images and low signal on T1-weighted images. Oil microscopy revealed abundant acid-fast-positive filaments in hydrarthrosis puncture fluid. The pathogen was identified as N. pseudobrasiliensis by matrix-assisted laser desorption ionization-time of flight mass spectrometry. In contrast to the 100% ciprofloxacin resistance displayed by N. brasiliensis, this clinical isolate of N. pseudobrasiliensis was completely susceptible. In summary, this is the first report of N. pseudobrasiliensis in joint effusion from a patient with arthritis.

Clinical characteristics of hospitalized patients with Nocardia genus detection by metagenomic next generation sequencing in a tertiary hospital from southern China

OBJECTIVE

As an opportunistic pathogen, Nocardia often occurring in the immunocompromised hosts. As the unspecifc clinical presentation and low identification rate of the culture dependent methods, Nocardia infection may be under-diagnosis. Recent study have reported physicians could benefit from metagenomic next-generation sequencing (mNGS) in Nocardia diagnosis. Herein, we present patients with a positive detection of nocardiosis in mNGS, aiming to provide useful information for an differential diagnosis and patients management.

METHODS

A total of 3756 samples detected for mNGS from March 2019 to April 2022 at the Fifth Affifiliated Hospital of Sun Yat-sen University, were screened. Clinical records, laboratory finding, CT images and mNGS results were reviewed for 19 patients who were positive for Nocardia genus.

RESULTS

Samples from low respiratory tract obtained by bronchoscope took the major part of the positive (15/19). 12 of 19 cases were diagnosis as Nocardiosis Disease (ND) and over half of the ND individuals (7/12) were geriatric. Nearly all of them (10/12) were immunocompetent and 2 patients in ND group were impressively asymptomatic. Cough was the most common symptom. Nocardia cyriacigeorgica (4/12) was more frequently occurring in ND, followed by Nocardia abscessus (3/12). There are 3 individuals detected more than one kind of Nocardia species (Supplementary table 1). Except one with renal failure and one allergic to sulfamethoxazole, all of them received co-sulfonamide treatment and relieved eventually.

CONCLUSION

Our study deciphered the clinical features of patients with positive nocardiosis detected by mNGS. Greater attention should be paid to the ND that occurred in the immunocompetent host and the geriatric. Due to the difficulties in establishing diagnosis of Nocardiosis disease, mNGS should play a much more essential role for a better assessment in those intractable cases. Co-sulfonamide treatment should still be the first choice of Nocardiosis disease.

Screening, molecular identification, population diversity, and antibiotic susceptibility pattern of Actinomycetes species isolated from meat and meat products of slaughterhouses, restaurants, and meat stores of a developing country, Iran

Introduction

Actinomycetes can colonize surfaces of tools and equipment and can be transferred to meat and meat products during manufacture, processing, handling, and storage. Moreover, washing the meat does not eliminate the microorganisms; it only spreads them. As a result, these opportunistic pathogens can enter the human body and cause various infections. Therefore, the aim of the current study was to screen, identify, and determine the antibiotic susceptibility of Actinomycetes species from meat and meat products in the Markazi province of Iran.

Methods

A total of 60 meat and meat product samples, including minced meat, mutton, beef, chicken, hamburgers, and sausages, were collected from slaughterhouses, butchers, and restaurants in the Markazi province of Iran. The samples were analyzed using standard microbiological protocols for the isolation and characterization of Actinomycetes. PCR amplification of hsp65 and 16SrRNA genes and sequence analysis of 16SrRNA were used for genus and species identification. The minimum inhibitory concentrations (MICs) of antimicrobial agents were determined by the broth microdilution method and interpreted according to the CLSI guidelines.

Results

A total of 21 (35%) Actinomycetes isolates from 5 genera and 12 species were isolated from 60 samples. The most prevalent Actinomycetes were from the genus Mycobacterium, with six (28.6%) isolates (M. avium complex, M. terrae, M. smegmatis, and M. novocastrense), followed by the genus Rhodococcus with five (23.8%) isolates (R. equi and R. erythropolis), the genus Actinomyces with four (19.1%) isolates (A. ruminicola and A. viscosus), the genus Nocardia with four (19.1%) isolates (N. asiatica, N. seriolae, and N. niigatensis), and the genus Streptomyces with two (9.5%) isolates (S. albus). Chicken and sausage samples had the highest and lowest levels of contamination, with six and one isolates. Respectively, the results of drug susceptibility testing (DST) showed that all isolates were susceptible to Ofloxacin, Amikacin, Ciprofloxacin, and Levofloxacin, whereas all of them were resistant to Doxycycline and Rifampicin.

Discussion

The findings suggest that meat and meat products play an important role as a reservoir for the transmission of Actinomycetes to humans, thus causing life-threatening foodborne diseases such as gastrointestinal and cutaneous disorders. Therefore, it is essential to incorporate basic hygiene measures into the cycle of meat production to ensure food safety.

The species distribution and antimicrobial resistance profiles of Nocardia species in China: A systematic review and meta-analysis

BACKGROUND

Nocardia species can cause local or disseminated infection. Prompt diagnosis and appropriate treatment of nocardiosis are required, because it can cause significant morbidity and mortality. Knowledge of local species distribution and susceptibility patterns is important to appropriate empiric therapy. However, knowledge on the epidemiology and antimicrobial susceptibility profiles of clinical Nocardia species remains limited in China.

METHODS

The data of isolation of Nocardia species were collected from databases such as Pubmed, Web of Science, Embase as well as Chinese databases (CNKI, Wanfang and VIP). Meta-analysis was performed using RevMan 5.3 software. Random effect models were used and tested with Cochran's Q and I2 statistics taking into account the possibility of heterogeneity between studies.

RESULTS

In total, 791 Nocardia isolates were identified to 19 species levels among all the recruited studies. The most common species were N. farcinica (29.1%, 230/791), followed by N. cyriacigeorgica (25.3%, 200/791), N. brasiliensis (11.8%, 93/791) and N. otitidiscaviarum (7.8%, 62/791). N. farcinica and N. cyriacigeorgica are widely distributed, N. brasiliensis mainly prevalent in the Southern, N. otitidiscaviarum mainly distributed in the east coastal provinces of China. Totally, 70.4% (223/317) Nocardia were cultured from respiratory tract specimens, 16.4% (52/317) from extra-pulmonary specimens, and 13.3% (42/317) from disseminated infection. The proportion of susceptible isolates as follows: linezolid 99.5% (197/198), amikacin 96.0% (190/198), trimethoprim-sulfamethoxazole 92.9% (184/198), imipenem 64.7% (128/198). Susceptibility varied by species of Nocardia.

CONCLUSIONS

N. farcinica and N. cyriacigeorgica are the most frequently isolated species, which are widely distributed in China. Pulmonary nocardiosis is the most common type of infection. Trimethoprim-sulfamethoxazole can still be the preferred agent for initial Nocardia infection therapy due to the low resistance rate, linezolid and amikacin could be an alternative to treat nocardiosis or a choice in a combination regimen.

Pathogenic Nocardia amamiensis infection: A rare case report and literature review

Background

To date, only six cases of Nocardia amamiensis infection have been reported, including two ocular cases, three pulmonary cases, and one disseminated case. However, no Nocardia amamiensis pulmonary infection cases have been reported in immunocompetent patients without structural pulmonary disease. This study describes a rare case and provides a detailed review of all previous cases.

Methods

A pulmonary infection caused by Nocardia amamiensis in a 64-year-old man with low-grade fever, night sweats, and weight loss was reported. All previously reported cases of Nocardia amamiensis infection were searched and reviewed.

Results

The pathogen was identified as Nocardia amamiensis using bronchoalveolar lavage fluid (BALF) mNGS, and the current case was successfully treated with trimethoprim-sulfamethoxazole (ST) monotherapy. mNGS and 16S rRNA PCR are standard tests to identify Nocardia.Conclusion: mNGS has high diagnostic performance for Nocardia amamiensis. Further studies are needed to clarify the clinical characteristics and explore more effective treatment protocols for this rare pathogen.

Evaluation of BACTEC MGIT 960 system for recovery of Nocardia from clinical specimens

Nocardia spp. is an aerobic Gram-positive bacillus responsible for nocardiosis. Herein, we performed a retrospective study to evaluate the performance of BACTEC MGIT 960 system, in comparison with smear microscopy and blood agar plate (BAP) culture, to recover Nocardia from different clinical specimens. Furthermore, the inhibitory effect of antibiotics contained in MGIT 960 tube on Nocardia was also evaluated. The sensitivities for Nocardia recovery using smear microscopy, BAP culture, and MGIT 960 were 39.4% (54/137), 46.1% (99/215), and 81.3% (156/192), respectively. N. farcinica was the most detected species (60.4%, 136/225). In MGIT 960-recovered Nocardia strains, N. farcinica accounted for 76.9%. Furthermore, trimethoprim in MGIT 960 tube inhibited less N. farcinica growth than that of other Nocardia species, partially explaining why MGIT 960 recovered more N. farcinica from sputa. The current study demonstrated that MGIT 960 could recover Nocardia strains from heavily-contaminated samples if its components and antibiotics are redesigned.

The Computed Tomography Findings and Follow-up Course of Pulmonary Nocardiosis

OBJECTIVE

Our study aimed to elucidate the computed tomography (CT) features and follow-up course of pulmonary nocardiosis patients to improve the understanding and diagnostic accuracy of this disease.

METHODS

The chest CT findings and clinical data of patients diagnosed with pulmonary nocardiosis by culture or histopathological examination in our hospital between 2010 and 2019 were retrospectively analyzed.

RESULTS

A total of 34 cases of pulmonary nocardiosis were included in our study. Thirteen patients were on long-term immunosuppressant therapy, among whom 6 had disseminated nocardiosis. Among the immunocompetent patients, 16 had chronic lung diseases or a history of trauma. Multiple or solitary nodules represented the most common CT feature (n = 32, 94.12%), followed by ground-glass opacities (n = 26, 76.47%), patchy consolidations (n = 25, 73.53%), cavitations (n = 18, 52.94%), and masses (n = 11, 32.35%). There were 20 cases (61.76%) with mediastinal and hilar lymphadenopathy, 18 (52.94%) with pleural thickening, 15 (44.12%) with bronchiectasis, and 13 (38.24%) with pleural effusion. Significantly higher rates of cavitations were observed among immunosuppressed patients (85% vs 29%, P = 0.005). At follow-up, 28 patients (82.35%) clinically improved with treatment, while 5 (14.71%) had disease progression, and 1 (2.94%) died.

CONCLUSIONS

Chronic structural lung diseases and long-term immunosuppressant use were found as risk factors for pulmonary nocardiosis. While the CT manifestations were highly heterogeneous, clinical suspicion should be raised upon findings of coexisting nodules, patchy consolidations, and cavitations, particularly in the presence of extrapulmonary infections such as those of the brain and subcutaneous tissues. A significant incidence of cavitations may be observed among immunosuppressed patients.

A multi-centre retrospective study of Nocardia speciation and antimicrobial susceptibility in Queensland, Australia

The study aims to characterise the species identification and antimicrobial susceptibility testing (AST) results of Nocardial isolates from adult patients across major public hospitals in Queensland, Australia, over a 15-year period. A multi-centre retrospective observational study of Nocardia sp. isolates was conducted from 7 major public hospitals in Queensland, Australia, over a 15-year period. Clinical samples from patients aged ≥ 18 years that isolated Nocardia sp. were included. Demographic and clinical data were collected, along with species identification and AST results. Overall, 484 Nocardia sp. were isolated. Most patients were male (297, 61%) with a mean (IQR) age of 60 (51-75) and a median (IQR) Charlson Comorbidity Index of 4 (2-6). Of these, 239 (49%) patients were immunosuppressed. Organisms were most frequently isolated from sputum (174, 36%), and superficial swabs (102, 21%). Patients presented with pulmonary infections (165, 35%) and superficial skin and soft tissue infections (87, 18%) most commonly. One hundred (21%) isolates were deemed pulmonary colonisation and were not treated. Of the speciated organisms, N. nova complex was the most common (93, 19%), followed by N. farcinica complex (79, 16%). Organisms were reliably susceptible to linezolid (240/245, 98%), amikacin (455/470, 97%), and trimethoprim/sulfamethoxazole (459/476, 96%), but less so to imipenem (243/472, 51%) and ceftriaxone (261/448, 58%). This is the largest Australian description of Nocardia sp. to date. Given antimicrobials are often commenced prior to AST results and sometimes even speciation, characterisation of local species and antibiogram data is important to guide empiric choices and local guidelines.

Design of a multi-epitope vaccine against six Nocardia species based on reverse vaccinology combined with immunoinformatics

Background

Nocardia genus, a complex group of species classified to be aerobic actinomycete, can lead to severe concurrent infection as well as disseminated infection, typically in immunocompromised patients. With the expansion of the susceptible population, the incidence of Nocardia has been gradually growing, accompanied by increased resistance of the pathogen to existing therapeutics. However, there is no effective vaccine against this pathogen yet. In this study, a multi-epitope vaccine was designed against the Nocardia infection using reverse vaccinology combined with immunoinformatics approaches.

Methods

First, the proteomes of 6 Nocardia subspecies Nocardia subspecies (Nocardia farcinica, Nocardia cyriacigeorgica, Nocardia abscessus, Nocardia otitidiscaviarum, Nocardia brasiliensis and Nocardia nova) were download NCBI (National Center for Biotechnology Information) database on May 1st, 2022 for the target proteins selection. The essential, virulent-associated or resistant-associated, surface-exposed, antigenic, non-toxic, and non-homologous with the human proteome proteins were selected for epitope identification. The shortlisted T-cell and B-cell epitopes were fused with appropriate adjuvants and linkers to construct vaccines. The physicochemical properties of the designed vaccine were predicted using multiple online servers. The Molecular docking and molecular dynamics (MD) simulation were performed to understand the binding pattern and binding stability between the vaccine candidate and Toll-like receptors (TLRs). The immunogenicity of the designed vaccines was evaluated via immune simulation.

Results

3 proteins that are essential, virulent-associated or resistant-associated, surface-exposed, antigenic, non-toxic, and non-homologous with the human proteome were selected from 218 complete proteome sequences of the 6 Nocardia subspecies epitope identification. After screening, only 4 cytotoxic T lymphocyte (CTL) epitopes, 6 helper T lymphocyte (HTL) epitopes, and 8 B cell epitopes that were antigenic, non-allergenic, and non-toxic were included in the final vaccine construct. The results of molecular docking and MD simulation showed that the vaccine candidate has a strong affinity for TLR2 and TLR4 of the host and the vaccine-TLR complexes were dynamically stable in the natural environment. The results of the immune simulation indicated that the designed vaccine had the potential to induce strong protective immune responses in the host. The codon optimization and cloned analysis showed that the vaccine was available for mass production.

Conclusion

The designed vaccine has the potential to stimulate long-lasting immunity in the host, but further studies are required to validate its safety and efficacy.

Diagnosis of Rare Bone Infection Caused by Nocardia by 16S rRNA Gene Sequencing

Nocardia is an aerobic actinomycete that causes serious opportunistic infections in immunocompromised individuals. Gene sequencing is the gold standard for pathogenic bacteria diagnosis. This study uses 16S rRNA gene sequencing to diagnose three cases of bone infections caused by Nocardia, including one rare case (N. cyriacigeorgica), and the clinial features, etiological characteristics, treatment, and prognosis of the patients.

A Rare Case of a Subcutaneous Abscess Caused by Nocardia cyriacigeorgica in an Immunocompetent Patient

Background

Nocardia cyriacigeorgica, which mainly causes pleuropulmonary and disseminated nocardiosis, has been proved to be one of the most common opportunistic pathogens in patients with immunodeficiency, but the cases that cause subcutaneous abscesses in normal individuals are rare and should be paid attention to.

Methods

The clinical data of a patient with cutaneous nocardiosis caused by Nocardia cyriacigeorgica in Zhejiang Provincial People's Hospital were retrospectively analyzed, including clinical manifestations, laboratory examinations, imaging examinations, medication and prognosis.

Results

Magnetic resonance imaging (MRI) showed that there was a 26 mm × 73 mm abscess under the skin. The pus in the abscess was green. Gram staining showed positive branched rod-shaped and undivided hyphae. After culture, small wrinkle dry white small colonies were observed, and it was identified as Nocardia cyriacigeorgica by MALDI-TOF MS.

Conclusion

We report the first case of a subcutaneous abscess caused by Nocardia cyriacigeorgica in an immunocompetent patient. Compared with cutaneous nocardiosis of which approximately 80% caused by Nocardia brasiliensis invasion, infection of Nocardia cyriacigeorgica is more insidious and latent, the features of the lesions are also unique. For this Nocardia cyriacigeorgica clinical isolate, the tested antibacterial drugs are generally sensitive and have an ideal prognosis after treatment with linezolid and timely debridement.

Successful control of scleritis caused by Nocardia farcinica: A case report

RATIONALE

Nocardia farcinica is an opportunistic pathogen that rarely causes ocular infections. This study reviewed a case of N. farcinica-mediated scleritis involving the corneal limbus.

PATIENT CONCERNS

A 56-year-old man was admitted to the Department of Keratology of Jinan Second People's Hospital due to "a red and swollen right eye accompanied with severe pain for >1 month." He denied any history of hypertension, diabetes, systemic immune diseases and eye surgery.

DIAGNOSES

Corneal defect and scleral necrosis were observed by slit lamp. Combination of anterior segment optical coherence tomography and ophthalmic ultrasound biomicroscopy was used for diagnosis and evaluation of corneal and scleral conditions. Culture and metagenomic sequencing verified that the pathogen of scleritis was N. farcinica.

INTERVENTIONS

The patient was treated by sulfacetamide sodium eye drops, oral administration of sulfamethoxazole tablets, amikacin anterior chamber flushing, scleral debridement, and allogeneic scleral transplantation.

OUTCOMES

The disease was successfully controlled.

LESSONS

Infectious scleritis caused by N. farcinica is extremely rare. Culture of pathogenic microorganisms remains to be the gold standard for the diagnosis of infectious eye diseases. Metagenomic sequencing shows potential promise in the diagnosis of infectious eye diseases. N. farcinica is sensitive to sulfonamides and amikacin.

Molecular, cellular and neurological consequences of infection by the neglected human pathogen Nocardia

Background

Nocardia is a facultative intracellular pathogen that infects the lungs and brains of immunocompromised patients with consequences that can be fatal. The incidence of such infections is rising, immunocompetent individuals are also being infected, and there is a need to learn more about this neglected bacterial pathogen and the interaction with its human host.

Results

We have applied dual RNA-seq to assess the global transcriptome changes that occur simultaneously in Nocardia farcinica (N. farcinica) and infected human epithelial alveolar host cells, and have tested a series of mutants in this in vitro system to identify candidate determinants of virulence. Using a mouse model, we revealed the profiles of inflammation-related factors in the lung after intranasal infection and confirmed that nbtB and nbtS are key virulence genes for Nocardia infection in vivo. Regarding the host response to infection, we found that the expression of many histones was dysregulated during the infection of lung cells, indicating that epigenetic modification might play a crucial role in the host during Nocardia infection. In our mouse model, Nocardia infection led to neurological symptoms and we found that 15 of 22 Nocardia clinical strains tested could cause obvious PD-like symptoms. Further experiments indicated that Nocardia infection could activate microglia and drive M1 microglial polarization, promote iNOS and CXCL-10 production, and cause neuroinflammation in the substantia nigra, all of which may be involved in causing PD-like symptoms. Importantly, the deletion of nbtS in N. farcinica completely attenuated the neurological symptoms.

Conclusions

Our data contribute to an in-depth understanding of the characteristics of both the host and Nocardia during infection and provide valuable clues for future studies of this neglected human pathogen, especially those addressing the underlying causes of infection-related neurological symptoms.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12915-022-01452-7.

Epidemiology of Nocardia Species at a Tertiary Hospital in Southern Taiwan, 2012 to 2020: MLSA Phylogeny and Antimicrobial Susceptibility

The identification and antimicrobial susceptibility of Nocardia spp. are essential for guiding antibiotic treatment. We investigated the species distribution and evaluated the antimicrobial susceptibility of Nocardia species collected in southern Taiwan from 2012 to 2020. A total of 77 Nocardia isolates were collected and identified to the species level using multi-locus sequence analysis (MLSA). The susceptibilities to 15 antibiotics for Nocardia isolates were determined by the broth microdilution method, and the MIC₅₀ and MIC₉₀ for each antibiotic against different species were analyzed. N. cyriacigeorgica was the leading isolate, accounting for 32.5% of all Nocardia isolates, and the prevalence of Nocardia isolates decreased in summer. All of the isolates were susceptible to trimethoprim/sulfamethoxazole, amikacin, and linezolid, whereas 90.9% were non-susceptible to cefepime and imipenem. The phylogenic tree by MLSA showed that the similarity between N. beijingensis and N. asiatica was as high as 99%, 73% between N. niigatensis and N. crassostreae, and 86% between N. cerradoensis and N. cyriacigeorgica. While trimethoprim/sulfamethoxazole, amikacin, and linezolid remained fully active against all of the Nocardia isolates tested, 90.9% of the isolates were non-susceptible to cefepime and imipenem.

Metagenomic next-generation sequencing provides prognostic warning by identifying mixed infections in nocardiosis

Nocardia is an opportunistic pathogen that mainly involves immunosuppressed patients and causes a high mortality rate. As an emerging approach to detect infectious pathogens, metagenomic next-generation sequencing (mNGS) was reported in the detection of Nocardia. However, there is no evidence demonstrating the effect of mNGS on the prognosis of Nocardia infection. In this retrospective study, we included 18 nocardiosis patients. Nocardia species were detected by mNGS from their clinical samples. All the patients were diagnosed with nocardiosis by clinical experts through a comprehensive evaluation. Of these 18 patients, fever is the most frequent initial symptom. Compared to traditional culture methods, mNGS provides a faster turnaround time (TAT) and higher sensitivity. Pulmonary nocardiosis was the most common clinical presentation in the study. mNGS detected 13 types of Nocardia species, of which Nocardia abscessus and Nocardia cyriacigeorgica were the most common species. The study’s most noteworthy discovery is that mNGS outperforms culture at detecting mixed infections (more than one pathogen detected in one clinical specimen, including bacteria, fungi, and excluding virus), and number of infectious species was an independent risk factor for nocardiosis patients’ prognostics after adjusting age, ICU days, gender and underlying diseases (adjusted HR = 1.47, 95% CI: 1.09-1.98, p = 0.011). As a result, we believe that by detecting mixed infections (more than one pathogenic species), mNGS can provide a clinical risk warning for the prognosis of nocardiosis.

Case Report: Disseminated Nocardiosis Caused by Nocardia vulneris in a Patient With Macroglobulinemia

This report describes a case of disseminated nocardiosis, caused by Nocardia vulneris, in a 61-year-old man with macroglobulinemia and presenting with repeated fever, cough, shortness of breath, and muscle pain. The isolated Nocardia strain was resistant to ciprofloxacin, but susceptible to amikacin, gentamicin, tobramycin, linezolid, trimethoprim-sulfamethoxazole, amoxicillin/clavulanic, moxifloxacin, ceftriaxone, cefotaxim, and imipenem. The patient was started on combined meropenem and doxycycline treatment, followed by trimethoprim-sulfamethoxazole, which was subsequently switched to a combination treatment of linezolid, amikacin, and trimethoprim-sulfamethoxazole. The patient recovered, and his condition remained stable. Although infection by Nocardia vulneris is rare, and it is easy to miss detection in clinical practice, clinicians should be aware of the possibility of this infection. In addition, the MIC value of the drug sensitivity test should be ascertained when there is a wide choice of medicines. The current case was treated successfully with linezolid, amikacin, and trimethoprim-sulfamethoxazole. In cases of disseminated nocardiosis, the patient should be treated with antimicrobial therapy for at least 12 months. Furthermore, bacteriological examination and antimicrobial susceptibility testing should be performed regularly.

CRISPR/Cas12a-Based Diagnostic Platform Accurately Detects Nocardia farcinica Targeting a Novel Species-Specific Gene

Under the COVID-19 pandemic background, nucleic acid detection has become the gold standard to rapidly diagnose the infectious disease. A rapid, low cost, reliable nucleic acid detection platform will be the key to control next potential pandemic. In this study, a nucleic acid detection platform, which combined CRISPR/Cas12a-based detection with loop-mediated isothermal amplification (LAMP), was developed and termed CRISPR-CLA. In the CRISPR-CLA system, LAMP preamplification was employed, and CRISPR/Cas12a-based detection was used to monitor the preamplicons. The forward inner primer (FIP) was engineered with a protospacer adjacent motif (PAM) site TTTA of Cas12a effector at the linker region; thus, the CRISPR-CLA platform can detect any sequence as long as the primer design meets the requirement of LAMP. To demonstrate the validity of the CRISPR-CLA system, it was applied for the molecular diagnosis of nocardiosis caused by Nocardia farcinica (N. farcinica). A highly conserved and species-specific gene pbr1 of N. farcinica, which was first reported in this study, was used as the target of detection. A set of LAMP primers targeting a fragment of pbr1 of the N. farcinica reference strain IFM 10152 was designed according to the principle of CRISPR-CLA. Three CRISPR RNAs (crRNAs) with different lengths were designed, and the most efficient crRNA was screened out. Additionally, three single-strand DNA (ssDNA) probes were tested to further optimize the detection system. As a result, the N. farcinica CRISPR-CLA assay was established, and the whole detection process, including DNA extraction (20 min), LAMP preamplification (70°C, 40 min), and CRISPR/Cas12a-mediated detection (37°C, 8 min), can be completed within 70 min. A fluorescence reader (for fluorescence CRISPR-CLA) or a lateral flow biosensor (for lateral-flow CRISPR-CLA) can be the media of the result readout. Up to 132 strains were used to examine the specificity of N. farcinica CRISPR-CLA assay, and no cross-reaction was observed with non-N. farcinica templates. The limit of detection (LoD) of the N. farcinica CRISPR-CLA assay was 100 fg double-strand DNA per reaction. N. farcinica was detected accurately in 41 sputum specimens using the N. farcinica CRISPR-CLA assay, which showed higher specificity than a real-time qPCR method. Hence, the N. farcinica CRISPR-CLA assay is a rapid, economic and accurate method to diagnose N. farcinica infection.