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

An unveiling case of Nocardia pansinusitis in a patient with chronic lymphocytic leukemia: a case report

BACKGROUND

Nocardia infections are rare infections in immunocompetent patients and occur mostly in immunocompromised individuals. Usually, nocardia affects skin, brain, and lungs, but in disseminated forms, which occurred mostly in immunocompromised patients, it can involve every organ. Nocardia sinusitis is extremely rare as our searches returned only a very few related studies.

CASE PRESENTATION

In this case report, we present, for the first time, a 55-year-old Iranian male patient diagnosed with chronic lymphocytic leukemia who was receiving chemotherapeutic drugs and developed a fever. Further laboratory tests and imaging revealed pansinusitis. Following rhinoendoscopy, the sinus mucosal biopsy pathology report showed sever inflammation accompanied by aggregation of filamentous thin-walled bacteria. The patient was treated with co-trimoxazole and meropenem. Following good clinical improvement the patient was discharged and advised to continue oral co-trimoxazole for 3 months.

CONCLUSION

This case highlights that patients with febrile neutropenia should be assessed for rare infectious disease etiologies, especially those with chronic lymphocytic leukemia, as they have humeral immunodeficiency, and in the later stages of the disease, cellular immunodeficiency may also be involved. Therefore, a multisystem evaluation of patients with febrile neutropenia is necessary, particulary when no obvious source is identified in initial surveys, to uncover rare etiologies.

Discovery of Novel Diagnostic Biomarkers for Common Pathogenic Nocardia Through Pan-Genome and Comparative Genome Analysis, with Preliminary Validation

The aim of this study was to reveal diagnostic biomarkers of considerable importance for common pathogenic Nocardia, utilizing pan-genomic and comparative genome analysis to accurately characterize clinical Nocardia infections. In this study, complete or assembled genome sequences of common pathogenic Nocardia and closely related species were obtained from NCBI as discovery and validation sets, respectively. Genome annotation was performed using Prokka software, and pan-genomic analysis and extraction of Nocardia core genes were performed using BPGA software. Comparative genome analysis of these core genes with the validation-set gene sequences was then performed using BLAT, with a threshold of 30% amino acid coverage and identity, in order to distinguish specific core genes. Finally, candidate gene-specific primers were designed using Snapgene software and DNA samples were obtained from clinical Nocardia strains and closely related species for validation. The analysis identified eighteen core genes specific to Nocardia spp., four core genes specific to N. farcinica, and forty-six core genes specific to N. cyriacigeorgica. After rigorous clinical validation, one gene from Nocardia spp. and five genes from N. cyriacigeorgica were confirmed to have high specificity and therefore can be used as reliable biomarkers for accurate diagnosis of Nocardia infection. This pioneering research reveals diagnostic biomarkers of considerable significance, with the potential to substantially enhance the precise diagnosis of common pathogenic Nocardia infections, thereby laying the groundwork for innovative diagnostic methodologies in subsequent studies.

Multicenter systematic review of clinical characteristics, diagnostic optimization, and personalized treatment for brain Nocardia infections

This study provides a systematic review of 512 reported cases of Nocardia brain infections from 2000 to mid-2024. It focuses on analyzing clinical manifestations, radiological findings, bacterial identification methods, and antibiotic resistance patterns. Special attention is given to the differences in outcomes between immunocompromised and non-immunocompromised patients. We also explored personalized treatment approaches by analyzing outcome-related factors through correlation analysis and linear discriminant analysis. Imaging findings commonly showed brain abscesses, lesions, and mass effects, with a high prevalence of antibiotic resistance. Diagnostic methods using conventional microbiological cultures were less effective compared to advanced molecular diagnostics, which enhanced detection accuracy and reduced time to diagnosis. This review also identifies key factors influencing treatment outcomes, including the timely initiation of appropriate antibiotics, particularly the combination of sulfonamides and β-lactams, as well as the importance of surgical intervention. These findings underscore the necessity of improving diagnostic and therapeutic strategies to achieve early diagnosis and personalized treatment.

A case of disseminated nocardia infection with initial symptoms manifesting as cognitive impairment: Case report and literature review

RATIONALE

Nocardia infections, although rare, pose significant challenges in diagnosis and treatment, especially when involving the central nervous system (CNS). Mortality rates in such cases can be high, highlighting the need for early recognition and tailored antimicrobial therapy.

PATIENT CONCERNS

A 58-year-old male with a history of chronic obstructive pulmonary disease, antineutrophil cytoplasmic antibody-associated glomerulonephritis, and steroid-induced diabetes mellitus presented with disorganized speech, fever, cough, dyspnea, and psychiatric symptoms.

DIAGNOSES

The patient was diagnosed with severe pneumonia, left pneumothorax, bilateral pulmonary bullae, and CNS involvement. Next-generation sequencing (NGS) identified Nocardia farcinica as the causative agent.

INTERVENTIONS

Initial treatment with ceftriaxone was ineffective. Upon identification of N. farcinica via NGS, the patient was started on a tailored antimicrobial regimen consisting of sulfamethoxazole, linezolid, and meropenem.

OUTCOMES

Despite initial clinical improvement, the patient was discharged early due to financial constraints. Unfortunately, he later succumbed to the infection.

LESSONS

This case underscores the difficulty of diagnosing Nocardia infections, particularly when they involve the CNS. The use of advanced diagnostic tools such as NGS, along with early and appropriate antimicrobial therapy, is crucial for improving patient outcomes. Financial and healthcare access challenges may impact the success of treatment, emphasizing the importance of comprehensive follow-up and patient support.

Multiple lymph nodes enlargement and fever as main manifestations of nocardiosis in immunocompetent individuals: Two case reports

Nocardia farcinica is an aerobic gram-positive bacterium that is pathogenic to humans. It usually causes local and adjacent tissues' diseases at the entry of infection (most commonly occur in the lungs, skin, or central nervous system), which can also spread to other organs through the bloodstream such as joints, kidneys, and liver. However, these infections are often seen as opportunistic that occur in immunocompromised patients. Here, we report for the first time two immunocompetent patients lacking evidence of local infections, with multiple lymph node enlargements and fever as main clinical manifestations, finally diagnosed as nocardiosis by Metagenomic Next-Generation Sequencing testing (mNGS) from formalin-fixed and paraffin-embedded (FFPE) lymph node tissue, after all the other standard tests were negative. Both patients recovered after receiving anti-nocardia therapies. These two cases indicates that in healthy population, there may be more potential nocardia infections than we expected. Multiple lymph node enlargements and fever suggest a possibility of nocardiosis, especially in patients with fever of unknown origin (FUO). mNGS detection from FFPE lymph node tissue is an accurate, reliable and traceable method for diagnosis of nocardiosis.

Clinical utility of metagenomic next-generation sequencing in pathogen detection for lower respiratory tract infections and impact on clinical outcomes in southernmost China

Background

Today, metagenomic next-generation sequencing (mNGS) has emerged as a diagnostic tool for infections. However, since Hainan has a complicated pathogen spectrum, the diagnostic value and impact on patient outcomes of mNGS in Hainan are to be explored.

Methods

From April 2020 to October 2021, 266 suspected lower respiratory tract infections (LRTIs) patients in Hainan were enrolled, and specimens were collected before antibiotic treatment. Bronchoalveolar lavage fluid (BALF) samples were subjected to mNGS and culture to compare the diagnostic performance. Other conventional microbiological tests (CMT) were also performed. Patients' treatments and clinical outcomes were recorded, and the antibiotic resistance genes (ARGs) were detected via mNGS workflow.

Results

The positive rate of mNGS outperformed that of culture (87.55% vs. 39.30%, p<0.001) and CMT (87.12% vs. 52.65%, p<0.001). Specifically, mNGS detected more P. aeruginosa (12.03% vs 9.02%, p<0.05), H. influenzae (9.77% vs 2.26%, p<0.001), Aspergillus fumigatus (3.00% vs 0.75%, p<0.05), Candida albicans (26.32% vs 7.52%, p<0.001) and uncommon pathogens. It also demonstrated great diagnostic advantages in Mycobacterium tuberculosis with 80% sensitivity and 97.4% specificity. Over half of the patients (147, 55.26%) had modified empirical treatment according to mNGS results and 89.12% of them responded well. For three deaths with modified treatment, multiple drug resistance was predicted by mNGS and confirmed by antibiotic susceptibility test.

Conclusions

The application of mNGS can benefit clinics in pathogen identification and antimicrobial treatment stewardship. Physicians should be alert to some emerging uncommon pathogens, including Chlamydia Psittaci, Nocardia otitidiscaviarum, and rare NTM.

Cerebral Abscess Infected by Nocardia gipuzkoensis

Purpose

Nocardia gipuzkoensis is a novel species that solely identified in patients with pulmonary infections by far. Growing evidence showed the excellent performance of metagenomics next-generation sequencing (mNGS) on pathogenic identification, especially for new species. Here, we described the first case of an elderly female patient suddenly suffering from neurological disorders owing to N. gipuzkoensis infection. And linezolid could effectively treat N. gipuzkoensis infection.

Patients and Methods

The results of imaging, laboratory cultures, and mNGS, as well as therapeutic process are shared.

Results

An elderly female patient suddenly suffered from neurological disorders with dysphasia and right limb trembles under no obvious causes. Subsequently, she was diagnosed as intracranial space-occupying lesions by magnetic resonance imaging (MRI). The isolate from brain secretion was further identified as N. gipuzkoensis through mNGS. The targeted therapy with linezolid according to the antimicrobial susceptibility was used to treat cerebral abscess induced by N. gipuzkoensis. During the follow-up, no relapse was observed for the patient after surgery for 104 days.

Conclusion

Cerebral abscess induced by N. gipuzkoensis is rare disorder with high mortality. mNGS has been identified as a promising tool in pathogen diagnosis for timely therapy. Linezolid as one of the antimicrobial drugs could effectively treat N. gipuzkoensis infection and prevent adverse outcomes.