Misdiagnosed tuberculosis being corrected as Nocardia farcinica infection by metagenomic sequencing: a case report

Longistylin A from Cajanus cajan (L.) Millsp. disturbs glycerophospholipid metabolism and cytokinin biosynthesis of Nocardia seriolae

ETHNOPHARMACOLOGICAL RELEVANCE

Nocardiosis is an uncommon infectious disease that bears certain similarities to tuberculosis, with a continuous increase in its incidence and a poor prognosis. In traditional Chinese medicine, the leaves of Cajanus cajan (L.) Millsp. are employed to treat wounds, malaria, coughs, and abdominal pain.

AIM OF THE STUDY

In this study, we investigated the effects and mechanisms of longistylin A (LGA), a natural stilbene isolated from C. cajan, as a potential antibiotic against nocardiosis.

MATERIALS AND METHODS

LGA was isolated from the leaves of C. cajan and assessed using a minimum bactericidal concentration (MBC) determination against Nocardia seriolae. Multi-omics analysis encompassing genes, proteins, and metabolites was conducted to investigate the impact of LGA treatment on N. seriolae. Additionally, quantitative analysis of 40 cytokinins in N. seriolae mycelium was performed to assess the specific effects of LGA treatment on cytokinin levels. Cryo-scanning electron microscopy was utilized to examine morphological changes induced by LGA treatment, particularly in the presence of exogenous trans-zeatin-O-glucoside (tZOG). The therapeutic effect of LGA was investigated by feeding N. seriolae-infected largemouth bass.

RESULTS

LGA exhibited significant efficacy against N. seriolae, with MBC value of 2.56 μg/mL. Multi-omics analysis revealed that LGA disrupted glycerophospholipid metabolism and hormone biosynthesis by notably reducing the expression of glycerol-3-phosphate dehydrogenase and calmodulin-like protein. Treatment with LGA markedly disrupted 12 distinct cytokinins in N. seriolae mycelium. Additionally, the addition of exogenous tZOG counteracted the inhibitory effects of LGA on filamentous growth, resulting in mycelial elongation and branching. Furthermore, LGA treatment improved the survival rate of largemouth bass infected with N. seriolae.

CONCLUSIONS

We found for the first time that LGA from C. cajan exhibited significant efficacy against N. seriolae by interfering with glycerophospholipid metabolism and cytokinin biosynthesis.

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.

Clinical and Radiographic Characteristics of Nocardia vs Non-Nocardia Brain Abscesses

Background and Objectives

Diagnosis and treatment of CNS nocardiosis is challenging and often delayed, which increases morbidity and mortality. The primary objective was to compare the clinical and radiographic characteristics of patients with CNS nocardiosis with non-Nocardia bacterial brain abscesses.

Methods

We performed a case-control study of patients with brain abscesses diagnosed between 1998 and 2018 at a tertiary academic center. We identified 56 patients with brain MRI demonstrating brain abscess from the institutional imaging database: 14 with culture-confirmed nocardiosis and 42 randomly selected prevalent controls with culture-confirmed non-Nocardia bacterial infection. The primary outcomes were the diagnosis of concomitant lung infection and history of immunosuppression. Secondary outcomes included abscess radiographic characteristics: multifocality, occipital lobe and/or infratentorial location, and bilobed morphology.

Results

Compared with patients with non-Nocardia brain abscesses, patients with CNS nocardiosis were older (median 61 years [IQR 59-69] vs 48 years [IQR 34-61]; p = 0.03), more likely to be immunosuppressed [71% (10) vs 19% (8); p < 0.001), have diabetes (36% (5) vs 10% [4]; p = 0.03), or a concomitant lung infection (86% [12] vs 2% [1]; p < 0.001). Radiographically, more cases of CNS nocardiosis exhibited multifocal abscesses (29% [4] vs 2% [1]; p = 0.01), which were located in the infratentorial (43% [6] vs 10% (4); p = 0.01) or occipital (36% [5] vs 5% [2]; p = 0.008) regions and had a bilobed (as opposed to unilobed) morphology (79% [11] vs 19% [8]; p < 0.001). Blood and CSF cultures were negative in most of the cases and controls, whereas neurosurgical specimen culture yielded a diagnosis in 100% of specimens.

Discussion

Patients with CNS nocardiosis were more likely to be older, have a history of diabetes or immunosuppression, or have a concomitant lung infection compared with those with non-Nocardia brain abscesses. Abscesses because of CNS nocardiosis were more likely to be multifocal, affect the infratentorial region or occipital lobe, or have a bilobed appearance. Neurosurgical specimen culture was most likely to yield a diagnosis for both Nocardia and non-Nocardia abscesses. The combination of clinical and imaging findings may suggest CNS nocardiosis and inform early initiation of targeted empiric treatment.

Metagenomic next-generation sequencing contributes to the diagnosis of mixed pulmonary infection: a case report

BACKGROUND

Pulmonary cryptococcosis (PC) and mixed pulmonary infection are difficult to be diagnosed due to the non-specificity and their overlapping clinical manifestations. In terms of the clinical diagnosis of PC and mixed pulmonary infection, conventional tests have limitations such as a long detection period, a limited range of pathogens, and low sensitivity. Metagenomics next-generation sequencing (mNGS) is a nascent and powerful method that can detect pathogens without culture, to diagnose known and unexplained infections in reduced time.

CASE PRESENTATION

A 43-year-old female was admitted to the hospital after suffering from a cough for one month. At the time of admission, a contrast-enhanced chest CT revealed multiple nodules and plaques in her right lung, as well as the formation of cavities. The blood routine assays showed evidently increased white blood cell count (mainly neutrophils), CRP, and ESR, which suggested she was in the infection phase. The serum CrAg-LFA test showed a positive result. Initially, she was diagnosed with an unexplained pulmonary infection. Bronchoalveolar lavage fluid (BALF) samples were collected for microbial culture, immunological tests and the mNGS. Microbial culture and immunological tests were all negative, while mNGS detected Corynebacterium striatum, Pseudomonas aeruginosa, Streptococcus pneumoniae, and Cryptococcus neoformans. The diagnosis was revised to PC and bacterial pneumonia. Lung infection lesions were healed after she received targeted anti-infection therapy with mezlocillin and fluconazole. In a follow-up after 2 months, the patient's symptoms vanished.

CONCLUSIONS

Here, we demonstrated that mNGS was capable of accurately distinguishing Cryptococcus from M. tuberculosis in pulmonary infection, and notably mNGS was capable of swiftly and precisely detecting pathogens in mixed bacterial and fungal pulmonary infection. Furthermore, the results of mNGS also have the potential to adjust anti-infective therapies.

Clinical value of metagenomic next-generation sequencing in complicated infectious diseases

Infectious diseases are commonly seen in clinical practice, and pathogen diagnosis is the key link in diagnosis and treatment; however, conventional pathogen detection methods cannot meet clinical needs due to time-consuming operation and low positive rate. As a new pathogen detection method, metagenomic next-generation sequencing (mNGS) has a wide detection range and can detect bacteria, viruses, fungi, parasites, rare pathogens, and even unknown pathogens. The technique of mNGS is unbiased and can rapidly, efficiently, and accurately obtain all nucleic acid information in test samples, analyze pathogens, and guide clinical diagnosis and treatment, thereby playing an important role in complicated infectious diseases. This article reviews the diagnostic advantages and clinical value of mNGS in bacterial, fungal, viral, and parasitic infections.

Disseminated Nocardia farcinica involves the spinal cord: a case report and review of the literature

Background

Nocardia is a relatively rare opportunistic pathogenic bacteria group, commonly seen in patients with immunocompromised or defective immune system. It can affect multiple organs of the body and cause disseminated infection, among which most occurs in the lung, secondly in the nervous system, soft tissues, rare in the spinal cord and pituitary. No case has been reported involving lung, spinal cord, skin and pituitary gland at the same time.

Case presentation

We report a 55-year-old female with Nocardia infection involving the lung, skin, spinal cord, and pituitary gland. The patient underwent a full set of imaging examinations and showed typical imaging findings. Chest computed tomography (CT) showed multiple nodules with cavities in the lungs. The magnetic resonance imaging (MRI) of the vertebral body showed abnormal signal of the entire spinal cord with cavity formation and ring enhancement. The subcutaneous nodules of the abdomen were punctured under ultrasound. Through the etiological tissue culture of subcutaneous nodules and the second generation sequencing of cerebrospinal fluid, the diagnosis was finally confirmed.

Conclusion

Disseminated Nocardiosis is an uncommon disease. This article will report a rare case of disseminated Nocardiosis simultaneously involving the lung, spinal cord, subcutaneous soft tissue and pituitary gland, especially with neuropathy as the initial symptom. Imaging is helpful for the early diagnosis of the disease and pathological and microbiological examinations are helpful for its confirming.