Metagenomic Analysis Identifying a Rare Leishmania Infection in an Adult With AIDS

Advances and Challenges in the Diagnosis of Leishmaniasis

Leishmaniasis remains a significant public health challenge, particularly in endemic regions with limited resources. Traditional diagnostic methods, including microscopy, culture, and serology, though widely utilized, often suffer from limitations such as variable  sensitivity, time delays, and the need for specialized infrastructure. Some of these limitations have been addressed with the emergence of molecular diagnostic techniques. Quantitative PCR (q-PCR), loop-mediated isothermal amplification (LAMP), and recombinase polymerase amplification (RPA) assays have improved  the diagnostic sensitivity and specificity, enabling species identification and detection of asymptomatic infections. Further, nanodiagnostics and portable sequencing technologies such as the MinION™, along with lab-on-chip platforms, are revolutionizing the diagnostic landscape of leishmaniasis by offering point-of-care (POC) options for remote settings and field-based diagnosis. This review provides an in-depth analysis of these cutting-edge advances, discusses their application in resource-constrained settings, and evaluates their potential to reshape the future of leishmaniasis diagnosis and management.

Metagenomic next-generation sequencing assists in the diagnosis of visceral leishmaniasis in non-endemic areas of China

Introduction

Leishmaniasis, a protozoan disease caused by infection by Leishmania, is a critical issue in Asia, South America, East Africa, and North Africa. With 12 million cases globally, leishmaniasis is one of the most serious neglected tropical diseases worldwide. Direct identification of infected tissues is currently the primary method of diagnosis; however, the low sensitivity and inconvenience of microscopic examination in detecting amastigotes, parasitic manifestations of Leishmania, leads to the possibility of misdiagnosis, delayed diagnosis, and underdiagnosis.

Methods

With the development of metagenomic nextgeneration sequencing (mNGS) technology for pathogen identification, it is possible to detect specific nucleic acid sequences characteristic of Leishmania parasites, which opens new avenues for the more accurate diagnosis of leishmaniasis. In this study, we report two cases of leishmaniasis from Henan Province, China, in which Leishmania parasites were identified using mNGS technology, massively expediting diagnosis and treatment.

Results

Our report demonstrates that the mNGS method is applicable to peripheral blood samples (PB), which are far more readily available in clinical settings, in addition to bone marrow aspirate samples (BM), which are traditionally used for diagnosis of visceral leishmaniasis.

Conclusion

Our report validates the efficacy of mNGS technology as a rapid and accurate method of diagnosis for leishmaniasis.

Metagenomic analysis identifying a polymicrobial pulmonary infection in a non-HIV immunocompromised patient: a case report

BACKGROUND

Polymicrobial pulmonary infections, common in immunocompromised patients, often manifest more severe symptoms than monomicrobial infections. Clinical diagnosis delays may lead to mortality, emphasizing the importance of fast and accurate diagnosis for these patients. Metagenomic next-generation sequencing (mNGS), as an unbiased method capable of detecting all microbes, is a valuable tool to identify pathogens, particularly in cases where infections are difficult to diagnosis using conventional methods.

CASE PRESENTATION

A 50-year-old male patient was admitted due to cough, expectoration and dyspnea. CT scan revealed diffuse inflammatory and cavernous lung lesion, and blood examination suggested a polymicrobial infection. However, no etiology was found by routine examination. mNGS of bronchoalveolar lavage fluid(BALF)simultaneously detected the presence of Pneumocystis jirovecii (P.jirovecii), Aspergillus fumigates (A.fumigates), Nocardia farcinica (N.farcinica), Salmonella enterica subsp. enterica (S.enterica subsp. enterica), and cytomegalovirus (CMV). The patient was successfully treated with compound sulfamethoxazole (SMZ-TMP), cefoperazone/sulbactam (SCF), moxifloxacin (MXF), voriconazole (VCZ), and ganciclovir. The patient recovered after two weeks of anti-infection therapy and maintained good health at a six-month follow-up.

CONCLUSION

For immunocompromised patients with multiple infections and atypical symptoms, mNGS emerged as a reliable approach to pathogen detection and guiding antibiotic therapy.

Comprehensive evaluation of plasma microbial cell-free DNA sequencing for predicting bloodstream and local infections in clinical practice: a multicenter retrospective study

Background

Metagenomic next-generation sequencing (mNGS) of plasma cell-free DNA (cfDNA) shows promising application for complicated infections that cannot be resolved by conventional microbiological tests (CMTs). The criteria for cfDNA sequencing are currently in need of agreement and standardization.

Methods

We performed a retrospective cohort observation of 653 patients who underwent plasma cfDNA mNGS, including 431 with suspected bloodstream infections (BSI) and 222 with other suspected systemic infections. Plasma mNGS and CMTs were performed simultaneously in clinical practice. The diagnostic efficacy of plasma mNGS and CMTs in the diagnosis of blood-borne and other systemic infections was evaluated using receiver operating characteristic (ROC) curves. The sensitivity and specificity of the two methods were analyzed based on the final clinical outcome as the gold standard.

Results

The mNGS test showed an overall positive rate of 72.3% (472/653) for detecting microorganisms in plasma cfDNA, with a range of 2 to 6 different microorganisms detected in 171 patient specimens. Patients with positive mNGS results were more immunocompromised and had a higher incidence of severe disease (P<0·05). The sensitivity of mNGS was higher for BSI (93·5%) and other systemic infections (83·6%) compared to CMTs (37·7% and 14·3%, respectively). The mNGS detected DNA from a total of 735 microorganisms, with the number of microbial DNA reads ranging from 3 to 57,969, and a higher number of reads being associated with clinical infections (P<0·05). Of the 472 patients with positive mNGS results, clinical management was positively affected in 203 (43%) cases. Negative mNGS results led to a modified clinical management regimen in 92 patients (14.1%). The study also developed a bacterial and fungal library for plasma mNGS and obtained comparisons of turnaround times and detailed processing procedures for rare pathogens.

Conclusion

Our study evaluates the clinical use and analytic approaches of mNGS in predicting bloodstream and local infections in clinical practice. Our results suggest that mNGS has higher positive predictive values (PPVs) for BSI and systemic infections compared to CMTs, and can positively affect clinical management in a significant number of patients. The standardized whole-process management procedure for plasma mNGS developed in this study will ensure improved pre-screening probabilities and yield clinically valuable data.

Microbiomes Detected by Bronchoalveolar Lavage Fluid Metagenomic Next-Generation Sequencing among HIV-Infected and Uninfected Patients with Pulmonary Infection

Comparison of lung microbiomes between HIV-infected and uninfected patients with pulmonary infection by metagenomic next-generation sequencing (mNGS) has not been described in China. The lung microbiomes detected in bronchoalveolar fluid (BALF) by mNGS among HIV-infected and uninfected patients with pulmonary infection were reviewed in the First Hospital of Changsha between January 2019 and June 2022. In total, 476 HIV-infected and 280 uninfected patients with pulmonary infection were enrolled. Compared with HIV-uninfected patients, the proportions of Mycobacterium (P = 0.011), fungi (P < 0.001), and viruses (P < 0.001) were significantly higher in HIV-infected patients. The higher positive rate of Mycobacterium tuberculosis (MTB; P = 0.018), higher positive rates of Pneumocystis jirovecii and Talaromyces marneffei (all P < 0.001), and higher positive rate of cytomegalovirus (P < 0.001) contributed to the increased proportions of Mycobacterium, fungi, and viruses among HIV-infected patients, respectively. The constituent ratios of Streptococcus pneumoniae (P = 0.007) and Tropheryma whipplei (P = 0.002) in the bacteria spectrum were significantly higher, while the constituent ratio of Klebsiella pneumoniae (P = 0.005) was significantly lower in HIV-infected patients than in HIV-uninfected patients. Compared with HIV-uninfected patients, the constituent ratios of P. jirovecii and T. marneffei (all P < 0.001) in the fungal spectrum were significantly higher, while the constituent ratios of Candida and Aspergillus (all P < 0.001) were significantly lower in HIV-infected patients. In comparison to HIV-infected patients without antiretroviral therapy (ART), the proportions of T. whipplei (P = 0.001), MTB (P = 0.024), P. jirovecii (P < 0.001), T. marneffei (P < 0.001), and cytomegalovirus (P = 0.008) were significantly lower in HIV-infected patients on ART. Significant differences in lung microbiomes exist between HIV-infected and uninfected patients with pulmonary infection, and ART influences the lung microbiomes among HIV-infected patients with pulmonary infection. IMPORTANCE A better understanding of lung microorganisms is conducive to early diagnosis and treatment and will improve the prognosis of HIV-infected patients with pulmonary infection. Currently, few studies have systematically described the spectrum of pulmonary infection among HIV-infected patients. This study is the first to provide comprehensive information on the lung microbiomes of HIV-infected patients with pulmonary infection (as assessed by more sensitive metagenomic next-generation sequencing of bronchoalveolar fluid) compared with those from HIV-uninfected patients, which could provide a reference for the etiology of pulmonary infection among HIV-infected patients.

A Case of Spontaneous Mediastinal and Subcutaneous Emphysema in a Patient with HIV-Infected Pneumonia

BACKGROUND

Acquired immunodeficiency syndrome is a chronic infectious disease with high mortality and is caused by the Human Immunodeficiency Virus (HIV). Pneumonia caused by HIV is common, but it rarely causes spontaneous mediastinal and subcutaneous emphysema.

CASE PRESENTATION

A 21-year-old man with severe pneumonia was hospitalized owing to dyspnea that had been persisting for 1 day; blood test results confirmed HIV infection. Initial chest Computed Tomography (CT) did not reveal mediastinal or subcutaneous emphysema. However, after 21 days of treatment, the patient experienced discomfort in the neck region and experienced the feeling of snowflakes on applying pressure. Chest CT showed mediastinal and subcutaneous emphysema, located in the bilateral cervical roots, anterior upper chest wall, left axillary chest wall, mediastinum, and other parts. Metagenomic Next Generation Sequencing (mNGS) of the sputum and blood samples suggested multiple pathogenic infections. Antiinfection treatment was initiated, and changes in the patient's condition were monitored. The patient's subcutaneous emphysema improved during the follow-up.

CONCLUSION

In HIV-infected patients with sudden mediastinal and subcutaneous emphysema, mNGS can be used to determine the etiological agent during symptomatic treatment. Targeted antipathogen therapy is helpful in improving the condition of patients with subcutaneous emphysema.