Nontuberculous Mycobacterial Pulmonary Disease in the Immunocompromised Host

Differentiating Nontuberculous Mycobacterial Pulmonary Disease from Pulmonary Tuberculosis in Resource-Limited Settings: A Pragmatic Model for Reducing Misguided Antitubercular Treatment

Background: Differentiating nontuberculous mycobacterial pulmonary disease (NTM-PD) from pulmonary tuberculosis (PTB) remains challenging due to overlapping clinical features, particularly in resource-limited settings where diagnostic errors are frequent. This retrospective case-control study (January 2023-June 2024) aimed to identify key clinical predictors and develop a diagnostic model to distinguish NTM-PD from PTB. Methods: Patients initially presumed to have PTB (meeting clinical-radiological criteria but lacking bacteriological confirmation at admission) at a tertiary tuberculosis hospital were enrolled. Final diagnoses of NTM-PD (n = 105) and PTB (n = 105) were confirmed by mycobacterial culture identification. Clinical, laboratory, and radiological data were compared using univariate analysis. Variables showing significant differences (p < 0.05) were entered into multivariable logistic regression. Diagnostic performance was evaluated via receiver operating characteristic (ROC) curve analysis. Results: Female sex (odds ratio [OR] = 2.51, 95% confidence interval [CI] 1.12-5.60), hemoptysis (OR = 2.20, 1.05-4.62), bronchiectasis (OR = 5.92, 2.56-13.71), and emphysema/pulmonary bullae (OR = 2.69, 1.16-6.24) emerged as independent predictors of NTM-PD, while systemic symptoms favored PTB (OR = 0.45, 0.20-0.99). The model demonstrated 91.4% specificity and 68.6% sensitivity with an area under the curve [AUC] of 0.871. Conclusions: This high-specificity model helps prioritize NTM-PD confirmation in females with hemoptysis and structural lung changes (computed tomography evidence of bronchiectasis and/or emphysema) while maintaining PTB suspicion when systemic symptoms (fever, night sweats, weight loss) dominate. The approach may reduce misguided antitubercular therapy in resource-limited settings awaiting culture results.

Clinical impact of bronchoalveolar lavage fluid metagenomic next-generation sequencing in immunocompromised patients with severe community-acquired pneumonia in ICU: a multicenter retrospective study

BACKGROUND

An increasing number of critically ill patients are immunocompromised. These patients are at high risk of intensive care unit (ICU) admission because of numerous complications. Acute respiratory failure due to severe community-acquired pneumonia (SCAP) is one of the leading causes of admission. Early targeted antibiotic therapy is crucial for improving the prognosis of these patients. Metagenomic next-generation sequencing (mNGS) in bronchoalveolar lavage fluid (BALF) has shown significant value in pathogen detection in recent years. However, there are few studies on summarizing pathogen profiles of SCAP in immunocompromised patients.

METHODS

We performed a multicenter retrospective analysis of patients with SCAP in the ICU diagnosed between May 2021 to October 2024. Bronchoalveolar lavage fluid (BALF), blood, and sputum samples were collected and subjected to mNGS and conventional microbiological tests (CMTs). The pathogen profiles detected by the two methods were compared.

RESULTS

In our study, compared to CMTs, mNGS increased the detection rates of mixed infections in the immunocompromised group (58.82% vs 17.96%, P < 0.05) and immunocompetent group (44.58% vs 18.72%, P < 0.05), while also reducing the rate of no pathogen detected (4.90% vs 38.73%, P < 0.05; 8.37% vs 32.76%, P < 0.05). In both groups, the proportion of positive clinical impacts (diagnosis) resulting from mNGS results exceeded 90% (96.57% vs 93.84%), and the treatment effectiveness rate in the immunocompromised group was higher than in the immunocompetent group (65.69% vs 56.40%, P < 0.05). Further analysis showed that when mNGS-guided treatment was effective, the 28-day mortality rate significantly improved in both the immunocompromised group (31.34% vs 74.29%, P < 0.05) and the immunocompetent group (42.36% vs 40.68%, P < 0.05) compared to when the treatment was ineffective.

CONCLUSION

This study indicates that ICU patients with SCAP, particularly those who are immunocompromised, are more likely to have polymicrobial infections. mNGS in BALF provides rapid and comprehensive pathogen profiling of pulmonary infections, thereby having a positive impact on both the diagnosis, treatment and prognosis of immunocompromised patients with SCAP.

Lung Nodules and Masses in Patients Who Are Not HIV Immunocompromised: A Clinical Imaging Algorithmic Approach

TOPIC IMPORTANCE

The incidence of pulmonary nodules and masses in immunocompromised patients without HIV has significantly increased due to advancements in hematopoietic stem cell transplantation and solid organ transplantation and the widespread use of chemotherapy and immunosuppressive therapies. Differentiating between infectious and noninfectious causes is critical for appropriate diagnosis and management, especially because radiologic and clinical presentations can be nonspecific.

REVIEW FINDINGS

This review provides a practical framework for evaluating pulmonary nodules and masses in immunocompromised patients without HIV, incorporating clinical, immunologic, and radiologic features. It emphasizes the importance of differentiating between infectious and noninfectious etiologies based on imaging and clinical context. The review highlights the importance of correlating imaging features with the patient's immune status and underlying clinical conditions to narrow down the differential diagnosis.

SUMMARY

Pulmonary nodules and masses in immunocompromised patients represent a diagnostic challenge due to overlapping radiologic and clinical presentations. By integrating clinical context, immune status, and imaging findings, clinicians can more accurately diagnose and manage these lesions, improving patient outcomes. This review presents an algorithmic approach for differentiating between various causes of pulmonary nodules and masses in immunocompromised individuals without HIV, providing a valuable tool for clinical practice.

Durlobactam to boost the clinical utility of standard of care β-lactams against Mycobacterium abscessus lung disease

β-Lactams present several desirable pharmacodynamic features leading to the rapid eradication of many bacterial pathogens. Imipenem (IPM) and cefoxitin (FOX) are injectable β-lactams recommended during the intensive treatment phase of pulmonary infections caused by Mycobacterium abscessus (Mab). However, their potency against Mab is many-fold lower than against Gram-positive and Gram-negative pathogens for which they were optimized, putting into question their clinical utility. Here, we show that adding the recently approved durlobactam-sulbactam (DUR-SUL) pair to either IPM or FOX achieves growth inhibition, bactericidal, and cytolytic activity at concentrations that are within those achieved in patients and below the clinical breakpoints established for each agent. Synergies between DUR-SUL and IPM or FOX were confirmed across a large panel of clinical isolates. Through in vitro resistant mutant selection, we also show that adding DUR-SUL abrogates acquired resistance to IPM and FOX. Since the use of β-lactam injectables is firmly grounded in clinical practice during the intensive treatment phase of Mab pulmonary disease, their potentiation by FDA-approved DUR-SUL to bring minimum inhibitory concentration distributions within achievable concentration ranges could offer significant short-term benefits to patients, while novel β-lactam combinations are optimized specifically against Mab pulmonary infections, for which no reliable cure exists.

Toward better cures for Mycobacterium abscessus lung disease

SUMMARYThe opportunistic pathogen Mycobacterium abscessus (Mab) causes fatal lung infections that bear similarities-and notable differences-with tuberculosis (TB) pulmonary disease. In contrast to TB, no antibiotic is formally approved to treat Mab disease, there is no reliable cure, and the discovery and development pipeline is incredibly thin. Here, we discuss the factors behind the unsatisfactory cure rates of Mab disease, namely intrinsic resistance and persistence of the pathogen, and the use of underperforming, often parenteral and toxic, repurposed drugs. We propose preclinical strategies to build injectable-free sterilizing and safe regimens: (i) prioritize oral bactericidal antibiotic classes, with an initial focus on approved agents or advanced clinical candidates to provide immediate options for desperate patients, (ii) test drug combinations early, (iii) optimize novel leads specifically for M. abscessus, and (iv) consider pharmacokinetic-pharmacodynamic targets at the site of disease, the lung lesions in which drug tolerant bacterial populations reside. Knowledge and tool gaps in the preclinical drug discovery process are identified, including validated mouse models and computational platforms to enable in vitro mouse-human translation. We briefly discuss recent advances in clinical development, the need for readouts and biomarkers that correlate with cure, and clinical trial concepts adapted to the uniqueness of Mab patient populations for new regimen development. In an era when most pharmaceutical firms have withdrawn from antimicrobial drug discovery, the breakthroughs needed to fill the regimen development pipeline will likely come from partnerships between academia, biotech, pharma, non-profit organizations, and governments, with incentives that reward cooperation.

Metagenomic next-generation sequencing may assist diagnosis of osteomyelitis caused by Mycobacterium houstonense: A case report

BACKGROUND

Mycobacterium houstonense (M. houstonense) belongs to the nontuberculous mycobacterium group. Infection caused by M. houstonense is prone to recurrence.

CASE SUMMARY

We present a patient who was diagnosed with osteomyelitis caused by M. houstonense and treated with a combination of cefoxitin, and amikacin combined with linezolid.

CONCLUSION

The emergence of metagenomic next-generation sequencing (NGS) has brought new hope for the diagnosis and treatment of listeria meningitis. NGS can analyze a large number of nucleic acid sequences in a short time and quickly determine the pathogen species in the sample. Compared with traditional cerebrospinal fluid culture, NGS can greatly shorten the diagnosis time and provide strong support for the timely treatment of patients. Regarding treatment, NGS can also play an important role. Rapid and accurate diagnosis can enable patients to start targeted treatment as soon as possible and improve the treatment effect. At the same time, by monitoring the changes in pathogen resistance, the treatment plan can be adjusted in time to avoid treatment failure.

Disseminated mycobacterium genavense infection with central nervous system involvement in an HIV patient: a case report and literature review

BACKGROUND

Immunodeficient patients, particularly HIV patients, are at risk of opportunistic infections. Nontuberculous mycobacteria can cause severe complications in immunodeficient patients.

CASE PRESENTATION

We describe a 57-year-old HIV patient, primarily presented with coughs and constitutional symptoms, with a unique Mycobacterium genavense abdominal, pulmonary, and central nervous system infection, accompanied by intracranial masses.

CONCLUSION

The diagnosis of NTM, including M. genavense, must always be considered by clinicians in immunodeficient patients, especially those with HIV, who have a compromised immune system.