Diagnostic limitations and challenges in current clinical guidelines and potential application of metagenomic sequencing to manage pulmonary invasive fungal infections in patients with haematological malignancies

BACKGROUND

Pulmonary invasive fungal infections (pIFI) disproportionately affect patients with haematological malignancies (HM). Establishing a rapid and accurate diagnosis of pIFI is challenging. Multiple guidelines recommend diagnostic testing of invasive fungal infections but lack consensus and may contribute to inconsistent diagnostic approaches.

OBJECTIVE

To identify key diagnostic challenges and review metagenomic sequencing data.

SOURCES

PubMed, professional consortium, and scientific society websites search to identify relevant, published, evidence-based clinical guidelines within the past 5 years. PubMed searchs for papers describing clinically relevant novel diagnostic technologies.

CONTENT

Current guidelines for patients with HM and suspected pIFI recommend chest computed tomography imaging and specimen testing with microscopic examination (including calcofluor white stain, histopathology, cytopathology, etc.), Aspergillus galactomannan, β-D-glucan, PCR, and culture, each with certain limitations. Emerging real-world data support the adjunctive use of metagenomic sequencing-based tests for the timely diagnosis of pIFI.

IMPLICATIONS

High-quality evidence from robust clinical trials is needed to determine whether guidelines should be updated to include novel diagnostic technologies. Trials should ask whether the combination of powerful novel diagnostics, such as pathogen-agnostic metagenomic sequencing technologies in conjunction with conventional testing can optimize the diagnostic yield for all potential pIFI pathogens that impact the health of patients with HM.

Klebsiella pneumoniae invasive syndrome with liver, lung, and brain abscesses complicated with pulmonary fungal infection: a case report and review of the literature

BACKGROUND

Klebsiella pneumoniae invasion syndrome (KPIS) is a severe multi-site infection that is usually caused by hypervirulent Klebsiella pneumoniae. The bacteria are relatively common in Asian diabetics and can cause organ abscesses or sepsis. When patients develop intracranial infection, the prognosis is poor. After anti-infective treatment, the Klebsiella pneumoniae-induced liver and lung abscesses and pulmonary fungal infection were relieved, but the brain abscesses worsened. Such complex and severe infection cases are rarely reported. Early identification of intracranial infection, selection of antibiotics with high concentrations in cerebrospinal fluid, and active treatment of complications such as diabetes and fungal infection are of great significance for the prognosis of patients.

CASE PRESENTATION

A 71-year-old patient diagnosed with liver abscess in another hospital was transferred to our hospital due to a worsening condition. On day 1 (day of admission), the patient was given invasive mechanical ventilation, continuous renal replacement therapy combined with endotoxin adsorption, antimicrobial treatment with imipenem-cilastatin, and percutaneous catheter drainage for liver abscess. Metagenomic next-generation sequencing in bronchoalveolar lavage fluid indicated Klebsiella pneumoniae (K. pneumoniae), Candida albicans, and Aspergillus flavus complex, and no viruses were detected. Blood and pus cultures revealed K. pneumoniae that was sensitive to piperacillin/tazobactam. The anti-infection therapy was adjusted to piperacillin/tazobactam combined with voriconazole. On day 14, a head computed tomography (CT) scan showed no significant changes, and a chest CT scan showed absorption of multiple abscesses in both lungs. The patient was still unconscious. After the endotracheal tube was removed, cranial magnetic resonance imaging (MRI) showed multiple brain abscesses. Finally, his family gave up, and the patient was discharged and died in a local hospital.

CONCLUSION

In cases of K. pneumoniae infection, the possibility of intracranial, liver, lung, or other site infections should be considered, and physicians should be vigilant for the occurrence of KPIS. For patients suspected of developing an intracranial infection, cerebrospinal fluid should be tested and cultured as soon as possible, a head MRI should be performed, and antibiotics with high distribution in cerebrospinal fluid should be used early. When patients are complicated with diabetes, in addition to glycemic control, vigilance for concurrent fungal infections is also needed.

Clinical characteristics and predictive model of pulmonary tuberculosis patients with pulmonary fungal coinfection

BACKGROUND

In clinical settings, pulmonary tuberculosis (PTB) patients were often found to have pulmonary fungal coinfection. This study aimed to assess the clinical characteristics of patients suffering from coinfection with TB and pulmonary fungal and construct a predictive model for evaluating the probability of pulmonary fungal coinfection in patients with pulmonary tuberculosis.

METHODS

The present case-control study retrospectively collected information from 286 patients affected by PTB who received treatment from December 6,2016- December 6,2021 at Beijing Chest Hospital, Capital Medical University. As control subjects, patients with sex and address corresponding to those of the case subjects were included in the study in a ratio of 1:1. These 286 patients were randomly divided into the training and internal validation sets in a ratio of 3:1. Chi-square test and logistic regression analysis were performed for the training set, and a predictive model was developed using the selected predictors. Bootstrapping was performed for internal validation.

RESULTS

Seven variables [illness course, pulmonary cavitation, broad-spectrum antibiotics use for at least 1 week, chemotherapy or immunosuppressants, surgery, bacterial pneumonia, and hypoproteinemia] were validated and used to develop a predictive model which showed good discrimination capability for both training set [area under the curve (AUC) = 0.860, 95% confidence interval (CI) = 0.811-0.909] and internal validation set (AUC = 0.884, 95% CI = 0.799-0.970). The calibration curves also showed that the probabilities predicted using the predictive model had satisfactory consistency with the actual probability for both training and internal validation sets.

CONCLUSIONS

We developed a predictive model that can predict the probability of pulmonary fungal coinfection in pulmonary tuberculosis patients. It showed potential clinical utility.

Lung cancer coexisting with Papiliotrema flavescens infection diagnosed by next-generation sequencing: a case report

BACKGROUND

Papiliotrema flavescens is a rare environmental yeast, which has been isolated from air, trees, kernels of wheat and corn, fermenting soya sauce, and cerebrospinal fluid of patient with AIDS. Additionally, it is also reported to cause subcutaneous infection in a dog. In this case, we describe primary lung adenocarcinoma coexisting with Papiliotrema flavescens infection in a female patient diagnosed by next-generation sequencing (NGS) technique, which is the first such reported case.

CASE PRESENTATION

The patient was a 52-year-old female with recurrent cough for 3 months. Chest CT examination revealed a ground glass nodule of 17 * 23 * 18 mm in the right upper lung, and 3 new pulmonary nodules appeared around it 2 months later. The patient underwent right upper lobe lobectomy and pathology confirmed that the primary 2-cm-lesion in the right upper lobe was invasive lung adenocarcinoma, and two of the three surrounding lung nodules were pathologically suggestive of pulmonary fungal infection (not known in specific fungal types). Hence, the patient received empirical anti-fungal treatments with fluconazole 400 mg/day for a week and follow-up CT scanning showed no tumor progression and no relapse of fungal infection. The specific pathogen was eventually identified as Papiliotrema flavescens by the next-generation sequencing of pathogen.

DISCUSSION AND CONCLUSION

We first reported that lung cancer coexisting with Papiliotrema flavescens infection in a female patient. The diagnosis of lung cancer with typical CT imaging features is relatively simple, while the diagnosis of lung cancer coexisting with rare fungal infection is challenging. NGS technique is an effective supplementary technique for clinical diagnosis of bacterial or fungal infectious diseases, enabling precise clinical decision-making and appropriate treatment. In this case, the lung cancer may result in a degree of immune suppression, at least locally, resulting in the formation of pulmonary fungal nodular lesions around the tumor.

Pulmonary Aspergillosis: What the Generalist Needs to Know

Aspergillus spp. is a ubiquitous mold found commonly in our environment that can cause a spectrum of pulmonary disorders, ranging from a hypersensitivity reaction to an acutely invasive disease with significant mortality. Allergic bronchopulmonary aspergillosis results from airway hypersensitivity from aspergillus colonization almost exclusively in patients with asthma and cystic fibrosis. Chronic pulmonary aspergillosis typically presents in immunocompetent patients with underlying lung pathology. Treatment is primarily with antifungal agents; however, other measures such as surgical resection may be necessary. Invasive pulmonary aspergillosis is a severe infection in immunocompromised patients and is characterized by invasion of pulmonary vasculature by the Aspergillus hyphae. Recent advances in the diagnosis and management of invasive pulmonary aspergillosis include emerging risk factors such as critically ill patients, and those with chronic obstructive pulmonary disease and liver disease. In addition, noninvasive biomarkers have made it easier to suspect and diagnose invasive pulmonary aspergillosis. There are more effective and better-tolerated antifungal agents that have improved patient outcomes. This review introduces the spectrum of pulmonary aspergillosis geared toward generalists, including disease manifestations, most recent diagnostic criteria, and first-line treatment options. Involving a multidisciplinary team is vital to the early diagnosis and management of these diseases.

Surgical resection for persistent localized pulmonary fungal infection prior to allogeneic hematopoietic stem cell transplantation: Analysis of six cases

OBJECTIVE

Although invasive fungal disease (IFD) is an important complication in allogeneic hematopoietic stem cell transplantation (HSCT), the clinical significance of surgery, including the role of surgical resection for persistent pulmonary fungal disease prior to allogeneic HSCT in the current era with a variety of available antifungal agents, is controversial. We investigated the role of surgical resection.

METHODS

We retrospectively investigated six patients who underwent surgical resection of suspected pulmonary fungal disease prior to allogeneic HSCT between April 2007 and June 2016 at our medical center.

RESULTS

We present six patients who underwent surgical resection of suspected pulmonary fungal disease prior to allogeneic HSCT. In our case series, three of four patients who were given a presurgical diagnosis of possible IFD were given a proven diagnosis after surgery, including two cases of invasive aspergillosis (IA) and one case of mucormycosis. All surgeries were performed by video-assisted thoracic surgery (VATS) for lobectomy without major complications. Recurrence of IFD was not observed after allogeneic HSCT in any of the six patients.

CONCLUSION

Our experience indicated that surgical resection of persistent localized pulmonary lesions of IFD before allogeneic HSCT was helpful for obtaining a definitive diagnosis and might be useful for reducing recurrence after HSCT.

CD4(+) FoxP3(+) regulatory T cells suppress fatal T helper 2 cell immunity during pulmonary fungal infection

The opportunistic fungal pathogen Cryptococcus neoformans causes lung inflammation and fatal meningitis in immunocompromised patients. Regulatory T (Treg) cells play an important role in controlling immunity and homeostasis. However, their functional role during fungal infection is largely unknown. In this study, we investigated the role of Treg cells during experimental murine pulmonary C. neoformans infection. We show that the number of CD4(+) FoxP3(+) Treg cells in the lung increases significantly within the first 4 weeks after intranasal infection of BALB/c wild-type mice. To define the function of Treg cells we used DEREG mice allowing selective depletion of CD4(+) FoxP3(+) Treg cells by application of diphtheria toxin. In Treg cell-depleted mice, stronger pulmonary allergic inflammation with enhanced mucus production and pronounced eosinophilia, increased IgE production, and elevated fungal lung burden were found. This was accompanied by higher frequencies of GATA-3(+) T helper (Th) 2 cells with elevated capacity to produce interleukin (IL)-4, IL-5, and IL-13. In contrast, only a mild increase in the Th1-associated immune response unrelated to the fungal infection was observed. In conclusion, the data demonstrate that during fungal infection pulmonary Treg cells are induced and preferentially suppress Th2 cells thereby mediating enhanced fungal control.