Viral reactivation in the lungs of patients with severe pneumonia is associated with increased mortality, a multicenter, retrospective study

Metagenomic next generation sequencing of bronchoalveolar lavage fluids for the identification of pathogens in patients with pulmonary infection: A retrospective study

Due to the limitations of traditional laboratory methods (TMs), identification of causative pathogens of numerous pulmonary infections (PIs) remains difficult. This study evaluated the value of metagenomic next generation sequencing (mNGS) in the identification of various respiratory pathogens. A total of 207 patients with TMs and mNGS data were collected for this retrospective study. TMs included sputum culture, blood, and bronchoalveolar lavage fluid (BALF) analysis, or polymerase chain reaction analysis of throat swabs. Otherwise, BALF was collected and analyzed using mNGS. For bacterial pathogens, sensitivities of mNGS as compared to TMs were 76.74 % and 58.14 % (P=0.012). For fungal pathogens, the detection rate of mNGS sensitivity was higher as compared to that of TMs (93.68 % vs 22.11 %; P<0.001). The positive predictive value and negative predictive value were also greater for mNGS. Use of mNGS for BALF analysis offers good specificity and thus facilitates to the clinical diagnosis of PIs.

Analysis of pulmonary microecology and clinical characteristics of patients carrying human herpesvirus

Aim: To investigate the impact of human herpes virus (HHV) carriage on lung microbiota, and its correlation with clinical features and laboratory indicators in patients.Methods: Retrospective analysis was conducted on 30 outpatient lung infection cases, which were divided into HHV (n = 15) and non-HHV (n = 15) groups. mNGS detected microbial composition. Microbial diversity and abundance were tested using Shannon and Chao1 indices. Their relationship with laboratory indicators were explored.Results: Significant differences in microbial abundance and distribution were found between two groups (p < 0.05). Moreover, HHV group showed negative correlations (p < 0.05) between Prevotella, Porphyromonas, Streptococcus and basophil/eosinophil percentages.Conclusion: HHV carriage impacts lung microbiota, emphasizing the need for clinicians to pay attention to HHV reactivation in outpatient lung infection patients.

Ventilator-associated pneumonia: pathobiological heterogeneity and diagnostic challenges

Ventilator-associated pneumonia (VAP) affects up to 20% of critically ill patients and induces significant antibiotic prescription pressure, accounting for half of all antibiotic use in the ICU. VAP significantly increases hospital length of stay and healthcare costs yet is also associated with long-term morbidity and mortality. The diagnosis of VAP continues to present challenges and pitfalls for the currently available clinical, radiological and microbiological diagnostic armamentarium. Biomarkers and artificial intelligence offer an innovative potential direction for ongoing future research. In this Review, we summarise the pathobiological heterogeneity and diagnostic challenges associated with VAP.

A single-center, retrospective study of hospitalized patients with lower respiratory tract infections: clinical assessment of metagenomic next-generation sequencing and identification of risk factors in patients

INTRODUCTION

Lower respiratory tract infections(LRTIs) in adults are complicated by diverse pathogens that challenge traditional detection methods, which are often slow and insensitive. Metagenomic next-generation sequencing (mNGS) offers a comprehensive, high-throughput, and unbiased approach to pathogen identification. This retrospective study evaluates the diagnostic efficacy of mNGS compared to conventional microbiological testing (CMT) in LRTIs, aiming to enhance detection accuracy and enable early clinical prediction.

METHODS

In our retrospective single-center analysis, 451 patients with suspected LRTIs underwent mNGS testing from July 2020 to July 2023. We assessed the pathogen spectrum and compared the diagnostic efficacy of mNGS to CMT, with clinical comprehensive diagnosis serving as the reference standard. The study analyzed mNGS performance in lung tissue biopsies and bronchoalveolar lavage fluid (BALF) from cases suspected of lung infection. Patients were stratified into two groups based on clinical outcomes (improvement or mortality), and we compared clinical data and conventional laboratory indices between groups. A predictive model and nomogram for the prognosis of LRTIs were constructed using univariate followed by multivariate logistic regression, with model predictive accuracy evaluated by the area under the ROC curve (AUC).

RESULTS

(1) Comparative Analysis of mNGS versus CMT: In a comprehensive analysis of 510 specimens, where 59 cases were concurrently collected from lung tissue biopsies and BALF, the study highlights the diagnostic superiority of mNGS over CMT. Specifically, mNGS demonstrated significantly higher sensitivity and specificity in BALF samples (82.86% vs. 44.42% and 52.00% vs. 21.05%, respectively, p < 0.001) alongside greater positive and negative predictive values (96.71% vs. 79.55% and 15.12% vs. 5.19%, respectively, p < 0.01). Additionally, when comparing simultaneous testing of lung tissue biopsies and BALF, mNGS showed enhanced sensitivity in BALF (84.21% vs. 57.41%), whereas lung tissues offered higher specificity (80.00% vs. 50.00%). (2) Analysis of Infectious Species in Patients from This Study: The study also notes a concerning incidence of lung abscesses and identifies Epstein-Barr virus (EBV), Fusobacterium nucleatum, Mycoplasma pneumoniae, Chlamydia psittaci, and Haemophilus influenzae as the most common pathogens, with Klebsiella pneumoniae emerging as the predominant bacterial culprit. Among herpes viruses, EBV and herpes virus 7 (HHV-7) were most frequently detected, with HHV-7 more prevalent in immunocompromised individuals. (3) Risk Factors for Adverse Prognosis and a Mortality Risk Prediction Model in Patients with LRTIs: We identified key risk factors for poor prognosis in lower respiratory tract infection patients, with significant findings including delayed time to mNGS testing, low lymphocyte percentage, presence of chronic lung disease, multiple comorbidities, false-negative CMT results, and positive herpesvirus affecting patient outcomes. We also developed a nomogram model with good consistency and high accuracy (AUC of 0.825) for predicting mortality risk in these patients, offering a valuable clinical tool for assessing prognosis.

CONCLUSION

The study underscores mNGS as a superior tool for lower respiratory tract infection diagnosis, exhibiting higher sensitivity and specificity than traditional methods.

A left-sided destroyed lung in a 11-year-old girl: A rare sequela after Mycoplasma pneumoniae infection

Mycoplasma pneumoniae infection is one of the most common causes of community-acquired pneumonia in children, usually experiencing a favorable prognosis.Cases of M. pneumoniae infection resulting in respiratory failure, severe pulmonary or extrapulmonary sequelae, and death are relatively rare.Currently, no cases related to a destroyed lung with Mycoplasma-associated infection have been reported.Therefore, we report a case of a destroyed lung in an 11-year-old girl with Mycoplasma-associated infection.

Microbiological Profile of Patients with Aspiration Pneumonia Identified by Combined Detection Methods

Purpose

Aspiration pneumonia (AP) challenges public health globally. The primary aim of this study was to ascertain the microbiological profile characteristics of patients with AP evaluated by combined detection methods, including conventional microbiological tests (CMTs), chips for complicated infection detection (CCID), and metagenomic next-generation sequencing (mNGS).

Patients and Methods

From June 2021 to March 2022, a total of thirty-nine patients with AP or community-acquired pneumonia with aspiration risk factors (AspRF-CAP) from 3 hospitals were included. Respiratory specimens, including bronchoalveolar lavage fluid (BALF), sputum, and tracheal aspirate, were collected for microorganism detection.

Results

Patients with AP were more inclined to be older, to have a shorter duration from illness onset to admission, to have a higher prevalence of different underlying diseases, particularly diabetes mellitus, chronic heart disease, and cerebrovascular disease, and to have a higher CURB-65 score (all P < 0.05). A total of 213 and 31 strains of microorganisms were detected in patients with AP and AspRF-CAP, respectively. The most common pathogens in AP were Corynebacterium striatum (17/213, 7.98%), Pseudomonas aeruginosa (15/213, 7.04%), Klebsiella pneumoniae (15/213, 7.04%), and Candida albicans (14/213, 6.57%). Besides, the most common pathogens in AspRF-CAP were Candida albicans (5/31, 16.13%), Pseudomonas aeruginosa (3/31, 9.68%) and Klebsiella pneumoniae (3/31, 9.68%). Moreover, Klebsiella pneumoniae (7/67, 10.45%) and Candida glabrata (5/67, 7.46%) were the most common pathogens among the 9 non-survived patients with AP.

Conclusion

The prevalent pathogens detected in cases of AP were Corynebacterium striatum, Pseudomonas aeruginosa, Klebsiella pneumoniae, and Candida albicans. Early combined detection methods for patients with AP enhance the positive detection rate of pathogens and potentially expedites the initiation of appropriate antibiotic therapeutic strategies.

Deciphering the microbial landscape of lower respiratory tract infections: insights from metagenomics and machine learning

Background

Lower respiratory tract infections represent prevalent ailments. Nonetheless, current comprehension of the microbial ecosystems within the lower respiratory tract remains incomplete and necessitates further comprehensive assessment. Leveraging the advancements in metagenomic next-generation sequencing (mNGS) technology alongside the emergence of machine learning, it is now viable to compare the attributes of lower respiratory tract microbial communities among patients across diverse age groups, diseases, and infection types.

Method

We collected bronchoalveolar lavage fluid samples from 138 patients diagnosed with lower respiratory tract infections and conducted mNGS to characterize the lung microbiota. Employing various machine learning algorithms, we investigated the correlation of key bacteria in patients with concurrent bronchiectasis and developed a predictive model for hospitalization duration based on these identified key bacteria.

Result

We observed variations in microbial communities across different age groups, diseases, and infection types. In the elderly group, Pseudomonas aeruginosa exhibited the highest relative abundance, followed by Corynebacterium striatum and Acinetobacter baumannii. Methylobacterium and Prevotella emerged as the dominant genera at the genus level in the younger group, while Mycobacterium tuberculosis and Haemophilus influenzae were prevalent species. Within the bronchiectasis group, dominant bacteria included Pseudomonas aeruginosa, Haemophilus influenzae, and Klebsiella pneumoniae. Significant differences in the presence of Pseudomonas phage JBD93 were noted between the bronchiectasis group and the control group. In the group with concomitant fungal infections, the most abundant genera were Acinetobacter and Pseudomonas, with Acinetobacter baumannii and Pseudomonas aeruginosa as the predominant species. Notable differences were observed in the presence of Human gammaherpesvirus 4, Human betaherpesvirus 5, Candida albicans, Aspergillus oryzae, and Aspergillus fumigatus between the group with concomitant fungal infections and the bacterial group. Machine learning algorithms were utilized to select bacteria and clinical indicators associated with hospitalization duration, confirming the excellent performance of bacteria in predicting hospitalization time.

Conclusion

Our study provided a comprehensive description of the microbial characteristics among patients with lower respiratory tract infections, offering insights from various perspectives. Additionally, we investigated the advanced predictive capability of microbial community features in determining the hospitalization duration of these patients.

Corticosteroid in non-COVID-19 induced community-acquired pneumonia, a meta-analysis

BACKGROUND

Corticosteroid treatment in non-COVID-19 induced Community-acquired pneumonia (CAP) remains inconclusive.

OBJECTIVES

We aimed to assess the role of corticosteroid treatment in CAP.

METHODS

We conducted a comprehensive search of online databases, including PubMed, Embase, and Cochrane, to identify articles published from January 1, 2000, to May 5, 2023. Double-blind RCTs were selected. Two authors screened studies and extracted data. The evidence was assessed using the Grading of Recommendations Assessment, Development, and Evaluation approach.

RESULTS

We analyzed data from 12 RCTs, involving 2446 patients. Corticosteroids therapy may reduce short-term mortality in patients with severe CAP (sCAP) and shorten the hospital length of stay in patients with CAP. Furthermore, corticosteroids treatment can decrease the risk of requiring mechanical ventilation, developing septic shock and multiple organ dysfunction syndrome (MODS). There were no significant differences between the corticosteroid and control groups concerning gastrointestinal bleeding and nosocomial infection. The use of corticosteroids could increase the risk of hyperglycemia.

CONCLUSION

Corticosteroid treatment for sCAP has the potential to provide benefits in reducing short-term mortality, but this conclusion necessitates more evidence. Besides, we found no evidence that strongly prevents us from using corticosteroids in patients with sCAP or those at risk of progressing to sCAP.

Epstein-Barr virus, Cytomegalovirus, and Herpes Simplex-1/2 reactivations in critically ill patients with COVID-19

OBJECTIVES

To assess the incidences of Herpes Simplex-1 and 2 (HSV-1, HSV-2), Cytomegalovirus (CMV), Epstein-Barr Virus (EBV) reactivations in critically ill COVID-19 patients. To determine the association between viral reactivation and in-hospital mortality, Intensive Care Unit Bloodstream infection (ICU-BSI), ventilator-associated pneumonia (VAP).

DESIGN

Observational retrospective cohort study.

SETTING

COVID-19 Intensive Care Unit.

PATIENTS

From November 2020 to May 2021, one hundred and twenty patients with COVID-19 severe pneumonia were enrolled and tested for HSV-1, HSV-2, CMV and EBV at the admission in ICU and weekly until discharge or death. The presence of VAP and ICU-BSI was evaluated according to clinical judgement and specific diagnostic criteria.

MEASUREMENTS AND MAIN RESULTS

One hundred and twenty patients were enrolled. Multiple reactivations occurred in 75/120 (63%) patients, single reactivation in 27/120 patients (23%). The most reactivated Herpesvirus was EBV, found in 78/120 (65%) patients. The multivariate analysis demonstrated that viral reactivation is a strong independent risk factor for in-hospital mortality (OR = 2.46, 95% CI 1.02-5.89), ICU-BSI (OR = 2.37, 95% CI 1.06-5.29) and VAP (OR = 2.64, 95% CI 1.20-5.82).

CONCLUSIONS

Human Herpesviruses reactivations in critically ill patients with COVID-19 severe Pneumonia are associated with mortality and with a higher risk to develop both VAP and ICU-BSI.

Herpes Simplex Virus Bronchopneumonitis in Critically Ill Patients with Acute on Chronic Liver Failure: A Retrospective Analysis

(1) Background: Critically ill patients are frequently diagnosed with pulmonary Herpes simplex virus-1 (HSV) reactivation, which then can lead to HSV bronchopneumonitis and is associated with higher mortality and longer mechanical ventilation. For the particular subgroup of critically ill patients with acute on chronic liver failure (ACLF), however, the impact of HSV reactivation is unknown. We investigated the impact of HSV reactivation in these patients. (2) Methods: We conducted a retrospective analysis, evaluating data from 136 mechanically ventilated patients with ACLF between January 2016 and August 2023. Clinical parameters were compared between patients with and without HSV bronchopneumonitis. (3) Results: 10.3% were diagnosed with HSV bronchopneumonitis (HSV group). Mortality did not differ between the HSV and non-HSV group (85.7% vs. 75.4%, p = 0.52). However, the clinical course in the HSV group was more complicated as patients required significantly longer mechanical ventilation (14 vs. 21 days, p = 0.04). Furthermore, fungal superinfections were significantly more frequent in the HSV group (28.6% vs. 6.6%, p = 0.006). (4) Conclusions: Mortality of critically ill patients with ACLF with HSV bronchopneumonitis was not increased in spite of the cirrhosis-associated immune dysfunction. Their clinical course, however, was more complicated with significantly longer mechanical ventilation.

The Impact of Pathogens on Sepsis Prevalence and Outcome

Sepsis, a severe global healthcare challenge, is characterized by significant morbidity and mortality. The 2016 redefinition by the Third International Consensus Definitions Task Force emphasizes its complexity as a "life-threatening organ dysfunction caused by a dysregulated host response to infection". Bacterial pathogens, historically dominant, exhibit geographic variations, influencing healthcare strategies. The intricate dynamics of bacterial immunity involve recognizing pathogen-associated molecular patterns, triggering innate immune responses and inflammatory cascades. Dysregulation leads to immunothrombosis, disseminated intravascular coagulation, and mitochondrial dysfunction, contributing to the septic state. Viral sepsis, historically less prevalent, saw a paradigm shift during the COVID-19 pandemic, underscoring the need to understand the immunological response. Retinoic acid-inducible gene I-like receptors and Toll-like receptors play pivotal roles, and the cytokine storm in COVID-19 differs from bacterial sepsis. Latent viruses like human cytomegalovirus impact sepsis by reactivating during the immunosuppressive phases. Challenges in sepsis management include rapid pathogen identification, antibiotic resistance monitoring, and balancing therapy beyond antibiotics. This review highlights the evolving sepsis landscape, emphasizing the need for pathogen-specific therapeutic developments in a dynamic and heterogeneous clinical setting.

Distribution Patterns of Pathogens Causing Lower Respiratory Tract Infection Based on Metagenomic Next-Generation Sequencing

Purpose

Lower Respiratory Tract Infection (LRTI) is a leading cause of morbidity and mortality worldwide. In this study, the distribution patterns of causative pathogens in LRTI were evaluated within a city-level hospital by combining conventional microbiological tests (CMT) with metagenomic next-generation sequencing (mNGS).

Patients and Methods

This retrospective cohort study involved 160 patients suspected of having LRTI in a single center. Specimens, including bronchoalveolar lavage fluid (BALF), blood, tissue, sputum, and pus were utilized to identify pathogens. The seasonal prevalence of pathogens and co-pathogens involved in multiple infections was analyzed.

Results

A total of 137 patients with 156 samples were included in this study. Pseudomonas aeruginosa, Corynebacterium striatum, Klebsiella pneumoniae, Candida, and human herpesvirus were the top prevalent pathogens. We observed seasonal dynamic variation in the top prevalent bacteria (Pseudomonas aeruginosa and Klebsiella pneumoniae) and herpesvirus (Epstein-Barr virus and Human herpesvirus-7). The majority of patients had single bacterial infections, followed by instances of bacterial-viral co-infections, as well as mixed infections involving bacteria, fungi, and viruses. Notably, the spectrum of co-infecting pathogens was broader among the elderly population, and positive Spearman correlations were observed among these co-infecting pathogens.

Conclusion

Co-infections were prevalent among patients with LRTI, and the pathogens displayed distinct seasonal distribution patterns. The findings underscored the significance of comprehending pathogen distribution and epidemic patterns, which can serve as a basis for early etiological identification.

Clinical Value of Sampling Time of Metagenomic Next-Generation Sequencing in Patients with Severe Pneumonia

Objective

Severe pneumonia is a common infectious disease with high morbidity and mortality. Early etiological diagnosis is crucial for improving the prognosis. The aim of this study is to evaluate the clinical value of sampling time of mNGS in patients with severe pneumonia.

Methods

This retrospective study enrolled 105 patients with severe pneumonia. mNGS was performed on bronchoalveolar lavage fluid (BALF). Patients were divided into the sampling time ≤ 72h vs sampling time >72h groups and survivors vs non-survivors groups according to their sampling time and prognosis. Clinical characteristics, the adjustment of antibiotics and clinical prognostic value were evaluated.

Results

Our study showed that, early sampling of mNGS can significantly shorten the mechanical ventilation time (p = 0.007) and hospitalization time (p = 0.004). In the non-survivors group, CURB-65, SOFA, and APACHE II scores were higher. Age (OR: 1.051, 95% CI: 1.004-1.100, p = 0.034), chronic respiratory diseases (OR: 4.639, 95% CI: 1.260-17.082, p = 0.021), immunosuppression (OR: 5.008, 95% CI: 1.617-15.510, p = 0.005) and SOFA score on the day of mNGS sampling (OR: 1.492, 95% CI: 1.212-1.837, p < 0.001) were independent risk factors of in-hospital mortality. The most common pathogens were Klebsiella pneumoniae and Human gammaherpesvirus 4. The proportion of appropriate and targeted antibiotics adjusted was significantly higher than that in the sampling time > 72h group, and the proportion of antifungal and antiviral agents adjusted was lower. In the early sampling group, it was significantly decreased in the CRP, PCT level and NEU% at discharge.

Conclusion

This study demonstrated that early sampling of mNGS could shorten the time of mechanical ventilation and hospitalization of patients with severe pneumonia. Patients with higher SOFA score on the day of sampling had a poorer prognosis. It emphasizes that early sampling of mNGS has a positive value.

Diagnosis of Non-Tuberculous Mycobacterial Pulmonary Disease by Metagenomic Next-Generation Sequencing on Bronchoalveolar Lavage Fluid

Purpose

Metagenomic next-generation sequencing (mNGS) has been extensively used in the diagnosis of infectious diseases but has rarely been applied in non-tuberculous mycobacterial pulmonary disease (NTMPD). This study analyzed the diagnostic performance of mNGS in bronchoalveolar lavage fluid (BALF) samples to identify non-tuberculous mycobacteria (NTM).

Patients and Methods

A total of 231 patients with suspected NTMPD were recruited from the First Affiliated Hospital, School of Medicine, Zhejiang University, from March 2021 to October 2022. A total of 118 cases were ultimately included. Of these patients, 61 cases were enrolled in the NTMPD group, 23 cases were enrolled in the suspected-NTMPD group, and 34 cases were enrolled in the non-NTMPD group. The diagnostic performance of traditional culture, acid-fast staining (AFS), and mNGS for NTMPD was assessed.

Results

Patients in the NTMPD group had a higher proportion of bronchiectasis (P=0.007). Among mNGS-positive samples in the NTMPD group, a significantly higher reads number of NTM was observed in AFS-positive patients [61.50 (22.00, 395.00) vs 15.50 (6.00, 36.25), P=0.008]. Meanwhile, mNGS demonstrated a sensitivity of 90.2%, which was far superior to AFS (42.0%) and culture (77.0%) (P<0.001). The specificity of mNGS in detecting NTM was 100%, which was the same as that of traditional culture. The area under the receiver operating characteristic curve of mNGS was 0.951 (95% CI 0.906-0.996), which was higher than that of culture (0.885 [95% CI 0.818-0.953]) and AFS (0.686 [95% CI 0.562-0.810]). In addition to NTM, other pulmonary pathogens were also found by mNGS.

Conclusion

mNGS using BALF samples is a rapid and effective diagnostic tool for NTMPD, and mNGS is recommended for patients with suspected NMTPD or NTM coinfected pneumonia.

Incidence and clinical features of HHV-7 detection in lower respiratory tract in patients with severe pneumonia: a multicenter, retrospective study

PURPOSE

The significance of detecting human herpesvirus 7 (HHV-7) in the lower respiratory tract of patients with severe pneumonia is unclear. This study aims to evaluate the clinical characteristics and prognosis of detecting HHV-7 in the lower respiratory tract of patients with severe pneumonia.

METHODS

Patients with severe pneumonia requiring invasive mechanical ventilation and underwent commercial metagenomic next-generation sequencing (mNGS) testing of bronchoalveolar lavage fluid from January 2019 to March 2023 were enrolled in 12 medical centers. Clinical data of patients were collected retrospectively, and propensity score matching was used for subgroup analysis and mortality assessment.

RESULTS

In a total number of 721 patients, 45 cases (6.24%) were identified with HHV-7 positive in lower respiratory tract. HHV-7 positive patients were younger (59.2 vs 64.4, p = 0.032) and had a higher rate of co-detection with Cytomegalovirus (42.2% vs 20.7%, p = 0.001) and Epstein-Barr virus (35.6% vs 18.2%, p = 0.008). After propensity score matching for gender, age, SOFA score at ICU admission, and days from ICU admission to mNGS assay, there was no statistically significant difference in the 28-day mortality rate between HHV-7 positive and negative patients (46.2% vs 36.0%, p = 0.395). Multivariate Cox regression analysis adjusting for gender, age, and SOFA score showed that HHV-7 positive was not an independent risk factor for 28-day mortality (HR 1.783, 95%CI 0.936-3.400, p = 0.079).

CONCLUSION

HHV-7 was detected in the lungs of 6.24% of patients with severe pneumonia. The presence of HHV-7 in patients with severe pneumonia requiring invasive mechanical ventilation is associated with a younger age and co-detected of Cytomegalovirus and Epstein-Barr virus. While HHV-7 positivity was not found to be an independent risk factor for mortality in this cohort, this result may have been influenced by the relatively small sample size of the study.

Clinical usefulness of metagenomic next-generation sequencing for Rickettsia and Coxiella burnetii diagnosis

Rickettsia and Coxiella burnetii are zoonotic tick-borne pathogens that cause febrile illnesses in humans. Metagenomic next-generation sequencing (mNGS) is a new technology used to diagnose infectious diseases. However, clinical experience with applying the test to rickettsioses and Q fever is relatively limited. Therefore, this study aimed to explore the diagnostic performance of mNGS in detecting Rickettsia and C. burnetii. We retrospectively studied patients with rickettsioses or Q fever between August 2021 and July 2022. Peripheral blood mNGS and polymerase chain reaction (PCR) were performed for all patients. Clinical data were retrieved for analysis. Thirteen patients were included in this study (eleven confirmed cases and two suspected cases). Signs and symptoms included fever (13, 100%), rash (7, 53.8%), muscle soreness (5, 38.5%), headache (4, 30.8%), skin eschar (3, 23.1%), and disturbance of consciousness (2, 15.4%). In addition, eight patients (61.6%) had thrombocytopenia, ten (76.9%) had liver function impairment, and two (15.4%) had renal function impairment. The results of mNGS revealed seven patients with R. japonica (53.8%), five with C. burneti (38.5%), two with R. heilongjiangensis (15.4%), and one with R. honei (7.7%). PCR results were positive in 11 patients (84.6%). After receiving doxycycline-based treatment, 12 (92.3%) patients returned to a normal temperature within 72 h. All patients were discharged in better health. Therefore, mNGS can help diagnose Rickettsia and C. burnetii and shorten the diagnosis time, especially for patients with atypical clinical manifestations and unclear epidemiologic evidence of a tick bite or exposure.

Case Report: Parvovirus B19 infection complicated by hemophagocytic lymphohistiocytosis in a heart-lung transplant patient

Immunosuppressed patients can contract parvovirus B19, and some may experience hemophagocytic lymphohistiocytosis (HLH). Herein, we describe the first report of hemophagocytic lymphohistiocytosis in a heart-lung transplant patient with concomitant parvovirus B19 infection. The patient was treated with intravenous immune globulin (IVIG) and the features of HLH were remission. This instance emphasizes the significance of parvovirus B19 monitoring in transplant patients with anemia; if HLH complicates the situation, IVIG may be an adequate remedy. Finally, a summary of the development in diagnosing and managing parvovirus B19 infection complicated by HLH is provided.