Fever of Unknown Origin (FUO) - A Call for New Research Standards and Updated Clinical Management

Combination of next-generation sequencing and traditional examinations for identifying Leuconostoc garlicum: A case report

BACKGROUND

Leuconostoc garlicum is commonly found in fermented foods and very few infected patients have been reported, who typically present symptoms such as fever and fatigue. Conventional clinical examinations often struggle to identify this bacterium, and routine anti-infective treatments are generally ineffective. Both diagnostic challenges and therapeutic limitations pose significant difficulties for clinicians.

CASE SUMMARY

We report a patient ultimately diagnosed with Leuconostoc garlicum infection. The primary manifestations included persistent fever, cough and fatigue. These symptoms lasted for 2 months. He received anti-infective treatment at a community hospital, but this was ineffective. After inquiring about the patient's medical history and conducting a physical examination, the patient underwent laboratory tests. Complete blood count tests revealed that the patient had a high proportion of neutrophils, C-reactive protein level was 235.9 mg/L, erythrocyte sedimentation rate was 67 mm/h, respiratory pathogen testing was negative, and he was then thought to have an infectious disease. However, conventional anti-infective treatments were ineffective. After excluding infectious neurological diseases, urologic diseases and digestive problems, we ultimately focused our attention on the lungs. A lung computed tomography scan indicated pulmonary inflammation. Bronchoalveolar lavage fluid for next-generation sequencing suggested lung infection with Leuconostoc garlicum. The patient's symptoms gradually improved following treatment with piperacillin tazobactam and linezolid. During the follow-up period, the patient's temperature remained normal.

CONCLUSION

For patients with suspected bacterial infection and experiencing fever, conventional anti-infective treatment can be ineffective in controlling their symptoms, and an infection due to rare bacteria or drug-resistant bacteria should be considered. Next-generation sequencing enables rapid and precise identification of infection-related pathogens in febrile patients.

Fever of unknown origin: Clinical significance of the etiology and common inflammatory parameters

OBJECTIVES

To analyze the fever of unknown origin (FUO) etiology and clinical characteristics and determine the diagnostic value of common inflammatory parameters.

METHODS

A total of 853 patients with classic FUO were prospectively enrolled from January 2014 to May 2021. According to the etiological diagnosis, the patients were divided according to etiology: infectious diseases (n = 430); non-infectious inflammatory diseases [NIIDs] (n = 153); neoplastic diseases (n = 125); miscellaneous diseases (n = 48); and no identifiable etiology (n = 97). The clinical features and common inflammatory parameters were analyzed.

RESULTS

The clinical characteristics and common inflammatory parameters varied among the FUO patients with different etiologies. The tuberculosis T lymphocyte spot test (T-SPOT.TB) and C-reactive protein (CRP) level might be used as indicators to diagnose infections in patients with FUO. Female gender, young age, high white blood cell (WBC) count and percentage of neutrophil percent (NP), high erythrocyte sedimentation rate (ESR), and elevated serum ferritin (SF) level contributed to the diagnosis of NIIDs. Male gender, old age, low hemoglobin (HB) concentration and platelet (PLT) count, and high lactate dehydrogenase (LDH) and SF levels contributed to the diagnosis of neoplastic diseases. Male gender, old age, and low LDH and SF levels contributed to the diagnosis of infectious diseases. The procalcitonin (PCT) and interleukin-6 (IL-6) levels were highest in FUO patients with neoplastic diseases.

CONCLUSIONS

Infectious diseases are the most frequent cause of FUO, followed by NIIDs. The clinical characteristics and common inflammatory markers have significant value in determining the etiology of FUO.

Risk Factors of Hemophagocytic Lymphohistiocytosis in Adults with Fever of Unknown Origin: A Retrospective Study

Purpose

Hemophagocytic lymphohistiocytosis (HLH) is a critical syndrome with a high mortality rate. In clinical practice, some patients with fever of unknown origin (FUO) can develop HLH, further complicating the diagnosis and treatment. However, studies on HLH in adults with FUO are limited. This study aimed to investigate the clinical characteristics of adult patients with FUO to facilitate the early identification of those at high risk of developing HLH.

Patients and Methods

We collected data from hospitalized patients with FUO between January 2014 and December 2020. Risk factors for HLH in adults with FUO were analyzed using univariate and multivariate analysis.

Results

A total of 988 patients with FUO were included in the study. The incidence of HLH in adults with FUO was 6.4%, with hematological tumors being the primary cause. Multivariate analysis indicated that skin rash and elevated alanine aminotransferase, total bilirubin, triglycerides, lactate dehydrogenase, and ferritin levels were independent risk factors for HLH in adults with FUO.

Conclusion

This study revealed the incidence rate, etiology distribution, and risk factors for HLH in adults with FUO. Comprehensive assessment of clinical and laboratory data at admission can assist in the early identification of FUO patients at risk for HLH.

The value of metagenomic next-generation sequencing in the diagnosis of fever of unknown origin

Fever of unknown origin (FUO) caused by infection is a disease state characterized by complex pathogens and remains a diagnostic dilemma. Metagenomic next-generation sequencing (mNGS) technology is a promising diagnostic tool for identifying pathogenic microbes of FUO caused by infection. Little is known about the clinical impact of mNGS in the etiological diagnosis of FUO. This study focuses on the value of mNGS in the etiologic diagnosis of FUO by diagnostic performance, further clarifying the value of mNGS in clinical management. In a single-centre retrospective cohort study, 263 FUO patients who underwent both mNGS and culture at the First Affiliated Hospital of Nanchang University were enrolled from December 2020 to February 2023. The sensitivity and specificity of culture and mNGS were analyzed based on the final clinical diagnosis as the gold standard to assess the diagnostic value of mNGS in FUO cases. Among the 263 patients, 69.96%(184/263) cases were diagnosed as infectious diseases, of which lower respiratory tract infections were the most common, accounting for 53.26%(98/184). 30.04%(79/263) cases had a diagnosis of non-infectious disease. From these cases, mNGS identified 150 true-positive cases, 21 false-positive cases, 58 true-negative cases, and 34 false-negative cases. The sensitivity of mNGS in infection diagnosis was much higher than that of culture [81.52%(150/184) vs. 47.28%(87/184)], but the specificity was the opposite[73.42%(58/79) vs. 84.81%(67/79)]. mNGS had a receiver operating characteristic (ROC) curve of 0.775 for infectious disease, which was significantly higher than that of culture (0.661, P < 0.05). mNGS detection revealed that bacteria were the most commonly identified potential pathogens. The top causative pathogens identified were Acinetobacter baumannii. Of the 263 patients with FUO, clinical management of 48.67% (128/263) patients was positively affected by mNGS, and 51.33% (135/263) patients were not affected by mNGS(P = 0.1074). To sum up, infectious diseases are the principal cause of FUO. mNGS could significantly improve the detected pathogen spectrum of FUO caused by infection. However, the FUO disease spectrum is relatively broad, including a large number of non-infectious diseases. Therefore, Further investigation is warranted into the specific clinical scenarios for which mNGS may offer the greatest clinical diagnostic value.

Onco-mNGS facilitates rapid and precise identification of the etiology of fever of unknown origin: a single-centre prospective study in North China

OBJECTIVES

Delayed diagnosis of patients with Fever of Unknown Origin has long been a daunting clinical challenge. Onco-mNGS, which can accurately diagnose infectious agents and identify suspected tumor signatures by analyzing host chromosome copy number changes, has been widely used to assist identifying complex etiologies. However, the application of Onco-mNGS to improve FUO etiological screening has never been studied before.

METHODS

In this single-centre prospective study, we included 65 patients with classic FUO, who were randomly divided into control group (sample cultivation) and mNGS group (cultivation + Onco-mNGS). We analyzed the infectious agents and symbiotic microbiological, tumor and clinical data of both groups.

RESULTS

Infection-related pathogenic detection efficiency rose from 25% (control group) to 48.48% (experimental group). Seven patients with chromosome copy number changes had later been confirmed tumors, indicating a 100% of clinical concordance rate of Onco-mNGS for tumors. In addition, the time frame for diagnosing or ruling out infection/tumor with Onco-mNGS had greatly reduced to approximately 2 days, which was 7.34 days earlier than that in the control group.

CONCLUSIONS

Onco-mNGS is an ideal rapid diagnostic aid to assist improving the early diagnostic efficiency of FUO-associated diseases.

Fever of Unknown Origin: A Rare Diagnosis Requiring High Suspicion

Fever is a classic reason for hospital visits, sometimes requiring admission. Its etiologies are numerous, ranging from simple and relatively common conditions to rare and complex pathologies, for which the differential diagnosis can present a true challenge for internists. A 78-year-old healthy female is referred to the emergency department due to marked fatigue for the past four months, with no other symptoms. Physical examination revealed fever, significant lower limb edema, and low blood pressure. Laboratory results revealed anemia and thrombocytopenia, associated with high ferritin and lactate dehydrogenase levels (1924 U/L and 1519 U/L, respectively) and mild hyponatremia (133 mEq/L). A thoracic-abdominal-pelvic CT scan showed only a splenomegaly of 17 cm without other significant findings. No microorganisms were found in multiple cultural samples, and fever persisted despite two courses of antibiotics. Viral serologies and zoonosis panel were negative. A bone marrow study was conducted to help explain the cytopenias, which revealed hemophagocytic cells, confirming the diagnosis of hemophagocytic syndrome. She started with systemic corticosteroid therapy, which improved her symptoms, and a few days later, it was confirmed a diffuse large B-cell lymphoma was the etiology. Because of its mostly unspecific manifestations, hemophagocytic syndrome requires a high degree of suspicion for timely diagnosis and treatment.

Fever of Unknown Origin (FUO) Criteria Influences Diagnostic Outcomes: A Systematic Review and Meta-Analysis

BACKGROUND

Criteria classifying fever of unknown origin (FUO) patients remains subject to discrepancies. A minimal standardized set of investigative tests serves as the foundation for the qualitative criteria, whereas quantitative incorporates the length of evaluation (7 or 3 days). A systematic review of studies would help physicians anticipate the frequency of illness types that could influence management.

METHODS

Prospective studies published in Medline (PubMed), Embase, Scopus, and Web of Science databases from January 1, 1997 to July 31, 2022, were included. A meta-analysis estimated associated pooled proportions between these criteria and diagnostic outcomes adjusted to the International Classification of Diseases, 10th edition (ICD-10) definitions.

RESULTS

Five qualitative studies corresponded to an increase of 15.3% (95% CI: 2.3%-28.3%, P = .021) in undiagnosed FUO proportions compared to eleven quantitative studies. Quantitative studies had 19.7% (95% CI: 6.0%-33.4%, P = .005) more in adjusted infectious disease proportions than qualitative studies. No significant differences in proportions between FUO defining criteria were noted for adjusted noninfectious inflammatory disorders (P = .318), oncology (P = .901), non-inflammatory miscellaneous disorders (P = .321), diagnostic evaluation process, gross national income (GNI), or World Health Organization (WHO) geographic region.

CONCLUSIONS

Use of either qualitative or quantitative FUO criteria was associated with a statistically significant risk of over- or under-estimating infectious diseases and undiagnosed illnesses when using an ICD-10 adjusted FUO five-category system. Clinicians should anticipate differences depending on which criteria are used. While further research is warranted, qualitative criteria provide the best framework for study comparisons.

EULAR/PReS recommendations for the diagnosis and management of Still's disease, comprising systemic juvenile idiopathic arthritis and adult-onset Still's disease

Systemic juvenile idiopathic arthritis (sJIA) and adult-onset Still's disease (AOSD) are considered the same disease, but a common approach for diagnosis and management is still missing.

METHODS

In May 2022, EULAR and PReS endorsed a proposal for a joint task force (TF) to develop recommendations for the diagnosis and management of sJIA and AOSD. The TF agreed during a first meeting to address four topics: similarity between sJIA and AOSD, diagnostic biomarkers, therapeutic targets and strategies and complications including macrophage activation syndrome (MAS). Systematic literature reviews were conducted accordingly.

RESULTS

The TF based their recommendations on four overarching principles, highlighting notably that sJIA and AOSD are one disease, to be designated by one name, Still's disease.Fourteen specific recommendations were issued. Two therapeutic targets were defined: clinically inactive disease (CID) and remission, that is, CID maintained for at least 6 months. The optimal therapeutic strategy relies on early use of interleukin (IL-1 or IL-6 inhibitors associated to short duration glucocorticoid (GC). MAS treatment should rely on high-dose GCs, IL-1 inhibitors, ciclosporin and interferon-γ inhibitors. A specific concern rose recently with cases of severe lung disease in children with Still's disease, for which T cell directed immunosuppressant are suggested. The recommendations emphasised the key role of expert centres for difficult-to-treat patients. All overarching principles and recommendations were agreed by over 80% of the TF experts with a high level of agreement.

CONCLUSION

These recommendations are the first consensus for the diagnosis and management of children and adults with Still's disease.

Recommendations for Updating Fever and Inflammation of Unknown Origin From a Modified Delphi Consensus Panel

Background

Fever of unknown origin (FUO) and inflammation of unknown origin (IUO) are syndromes commonly used as medical diagnoses. Since the existing literature has a mixture of diagnostic approaches, developing consensus-based recommendations would be helpful for clinicians, researchers, and patients.

Methods

A modified Delphi process was performed from October 2022 to July 2023, involving 4 rounds of online surveys and 2 live video conferences. The panel comprised international experts recruited based on peer-reviewed published publications and studies.

Results

Among 50 invited experts, 26 (52.0%) agreed to participate. Twenty-three panelists completed round 1 of the survey, 21 completed rounds 2 and 3, 20 completed round 4, and 7 participated in round 5 live video discussions. Of the participants, 18 (78.3%) were academic-based clinicians and researchers, 5 (21.7%) practiced in a community-based hospital, and 6 (26.1%) were female. Consensus was reached on 5 themes: (1) incorporating epidemiologic factors, such as geographic location and travel history; (2) updated criteria for classifying FUO or IUO; (3) initial evaluation approaches; (4) a classification system for diagnoses; and (5) recommendations for judicious limitation of empiric therapies. Experts strongly disagreed with using 2-deoxy-2-[18F] fluoro-D-glucose positron emission tomography/computed tomography as part of the diagnostic criteria for FUO. There were mixed opinions about the importance of the temperature measurement site, the 3-week minimum illness criterion, the need for a standard definition of relapsing fevers, and the use of similar evaluation strategies for FUO and IUO.

Conclusions

These Delphi-generated consensus-based recommendations offer potential improvements compared with earlier definitions and a guide for clinical practice and future research.

EANM consensus document on the use of [18F]FDG PET/CT in fever and inflammation of unknown origin

PURPOSE

Patients with fever and inflammation of unknown origin (FUO/IUO) are clinically challenging due to variable clinical presentations with nonspecific symptoms and many differential diagnoses. Positron emission tomography/computed tomography (PET/CT) with 2-deoxy-2-[18F]fluoro-D-glucose ([18F]FDG) is increasingly used in FUO and IUO, but the optimal diagnostic strategy remains controversial. This consensus document aims to assist clinicians and nuclear medicine specialists in the appropriate use of [18F]FDG-PET/CT in FUO and IUO based on current evidence.

METHODS

A working group created by the EANM infection and inflammation committee performed a systematic literature search based on PICOs with "patients with FUO/IUO" as population, "[18F]FDG-PET/CT" as intervention, and several outcomes including pre-scan characteristics, scan protocol, diagnostic yield, impact on management, prognosis, and cost-effectiveness.

RESULTS

We included 68 articles published from 2001 to 2023: 9 systematic reviews, 49 original papers on general adult populations, and 10 original papers on specific populations. All papers were analysed and included in the evidence-based recommendations.

CONCLUSION

FUO and IUO remains a clinical challenge and [18F]FDG PET/CT has a definite role in the diagnostic pathway with an overall diagnostic yield or helpfulness in 50-60% of patients. A positive scan is often contributory by directly guiding treatment or subsequent diagnostic procedure. However, a negative scan may be equally important by excluding focal disease and predicting a favorable prognosis. Similar results are obtained in specific populations such as ICU-patients, children and HIV-patients.

Nuclear Medicine Imaging Tools in Fever of Unknown Origin: Time for a Revisit and Appropriate Use Criteria

Fever of unknown origin (FUO) is a clinical conundrum for patients and clinicians alike, and imaging studies are often performed as part of the diagnostic workup of these patients. Recently, the Society of Nuclear Medicine and Molecular Imaging convened and approved a guideline on the use of nuclear medicine tools for FUO. The guidelines support the use of 2-18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET)/computed tomography (CT) in adults and children with FUO. 18F-FDG PET/CT allows detection and localization of foci of hypermetabolic lesions with high sensitivity because of the 18F-FDG uptake in glycolytically active cells that may represent inflammation, infection, or neoplasia. Clinicians should consider and insurers should cover 18F-FDG PET/CT when evaluating patients with FUO, particularly when other clinical clues and preliminary studies are unrevealing.

Update on imaging in fever and inflammation of unknown origin: focus on infectious disorders

BACKGROUND

Fever of unknown origin (FUO) and inflammation of unknown origin (IUO) are diagnostic challenges that often require an extensive work-up. When first-line tests do not provide any or only misleading clues, second-line investigations such as specialized imaging techniques are often warranted.

OBJECTIVES

To provide an overview of the diagnostic value of imaging techniques that are commonly used in patients with FUO/IUO.

SOURCES

MEDLINE database was searched to identify the most relevant studies, trials, reviews, or meta-analyses until 31 March 2023.

CONTENT

The most important types of second-line imaging tests for FUO and IUO are outlined, including [67Ga]-citrate single-photon emission computed tomography/computed tomography (CT), labelled leukocyte imaging, [18F]-fluorodeoxyglucose positron emission tomography CT ([18F]-FDG-PET), and whole-body magnetic resonance imaging. This review summarizes the diagnostic yield, extends on potential future imaging techniques (pathogen-specific bacterial imaging and [18F]-FDG-PET/magnetic resonance imaging), discusses cost-effectiveness, highlights practical implications and pitfalls, and addresses future perspectives. Where applicable, we provide additional data specifically for the infection subgroup.

IMPLICATIONS

Although many imaging examinations are proven to be useful in FUO and IUO, [18F]-FDG-PET/CT is the preferred second-line test when available as it provides a high diagnostic yield in a presumably cost-effective way.

Development of a Consensus-Based List of Potential Quality Indicators for Fever and Inflammation of Unknown Origin

With a growing emphasis on value-based reimbursement, developing quality indicators for infectious diseases has gained attention. Quality indicators for fever of unknown origin and inflammation of unknown origin are lacking. An assembled group of international experts developed 12 quality measures for these conditions, which could be validated with additional study.

Fever of Unknown Origin

Fever of unknown origin in adolescents is a challenging disease state for which potential underlying etiology can include infectious, non-infectious inflammatory, and malignancy processes. Careful and thorough history (including exposure history), serial examination, and targeted laboratory and imaging testing is critical for these patients. In adolescents in which an etiology is discovered, infectious etiology remains the most prevalent, followed by non-infectious inflammatory diseases. In patients with non-diagnostic overall reassuring work up, the prognosis is typically self-limiting and favorable.

Incidence and outcomes of fever of unknown origin after kidney transplant in the modern era

BACKGROUND

While presumably less common with modern molecular diagnostic and imaging techniques, fever of unknown origin (FUO) remains a challenge in kidney transplant recipients (KTRs). Additionally, the impact of FUO on patient and graft survival is poorly described.

METHODS

A cohort of adult KTRs between January 1, 1995 and December 31, 2018 was followed at the University of Wisconsin Hospital. Patients transplanted from January 1, 1995 to December 31, 2005 were included in the "early era"; patients transplanted from January 1, 2006 to December 31, 2018 were included in the "modern era". The primary objective was to describe the epidemiology and etiology of FUO diagnoses over time. Secondary outcomes included rejection, graft and patient survival.

RESULTS

There were 5590 kidney transplants at our center during the study window. FUO was identified in 323 patients with an overall incidence rate of .8/100 person-years. Considering only the first 3 years after transplant, the incidence of FUO was significantly lower in the modern era than in the early era, with an Incidence Rate Ratio (IRR) per 100 person-years of .48; 95% CI: .35-.63; p < .001. A total of 102 (31.9%) of 323 patients had an etiology determined within 90 days after FUO diagnosis: 100 were infectious, and two were malignancies. In the modern era, FUO remained significantly associated with rejection (HR = 44.1; 95% CI: 16.6-102; p < .001) but not graft failure (HR = 1.21; 95% CI: .68-2.18; p = .52) total graft loss (HR = 1.17; 95% CI: .85-1.62; p = .34), or death (HR = 1.17; 95% CI: .79-1.76; p = .43.

CONCLUSIONS

FUO is less common in KTRs during the modern era. Our study suggests infection remains the most common etiology. FUO remains associated with significant increases in risk of rejection, warranting further inquiry into the management of immunosuppressive medications in SOT recipients in the setting of FUO.

Multidisciplinary approach to diagnosis and management of fever of unknown origin: A case report

INTRODUCTION

Fever of unknown origin (FUO) poses a diagnostic challenge, often requiring a systematic evaluation to uncover its elusive cause. This case study delves into the presentation of a 42-year-old Chinese male with persistent fever, muscle pain, and a perplexing rash.

PATIENT CONCERNS

The patient's symptoms included a prolonged fever, chills, muscle pain, and throat discomfort, with a history of pulmonary tuberculosis. Initial diagnoses of upper respiratory infection and unspecified infection were followed by antibiotic treatments, yet the fever persisted, accompanied by an exacerbating rash.

DIAGNOSIS

Extensive diagnostic investigations, including laboratory tests, imaging studies, and skin dermoscopy, provided valuable insights. The patient exhibited elevated inflammatory markers, hepatosplenomegaly, lymphadenopathy, and lung nodules. Differential diagnoses included adult-onset Still disease and drug-induced hypersensitivity syndrome.

INTERVENTIONS

The patient received a series of antibiotic treatments, which initially had limited success. Upon considering an autoimmune etiology, corticosteroids were introduced, followed by cyclosporine. The patient exhibited a positive response to this immunosuppressive therapy.

OUTCOMES

Treatment adjustments were made, and the patient responded positively to a combination of corticosteroids and cyclosporine. His fever subsided, and laboratory markers normalized. One month after discharge, the patient showed continued improvement.

CONCLUSION

FUO cases often demand a multidisciplinary approach, considering rare and uncommon diseases. This case underscores the importance of thorough evaluation, collaboration between specialties, and vigilant monitoring of treatment responses. The patient's unique presentation emphasizes the need to consider drug-induced reactions, even when symptoms deviate from typical disease patterns, highlighting the complexities in diagnosing and managing FUO.

Risk factors identification of COVID-19 patients with chronic obstructive pulmonary disease: A retrospective study in Punjab-Pakistan

BACKGROUND

Accessibility to the immense collection of studies on noncommunicable diseases related to coronavirus disease of 2019 (COVID-19) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is an immediate focus of researchers. However, there is a scarcity of information about chronic obstructed pulmonary disease (COPD), which is associated with a high rate of infection in COVID-19 patients. Moreover, by combining the effects of the SARS-CoV-2 on COPD patients, we may be able to overcome formidable obstacles factors, and diagnosis influencers.

MATERIALS AND METHODS

A retrospective study of 280 patients was conducted at DHQ Hospital Muzaffargarh in Punjab, Pakistan. Negative binomial regression describes the risk of fixed successive variables. The association is described by the Cox proportional hazard model and the model coefficient is determined through log-likelihood observation. Patients with COPD had their survival and mortality plotted on Kaplan-Meier curves.

RESULTS

The increased risk of death in COPD patients was due to the effects of variables such as cough, lower respiratory tract infection (LRTI), tuberculosis (TB), and body-aches being 1.369, 0.693, 0.170, and 0.217 times higher at (95% confidence interval [CI]: 0.747-1.992), (95% CI: 0.231-1.156), (95% CI: 0.008-0.332), and (95% CI: -0.07 to 0.440) while it decreased 0.396 in normal condition.

CONCLUSION

We found that the symptoms of COPD (cough, LRTI, TB, and bodyaches) are statistically significant in patients who were most infected by SARS-CoV-2.

Microbial and Host Metabolites at the Backstage of Fever: Current Knowledge about the Co-Ordinate Action of Receptors and Molecules Underlying Pathophysiology and Clinical Implications

Fever represents an elevation of body temperature, that exerts a protective effect against pathogens. Innate immune cells and neurons are implicated in the regulation of body temperature. Pathogen-associated molecular patterns, i.e., lipopolysaccharides from Gram-negative bacteria and peptidoglycan and lipoteichoic acid from Gram-positive bacteria are exogenous pyrogens, that bind to Toll-like receptors on immune and non-immune cells. The subsequent release of pro-inflammatory cytokines [interleukin-1 (IL-1), IL-6 and Tumor necrosis factor-alpha] and their passage through the brain trigger the febrile response. In fact, neurons of the pre-optic area produce prostaglandin E2 (PGE2), that, in turn, bind to the PGE2 receptors; thus, generating fever. Apart from classical non-steroidal anti-inflammatory drugs, i.e., aspirin and acetaminophen, various botanicals are currently used as antipyretic agents and, therefore, their mechanisms of action will be elucidated.

Fever of Unknown Origin and Atrial Fibrillation: A Case Report

Fever of unknown origin describes a temperature greater than 100.9°F which is present on multiple instances for a period over three weeks with no confirmed diagnosis despite a minimum of three outpatient visits, three days of inpatient testing, or one week of extensive outpatient testing. This diagnosis presents challenges in clinical management due to the unknown etiology. This case highlights a fever of unknown origin presenting with new-onset atrial fibrillation in a patient with no previous cardiac history. A 62-year-old Caucasian male presented to the ED with a nine-day history of intermittent fevers and chills. He returned from a rafting trip in North Carolina two weeks ago but reported no tick bites, animal encounters, or river water ingestion. Further evaluation was significant for an elevated white blood cell count and elevated inflammatory markers. Laboratory and radiologic testing for a wide array of infectious and malignant etiologies were unremarkable. Soon after hospital presentation, he developed a fever of 102.9°F with new onset palpitations and chest tightness due to atrial fibrillation. Episodes of atrial fibrillation continued for his seven-day hospital course with more severe symptoms in the evenings. He was administered broad-spectrum antibiotics and tested extensively with no definitive etiology. His fever curve downtrended with max temperatures below 100.9°F on hospital days six and seven with asymptomatic episodes of atrial fibrillation, prompting discharge. He continued to have low-grade fevers measured below 100.9°F for several days post-discharge with no associated symptoms, resulting in a diagnosis of fever of unknown origin following the 21st day. Fever of unknown origin is a clinical challenge, particularly in cases with no diagnosis discovered and cases with potentially life-threatening complications such as atrial fibrillation. This patient had multiple potential etiologies for his condition, but none had sufficient evidence for diagnosis, resulting in uncertainty regarding the ideal management. As a result, constant monitoring with supportive treatments and broad-spectrum antibiotics was utilized. These measures allowed for symptom remission and hospital discharge for outpatient follow-up. This case highlights a rare presentation of fever of unknown origin with new-onset atrial fibrillation in an otherwise healthy adult.

Simultaneous Detection of Pathogens and Tumors in Patients With Suspected Infections by Next-Generation Sequencing

Background

Differential diagnosis of patients with suspected infections is particularly difficult, but necessary for prompt diagnosis and rational use of antibiotics. A substantial proportion of these patients have non-infectious diseases that include malignant tumors. This study aimed to explore the clinical value of metagenomic next-generation sequencing (mNGS) for tumor detection in patients with suspected infections.

Methods

A multicenter, prospective case study involving patients diagnosed with suspected infections was conducted in four hospitals in Shanghai, China between July 2019 and January 2020. Based upon mNGS technologies and chromosomal copy number variation (CNV) analysis on abundant human genome, a new procedure named Onco-mNGS was established to simultaneously detect pathogens and malignant tumors in all of the collected samples from patients.

Results

Of 140 patients screened by Onco-mNGS testing, 115 patients were diagnosed with infections; 17 had obvious abnormal CNV signals indicating malignant tumors that were confirmed clinically. The positive percent agreement and negative percent agreement of mNGS testing compared to clinical diagnosis was 53.0% (61/115) and 60% (15/25), vs. 20.9% (24/115) and 96.0% (24/25), respectively, for conventional microbiological testing (both P <0.01). Klebsiella pneumoniae (14.8%, 9/61) was the most common pathogen detected by mNGS, followed by Escherichia coli (11.5%, 7/61) and viruses (11.5%, 7/61). The chromosomal abnormalities of the 17 cases included genome-wide variations and local variations of a certain chromosome. Five of 17 patients had a final confirmed with malignant tumors, including three lung adenocarcinomas and two hematological tumors; one patient was highly suspected to have lymphoma; and 11 patients had a prior history of malignant tumor.

Conclusion

This preliminary study demonstrates the feasibility and clinical value of using Onco-mNGS to simultaneously search for potential pathogens and malignant tumors in patients with suspected infections.

Prospective Studies Comparing Structured vs Nonstructured Diagnostic Protocol Evaluations Among Patients With Fever of Unknown Origin: A Systematic Review and Meta-analysis

Importance

Patients meeting the criteria for fever of unknown origin (FUO) can be evaluated with structured or nonstructured approaches, but the optimal diagnostic method is unresolved.

Objective

To analyze differences in diagnostic outcomes among patients undergoing structured or nonstructured diagnostic methods applied to prospective clinical studies.

Data Sources

PubMed, Embase, Scopus, and Web of Science databases with librarian-generated query strings for FUO, PUO, fever or pyrexia of unknown origin, clinical trial, and prospective studies identified from January 1, 1997, to March 31, 2021.

Study Selection

Prospective studies meeting any adult FUO definition were included. Articles were excluded if patients did not precisely fit any existing adult FUO definition or studies were not classified as prospective.

Data Extraction and Synthesis

Abstracted data included years of publication and study period, country, setting (eg, university vs community hospital), defining criteria and category outcome, structured or nonstructured diagnostic protocol evaluation, sex, temperature threshold and measurement, duration of fever and hospitalization before final diagnoses, and contribution of potential diagnostic clues, biochemical and immunological serologic studies, microbiology cultures, histologic analysis, and imaging studies. Structured protocols compared with nonstructured diagnostic methods were analyzed using regression models.

Main Outcomes and Measures

Overall diagnostic yield was the primary outcome.

Results

Among the 19 prospective trials with 2627 unique patients included in the analysis (range of patient ages, 10-94 years; 21.0%-55.3% female), diagnoses among FUO series varied across and within World Health Organization (WHO) geographic regions. Use of a structured diagnostic protocol was not significantly associated with higher odds of yielding a diagnosis compared with nonstructured protocols in aggregate (odds ratio [OR], 0.98; 95% CI, 0.65-1.49) or between Western Europe (Belgium, France, the Netherlands, and Spain) (OR, 0.95; 95% CI, 0.49-1.86) and Eastern Europe (Turkey and Romania) (OR, 0.83; 95% CI, 0.41-1.69). Despite the limited number of studies in some regions, analyses based on the 6 WHO geographic areas found differences in the diagnostic yield. Western European studies had the lowest percentage of achieving a diagnosis. Southeast Asia led with infections at 49.0%. Noninfectious inflammatory conditions were most prevalent in the Western Pacific region (34.0%), whereas the Eastern Mediterranean region had the highest proportion of oncologic explanations (24.0%).

Conclusions and Relevance

In this systematic review and meta-analysis, diagnostic yield varied among WHO regions. Available evidence from prospective studies did not support that structured diagnostic protocols had a significantly better rate of achieving a diagnosis than nonstructured protocols. Clinicians worldwide should incorporate geographical disease prevalence in their evaluation of patients with FUO.

Geographic Variation of Infectious Disease Diagnoses Among Patients with Fever of Unknown Origin (FUO) – A Systematic Review and Meta-analysis

Background

Fever of unknown origin (FUO) investigations yield a substantial number of patients with infectious diseases. This systematic review and meta-analysis aimed to quantify more common FUO infectious diseases etiologies and to underscore geographic variation.

Methods

Four databases (PubMed, Embase, Scopus, and Web of Science) were searched for prospective studies reporting FUO rates among adult patients from 1 January 1997 to 31 March 2021. The pooled proportion for infectious diseases etiology was estimated using the random-effects meta-analysis model.

Results

Nineteen prospective studies were included with 2667 total cases. No studies were available for Africa or the Americas. Overall, 37.0% (95.0% confidence interval [CI], 30.0%–44.0%) of FUO patients had an infectious disease etiology. Infections were more likely from Southeastern Asia (pooled proportion, 0.49 [95% CI, .43–.55]) than from Europe (pooled proportion, 0.31 [95% CI, .22–.41]). Among specifically reported infectious diseases (n = 832), Mycobacterium tuberculosis complex predominated across all geographic regions (n = 285 [34.3%]), followed by brucellosis (n = 81 [9.7%]), endocarditis (n = 62 [7.5%]), abscesses (n = 61 [7.3%]), herpesvirus (eg, cytomegalovirus and Epstein-Barr virus) infections (n = 60 [7.2%]), pneumonia (n = 54 [6.5%]), urinary tract infections (n = 54 [6.5%]), and enteric fever (n = 40 [4.8%]).

Conclusions

FUO patients from Southeastern Asia were more likely to have an infectious diseases etiology when compared to other regions. The predominant factor for this finding appears to be differences in disease prevalence among various geographical locations or other factors such as access to timely care and diagnosis. Noting epidemiological disease factors in FUO investigations could improve diagnostic yields and clinical outcomes.

Fever of unknown origin (FUO) in children: a single-centre experience from Beijing, China

OBJECTIVE

To date, there is no standard diagnostic practice to identify the underlying disease-causing mechanism for paediatric patients suffering from chronic fever without any specific diagnosis, which is one of the leading causes of death in paediatric patients. Therefore, we aimed this retrospective study to analyse medical records of paediatric patients with fever of unknown origin (FUO) to provide a preliminary basis for improving the diagnostic categories and facilitate the treatment outcomes.

DESIGN

A retrospective study.

SETTING

Beijing Children's Hospital.

PARTICIPANTS

Clinical data were collected from 1288 children between 1 month and 18 years of age diagnosed with FUO at Beijing Children's Hospital between January 2010 and December 2017.

INTERVENTIONS

According to the aetiological composition, age, duration of fever and laboratory examination results, the diagnostic strategies were analysed and formulated.

PRIMARY AND SECONDARY OUTCOME MEASURES

The statistical analyses were carried out using SPSS V.24.0 platform along with the χ² test and analysis of variance (p<0.05).

RESULTS

The duration of fever ranged from 2 weeks to 2 years, with an average of 6 weeks. There were 656 cases (50.9%) of infectious diseases, 63 cases (4.9%) of non-infectious inflammatory diseases (NIIDs), 86 cases (6.7%) of neoplastic diseases, 343 cases (26.6%) caused by miscellaneous diseases and 140 cases (10.9%) were undiagnosed. With increasing age, the proportion of FUO from infectious diseases gradually decreased from 73.53% to 44.21%. NIID was more common in children over 3 years old, and neoplastic diseases mainly occurred from 1 to 6 years of age. Among miscellaneous diseases, the age distribution was mainly in school-aged children over 6 years. Respiratory tract infection was the most common cause of FUO in children, followed by bloodstream infections. Bacterial infection was the most common cause in children with less than 1 year old, while the virus was the main pathogen in children over 1 year old.

CONCLUSIONS

The diagnosis of neoplastic diseases and miscellaneous diseases-related diseases still depends mainly on invasive examination. According to our clinical experience, the diagnostic process was formulated based on fever duration and the type of disease. This process can provide a guide for the diagnosis and treatment of paediatric FUO in the future.

Reliability of Non-Contact Infrared Thermometers for Fever Screening Under COVID-19

Purpose

Fever is one of the most typical clinical symptoms of coronavirus disease 2019 (COVID-19), and non-contact infrared thermometers (NCITs) are commonly used to screen for fever. However, there is a lack of authoritative data to define a “fever” when an NCIT is used and previous studies have shown that NCIT readings fluctuate widely depending on ambient temperatures and the body surface site screened. The aim of this study was to establish cut-off points for normal temperatures of different body sites (neck, forehead, temples, and wrist) and investigate the accuracy of NCITs at various ambient temperatures to improve the standardization and accuracy of fever screening.

Patients and Methods

A prospective investigation was conducted among 904 participants in the outpatient and emergency departments of Chengdu Women’s and Children’s Central Hospital. Body temperature was measured using NCITs and mercury axillary thermometers. A receiver operating characteristic curve was used to determine the accuracy of body temperature detection at the four body surface sites. Data on participant characteristics were also collected.

Results

Among the four surface sites, the neck temperature detection group had the highest accuracy. When the neck temperature was 37.35°C as the optimum fever diagnostic threshold, the sensitivity was 0.866. The optimum fever diagnostic thresholds for forehead, temporal, and wrist temperature were 36.65°C, 36.65°C, and 36.75°C, respectively. Moreover, triple neck temperature detection had the highest sensitivity, up to 0.998, whereas the sensitivity of triple wrist temperature detections was 0.949. Notably, the accuracy of NCITs significantly reduced when the temperature was lower than 18°C.

Conclusion

Neck temperature had the highest accuracy among the four NCIT temperature measurement sites, with an optimum fever diagnostic threshold of 37.35°C. Considering the findings reported in our study, we recommend triple neck temperature detection with NCITs as the fever screening standard for COVID-19.

Application of Machine Learning for the Prediction of Etiological Types of Classic Fever of Unknown Origin

Background: The etiology of fever of unknown origin (FUO) is complex and remains a major challenge for clinicians. This study aims to investigate the distribution of the etiology of classic FUO and the differences in clinical indicators in patients with different etiologies of classic FUO and to establish a machine learning (ML) model based on clinical data. Methods: The clinical data and final diagnosis results of 527 patients with classic FUO admitted to 7 medical institutions in Chongqing from January 2012 to August 2021 and who met the classic FUO diagnostic criteria were collected. Three hundred seventy-three patients with final diagnosis were divided into 4 groups according to 4 different etiological types of classical FUO, and statistical analysis was carried out to screen out the indicators with statistical differences under different etiological types. On the basis of these indicators, five kinds of ML models, i.e., random forest (RF), support vector machine (SVM), Light Gradient Boosting Machine (LightGBM), artificial neural network (ANN), and naive Bayes (NB) models, were used to evaluate all datasets using 5-fold cross-validation, and the performance of the models were evaluated using micro-F1 scores. Results: The 373 patients were divided into the infectious disease group (n = 277), non-infectious inflammatory disease group (n = 51), neoplastic disease group (n = 31), and other diseases group (n = 14) according to 4 different etiological types. Another 154 patients were classified as undetermined group because the cause of fever was still unclear at discharge. There were significant differences in gender, age, and 18 other indicators among the four groups of patients with classic FUO with different etiological types (P < 0.05). The micro-F1 score for LightGBM was 75.8%, which was higher than that for the other four ML models, and the LightGBM prediction model had the best performance. Conclusions: Infectious diseases are still the main etiological type of classic FUO. Based on 18 statistically significant clinical indicators such as gender and age, we constructed and evaluated five ML models. LightGBM model has a good effect on predicting the etiological type of classic FUO, which will play a good auxiliary decision-making function.