Recommendations for treatment of human infections caused by Bartonella species

Unmasking Bartonella henselae infection in the shadows of long COVID thanks to clinical metagenomics

The diagnosis of long COVID often relies on symptoms post-COVID-19, occasionally lacking biological evidence. This case study illustrates how investigating long COVID uncovered an underlying bartonellosis through clinical metagenomics. Following mild COVID-19, a 26-year-old woman experienced persistent symptoms during 5 months, including axillary adenopathy. Pathological examination, 16 S rRNA PCR, and clinical metagenomic analysis were done on an adenopathy biopsy. The latter revealed Bartonella henselae DNA and RNA. Treatment with clarithromycin improved symptoms. This case underscores the relevance of clinical metagenomics in diagnosing hidden infections. Post-COVID symptoms warrant thorough investigation, and bartonellosis should be considered in polyadenopathy cases, regardless of a recent history of cat or flea exposures.

Simplified Spectrum Score (S3) app for pathogen-agnostic antimicrobial drug spectrum ranking to assess for antimicrobial de-escalation events

Antimicrobial/antibiotic de-escalation (ADE) is a key feature of antimicrobial stewardship programs (ASP) that relies mainly on individual panels for determining ADE events based on subjective ranking of antibiotics' spectrum activity. The lack of consensus among ASP experts leads to reproducibility issues in the measure of this clinical outcome, making difficult to assess its real impact on patient care. The S3 score (Simplified Spectrum Score) app was developed to allow an objective ranking of antibiotics. Ranking was achieved by developing a database harboring pairs of bacteria-antibiotics for which each molecule was assigned a score based on published and clinically validated data from a recognized international committee. S3 score shows a strong correlation relationship and substantial agreement to a clinically validated spectrum score, and its framework enables any person to use it for ADE detection without assuming prior knowledge or training. In addition, its design enables regular updates and sustainability.

Post-COVID reactivation of latent Bartonella henselae infection: a case report and literature review

Cat scratch disease (CSD) is caused by Bartonella henselae (B. henselae) and presents as lymphadenopathy following close contact with cats. However, in context of the global COVID-19 pandemic, clinical manifestations of CSD may vary, posing new challenges for healthcare professionals. Here we describe a case of a 54-year-old male with painful left upper arm mass, which gradually resolved until he was infected with COVID-19. The mass then rapidly progressed before admission. Meanwhile, pulmonary symptoms including pleural effusion emerged simultaneously. The cause was undetermined with routine blood culture and pathological test until the next generation sequencing (NGS) confirmed the presence of B. henselae. We believe this case is the first to report localized aggravation of CSD after COVID-19 infection and hopefully, offers treatment experience for clinicians worldwide.

A Retrospective Analysis of Systemic Bartonella henselae Infection in Children

Systemic Bartonella henselae infection, also known as cat-scratch disease (CSD), presents a diagnostic challenge due to the variability of clinical manifestations and the potential for serological cross-reactivity with other organisms. This study aimed to retrospectively analyze the epidemiological, clinical, laboratory, and imaging characteristics of pediatric patients diagnosed with systemic B. henselae infection, to improve understanding and facilitate timely diagnosis and treatment. We conducted a 10-year retrospective study at the "Louis Turcanu" Children's Emergency Hospital and private clinics in Timisoara, Romania, reviewing records for confirmed cases of B. henselae infection from January 2014 to January 2024. The study adhered to the Declaration of Helsinki and received approval from the Institutional Review Board. Diagnostic criteria included contact with animals, prolonged fever, hematological and/or hepatosplenic manifestations, and positive serological tests for B. henselae. Nineteen pediatric patients were identified with a median age of 8.1 years. The majority were exposed to felines (94.7%), reflecting the disease's epidemiological profile. Clinical findings highlighted fever (47.4%), lymphadenopathy (78.9%), and less frequently, abdominal pain and headache (both 10.5%). Laboratory analyses revealed a mean hemoglobin of 12.6 mg/dL, WBC count of 13.1 × 103 cells/microliter, and platelet count of 340.6 × 103 per microliter. Significant findings included elevation in ESR and CRP in 47.4% and 21.1% of patients, respectively, and high seropositivity rates for B. henselae IgM (63.2%) and IgG (94.7%). Imaging studies demonstrated widespread lymphadenopathy and occasional splenomegaly and hepatic microabscesses. All patients received antibiotic therapy, with azithromycin being the most commonly used (94.7%). Co-infections with Epstein-Barr Virus, Cytomegalovirus, and Toxoplasma gondii were documented, indicating the complex infectious status of the patients. Systemic B. henselae infection in children predominantly manifests with fever and lymphadenopathy, with a significant history of exposure to felines. Laboratory and imaging findings support the diagnosis, which is further complicated by potential co-infections. Effective antibiotic therapy, primarily with azithromycin, underscores the need for comprehensive diagnostic and treatment strategies. This study emphasizes the importance of considering systemic B. henselae infection in pediatric patients with prolonged fever and contact with cats, to ensure timely and appropriate treatment.

A Man in His Forties with Recurrent Cat-Scratch Disease

Cat-scratch disease (CSD) is a self-limited zoonotic infection transmitted by felines caused by the Gram-negative bacillus Bartonella henselae. It usually presents with lymphadenopathy and constitutional symptoms that resolve within eight weeks, with, or without antibiotic treatment. The diagnosis is made by serology, molecular diagnosis in a biopsy, or a positive culture. The recurrence or reactivation of B. henselae has rarely been reported. We present the case of a 45-year-old man with a history of CSD two years before who presented to the clinic with groin lymphadenopathy. The patient had a history of close contact with felines though no known risk exposure was reported. The diagnosis was made with a positive serology suggestive of recent infection along with histopathological changes suggestive of CSD. Subsequently, azithromycin was administered with complete resolution of symptoms.

Epidemiology and treatment of invasive Bartonella spp. infections in the United States

OBJECTIVES

Bartonella spp., renowned for cat-scratch disease, has limited reports of dissemination. Tissue and blood cultures have limitations in detecting this fastidious pathogen. Molecular testing (polymerase chain reaction, PCR) and cell-free DNA have provided an avenue for diagnoses. This retrospective observational multicenter study describes the incidence of disseminated Bartonella spp. and treatment-related outcomes.

METHODS

Inclusion criteria were diagnosis of bartonellosis via diagnosis code, serology testing of blood, polymerase chain reaction (PCR) of blood, 16/18S tests of blood or tissue, cultures of blood or tissue, or cell-free DNA of blood or tissue from January 1, 2014, through September 1, 2021. Exclusions were patients who did not receive treatment, insufficient data on treatment course, absence of dissemination, or retinitis as dissemination.

RESULTS

Patients were primarily male (n = 25, 61.0%), white (n = 28, 68.3%), with mean age of 50 years (SD 14.4), and mean Charlson comorbidity index of 3.5 (SD 2.1). Diagnosis was primarily by serology (n = 34, 82.9%), with Bartonella henselae (n = 40, 97.6%) as the causative pathogen. Treatment was principally doxycycline with rifampin (n = 17, 41.5%). Treatment failure occurred in 16 (39.0%) patients, due to escalation of therapy during treatment (n = 5, 31.3%) or discontinuation of therapy due to an adverse event or tolerability (n = 5, 31.3%).

CONCLUSIONS

In conclusion, this is the largest United States-based cohort of disseminated Bartonella spp. infections to date with a reported 39% treatment failure. This adds to literature supporting obtaining multiple diagnostic tests when Bartonella is suspected and describes treatment options.

A Pediatric Case of Disseminated Bartonella henselae Infection Accompanied by Multiple Intracranial Lesions

We report a pediatric case of disseminated Bartonella henselae infection accompanied by multiple intracranial lesions. The patient developed multiple intracranial lesions despite treatment with azithromycin and gentamicin. After switching to rifampicin, the clinical symptoms of the patient improved. Given its good penetration into the central nervous system, rifampicin may be recommended for the treatment of B. henselae infection accompanied by intracranial lesions.

Pleural and pericardial effusions with fever and altered mental status: an atypical presentation of bartonellosis

A male in his 60s presented to the emergency department (ED) with a 3-week history of fever and progressive confusion. Initial laboratory and radiographic workup was largely unremarkable except for moderate bilateral pleural effusions. The patient was admitted on broad-spectrum antibiotics and further workup for fever of unknown aetiology. The differential diagnosis was broadened to different zoonotic infections, and subsequent laboratory testing showed a markedly elevated Bartonella henselae IgG and Bartonella quintana IgG (1:4096 and 1:512, respectively) in addition to positive B. henselae IgM titre (>1:20). During hospitalisation, the patient became more hypoxic and was found to have enlarging pleural effusions as well as a new pericardial effusion. The patient was treated with intravenous then oral doxycycline 100 mg two times per day and oral rifampin 300 mg two times per day for 4 weeks with subsequent improvement in clinical status as well as both effusions. This case highlights a unique presentation of Bartonella and its rare manifestation of pleural and pericardial effusions.

Clinicopathological differences between Bartonella and other bacterial endocarditis-related glomerulonephritis - our experience and a pooled analysis

Background

Although Staphylococcus aureus is the leading cause of acute infective endocarditis (IE) in adults, Bartonella spp. has concomitantly emerged as the leading cause of "blood culture-negative IE" (BCNE). Pre-disposing factors, clinical presentation and kidney biopsy findings in Bartonella IE-associated glomerulonephritis (GN) show subtle differences and some unique features relative to other bacterial infection-related GNs. We highlight these features along with key diagnostic clues and management approach in Bartonella IE-associated GN.

Methods

We conducted a pooled analysis of 89 cases of Bartonella IE-associated GN (54 published case reports and case series; 18 published conference abstracts identified using an English literature search of several commonly used literature search modalities); and four unpublished cases from our institution.

Results

Bartonella henselae and Bartonella quintana are the most commonly implicated species causing IE in humans. Subacute presentation, affecting damaged native and/or prosthetic heart valves, high titer anti-neutrophil cytoplasmic antibodies (ANCA), mainly proteinase-3 (PR-3) specificity, fastidious nature and lack of positive blood cultures of these Gram-negative bacilli, a higher frequency of focal glomerular crescents compared to other bacterial infection-related GNs are some of the salient features of Bartonella IE-associated GN. C3-dominant, but frequent C1q and IgM immunofluorescence staining is seen on biopsy. A "full-house" immunofluorescence staining pattern is also described but can be seen in IE -associated GN due to other bacteria as well. Non-specific generalized symptoms, cytopenia, heart failure and other organ damage due to embolic phenomena are the highlights on clinical presentation needing a multi-disciplinary approach for management. Awareness of the updated modified Duke criteria for IE, a high index of suspicion for underlying infection despite negative microbiologic cultures, history of exposure to animals, particularly infected cats, and use of send-out serologic tests for Bartonella spp. early in the course of management can help in early diagnosis and initiation of appropriate treatment.

Conclusion

Diagnosis of IE-associated GN can be challenging particularly with BCNE. The number of Bartonella IE-associated GN cases in a single institution tends to be less than IE due to gram positive cocci, however Bartonella is currently the leading cause of BCNE. We provide a much-needed discussion on this topic.

A case report of diagnosis of cat-scratch disease using metagenomic next-generation sequencing

Cat-scratch disease (CSD) is an anthropozoonotic infection caused by Bartonella henselae, and it is one of the most common causes of lymph node infections in children and adolescents. B. henselae, belonging to the genus Bartonella, is a common human pathogen of human beings. CSD commonly develops as a result of cat scratches and bites or when injured skin comes into contact with cat saliva. The manifestation of CSD clinically differs for each patient based on their immune system. Individuals who have healthy immune systems generally manifest minimal clinical symptoms and do not necessitate any form of treatment. However, patients who have hypo-immunity require prompt medical attention due to the potential manifestation of severe symptoms that affect multiple systems of the body. Long latency and atypical clinical manifestations are characteristics of CSD. Bartonella isolation and identification are challenging procedures that require specialized equipment. There is no gold standard method for CSD diagnosis, and misdiagnosis and missed diagnosis rates are typically high. We present the case of a middle-aged male patient who developed fever, chills, anal distension, dizziness, and muscle pain for 10 days. The patient had a documented history of cat bites 1 month prior to the onset of symptoms. Following admission, he underwent an examination to determine superficial lymphadenopathy and hypoimmunity. Additionally, he had a fever during the disease. As the patient refused a needle biopsy of lymph nodes, metagenomic next-generation sequencing (mNGS) was employed and B. henselae was detected in the peripheral blood. The patient was diagnosed with CSD and treated with a combination of azithromycin and doxycycline. The fever symptoms were alleviated, and the patient was ultimately discharged. As a result of this case, we suggest that mNGS be used as a crucial supplementary diagnostic tool for individuals with compromised immune systems who may have CSD, especially when conventional diagnostic methods are inconclusive.

Optic Neuritis and Vertebral Osteomyelitis: An Uncommon Presentation of Cat-Scratch Disease

In cat-scratch disease (CSD), hematogenous spread may result in atypical presentations. Ocular manifestations develop in a minority of patients, with treatment being important in reducing long-term visual sequelae. Bone infection is rare. We present the case of a 52-year-old woman, with close contact with cats, reporting acute unilateral blurred vision and presenting papilledema, optic disc pallor, and peripapillary hemorrhage. Etiologic study of optic neuritis revealed an elevated positive Bartonella IgG; hence, treatment for CSD with doxycycline plus rifampin and corticosteroids was started. Concomitant lumbar pain of increasing intensity warranted magnetic resonance imaging, which revealed L3-L4 vertebral osteomyelitis with spondylodiscitis. Given the temporal link with CSD diagnosis and the significant clinical improvement since its treatment was started, an etiologic link was presumed and antibiotics were prolonged. This case stands out for the presence of distinct atypical CSD manifestations in the same patient. Further studies are needed to determine the optimal treatment for rare manifestations, particularly bone infection.

Bartonella henselae as a putative trigger for chronic type 2 leprosy reactions

Leprosy reactions are an acute inflammatory phenomenon that can arise before diagnosis, during treatment, or after cure of leprosy. These reactions are considered one of the main diseases that cause physical disabilities. Immunosuppressive treatment for these immune responses makes these patients susceptible to coinfections, which can trigger new leprosy reactions. The main objective of this study was to evaluate the occurrence of infection by Bartonella sp. in blood samples from 47 patients who had untreatable episodes of type 2 leprosy reactions for more than six months, comparing them with a control group. Cultures and molecular methods (PCR) were used. Amplicons from species-specific reactions and sequencing showed a higher prevalence of Bartonella henselae infection in patients, 19/47 (40.4 %), compared to control, 9/50 (18.0 %), p = 0.0149. Five patients accepted treatment for coinfection, and all showed improvement in leprosy reactions with treatment for B. henselae infection. We conclude that these bacteria can trigger chronic reactions of type 2 leprosy and should be investigated in these patients. SUMMARY LINE: Patients who have chronic type 2 leprosy reactions are more susceptible to Bartonella henselae infection than controls: 19/47 (40.4 %) compared 9/50 (18.0 %), p = 0.0149.

Bartonella in Norway rats (Rattus norvegicus) from the urban slum environment in Brazil

Bartonella are rodent-borne bacteria that cause varied human etiologies. Studies on synanthropic rodents are rare, causing gaps in epidemiological knowledge. We tested bloodclot samples from 79 rats from an urban slum in Salvador, Brazil through PCR targeting gltA gene. Nine samples (11.4%) were positive: six had 100% identity with Bartonella sp. isolate JF429580 and 99.5% with B. queenslandensis strain AUST/NH8; three were 100% identical to isolate JF429532 and 99.7% to B. tribocorum. This is the second report on urban rat Bartonella indicating bacterial circulation at detectable rates. Its presence in rats from vulnerable human settlements demands public health attention.

Emerging bacterial infectious diseases/pathogens vectored by human lice

Human lice have always been a major public health concern due to their vector capacity for louse-borne infectious diseases, like trench fever, louse-borne relapsing fever, and epidemic fever, which are caused by Bartonella quintana, Borrelia recurrentis, and Rickettsia prowazekii, respectively. Those diseases are currently re-emerging in the regions of poor hygiene, social poverty, or wars with life-threatening consequences. These louse-borne diseases have also caused outbreaks among populations in jails and refugee camps. In addition, antibodies and DNAs to those pathogens have been steadily detected in homeless populations. Importantly, more bacterial pathogens have been detected in human lice, and some have been transmitted by human lice in laboratories. Here, we provide a comprehensive review and update on louse-borne infectious diseases/bacterial pathogens.

A Rare Case of Bartonella henselae Infective Endocarditis Causing an Embolic Cerebrovascular Accident

Bartonella is a facultative intracellular Gram-negative aerobic rod that is an important cause of culture-negative endocarditis that only accounts for 3% of all infective endocarditis (IE) cases. Throughout the literature, there have been very few documented cases of an embolic stroke caused by Bartonella henselae (B. henselae) IE. Following a comprehensive review of the literature, it appears that only a small number of articles have reported on the correlation between cerebrovascular accidents (CVAs) and Bartonella IE. Here, we present a case of a 42-year-old male with a cerebral embolic event as a complication of B. henselae IE.

Advancements in understanding the molecular and immune mechanisms of Bartonella pathogenicity

Bartonellae are considered to be emerging opportunistic pathogens. The bacteria are transmitted by blood-sucking arthropods, and their hosts are a wide range of mammals including humans. After a protective barrier breach in mammals, Bartonella colonizes endothelial cells (ECs), enters the bloodstream, and infects erythrocytes. Current research primarily focuses on investigating the interaction between Bartonella and ECs and erythrocytes, with recent attention also paid to immune-related aspects. Various molecules related to Bartonella's pathogenicity have been identified. The present review aims to provide a comprehensive overview of the newly described molecular and immune responses associated with Bartonella's pathogenicity.

Cerebral venous sinus thrombosis and skull base osteomyelitis as manifestations of cat-scratch disease in a pediatric patient: A case report and literature review

Cat-scratch disease (CSD) is caused by Bartonella henselae and usually presents with regional lymphadenopathy. Skull base osteomyelitis and cerebral venous sinus thrombosis are rarely reported, particularly in immunocompetent children. CSD should be considered in the differential diagnosis of any patient with persistent headaches in the setting of cat exposure.

Comparison of molecular methods for Bartonella henselae detection in blood donors

The Bartonella genus consists of neglected pathogens associated with potentially transfusional-transmitted and fatal human diseases. We aimed to evaluate Bartonella sp. prevalence in 500 blood donors and compare the results with the data already published about these samples. We used molecular diagnostic methods to detect Bartonella sp.-DNA from blood and liquid culture samples: (A) conventional PCR for two gene regions, the ITS targeting the genus Bartonella and the specific gltA Bartonella henselae; (B) nested PCR for the ftsZ gene and (C) qualitative real-time PCR for the gltA gene, both B. henselae specific. We obtained 30/500 (6%) DNA detections from the blood samples; 77/500 (15.4%) DNA detections from liquid culture samples and five (1%) samples had DNA detection from both. In total, we detected B. henselae DNA from 102/500 (20.4%) donors. The samples used in this study had already been submitted for Bartonella sp.-DNA detection using only a conventional PCR in liquid culture. Sixteen samples (3.2%) were positive previously, and from these 16 samples, 13 were negative in the new investigation. We concluded that the use of liquid culture combined with different molecular tests increases the possibility of detecting Bartonella sp.-DNA, but the tests do not avoid false-negative results. More than a fifth of blood donors had at least one PCR that detected Bartonella sp.-DNA among the eight molecular reactions performed now (four reactions in whole blood and four in liquid culture). Seven percent had B. henselae-DNA detection for two or more distinct regions. Considering the results obtained previously, the DNA of Bartonella spp. was detected or the agent isolated in 23% of analyzed blood donors. The results establish that the low bacteremia and the fastidious characteristics of the bacterium are challenges to laboratory diagnosis and can make it difficult to confirm the infection in patients with bartonelloses.

Advanced approaches for the diagnosis and chemoprevention of canine vector-borne pathogens and parasites-Implications for the Asia-Pacific region and beyond

Vector-borne pathogens (VBPs) of canines are a diverse range of infectious agents, including viruses, bacteria, protozoa and multicellular parasites, that are pernicious and potentially lethal to their hosts. Dogs across the globe are afflicted by canine VBPs, but the range of different ectoparasites and the VBPs that they transmit predominate in tropical regions. Countries within the Asia-Pacific have had limited prior research dedicated to exploring the epidemiology of canine VBPs, whilst the few studies that have been conducted show VBP prevalence to be high, with significant impacts on dog health. Moreover, such impacts are not restricted to dogs, as some canine VBPs are zoonotic. We reviewed the status of canine VBPs in the Asia-Pacific, with particular focus on nations in the tropics, whilst also investigating the history of VBP diagnosis and examining recent progress in the field, including advanced molecular methods, such as next-generation sequencing (NGS). These tools are rapidly changing the way parasites are detected and discovered, demonstrating a sensitivity equal to, or exceeding that of, conventional molecular diagnostics. We also provide a background to the armoury of chemopreventive products available for protecting dogs from VBP. Here, field-based research within high VBP pressure environments has underscored the importance of ectoparasiticide mode of action on their overall efficacy. The future of canine VBP diagnosis and prevention at a global level is also explored, highlighting how evolving portable sequencing technologies may permit diagnosis at point-of-care, whilst further research into chemopreventives will be essential if VBP transmission is to be effectively controlled.

Limitations of Serological Diagnosis of Typical Cat Scratch Disease and Recommendations for the Diagnostic Procedure

Introduction

Cat scratch disease (CSD) is the most common cause of bacterial infectious lymphadenopathy, especially in children, but its diagnosis still remains challenging. Serological assays are widely applied due to their simplicity and the non-invasive sampling. However, these techniques present several limitations, including not well-defined antigen preparation, assay conditions and cutoff titers, severe cross-reactions with other species and organisms, and the notably ranging seroprevalence in the normal population. The objective of this study is to review the literature in order to determine the best diagnostic procedure for the diagnosis of CSD.

Methods

Databases including PubMed, Medline, Google Scholar, and Google were searched to determine the best diagnostic procedure for the diagnosis of CSD. A total of 437 papers were identified and screened, and after exclusion of papers that did not fulfill the including criteria, 63 papers were used.

Results

It was revealed that sensitivities of serological assays varied from 10% to 100%. Indeed, more than half of the studies reported a sensitivity lower than 70%, while 71% of them had a sensitivity lower than 80%. Moreover, specificities of serological assays ranged from 15% to 100%, with 25 assays reporting a specificity lower than 90%.

Conclusion

It is considered that molecular assays should be the gold standard technique for CSD confirmation, and physicians are reinforced to proceed to lymph node biopsy in suspicious CSD cases.

Erythromycin Formulations—A Journey to Advanced Drug Delivery

Erythromycin (ERY) is a macrolide compound with a broad antimicrobial spectrum which is currently being used to treat a large number of bacterial infections affecting the skin, respiratory tract, intestines, bones and other systems, proving great value from a clinical point of view. It became popular immediately after its discovery in 1952, due to its therapeutic effect against pathogens resistant to other drugs. Despite this major advantage, ERY exhibits several drawbacks, raising serious clinical challenges. Among them, the very low solubility in water and instability under acidic conditions cause a limited efficacy and bioavailability. Apart from this, higher doses promote drug resistance and undesirable effects. In order to overcome these disadvantages, during the past decades, a large variety of ERY formulations, including nanoparticles, have emerged. Despite the interest in ERY-(nano)formulations, a review on them is lacking. Therefore, this work was aimed at reviewing all efforts made to encapsulate ERY in formulations of various chemical compositions, sizes and morphologies. In addition, their preparation/synthesis, physico-chemical properties and performances were carefully analysed. Limitations of these studies, particularly the quantification of ERY, are discussed as well.

Haemophagocytic lymphohistiocytosis associated with bartonella peliosis hepatis following kidney transplantation in a patient with HIV

Bacillary peliosis hepatis is a well recognised manifestation of disseminated Bartonella henselae infection that can occur in immunocompromised individuals. Haemophagocytic lymphohistiocytosis is an immune-mediated condition with features that can overlap with a severe primary infection such as disseminated Bartonella spp infection. We report a case of bacillary peliosis hepatis and secondary haemophagocytic lymphohistiocytosis due to disseminated Bartonella spp infection in a kidney-transplant recipient with well controlled HIV. The patient reported 2 weeks of fever and abdominal pain and was found to have hepatomegaly. He recalled exposure to a sick dog but reported no cat exposures. Laboratory evaluation was notable for pancytopenia and cholestatic injury. The patient met more than five of eight clinical criteria for haemophagocytic lymphohistiocytosis. Pathology review of a bone marrow core biopsy identified haemophagocytosis. A transjugular liver biopsy was done, and histopathology review identified peliosis hepatis. Warthin-Starry staining of the bone marrow showed pleiomorphic coccobacillary organisms. The B henselae IgG titre was 1:512, and Bartonella-specific DNA targets were detected by peripheral blood PCR. Treatment with doxycycline, increased prednisone, and pausing the mycophenolate component of his transplant immunosuppression regimen resulted in an excellent clinical response. Secondary haemophagocytic lymphohistiocytosis can be difficult to distinguish from severe systemic infection. A high index of suspicion can support the diagnosis of systemic Bartonella spp infection in those who present with haemophagocytic lymphohistiocytosis, especially in patients with hepatomegaly, immunosuppression, and germane animal exposures.

Cat Scratch Disease with Generalized Bone Lesions in an Immunocompetent Child

A 9-year-old immunocompetent girl with prolonged fever for 1 month was suspected of having a malignancy because of generalized bone abnormalities identified by MRI. Histopathology of liver tissues indicated the diagnosis of cat-scratch disease (CSD). Results of NGS, immunofluorescence and immunochemical assay confirmed the causative agent was Bartonella henselae. Paediatricians should increase their awareness of CSD as a cause for bone lesions, except for malignancy.

Metagenomic next-generation sequencing may assist diagnosis of cat-scratch disease

Bartonella henselae, the pathogen that causes cat-scratch disease (CSD), is relatively rare in the clinic. CSD usually causes mild clinical manifestations, which self-heal in a matter of weeks. However, in immunocompromised patients, CSD may cause systemic disorders that can lead to critical illness. Due to the diversity of symptom signs and the lack of a golden standard for diagnosis, identifying atypical CSD in a timely manner presents a challenge. Metagenomic next-generation sequencing (mNGS), is a promising technology that has been widely used in the detection of pathogens in clinical infectious diseases in recent years. mNGS can detect multiple pathogens quickly and accurately from any given source. Here, we present a case of atypical CSD, which was diagnosed using mNGS. The patient manifested a fever of unknown infectious origin, and routine antibiotic treatment was ineffective. mNGS was employed to test the patient’s peripheral blood, which led to the detection of B. henselae. This was rarely seen in previous CSD reports. We surmised that the patient presented with atypical CSD and thus a targeted therapy was recommended. Crucially, the patient recovered rapidly. Based on this case study findings, we recommend that CSD should be included in the differential diagnosis for fever of unknown origin and that mNGS may be helpful in the diagnosis of CSD.

Cryptogenic hepatitis patients have a higher Bartonella sp.-DNA detection in blood and skin samples than patients with non-viral hepatitis of known cause

Background

This study aimed to assess the prevalence of Bartonella sp.-DNA detection in blood and skin samples from patients with non-viral end-stage liver disease awaiting liver transplantation.

Methodology/Principal findings

Blood samples and healthy skin fragments from 50 patients were tested using microbiological and molecular methods. Fifteen patients had cryptogenic hepatitis (CH) and 35 had alcoholic, drug-induced or autoimmune liver disease. DNA was extracted from whole blood and liquid culture samples, isolates, and skin fragments. Thirteen of the 50 patients (26%) had Bartonella henselae DNA detection in their blood (9/50) and/or skin (5/50) samples. Colonies were isolated in 3/50 (6%) and infection was detected in 7/50 (14%) of the 50 patients. B. henselae-DNA detection was more prevalent in patients with CH than in other patients (p = 0.040). Of 39 patients followed-up for at least two years, a higher mortality rate was observed among patients with CH infected with B. henselae (p = 0.039).

Conclusions/Significance

Further studies assessing the role of B. henselae infection in the pathogenesis of hepatitis patients must be urgently conducted.

One in four patients with end-stage liver disease awaiting liver transplantation for hepatitis of non-viral origin had documented B. henselae-DNA detection and cryptogenic hepatitis patients have a higher bacterium molecular detection than patients with non-viral hepatitis of known cause.

Case Report: Treatment of Severe Neuroretinitis and other Sequelae Associated with Cat Scratch Disease

SIGNIFICANCE

Severe vision loss from Bartonella neuroretinitis can best be treated to improve visual outcomes with a combination of systemic corticosteroids and antibiotics. Topical ketorolac 0.5% and difluprednate 0.05% are presented as a new adjunct therapy to potentially improve visual outcomes.

PURPOSE

This case illustrates severe posterior pole complications that can occur with cat scratch disease disseminated to the eye. Combination therapy with antibiotics and corticosteroids results in better visual outcomes. Topical treatment might further enhance visual outcome by preventing inflammatory damage without significant immunosuppression.

CASE REPORT

A 17-year-old male presented with right eye vision loss. He had been hospitalized two weeks prior for optic neuritis and treated with intravenous methylprednisolone. After 3 days vision had improved from 20/200 to 20/40. After positive serology for Bartonella henselae was obtained, he was released and treated with oral rifampin, doxycycline and prednisone. Sixteen days later he regressed to 20/200 and many more ophthalmic complications were observed. After discontinuation of rifampin, oral prednisone was continued for an additional two weeks and doxycycline was continued for approximately 3 weeks. Topical drops ketorolac 0.5% BID and difluprednate 0.05% QID were used for over 6 weeks before tapering after vision returned to normal.

CONCLUSIONS

Bartonella neuroretinitis associated with preretinal hemorrhage, vitritis and subretinal hemorrhage can be successfully treated with a combination of systemic medications and topical drops. Monotherapy with doxycycline is effective and well tolerated. Rifampin can cause rapid metabolization and reduction in plasma levels of both prednisone and doxycycline and should be avoided with combined therapy. Oral prednisone and topical difluprednate are recommended to quell initial inflammation during the first few weeks. The anti-inflammatory effects of doxycycline and topical ketorolac used for longer duration may be beneficial in preventing tissue damage without systemic immunosuppression and result in better visual outcomes.

Detection of Bartonella vinsonii subsp. berkhoffii in a HIV patient using metagenomic Next Generation Sequencing

Bartonella species are fastidious, aerobic bacteria that are transmitted by blood-sucking arthropods. Bartonella spp. are responsible for cat scratch disease, Carrion’s disease, bacillary angiomatosis and trench fever. On the other hand, Bartonella vinsonii is rarely reported in the literature and there exist a few reports of systemic infection caused by Bartonella vinsonii in patients with acquired immunodeficiency syndrome. A 31-year-old male (diagnosed with AIDS six years ago) had persistent fever and ulceration in the right knee. The elevated levels of inflammatory markers suggested an infectious aetiology. Despite the negative findings of blood culture, metagenomic Next-Generation Sequencing of plasma detected Bartonella vinsonii. The polymerase chain reaction of whole blood and Sanger sequencing confirmed the mNGS findings. Immunohistochemical staining had later suggested bacillary angiomatosis, which was consistent with Bartonella infection. Following antibiotic treatment, the ulcers subsided significantly, but a high fever persisted. The patient died due to sudden respiratory failure.

Choroidal granulomas due to Bartonella henselae infection: A case series

PURPOSE

To report a case series of 3 patients with choroidal granulomas due to Bartonella henselae infection in order to raise awareness about this etiology in the differential diagnosis of choroidal granulomas.

METHODS, PATIENTS

A retrospective case series of patients with choroidal granulomas due to Bartonella henselae infection who consulted between 2018 and 2020. Data were collected from the medical records (demographics, visual acuity (VA), laboratory tests, treatment, imaging).

RESULTS

Patients were a 48-year old man, a 14-year old girl and a 31-year old man. They all had a choroidal granuloma seen on optical coherence tomography (OCT) and angiography. The laboratory work-up revealed a positive serology for Bartonella henselae in all patients.

CONCLUSION

On multimodal imaging choroidal granulomas in B Henselae appeared as single or multiple, uni or bilateral round yellowish lesions. Fluorescein and indocyanine green angiography of the granuloma showed respectively a late staining and a hypofluorescence. On EDI-OCT choroidal granuloma appeared as a round hyporeflective lesion in the choroid with a retinal elevation. The exclusion of other diagnosis, the natural course and the serology must lead the ophthalmologist to evoke the diagnosis.

The Passenger Domain of Bartonella bacilliformis BafA Promotes Endothelial Cell Angiogenesis via the VEGF Receptor Signaling Pathway

Bartonella bacilliformis is a Gram-negative bacterial pathogen that provokes pathological angiogenesis and causes Carrion’s disease, a neglected tropical disease restricted to South America. Little is known about how B. bacilliformis facilitates vasoproliferation resulting in hemangioma in the skin in verruga peruana, the chronic phase of Carrion’s disease. Here, we demonstrate that B. bacilliformis extracellularly secrets a passenger domain of the autotransporter BafA exhibiting proangiogenic activity. The B. bacilliformis-derived BafA passenger domain (BafA_Bba) increased the number of human umbilical endothelial cells (HUVECs) and promoted tube-like morphogenesis. Neutralizing antibody against BafA_Bba detected the BafA derivatives from the culture supernatant of B. bacilliformis and inhibited the infection-mediated hyperproliferation of HUVECs. Moreover, stimulation with BafA_Bba promoted phosphorylation of vascular endothelial growth factor receptor 2 (VEGFR2) and extracellular-signal-regulated kinase 1/2 in HUVECs. Suppression of VEGFR2 by anti-VEGFR2 antibody or RNA interference reduced the sensitivity of cells to BafA_Bba. In addition, surface plasmon resonance analysis confirmed that BafA_Bba directly interacts with VEGFR2 with lower affinity than VEGF or Bartonella henselae-derived BafA. These findings indicate that BafA_Bba acts as a VEGFR2 agonist analogous to the previously identified B. henselae- and Bartonella quintana-derived BafA proteins despite the low sequence similarity. The identification of a proangiogenic factor produced by B. bacilliformis that directly stimulates endothelial cells provides an important insight into the pathophysiology of verruga peruana.

IMPORTANCEBartonella bacilliformis causes life-threatening bacteremia or dermal eruption known as Carrion’s disease in South America. During infection, B. bacilliformis promotes endothelial cell proliferation and the angiogenic process, but the underlying molecular mechanism has not been well understood. We show that B. bacilliformis induces vasoproliferation and angiogenesis by producing the proangiogenic autotransporter BafA. As the cellular/molecular basis for angiogenesis, BafA stimulates the signaling pathway of vascular endothelial growth factor receptor 2 (VEGFR2). Identification of functional BafA protein from B. bacilliformis in addition to B. henselae and B. quintana, the causes of cat scratch disease and trench fever, raises the possibility that BafA is a common virulence factor for human-pathogenic Bartonella.

A case of Bartonella henselae native valve endocarditis presenting with crescentic glomerulonephritis

Bartonella endocarditis is often an elusive diagnosis, usually derived from evaluating multiple laboratory tests and assessment of presenting symptoms. Herein we describe a case of Bartonella henselae native mitral valve endocarditis with an initial presentation of volume overload and renal failure. The Bartonella organism is tedious to isolate from culture medium, causing most diagnoses to be delayed. Due to the destructive nature of B. henselae endocarditis, the need for rapid identification remains prudent. This therefore creates an opportunity for Next Generation Sequencing (NGS) to be used. We further summarize the varied presentations that may be associated with B. henselae endocarditis, and hope that this will heighten the clinicians' awareness of this entity when presented with acute onset renal failure and culture negative vegetations.

Bartonella henselae masquerading as possible gamma-delta T-cell lymphoma in a paediatric patient with 22q11.2 deletion syndrome

A 14-year-old boy with 22q11.2 deletion syndrome and a right ventricular to pulmonary artery xenograft conduit presented to an Australian tertiary children's hospital with prolonged fevers, weight loss, splenomegaly and a high proportion of gamma-delta T cells in peripheral blood and bone marrow, concerning for possible gamma-delta T-cell lymphoma. However, investigations did not reveal evidence of lymphoma or autoimmune disease. After 5 months of intermittent fever episodes and ongoing symptoms, he was found to have an extremely high Bartonella henselae titre (8192) on serological testing, with the organism also detected on blood PCR. After 6 months of oral azithromycin and rifampicin, with complete resolution of his symptoms 3 months into treatment, his blood PCR was negative and gamma-delta T cells in peripheral blood were decreasing. The B. henselae titre remained unchanged for some time, but decreased to 2048 around 1 year after treatment was started.

Bats and their ectoparasites (Nycteribiidae and Spinturnicidae) carry diverse novel Bartonella genotypes, China

Bartonella species are facultative intracellular bacteria and recognized worldwide as emerging zoonotic pathogens. Bartonella were isolated or identified by polymerase chain reaction (PCR) in bats and their ectoparasites worldwide, whereas the association between them was scarce, especially in Asia. In this study, a retrospective analysis with frozen samples was carried out to identify the genetic diversity of Bartonella in bats and their ectoparasites and to investigate the relationships of Bartonella carried by bats and their ectoparasites. Bats and their ectoparasites (bat flies and bat mites) were collected from caves in Hubei Province, Central China, from May 2018 to July 2020. Bartonella were screened by PCR amplification and sequencing of three genes (gltA, rpoB, and ftsZ). Bats, bat flies, and bat mites carried diverse novel Bartonella genotypes with a high prevalence. The sharing of some Bartonella genotypes between bats and bat flies or bat mites indicated a potential role of bat flies and bat mites as vectors of bartonellae, while the higher genetic diversity of Bartonella in bat flies than that in bats might be due to the vertical transmission of this bacterium in bat flies. Therefore, bat flies might also act as reservoirs of Bartonella. In addition, human‐pathogenic B. mayotimonesis was identified in both bats and their ectoparasites, which expanded our knowledge on the geographic distribution of this bacterium and suggested a potential bat origin with bat flies and bat mites playing important roles in the maintenance and transmission of Bartonella.

Bartonella spp. seroprevalence in tick-exposed Swedish patients with persistent symptoms

Background

Bartonella spp. are emerging pathogens transmitted by arthropod vectors, possibly including ticks. We have investigated signs of bartonellosis in Swedish patients with presumed tick-bite exposure and symptom duration of at least 6 months.

Methods

Serological testing for Bartonella henselae and Bartonella quintana was performed in 224 patients. Symptoms, tick exposure, evidence of co-infection and previous treatments were evaluated. Seropositive patients were compared to a matched group (twofold larger and negative serology) from the same study cohort.

Results

Seroprevalence was 7% for B. henselae and 1% for B. quintana, with one patient testing positive to both agents. Tick bites were reported by 63% of the patients in the seropositive group and 88% in the seronegative group and presumed tick exposure was more common in the seronegative group. Animal contact was equally common in both groups, along with reported symptoms. The most common symptoms were fatigue, muscular symptoms, arthralgia and cognitive symptoms. Exposure to co-infections was evenly distributed in the seropositive and seronegative groups.

Conclusions

Antibodies to Bartonella were more common in this cohort of patients than in cohorts of healthy Swedish blood donors in previous studies but lower than those in blood donors from southern Europe. Positive Bartonella serology was not linked to any specific symptom, nor to (suspected) tick-bite exposure.

Graphical abstract

Isolated hepatosplenic abscess from cat scratch disease in a patient with HIV

Bartonella henselae infection, or cat scratch disease, typically is a self-limiting disease presenting as lymphadenopathy and fever after a bite or scratch from a cat. The most commonly reported presentation in immunocompromised patients includes bacillary angiomatosis and peliosis hepatitis, which resemble Kaposi's sarcoma. Isolated hepatosplenic abscess without diffuse lymphadenopathy or vasoproliferative disease is seldom reported in adult immunocompromised patients. Although several advances have been made in identifying the organism and antibodies with serological tests, biopsy, and polymerase chain reaction, there is little information about treatment. We report a case of an isolated hepatosplenic abscess without lymphadenopathy or vasoproliferative disease caused by B. henselae in an adult immunocompromised patient with HIV.

Cat Inflicted Eye Injury in a Child

Ocular injuries, especially corneal abrasions are a common phenomenon noted in the pediatric emergency department. Most of these are minor injuries and are well described in literature. However, there is very limited data on corneal cat scratch injuries and their management. We present the case of a 10-year-old female with cat scratch inflicted superficial corneal laceration. In addition to immediate identification of the injury, it is essential to investigate and evaluate the depth of the ocular injury for prompt management, including route of antibiotics, need for an immediate surgical intervention and future follow-up.

A case of Bartonellosis presenting as a puzzling multisystem disorder complicated by nosocomial COVID-19 infection

The most commonly considered infection with a Bartonella species is cat-scratch disease caused by Bartonella henselae Here, we discuss a unique case of a 60-year-old man who presented with Bartonella infection complicated by nosocomial COVID-19. He was admitted with a history of chest pain, persistent fever, rash and influenza-like symptoms. Positive Bartonella serology confirmed diagnosis and the patient developed complications of pericardial effusion in addition to COVID-19 infection, requiring non-invasive ventilation and admission to the intensive care unit. We discuss his symptoms, investigations, treatment and outcomes, while also highlighting the challenges of assessing patients presenting with fever of unknown origin during the COVID-19 pandemic.