A Case Report of Bartonella henselae Infection Causing Fever of Unknown Origin: Unveiling a Stealthy Pathogen

Bartonella species are bacterial pathogens responsible for Cat Scratch Disease (CSD) with various clinical manifestations, ranging from self-limiting febrile illnesses to severe systemic infections. Diagnosis is often challenging due to its insidious nature and variable presentation based on the body’s immune status. Such a scenario emerged when a 25-year-old male presented to our hospital with nonspecific symptoms of Fever of unknown origin that were not responding to antibiotics until a timely diagnosis of Bartonella infection. This case report highlights the importance of considering Bartonella as a potential etiology in patients with prolonged Fever of unknown origin, especially in endemic regions.

Optimization of Bartonella henselae multilocus sequence typing scheme using single-nucleotide polymorphism analysis of SOLID sequence data

Background Multi-locus sequence typing （MLST） is widely used to explore the population structure of numerous bacterial pathogens. However, for genotypically-restricted pathogens, the sensitivity of MLST is limited by a paucity of variation within selected loci. For Bartonella henselae （B. henselae）, although the MLST scheme currently used has been proven useful in defining the overall population structure of the species, its reliability for the accurate delineation of closely-related sequence types, between which allelic variation is usually limited to, at most, one or two nucleotide polymorphisms. Exploitation of high-throughput sequencing data allows a more informed selection of MLST loci and thus, potentially, a means of enhancing the sensitivity of the schemes they comprise. Methods We carried out SOLID resequencing on 12 representative B. henselae isolates and explored these data using single nucleotide polymorphism （SNP） analysis. We determined the number and distribution of SNPs in the genes targeted by the established MLST scheme and modified the position of loci within these genes to capture as much genetic variation as possible. Results Using genome-wide SNP data, we found the distribution of SNPs within each open reading frame （ORF） of MLST loci, which were not represented by the established B. henselae MLST scheme. We then modified the position of loci in the MLST scheme to better reflect the polymorphism in the ORF as a whole. The use of amended loci in this scheme allowed previously indistinguishable ST1 strains to be differentiated. However, the diversity of B. henselae was still rare in China. Conclusions Our study demonstrates the use of SNP analysis to facilitate the selection of MLST loci to augment the currently-described scheme for B. henselae. And the diversity among B. henselae strains in China is markedly less than that observed in B. henselae populations elsewhere in the world.

Bartonella henselae neuroretinitis in a patient without cat scratch

Neuroretinitis is characterized by optic disc swelling with macular star,and affects 1%-2%of the patients with Bartonella henselae infection.This condition needs to be considered in the differential diagnosis of unilateral optic neuropathy in young adults.A 44-year-old woman presented with a progressive visual loss in right eye that was described as a central scotoma with altered color perception.Medical history was negative except for Hashimoto's thyroiditis.The examination evidenced a relative afferent pupillary defect in right eye and marked papillary oedema involving the macular region.Brain and orbits magnetic resonance imaging were normal,and fundoscopy showed star-shaped hard exudates.Autoimmune and infective screening revealed IgM and IgG antibodies against Bartonella henselae,suggesting for recent cat-scratch disease.She was treated with high-dose intravenous steroids and doxycycline.One month later she fully recovered,and she had no relapses.We diagnosed a Bartonella henselae neuroretinitis(finally the patient recalled she had stroked stray cats,not being scratched).In conclusion time course and absence of pain differentiate neuroretinitis from other optic neuropathies.Fundoscopic image of macular star is a clue for diagnosis,and visual recovery is usually excellent.

Botanical Medicines With Activity Against Stationary Phase Bartonella henselae

Bartonella henselae is a Gram-negative bacterium and is the causative agent of cat scratch disease.In humans,infections with B.henselae can result in acute or chronic systemic infections with diverse clinical symptoms.The current treatment for Bartonella infections with antibiotics such as doxycycline and rifampin is not always effective,presumably due in part to bacterial persistence.There are various anecdotal reports of herbal extracts used for treating patients with persistent Bartonella infections but their activity on B.henselae is unknown.In order to identify more effective therapies for persistent Bartonella infections,in this study,we tested the antimicrobial activity of botanical and herbal medicines and screened an herbal product collection against stationary phase B.henselae in vitro using a SYBR Green I/propidium iodide viability assay.We identified five herbal product extracts(at 1.67 mg/mL or 2.5mg/mL),including Cryptolepis sanguinolenta,Juglans nigra,Polygonum cuspidatum,Scutellaria baicalensis,and Scutellaria barbata,that had high activity against stationary phase B.henselae.Among them,C.sanguinolenta,J.nigra,and P.cuspidatum could eradicate all stationary phase B.henselae cells within 7days at 0.83 mg/mL or 1.25 mg/mL in drug exposure time-kill assays,whereas S.baicalensis and S.barbata showed relatively poor activity.These top hits were active against both stationary phase nongrowing B.henselae and log phase growing B.henselae in minimum inhibitory concentration testing.These findings may have implications for improved treatment of persistent Bartonella infections.

Seronegative disseminated Bartonella spp. infection in an immunocompromised patient

An 11 year old, hispanic girl with a history of B-cell acute lymphoblastic leukemia was admitted to the hospital for symptoms compatible with Bartonella henselae infection. The first molecularly diagnosed case of disseminated Bartonella henselae infection was reported in an immunocompromised patient in Lima, Peru. The analysis was confirmed by Polymerase Chain Reaction and automated sequencing of a liver biopsy sample, even though the serologic tests were negative. In conclusion, Bartonella spp. infection should have a particular diagnostic consideration in immunocompromised patients with fever of unknown origin and further investigation regarding the patient's past exposures with cats should also be elicited.

Serological Evidence of Human Coinfection by Brazilian Spotted Fever and Bartonellosis

Brazilian spotted fever and bartonellosis are zoonotic, emerging and under diagnosed diseases. Pets may be co-infected by multiple pathogens and become transmissions sources to humans. The study reports the first case of active co-infection by Brazilian spotted fever and bartonellosis based on serological evidence. The authors aim to demonstrate the importance of performing systematic syndromic investigations on nonspecific febrile syndromes, guided by the epidemiological history and considering the possibility of co-infection by zoonosis sharing the same ecological niche.

Cat scratch disease in children with nocturnal fever:A case report

BACKGROUND Cat scratch disease(CSD)is the most common human infection caused by Barto-nella henselae(B.henselae).The main manifestation is self-limited lymphaden-opathy that primarily affects adolescents,and typically resolves without treat-ment within 2-4 months.However,individuals with compromised immune systems or immunodeficiency require specific antibacterial therapy following diagnosis.Due to its low incidence,nonspecific clinical manifestations,and diagnostic limitations,this condition often poses challenges for clinicians in terms of missed diagnoses and misdiagnoses.CASE SUMMARY The child was ultimately diagnosed with CSD.The primary manifestations included nocturnal fever,enlargement of lymph nodes in the neck,axilla and groin,and suspected brucellosis;however,both brucellosis tests conducted during the course of the illness yielded negative results.Bone marrow cytology indicated stimulated proliferation.Lymph node biopsy indicated hyperplasia of lymphoid tissue in the cervical lymph nodes(right),with combined immunohisto-chemical findings indicating reactive hyperplasia.Immunohistochemical analysis revealed CD20 B(+),CD3 T(+),BCL-6(+),and BCL-2(-).CD21 FDC networks were present and Ki67 expression in the germinal center was~80%.Blood next-generation sequencing indicated B.henselae sequence number was 3.Serological test results demonstrated positive antibody response to B.henselae IgG(+),B.henselae IgM(+),Bartonella quintana(B.quintana)IgG(-)and B.quintana IgM(-),and the final diagnosis was CSD.CONCLUSION In patients presenting with fever at night and swollen lymph nodes of unknown origin,CSD should be considered.