Queuosine salvage in Bartonella henselae Houston 1: a unique evolutionary path.

Queuosine (Q) stands out as the sole tRNA modification that can be synthesized via salvage pathways. Comparative genomic analyses identified specific bacteria that showed a discrepancy between the projected Q salvage route and the predicted substrate specificities of the two identified salvage proteins: (1) the distinctive enzyme tRNA guanine-34 transglycosylase (bacterial TGT, or bTGT), responsible for inserting precursor bases into target tRNAs; and (2) queuosine precursor transporter (QPTR), a transporter protein that imports Q precursors. Organisms such as the facultative intracellular pathogen Bartonella henselae, which possess only bTGT and QPTR but lack predicted enzymes for converting preQ1 to Q, would be expected to salvage the queuine (q) base, mirroring the scenario for the obligate intracellular pathogen Chlamydia trachomatis. However, sequence analyses indicate that the substrate-specificity residues of their bTGTs resemble those of enzymes inserting preQ1 rather than q. Intriguingly, MS analyses of tRNA modification profiles in B. henselae reveal trace amounts of preQ1, previously not observed in a natural context. Complementation analysis demonstrates that B. henselae bTGT and QPTR not only utilize preQ1, akin to their Escherichia coli counterparts, but can also process q when provided at elevated concentrations. The experimental and phylogenomic analyses suggest that the Q pathway in B. henselae could represent an evolutionary transition among intracellular pathogens - from ancestors that synthesized Q de novo to a state prioritizing the salvage of q. Another possibility that will require further investigations is that the insertion of preQ1 confers fitness advantages when B. henselae is growing outside a mammalian host.

Atypical Haemorrhagic Presentation of Neuro-Retinitis and Serous Retinal Detachment Secondary to Cat-Scratch Disease.

Cat-scratch disease (CSD) is a self-limited disease caused by Bartonella henselae, a fastidious gram-negative intracellular bacillus bacterium. Neuroretinitis, a form of optic neuropathy characterised clinically by optic disc swelling and a macular star, is an uncommon manifestation of CSD occurring in approximately 1-2% of cases. We report a case of a 14-year-old female who presented to the emergency department with a chief complaint of acute painless vision loss described as a large black spot in the centre of her right eye vision 2 weeks after being scratched by cats. Fundus examination revealed Frisen grade 5 disc oedema with an atypically diffuse disc and peripapillary haemorrhages with associated subretinal fluid and a macular star in the right eye. Optical coherence tomography (OCT) of the macula and retinal nerve fibre layer showed subretinal fluid involving the fovea, a serous retinal detachment of the nasal macula, and significant optic disc oedema in the right eye. The patient was admitted and treated with doxycycline, rifampin, and prednisone taper. After completing the treatment course, the patient's vision improved, fundus examination showed significantly improved disc oedema and haemorrhages, and OCT demonstrated resolution of the subretinal fluid in the right eye.

Bartonella Neuroretinitis with Initial Seronegativity and an Absent Macular Star: A Case Report and Literature Review.

Cat-scratch disease (CSD) is an infectious disease caused by Bartonella henselae, presenting with fever and lymphadenopathy following contact with felines. The ocular manifestations include neuroretinitis, characterised by optic nerve swelling and a macular star. Case Presentation: We discuss a case of neuroretinitis that presented atypically, without a macular star. There was an initial suspicion of Bartonella, but the serology was negative. Our patient was eventually empirically treated for infective neuroretinitis based on a positive contact history (recently scratched by one of his three pet cats). There was progression to a macular star upon serial dilated fundus examination, and the repeated serology one week after symptom onset showed rising titres, supporting a diagnosis of CSD. Conclusions: A judicious review of systems, repeat assays, serial dilated fundus examination, and early ophthalmic evaluation are useful in cases of suspected neuroretinitis, remaining an important differential in the evaluation of sudden-onset painless vision loss and unilateral disc swelling.

Cat Scratch Disease Presenting with Right Branch Retinal Artery Occlusion and Left Neuroretinitis.

Introduction: Bartonella henselae, the causative agent of cat scratch disease (CSD), presents with diverse ocular manifestations, posing diagnostic challenges. This study aimed to elucidate the diagnostic complexities through a unique case. Case Presentation: A 42-year-old male presented with vision loss in the right eye, subsequent to flu-like symptoms following exposure to a stray kitten. Clinical examination revealed branch retinal artery occlusion (BRAO) in the right eye and neuroretinitis in the left, indicating concurrent ocular manifestations of CSD. Thorough investigations, including serological testing, ruled out alternative causes, highlighting the rarity of such coexisting ocular complications. Conclusions: The coexistence of BRAO and neuroretinitis in different eyes underscores the variable presentation of CSD. Recognition of infectious etiologies, particularly Bartonella, is paramount in diagnosing ocular vasculopathies. This case emphasizes the importance of considering Bartonella infection in patients with ocular vascular occlusions, especially in the context of recent cat exposure and systemic symptoms suggestive of CSD.

Cat scratch disease unveils hidden breast carcinoma: A diagnostic twist.

Cat scratch disease is a rare condition that can present with different clinical manifestations, including axillary lymphadenopathy. Here, we report the case of a 45-year-old female who presented with axillary lymphadenopathy attributable to a process of differential diagnosis to cat scratch disease. During the thorough investigation of her condition, a routine mammogram was performed, due to the unilateral axillary lymphadenopathy, revealing the presence of previously undiagnosed breast carcinoma in situ; in fact, a DCIS (invasive ductal carcinoma with spread to the ipsilateral axillary nodes) was incidentally found. This case highlights the importance of comprehensive differential diagnosis and a multidisciplinary approach in managing patients with atypical presentations of common diseases, given that other alarming but unrelated findings are visible.

Seroprevalence of zoonotic pathogens in stray cats in an urban area of northeast Spain.

The feline population is extensive in urban areas worldwide, comprising stray and domestic cats. Cats, acting as reservoirs, can transmit various zoonotic organisms to humans, which can cause significant public health issues. We evaluated the seroprevalence of zoonotic pathogens in stray cats in an urban area of northeast Spain (the city of Zaragoza) to assess potential risks to human health. A total of 88 sampled cats (52 females and 36 males) underwent antibody evaluation using the indirect immunofluorescence technique. Seroprevalence rates were determined for IgG antibodies to Bartonella henselae (36.3%), Toxoplasma gondii (31.8%), Rickettsia felis (14.7%), Rickettsia typhi (9%), and Leishmania infantum (10.2%). Our results confirmed the presence in stray cats of antibodies against all those pathogens, indicating that they all circulate in the feline population in Zaragoza. Male cats exhibited a higher predisposition to T. gondii, whereas females showed an increased likelihood of contracting B. henselae. This difference may be attributed to distinct behaviors according to sex. Our findings underscore the importance of maintaining and intensifying surveillance coupled with preventive measures against zoonotic pathogens in cats. They highlight the need for comprehensive control strategies designed to mitigate public health risks associated with feline populations.

Paws and Pathogens: A Multidisciplinary Approach Through Bartonella henselae Endocarditis and Hepatosplenic T-Cell Lymphoma.

Bartonella species are gram-negative coccobacilli that are globally recognized as significant pathogens causing zoonotic infections. Among Bartonella species, B. henselae, B. quintana, and B. bacilliformis are prominent pathogens causing infections in humans, often manifesting as infective endocarditis. Bartonella endocarditis can pose diagnostic challenges due to its indolent presentation and limitations of standard microbiological culture techniques to identify the organism. We report a case of a 23-year-old male, who initially presented with the manifestations of hepatosplenic T-cell lymphoma, later diagnosed with blood culture-negative endocarditis caused by B. henselae. The patient had a complicated clinical course including pancytopenia, hepatosplenomegaly, and severe aortic valve regurgitation. Despite negative blood cultures, diagnostic clues included persistent fevers and bicuspid aortic valve with abscess. High Bartonella IgG titers (>1:800) supported the diagnosis. This case underscores the importance of considering Bartonella species in patients with suspected endocarditis, particularly in those with predisposing factors and negative blood cultures. Diagnosis relies heavily on serologic assays due to low sensitivity of conventional culture methods. Treatment involves a multidisciplinary approach with antibiotics and surgical intervention for optimal outcomes. Timely recognition and management are crucial to mitigate the high mortality associated with Bartonella endocarditis, and we hope this article offers insight for clinicians.

Bacillary Angiomatosis in a Patient With HIV and Disseminated Mycobacterium avium Complex Infection.

Bartonella is a genus of arthropod-borne bacterial pathogens that typically cause persistent infections of erythrocytes and endothelial cells in mammalian hosts. The species that primarily infect humans are Bartonella henselae and Bartonella quintana. Depending on immune status, the clinical presentation of B. henselae may differ, manifesting as cat-scratch disease in immunocompetent individuals or bacillary angiomatosis (BA) and peliosis in immunocompromised patients. The cutaneous manifestations of BA are typically characterized by occasionally painful, angiomatous papules and nodules, often with a chronic, persistent course. Herein, we present a case of biopsy-confirmed B. henselae infection in a 32-year-old HIV-positive female with acquired immunodeficiency syndrome in the setting of disseminated Mycobacterium avium complex infection, an association that has been less frequently described. This case serves as an important reminder to consider uncommon opportunistic infectious etiologies when examining immunocompromised patients, as prompt diagnosis and treatment are essential in this patient population.

Metagenomic Next-Generation Sequencing for the Diagnosis of Viral Infectious Uveitis and Its Mimics.

PURPOSE: To investigate the value of metagenomic next-generation sequencing (mNGS) for virus detection in patients with suspected viral infectious uveitis. METHODS: In this retrospective, multicenter case series study, 70 patients with suspected viral infectious uveitis were recruited. All patients underwent mNGS test using intraocular fluid samples and serological screening tests for pathogens. Twelve cases also underwent a PCR panel test for herpetic viruses using intraocular fluid samples; 7 cases also underwent aqueous anti-herpetic viral IgG level tests. RESULTS: Among 70 patients with suspected viral infectious uveitis, 34 cases were female, mean age was 45.3 years with a range from 6 to 78 years; 53 cases (75.7%) were diagnosed as infectious uveitis, 17 cases (24.3%) diagnosed as non-infectious uveitis. Among 53 cases with infectious uveitis, herpetic viruses, Bartonella henselae, Toxoplasma gondii, and Treponema pallidum were detected in 43, 6, 4, and 1 case, respectively. Among 43 cases with viral infectious uveitis, herpetic virus was detected in 39 cases by mNGS, the other 4 cases showed negative results in mNGS test, but positive results in 2 cases in serological screening tests, in 1 case in PCR, and in 1 case in aqueous anti-herpetic viral IgG level test, respectively. The sensitivity, specificity, positive predictive value, negative predictive value of mNGS in detecting viruses were 90.7%, 100%, 100%, and 81.0%, respectively. CONCLUSIONS: mNGS is a sensitive and valuable method to detect viruses in intraocular fluid samples, and an alternative for pathogen detection in cases with suspected viral infectious uveitis but negative test results in PCR.

Vague Presentation of Cat Scratch Disease in a Child.

Background: Prolonged fever for more than a week or fever of unknown origin in pediatric patients with or without soft tissue infection should raise suspicion for Bartonella henselae infection. Case Report: A 10-year-old female presented to urgent care with a "bug bite" on the left ring finger, cough, and 2 to 3 days of low-grade fever. Ten days later, her symptoms progressed to soft tissue swelling of the left elbow without fracture on radiograph. Magnetic resonance imaging revealed multiple reniform masses with avid contrast enhancement consistent with suppurative adenitis. She was admitted for irrigation and debridement. The patient underwent surgical debridement with removal of infected lymph nodes. Histology revealed necrotizing granulomatous lymphadenitis. Polymerase chain reaction was positive for B henselae. Antibody titer revealed B henselae immunoglobulin G titer of 1:512 (reference, 1:64), and negative immunoglobulin M titers were indicative of mature immune response. The patient was treated with azithromycin 250 mg tablets twice daily for 3 days followed by 3 days of the 250 mg tablet once daily. Follow-up showed resolution of infection without symptoms concerning for visceral organ infection. Conclusion: While the patient's initial presentation was vague, a complete history, quick follow-up, and decisive intervention prevented significant sequelae such as visceral organ involvement.

[Cat-scratch disease, clinical features in adults]. / Características clínicas de pacientes adultos con enfermedad por arañazo de gato.

INTRODUCTION: Cat-scratch disease (CSD) is caused by Bartonella henselae and it is under-recognized in adults because it mainly affects children. Clinical course is commonly benign and self-limited; occasionally, there may be systemic involvement. METHODS: Case-series study carried out in a tertiary care hospital in Buenos Aires suburbs. Patients older than 15 years diagnosed with CSD over a 5-year period were included (2016-2021). RESULTS: 30 adult patients were analyzed, with a median age of 20.5 years (IQR 17-29), 73% (n = 22) were male; 96% (n = 27) had history of exposure to cats. The most common clinical presentation of CSD was peripheral lymphadenopathy (90%), the average complication rate was 33% (n = 10), 86.7% (n = 26) received antimicrobial therapy, with a median duration of 5 days (IQR 5-10). Outcome was favorable in 83% (n = 25), 16% (n = 5) were lost to follow-up. DISCUSSION: Clinical features of CSD in adults are poorly described in the worldwide literature. Diagnosis can be challenging because the clinical hallmark is regional lymphadenopathy.

Introducción: La enfermedad por arañazo de gato (EAG) es producida por Bartonella henselae y debido a que afecta principalmente niños, es poco reconocida en adultos. El cuadro evolutivo es generalmente benigno y autolimitado, aunque ocasionalmente puede haber compromiso sistémico. Métodos: Estudio observacional, descriptivo y retrospectivo realizado en un hospital de tercer nivel del conurbano bonaerense. Se incluyeron pacientes mayores de 15 años con diagnóstico de EAG en un período de 5 años (2016-2021). Resultados: Se analizaron 30 pacientes adultos, con una mediana de edad de 20.5 años (17-29), el 73% (n = 22) fueron varones. El 96% (n = 27) presentó contacto estrecho con gatos. La presentación clínica más frecuente fue adenopatías periféricas (90%); el porcentaje de complicaciones fue de 33% (n = 10). La indicación de antibioticoterapia fue de 86.7% (n = 26), con una mediana de duración de 5 días (5-10). La evolución fue favorable en el 83% (n = 25), en el 16% (n = 5) se perdió seguimiento. Discusión: La EAG es poco reconocida en adultos; las características clínicas de este grupo etario se encuentran poco descriptas en la literatura. Es un desafío diagnóstico debido a que su forma de presentación más frecuente es la adenopatía localizada.

First report of Bartonella henselae and Bartonella clarridgeiae carriage in stray cats from Ecuador and its link to a cat scratch disease outbreak in 2022.

INTRODUCTION: The genus Bartonella includes species and subspecies of fastidious, facultative intracellular Gram-negative bacilli that infect a wide variety of mammalian reservoirs including cats and humans. In 2022, the Ecuadorian Ministry of Health reported an outbreak of cat scratch disease caused by B. henselae in the city of Guayaquil. Therefore, we aimed to characterize the presence of Bartonella spp. in domestic and stray cats from the area of Guayaquil where the outbreak happened in 2022. METHODS: Whole blood samples of 100 domestic and stray cats were collected. Riboflavin synthase (ribC) and 16S rRNA genes detection was performed by PCR using Bartonella spp. specific primers, followed by Sanger sequencing and phylogenetic analysis. RESULTS: 14 cats were positive for Bartonella spp. carriage. Phylogenetic analysis confirmed the presence of 12 cats infected with B. henselae and 2 cats with B. clarridgeiae. CONCLUSIONS: There is a high prevalence of Bartonella spp. carriage in cats in the city of Guayaquil within the area where a recent cat scratch disease outbreak happened. Considering the high presence of cats and other domestic and stray animals in the city of Guayaquil, a One Health approach for surveillance and prevention of zoonotic diseases like cat scratch disease is needed.

Parinaud's oculoglandular syndrome: Coinfection by Bartonella henselae and Sporothrix brasiliensis.

A 26-year-old woman presented an eyelid lesion, after being scratched by a cat that had a similar skin lesion. It evolved into a cervical lymph node enlargement. With a hypothesis of Parinaud´s oculoglandular syndrome (POS) due to cat scratch disease (CSD), doxycycline was prescribed. After two weeks of treatment without improvement, a biopsy and blood sample were obtained. Itraconazole was prescribed and the skin lesion improved, but not the lymph node enlargement. A Sporothrix schenckii complex was isolated from the skin sample. Also, a specie-specific polymerase chain reaction detected Bartonella henselae DNA in her blood sample. Azithromycin was included to treat the bacterial infection, whereupon the lymph node also receded successfully. Sporotrichosis and CSD are zoonoses that can be transmitted to humans by traumatic inoculation due to scratches or bites from cats. Both can evolve with POS. Patients who present skin lesions and/or POS after being wounded by a cat should be investigated for both diseases.

Development and Diagnostic Potential of a Novel Bartonella henselae-Specific Immunoglobulin.

Bartonella henselae is a gram-negative rod-shaped bacterium and is the primary causative agent of Cat Scratch Disease (CSD). Although the prevalence of CSD is low in the human population, the possibility of developing multi-organ complications, especially in vulnerable individuals, remains a serious cause for concern. The immunofluorescent assay (IFA) is currently one of the most common laboratory tests for the detection of antibodies to B. henselae in serum, however, it has several disadvantages. The enzyme-linked immunosorbent assay (ELISA) technique offers a more quantitative, sensitive, and cost-effective alternative to conventional IFAs. Here, we report the purification of a novel bioidentical polyclonal antibody from discarded human serum for use as a standard in ELISAs against B. henselae. This novel method of antibody production overcomes the many limitations of animal-derived antibodies while also offering a more robust, reproducible, and scalable antibody production alternative for the diagnosis of CSD.

Bartonella species in dromedaries and ruminants from Lower Shabelle and Benadir regions, Somalia.

BACKGROUND: Bartonellosis, caused by bacteria of the genus Bartonella, is a zoonotic disease with several mammalian reservoir hosts. In Somalia, a country heavily reliant on livestock, zoonotic diseases pose significant public health and economic challenges. To the best of our knowledge, no study has been performed aiming to verify the occurrence of Bartonella spp. in Somalia. This study investigated the occurrence and molecular characterization of Bartonella in dromedary (Camelus dromedarius, Linnaeus, 1758), cattle, sheep, and goats from Somalia. MATERIALS AND METHODS: 530 blood samples were collected from various animals (155 dromedary, 199 goat, 131 cattle, and 45 sheep) in Benadir and Lower Shabelle regions. DNA was extracted for molecular analysis, and a qPCR assay targeting the NADH dehydrogenase gamma subunit (nuoG) gene was used for Bartonella screening. Positive samples were also subjected to PCR assays targeting seven molecular markers including: nuoG, citrate synthase gene (gltA), RNA polymerase beta-subunit gene (rpoB), riboflavin synthase gene (ribC), 60 kDa heat-shock protein gene (groEL), cell division protein gene (ftsZ), and pap31 and qPCR targeting the 16-23S rRNA internal transcribed spacer (ITS) followed by Sanger sequencing, BLASTn and phylogenetic analysis. RESULTS: Out of 530 tested animals, 5.1% were positive for Bartonella spp. by the nuoG qPCR assay. Goats showed the highest Bartonella occurrence (17/199, 8.5%), followed by sheep (6/44, 6.8%), cattle (4/131, 3.1%), and dromedary (1/155, 1.9%). Goats, sheep, and cattle had higher odds of infection compared to dromedary. Among nuoG qPCR-positive samples, 11.1%, 14.8%, 11.1%, and 25.9% were positive in PCR assays based on nuoG, gltA, and pap31 genes, and in the qPCR based on the ITS region, respectively. On the other hand, nuoG qPCR-positive samples were negative in the PCR assays targeting the ribC, rpoB, ftsZ, and groEL genes. While Bartonella bovis sequences were detected in cattle (nuoG and ITS) and goats (gltA), Bartonella henselae ITS sequences were detected in dromedary, goat, and sheep. Phylogenetic analysis placed gltA Bartonella sequence from a goat in the same clade of B. bovis. CONCLUSION: The present study showed, for the first time, molecular evidence of Bartonella spp. in dromedary and ruminants from Somalia and B. henselae in sheep and goats globally. These findings contribute valuable insights into Bartonella spp. occurrence in Somali livestock, highlighting the need for comprehensive surveillance and control measures under the One Health approach.

Subtractive Proteomics and Reverse-Vaccinology Approaches for Novel Drug Target Identification and Chimeric Vaccine Development against Bartonella henselae Strain Houston-1.

Bartonella henselae is a Gram-negative bacterium causing a variety of clinical symptoms, ranging from cat-scratch disease to severe systemic infections, and it is primarily transmitted by infected fleas. Its status as an emerging zoonotic pathogen and its capacity to persist within host erythrocytes and endothelial cells emphasize its clinical significance. Despite progress in understanding its pathogenesis, limited knowledge exists about the virulence factors and regulatory mechanisms specific to the B. henselae strain Houston-1. Exploring these aspects is crucial for targeted therapeutic strategies against this versatile pathogen. Using reverse-vaccinology-based subtractive proteomics, this research aimed to identify the most antigenic proteins for formulating a multi-epitope vaccine against the B. henselae strain Houston-1. One crucial virulent and antigenic protein, the PAS domain-containing sensor histidine kinase protein, was identified. Subsequently, the identification of B-cell and T-cell epitopes for the specified protein was carried out and the evaluated epitopes were checked for their antigenicity, allergenicity, solubility, MHC binding capability, and toxicity. The filtered epitopes were merged using linkers and an adjuvant to create a multi-epitope vaccine construct. The structure was then refined, with 92.3% of amino acids falling within the allowed regions. Docking of the human receptor (TLR4) with the vaccine construct was performed and demonstrated a binding energy of -1047.2 Kcal/mol with more interactions. Molecular dynamic simulations confirmed the stability of this docked complex, emphasizing the conformation and interactions between the molecules. Further experimental validation is necessary to evaluate its effectiveness against B. henselae.

Bartonella Henselae Related Unilateral Anterior Uveitis and Subsequent Multifocal Retinitis in a Case Under Certolizumab Treatment.

Introduction: A case of ocular bartonellosis under anti-tumour necrosis factor treatment is described. Case description: A 29-year-old woman with psoriasis who had been on certolizumab treatment was examined with a left visual deterioration following a fever bout, malaise, and placoid erythematous rashes on her neck. As there was acute anterior uveitis in her left eye, it was recommended to stop certolizumab treatment for a possible infectious aetiology. However, her physician elected to continue the certolizumab treatment. Ten days later, the patient noticed further visual decline despite the topical steroid treatment. This time, there were scattered yellow-white small retinitis foci at the left posterior pole. Infectious agents were searched and while Bartonella henselae antibodies were negative for immunoglobulin M, the immunoglobulin G titre was 1/80. Clinical findings were improved with the systemic treatment of oral trimethoprim-sulfamethoxazole (160/800 mg twice daily for six weeks) and azithromycin (500 mg once daily for two weeks). Discussion: Though extremely rare, ocular bartonellosis should be kept in mind in patients on anti-tumour necrosis factor treatment as rapid and accurate diagnosis may end up with an excellent visual outcome and full recovery. LEARNING POINTS: Anti-tumour necrosis factor treatment is fraught with several ocular side effects including myositis, corneal infiltrates, scleritis, uveitis, optic neuritis, retinal vasculitis and ophthalmoplegia.When a new uveitis episode occurs in cases undergoing anti-tumour necrosis factor therapy, its cause poses a diagnostic challenge as it can have either an infectious or a non-infectious nature.Though very rare, ocular bartonellosis may also occur in immunocompromised individuals and a prompt diagnosis and appropriate treatment can lead to an excellent visual recovery.

Application of metagenomic next-generation sequencing in the diagnosis of Bartonella neuroretinitis: a case report and literature review.

BACKGROUND: Cat-scratch disease (CSD) is caused by Bartonella henselae infection. In atypical cases of CSD, pathogen determination is challenging. We report a case of Bartonella neuroretinitis with neither a clear history of scratches nor typical general symptoms. The diagnosis was made using metagenomic next-generation sequencing (mNGS), a high-throughput sequencing technology. CASE PRESENTATION: A female patient presented to the ophthalmologist with complaint of blurred vision in her right eye. Although with history of raising a cat, she reported no clear history of scratches or typical general symptoms, except a fever of unknown origin which resolved spontaneously. The best corrected visual acuity (BCVA) of the right eye was count fingers. Fundus examination showed optic disc oedema, macular exudates and inferior exudative retinal detachment. Laboratory examination results showed increased value of serum C-reactive protein and erythrocyte sedimentation rate. Ocular involvement of toxoplasmosis, syphilis and tuberculosis were excluded. To identify the possible causative pathogen of the disease, mNGS of aqueous humour sample was performed and 521 reads of B. henselae were identified. Serological test results further showed a positive immunoglobulin G (IgG) titre of 1:64. Taking the contact history, clinical manifestations, mNGS and serological results into consideration, the diagnosis of Bartonella neuroretinitis (ocular CSD) was made. After appropriate treatment, the BCVA of the right eye improved to 20/25 in the last follow-up. Fundus examination showed a normal optic disc and macula, and the exudates had reduced. CONCLUSION: mNGS, a fast and unbiased method, can be used to detect B. henselae (if present) in intraocular fluid samples.; however, the results should be interpreted together with the clinical symptoms and other auxiliary test results.

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.