Recommendations for treatment of human infections caused by Bartonella species

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.

Cerebral epidural empyema due to Bartonella henselae: a case report

BACKGROUND

Cat scratch disease frequently involves a benign, self-limited disease. Neurological forms associated with Bartonella henselae are uncommon, consisting mostly in neuroretinitis, encephalitis and meningitis. Cerebral epidural empyema has never described.

CASE PRESENTATION

An adult patient was hospitalized for isolated headaches. Magnetic Resonance Imaging (MRI) identified typical features of cerebral epidural empyema. The diagnosis of B. henselae was performed incidentally by 16S rDNA gene sequencing on the abscess fluid, and confirmed by specific qPCR. We report here the first case, to our knowledge, of cerebral epidural empyema associated with B. henselae. Further follow-up visits allowed identifying frequent cat scratches on the scalp as the presumptive source of infection.

CONCLUSIONS

This case report alerts about such atypical clinical presentation, which requires an extensive clinical investigation. It also emphasizes on the usefulness of additional molecular diagnosis techniques in such CNS infection cases.

Bartonella henselae infection in the pediatric solid organ transplant recipient

Bartonella henselae infection can cause a wide spectrum of diseases in both the immunocompetent and immunocompromised host with BA a severe form relegated to immunocompromised hosts, including solid organ transplant population. There are established criteria for diagnosis of Bartonella infection based on clinical presentation, serologic testing, imaging studies and, when indicated, tissue sampling for histopathological evaluation, particularly for BA. However, treatment recommendations for BA are inconclusive. Furthermore, there are no studies in the pediatric solid organ transplant population for antimicrobial therapy during BA secondary to Bartonella henselae infection. A case of BA following heart transplant is presented along with a literature review of clinical presentation; diagnosis and therapy for BA in the pediatric solid organ transplant population.

Cat scratch disease sepsis in an immunocompromised patient

As a greater number of households have pets, the likelihood of zoonotic infections can rise too. Although in most healthy individuals these infections are self-limiting, they are more serious and can lead to adverse outcomes in the immunocompromised. There is minimal information available for the immunocompromised patient who are pet owners or on pet handling. We report a case of cat scratch disease-related sepsis in an immunocompromised patient. This case illustrates the need for a detailed history, including a pet history, in immunocompromised patients presenting with fever of unknown origin and the need for UK-based information for the immunocompromised on pet care and risks associated with having a pet.

Adaptive resistance mutations at supra-inhibitory concentrations independent of SOS mutagenesis

Emergence of resistant bacteria during antimicrobial treatment is one of the most critical and universal health threats. It is known that several stress-induced mutagenesis and heteroresistance mechanisms can enhance microbial adaptation to antibiotics. Here, we demonstrate that the pathogen Bartonella can undergo stress-induced mutagenesis despite the fact it lacks error-prone polymerases, the rpoS gene and functional UV-induced mutagenesis. We demonstrate that Bartonella acquire de novo single mutations during rifampicin exposure at suprainhibitory concentrations at a much higher rate than expected from spontaneous fluctuations. This is while exhibiting a minimal heteroresistance capacity. The emerged resistant mutants acquired a single rpoB mutation, whereas no other mutations were found in their whole genome. Interestingly, the emergence of resistance in Bartonella occurred only during gradual exposure to the antibiotic, indicating that Bartonella sense and react to the changing environment. Using a mathematical model, we demonstrated that, to reproduce the experimental results, mutation rates should be transiently increased over 1,000-folds, and a larger population size or greater heteroresistance capacity is required. RNA expression analysis suggests that the increased mutation rate is due to downregulation of key DNA repair genes (mutS, mutY, and recA), associated with DNA breaks caused by massive prophage inductions. These results provide new evidence of the hazard of antibiotic overuse in medicine and agriculture.

Early post-transplant cutaneous bacillary angiomatosis in a kidney recipient: Case report and review of the literature

Bacillary angiomatosis (BA) is an uncommon systemic disease caused by Bartonella henselae (BH) or Bartonella quintana (BQ) that occurs primarily in immunocompromised hosts. Few cases of BA recipients have been reported in adult solid transplant recipients over the years, with most cases presenting years after transplant. We describe a case of a kidney transplant recipient who developed cutaneous BA very early in the post-transplant period despite not having any exposures. Retrospective testing of donor and recipient's serum was performed and raised the concern for possible donor-derived infection. A literature review encompassing 1990 to present was also performed in order to better understand the clinical presentation, diagnostics and therapeutic approach of this unusual disease. Combined serology, histopathology and molecular testing (polymerase chain reaction [PCR]) were useful in diagnosing BA in our patient as serology alone might be unreliable. Macrolides or doxycycline for at least 3 months is the recommended therapeutic strategy; however, the optimal duration of treatment is not well established in transplant recipients. In our patient, we decided to use doxycycline for 1 year due to gradual resolution of lesions and ongoing immunosuppression. Patient responded successfully without any documented relapse.

Glomerulonephritis Caused by Bartonella spp. Infective Endocarditis: The Difficulty and Importance of Differentiation from Anti-neutrophil Cytoplasmic Antibody-related Rapidly Progressive Glomerulonephritis

A 65-year-old man with valvular disorder presented to his physician because of widespread purpura in both lower extremities. Blood tests showed elevated serum creatinine levels and proteinase 3-anti-neutrophil cytoplasmic antibody (ANCA) with hematuria, suggesting ANCA-related rapidly progressive glomerulonephritis (RPGN). Although multiple blood cultures were negative, transthoracic echocardiography revealed warts in the valves, and a renal biopsy also showed findings of glomerular infiltration by mononuclear leukocytes and C3 deposition in the glomeruli, suggesting infection-related glomerulonephritis. Later, Bartonella antibody turned positive. Antimicrobial treatment improved the purpura and renal function without any recurrence. ANCA-positive RPGN requires the exclusion of infective endocarditis, especially that induced by Bartonella spp.

Costal osteomyelitis due to Bartonella henselae in a 10-year-old girl

Bartonella henselae is the bacterial agent responsible for cat scratch disease. This infection is frequently the cause of localized lymphadenitis in children. It is also sometimes responsible for endocarditis, encephalitis, hepatic peliosis and in rare cases osteomyelitis. We describe the second known case of unifocal thoracic osteomyelitis in a 10-year-old child.

From Genome to Drugs: New Approaches in Antimicrobial Discovery

Decades of successful use of antibiotics is currently challenged by the emergence of increasingly resistant bacterial strains. Novel drugs are urgently required but, in a scenario where private investment in the development of new antimicrobials is declining, efforts to combat drug-resistant infections become a worldwide public health problem. Reasons behind unsuccessful new antimicrobial development projects range from inadequate selection of the molecular targets to a lack of innovation. In this context, increasingly available omics data for multiple pathogens has created new drug discovery and development opportunities to fight infectious diseases. Identification of an appropriate molecular target is currently accepted as a critical step of the drug discovery process. Here, we review how diverse layers of multi-omics data in conjunction with structural/functional analysis and systems biology can be used to prioritize the best candidate proteins. Once the target is selected, virtual screening can be used as a robust methodology to explore molecular scaffolds that could act as inhibitors, guiding the development of new drug lead compounds. This review focuses on how the advent of omics and the development and application of bioinformatics strategies conduct a "big-data era" that improves target selection and lead compound identification in a cost-effective and shortened timeline.

Antibiotic Susceptibility of Bartonella Grown in Different Culture Conditions

Bartonellosis is caused by a Gram-negative intracellular bacterium with a zoonotic transmission. The disease, caused by any of several genospecies of Bartonella can range from a benign, self-limited condition to a highly morbid and life-threatening illness. The current standard of care antibiotics are generally effective in acute infection; these include azithromycin or erythromycin, doxycycline, gentamicin, rifampin, and ciprofloxacin. However, treatment of chronic infection remains problematic. We tested six different antibiotics for their ability to stop the growth of Bartonella sp. in the standard insect media and in an enrichment media. All antibiotics (ceftriaxone, doxycycline, gentamycin, azithromycin, ampicillin, and azlocillin) had minimum inhibitory concentrations (MICs) below 0.5 µg/mL in the BAPGM enrichment media but were ineffective at inhibiting growth when the standard insect media was used. Azlocillin was the most potent, with a MIC of 0.01 µg/mL. When Bartonella was tested under intracellular growth conditions, none of the antibiotics were efficacious singly. However, growth inhibition was observed when azlocillin and azithromycin were combined. These studies illustrate the impact of growth medium and intracellular environment on antibiotic susceptibility testing and indicate that azlocillin combined with azithromycin may be an effective drug combination for the treatment of Bartonellosis.

Anorexia Nervosa Caused by Polymicrobial Tick-Borne Infections: A Case Study

The etiology of anorexia nervosa (AN) is multifactorial, and infections may play a contributory and possibly a prominent role. A case is presented which is indicative of a causal association between tick-borne infections and AN. This adolescent female was diagnosed with AN at an eating disorder clinic after excessive food restriction and an irrational fear of weight gain necessitating nasogastric tube feeding. Her history was consistent with systemic infections and she tested serologically positive to Borrelia burgdorferi, Babesia microti, and Mycoplasma pneumoniae; in addition, her clinical presentation was consistent with a Bartonella infection. After treatment with oral and intravenous antimicrobials, she stopped food restriction and no longer had body image concerns. Physicians should be aware of the possibility that tick-borne infections could underly a diagnosis of AN. The role of tick-borne infections in the etiology of AN warrants further study.

Disseminated bartonellosis in a child with steroid-dependent nephrotic syndrome receiving mycophenolate mofetil monotherapy

Cat scratch disease, usually a benign infectious disease, may develop as multisystem disease with multiorgan involvement, particularly in immunocompromised patients. We report on a patient who developed disseminated bartonellosis while receiving mycophenolate mofetil monotherapy treating steroid-dependent nephrotic syndrome, highlighting that severe infection can be observed in those patients. Therefore, this category of patients should be cautious when having contact with kittens and receives proper prevention advice.

Atypical bartonellosis in children: What do we know?

AIM

To characterise Bartonella infections in a paediatric population requiring hospital admission and review its treatment.

METHODS

Longitudinal observational retrospective data analysis of children and adolescents admitted with Bartonella infection at a paediatric tertiary hospital from 2010 to 2019.

RESULTS

We identified 16 cases of bartonellosis, with a mean age of 8.0 ± 4.5 years old, no sex predominance and 14 had contact with cats. Most of the cases occurred in fall and winter. Clinical presentations included osteomyelitis/arthritis (n = 9), hepatosplenic disease (n = 2), lymphadenitis (n = 2), neuroretinitis (n = 2) and encephalitis (n = 1). Clinical diagnosis was confirmed by serology (n = 16) and Bartonella DNA detection in patient's lymph nodes/hepatic lesion (n = 3). Therapeutic approach varied according to the clinical presentation: azithromycin in lymphadenitis, rifampicin plus ciprofloxacin in hepatosplenic disease, rifampicin and doxycycline in neuroretinitis, ceftriaxone in encephalitis and azithromycin, cotrimoxazole or rifampicin plus azithromycin, cefuroxime, ciprofloxacin or doxycycline in osteomyelitis/arthritis. Immunodeficiency was excluded in seven patients. Seven patients' cats were screened by veterinarians and treated when infected (n = 5).

CONCLUSIONS

In these clinical presentations, where other infections may be involved, a high index of suspicion is necessary, with emphasis on the epidemiological context. The association of systemic forms with immunodeficiency did not occur in our study. The lack of recommendations for treatment of atypical infection makes the approach of these cases a challenge. Randomised control studies are essential to define the best approach in each case.

A Case of Atypical Bartonellosis in a 4-Year-Old Immunocompetent Child

In most cases, infection due to Bartonella henselae causes a mild disease presenting with a regional lymphadenopathy frequently associated with a low-grade fever, headache, poor appetite and exhaustion that spontaneously resolves itself in a few weeks. As the infection is generally transmitted by cats through scratching or biting, the disease is named cat scratch disease (CSD). However, in 5–20% of cases, mainly in immunocompromised patients, systemic involvement can occur and CSD may result in major illness. This report describes a case of systemic CSD diagnosed in an immunocompetent 4-year-old child that can be used as an example of the problems that pediatricians must solve to reach a diagnosis of atypical CSD. Despite the child’s lack of history suggesting any contact with cats and the absence of regional lymphadenopathy, the presence of a high fever, deterioration of their general condition, increased inflammatory biomarkers, hepatosplenic lesions (i.e., multiple abscesses), pericardial effusion with mild mitral valve regurgitation and a mild dilatation of the proximal and medial portion of the right coronary artery, seroconversion for B. henselae (IgG 1:256) supported the diagnosis of atypical CSD. Administration of oral azithromycin was initiated (10 mg/kg/die for 3 days) with a progressive normalization of clinical, laboratory and US hepatosplenic and cardiac findings. This case shows that the diagnosis of atypical CSD is challenging. The nonspecific, composite and variable clinical features of this disease require a careful evaluation in order to achieve a precise diagnosis and to avoid both a delayed diagnosis and therapy with a risk of negative evolution.

What Is in a Cat Scratch? Growth of Bartonella henselae in a Biofilm

Bartonella henselae (B. henselae) is a gram-negative bacterium that causes cat scratch disease, bacteremia, and endocarditis, as well as other clinical presentations. B. henselae has been shown to form a biofilm in vitro that likely plays a role in the establishment and persistence of the bacterium in the host. Biofilms are also known to form in the cat flea vector; hence, the ability of this bacterium to form a biofilm has broad biological significance. The release of B. henselae from a biofilm niche appears to be important in disease persistence and relapse in the vertebrate host but also in transmission by the cat flea vector. It has been shown that the BadA adhesin of B. henselae is critical for adherence and biofilm formation. Thus, the upregulation of badA is important in initiating biofilm formation, and down-regulation is important in the release of the bacterium from the biofilm. We summarize the current knowledge of biofilm formation in Bartonella species and the role of BadA in biofilm formation. We discuss the evidence that defines possible mechanisms for the regulation of the genes required for biofilm formation. We further describe the regulation of those genes in the conditions that mimic both the arthropod vector and the mammalian host for B. henselae. The treatment for persistent B. henselae infection remains a challenge; hence, a better understanding of the mechanisms by which this bacterium persists in its host is critical to inform future efforts to develop drugs to treat such infections.

Systemic Cat-Scratch Disease: a "Troublesome" Diagnosis

Diagnosis of systemic cat scratch disease may be challenging. Here, we describe a case of an immunocompetent girl exhibiting fever and multifocal hepatosplenic abscesses. Diagnostic tests for Bartonella henselae infection (enzyme immunoassay and polymerase chain reaction) were found steadily negative and the diagnosis, suspected on the basis of the Margilet's criteria, was finally confirmed by indirect immunofluorescent antibodies.

Bacterial membrane vesicles from Acinetobacter baumannii induced by ceftazidime are more virulent than those induced by imipenem

Patients with Acinetobacter baumannii bacteremia treated with antipseudomonal cephalosporins showed higher 14-day mortality than patients treated with antipseudomonal carbapenems. We hypothesized that the bacterial membrane vesicles (BMVs) induced by antipseudomonal cephalosporins are more virulent than BMVs induced by antipseudomonal carbapenems.

To simulate the clinical condition with inadequate antimicrobial treatment, carbapenem-resistant A. baumannii was treated with ceftazidime (an antipseudomonal cephalosporin) or imipenem (an antipseudomonal carbapenem) at 1/2 the minimum inhibitory concentration. BMVs and BMV-carried lipopolysaccharide were measured by nanoparticle tracking analysis and western blotting, respectively. Cytokine expression in RAW264.7 macrophages or mice serum induced by the BMVs was determined by ELISA, fluorescent bead-based immunoassay or western blotting. The virulence of the BMVs was assessed in mice. Liquid chromatography tandem-mass spectrometry was used to determine the protein contents of the BMVs.

We found that ceftazidime induced a higher number of BMVs (CAZ-BMV), which carried more LPS, and induced higher expression levels of iNOS, IL-1β, and IL-6 in macrophages, higher expression of many cytokines in mice, more neutrophil infiltration in lung interstitium, and higher mortality in mice than imipenem-induced BMVs (IMP-BMV). When adjusted to same amount of LPS, CAZ-BMV still led to higher mortality than IMP-BMV. Proteomic analysis revealed different protein contents in CAZ-BMV and IMP-BMV. In conclusion, A. baumannii BMVs induced by ceftazidime are more virulent than BMVs induced by imipenem.

Multiple ocular manifestations in a case of cat scratch disease without systemic signs

A 43-year-old woman presented with impaired vision and redness in her left eye of 2 weeks duration. She had a pet cat that scratched her forehead 3 weeks before she presented to us. She had no systemic signs such as lymphadenopathy, fever, or fatigue. The respective right and left corrected visual acuities were 20/16 and 20/2000. The anterior chamber of the left eye exhibited inflammation; a fundus examination of that eye revealed optic disc swelling and a serous macular detachment with hard stellate exudates. Based on the recent cat scratch and the ocular findings, cat scratch disease (CSD) was suspected. The results of serologic testing showed elevated titres of IgM and IgG antibodies to Bartonella henselae. Administration of doxycycline and a steroid was initiated. This report describes the occurrence of multiple ocular manifestations of CSD in both the posterior and the anterior segment.

Bartonella osteomyelitis versus vertebral sarcoidosis: A tale of two cases

BACKGROUND

Osteomyelitis is an uncommon manifestation of Bartonella henselae. Similarly, bony involvement may occur with sarcoidosis. Even though these are pathologically distinct entities, they can have overlapping imaging manifestations and therefore mimic one another. This is further complicated by the fact that both entities show non-caseating granulomatous inflammation on histopathology. We present two cases with similar imaging findings, with one case eventually diagnosed as Bartonella osteomyelitis, while the other proved to be vertebral sarcoidosis. Both patients exhibited vertebral involvement in common, and improved clinically and radiographically following antibiotics and steroids treatment, respectively. Given the overlapping pathological and imaging manifestations, and the non-specific clinical presentation, these entities may be considered in the differential consideration of each other. The presence of associated findings in such cases may be helpful.

Bartonella quintana infective endocarditis in northern Alberta: A case report

We present a case of Bartonella quintana infective endocarditis requiring valvular surgery in an Indigenous patient from northern Alberta that was identified months after initial presentation to hospital with undifferentiated laboratory abnormalities. Syndromes caused by B. quintana are often challenging to diagnose due to their non-specific presentation and the difficulty in detecting this organism using traditional culture methods. Additionally, risk factors for B. quintana include marginal housing and alcohol use disorder, which often impede access to health care. Indigenous patients in northern Canada often face worse health outcomes compared with other regions owing to poor economic conditions, substandard housing, and limited access to health care resources. Given that risk factors for B. quintana are prevalent throughout northern Canada and that this infection is difficult to diagnose, we surmise that the prevalence of B. quintana infection is underestimated in northern Canada.

The clinical spectrum of ocular bartonellosis: a retrospective study at a tertiary centre in Malaysia

BACKGROUND

Cat scratch disease (CSD) is a systemic illness caused by the gram-negative bacillus, Bartonella henselea, which can occasionally involve the ocular structures. The objective of this study is to evaluate the various clinical presentations of ocular bartonellosis at our institution. A retrospective review of the clinical records of 13 patients (23 eyes) with ocular manifestations of Bartonella infections over a 3-year period between January 2016 to December 2018 was undertaken at our institution.

RESULTS

The diagnosis was made based on clinical findings and in addition, with the support of the evidence of Bartonella hensalae IgG and/or IgM. Small retinal white lesions were the most common ocular findings in this series of patients (82.6% of eyes, 76.9% of patients). Neuroretinitis was the second most common finding (47.8% of eyes, 69.2% of patients), followed by exudative retinal detachment involving the macula (34.8% of eyes, 53.8% of patients) and Parinaud's oculoglandular syndrome (17.4% of eyes, 23.1% of patients). Other findings like isolated optic disc oedema without macular star (8.7% of eyes, 15.4% of patients) and vitritis (4.3% of eyes, 7.7% of patients) were also observed. Ten patients (76.9%) had bilateral ocular involvement. Most of the patients were young, immunocompetent and had systemic symptoms like fever prior to their ocular symptoms. The visual acuity (VA) at initial presentation ranged from 6/6 to hand movement (mean, 6/20), and at final visit 6/6 to 6/60, (mean, 6/9). 91.7% of patients were treated with antibiotics. Only 2 patients received oral corticosteroids together with antibiotics due to very poor vision on presentation. The visual prognosis of ocular bartonellosis is generally good with 16 (88.9%) of 23 eyes having VA of 6/12 or better at final follow-up visit.

CONCLUSION

Small foci of retinal white lesions were the most common manifestation of ocular bartonellosis in this series, followed by neuroretinitis, though an array of other ocular findings may also occur. Therefore, we should consider bartonella infection as a possible differential diagnosis in those patients.

Antimicrobial guide to posterior segment infections

PURPOSE

This review article is meant to serve as a reference guide and to assist the treating physician in making an appropriate selection and duration of an antimicrobial agent.

METHODS

Literature review.

RESULTS

Infections of the posterior segment require prompt medical or surgical therapy to reduce the risk of permanent vision loss. While numerous options exist to treat these infections, doses and alternative therapies, especially with contraindications for first-line therapy, are often elusive. Antimicrobial agents to treat posterior segment infections can be administered via various routes, including topical, intravitreal, intravenous, and oral.

CONCLUSIONS

Although there are many excellent review articles on the management of endophthalmitis, we take the opportunity in this review to comprehensively summarize the appropriate antimicrobial regimen of both common and rare infectious etiologies of the posterior segment, using evidence from clinical trials and large case series.

Bartonella henselae infection induces a persistent mechanical hypersensitivity in mice

Bartonella spp. are re-emerging and neglected bacterial pathogens. The natural reservoirs for several species of this genus are domestic animals such as cats and dogs, the most common pets in the USA and Brazil. Some cat studies suggest that the infection is more prevalent in tropical and poverty-stricken areas. These bacteria were associated with a wide spectrum of clinical manifestations: fever of unknown origin, endocarditis, angiomatosis, chronic lymphadenopathy, hepatitis, fatigue, paresthesia and pain. Our group has already demonstrated that B. henselae -infected sickle cell disease mice present with hyperalgesia. We hypothesized that even immunocompetent mice infected by B. henselae would show an increased and persistent mechanical sensitivity. Five ten-week old male BALB/c mice were intraperitoneally inoculated with a 30 µL of suspension containing 10 4 CFU/mL of B. henselae, while five others were inoculated with an equal volume of saline solution. Four days after bacterial inoculation, the mechanical paw withdrawal threshold was measured using von Frey filaments in all animals, for five consecutive days. The infected animals showed hypersensitivity to mechanical stimuli for five consecutive days. The present study has demonstrated that B. henselae infection induces persistent mechanical hypersensitivity, a signal consistent with pain.

Cat-scratch Disease in the Pediatric Population: 6 Years of Evaluation and Follow-up in a Public Hospital in Chile

BACKGROUND

Bartonella henselae is the etiologic agent of cat-scratch disease, which affects the entire world population. Due to how poorly characterized the child population is, the objective was to describe the clinical behavior of this disease in children younger than 16 years of age.

METHODS

This was a descriptive study with prospective follow-up of all children younger than 16 years with clinical and serologic diagnoses between 2013 and 2018.

RESULTS

There were 142 patients; of these, 55.6% had localized disease, 34.5% disseminated with hepatosplenic involvement and 9.8% had atypical disease. The cases of atypical disease were prolonged febrile illness, Parinaud syndrome, subacute bacterial endocarditis/glomerulonephritis and aseptic meningitis. Cervical lymphadenopathy was the most frequent, followed by inguinal adenopathy. There were no differences between the type of manifestation and laboratory values except for a higher erythrocyte sedimentation rate tendency in patients with disseminated and/or atypical disease. The serologic titers throughout were distributed as follows: titer of 1/1024, 71.7%; titer of 1/512, 10.4% and titer of 1/256, 17.9%.

CONCLUSIONS

This is, to our knowledge, the largest series of cat-scratch disease published. We demonstrate that in our environment, the inguinal location is suggestive of this disease, the disseminated presentation, frequent, and that the titers are probably much higher than in other populations, which perhaps indicates the need to re-examine the cut-off point for positivity.

Performance and Application of 16S rRNA Gene Cycle Sequencing for Routine Identification of Bacteria in the Clinical Microbiology Laboratory

This review provides a state-of-the-art description of the performance of Sanger cycle sequencing of the 16S rRNA gene for routine identification of bacteria in the clinical microbiology laboratory. A detailed description of the technology and current methodology is outlined with a major focus on proper data analyses and interpretation of sequences. The remainder of the article is focused on a comprehensive evaluation of the application of this method for identification of bacterial pathogens based on analyses of 16S multialignment sequences. In particular, the existing limitations of similarity within 16S for genus- and species-level differentiation of clinically relevant pathogens and the lack of sequence data currently available in public databases is highlighted. A multiyear experience is described of a large regional clinical microbiology service with direct 16S broad-range PCR followed by cycle sequencing for direct detection of pathogens in appropriate clinical samples. The ability of proteomics (matrix-assisted desorption ionization-time of flight) versus 16S sequencing for bacterial identification and genotyping is compared. Finally, the potential for whole-genome analysis by next-generation sequencing (NGS) to replace 16S sequencing for routine diagnostic use is presented for several applications, including the barriers that must be overcome to fully implement newer genomic methods in clinical microbiology. A future challenge for large clinical, reference, and research laboratories, as well as for industry, will be the translation of vast amounts of accrued NGS microbial data into convenient algorithm testing schemes for various applications (i.e., microbial identification, genotyping, and metagenomics and microbiome analyses) so that clinically relevant information can be reported to physicians in a format that is understood and actionable. These challenges will not be faced by clinical microbiologists alone but by every scientist involved in a domain where natural diversity of genes and gene sequences plays a critical role in disease, health, pathogenicity, epidemiology, and other aspects of life-forms. Overcoming these challenges will require global multidisciplinary efforts across fields that do not normally interact with the clinical arena to make vast amounts of sequencing data clinically interpretable and actionable at the bedside.

Prioritisation of potential drug targets against Bartonella bacilliformis by an integrative in-silico approach

BACKGROUND Carrion's disease (CD) is a neglected biphasic illness caused by Bartonella bacilliformis, a Gram-negative bacteria found in the Andean valleys. The spread of resistant strains underlines the need for novel antimicrobials against B. bacilliformis and related bacterial pathogens. OBJECTIVE The main aim of this study was to integrate genomic-scale data to shortlist a set of proteins that could serve as attractive targets for new antimicrobial discovery to combat B. bacilliformis. METHODS We performed a multidimensional genomic scale analysis of potential and relevant targets which includes structural druggability, metabolic analysis and essentiality criteria to select proteins with attractive features for drug discovery. FINDINGS We shortlisted seventeen relevant proteins to develop new drugs against the causative agent of Carrion's disease. Particularly, the protein products of fabI, folA, aroA, trmFO, uppP and murE genes, meet an important number of desirable features that make them attractive targets for new drug development. This data compendium is freely available as a web server (http://target.sbg.qb.fcen.uba.ar/). MAIN CONCLUSION This work represents an effort to reduce the costs in the first phases of B. bacilliformis drug discovery.

Disseminated Cat Scratch Disease in Pediatric Patients in Hawai'i

Cat scratch disease is known to be a generally benign, self-resolving illness associated with non-specific symptoms, including lymphadenopathy, fever, fatigue, anorexia, and headaches. However, it can also cause disseminated disease with a wide range of manifestations, including liver and spleen microabscesses, osteomyelitis, encephalitis, and uveitis. Eighteen pediatric cases of disseminated cat scratch disease at a single center in Hawai'i are described. This case series emphasizes the importance of disease recognition and use of appropriate diagnostic tools and disease management. The disease burden of pediatric patients with disseminated cat scratch disease in the state of Hawai'i has a high incidence and should be considered in pediatric patients with prolonged febrile illnesses.

Effect of different drugs and drug combinations on killing stationary phase and biofilms recovered cells of Bartonella henselae in vitro

BACKGROUND

Bartonella henselae is a Gram-negative bacterium transmitted to humans by a scratch from cat in the presence of ectoparasites. Humans infected with B. henselae can result in various clinical diseases including local lymphadenopathy and more serious systemic disease such as persistent bacteremia and endocarditis. The current treatment of persistent B. henselae infections is not very effective and remains a challenge. To find more effective treatments for persistent and biofilm Bartonella infections, in this study, we evaluated a panel of drugs and drug combinations based on the current treatment and also promising hits identified from a recent drug screen against stationary phase and biofilm recovered cells of B. henselae.

RESULTS

We evaluated 14 antibiotics and 25 antibiotic combinations for activity against stationary phase B. henselae (all antibiotics were at 5 μg/ml) and found that ciprofloxacin, gentamicin, and nitrofurantoin were the most active agents, while clofazimine and miconazole had poor activity. Drug combinations azithromycin/ciprofloxacin, azithromycin/methylene blue, rifampin/ciprofloxacin, and rifampin/methylene blue could rapidly kill stationary phase B. henselae with no detectable CFU after 1-day exposure. Methylene blue and rifampin were the most active agents against the biofilm B. henselae after 6 days of drug exposure. Antibiotic combinations (azithromycin/ciprofloxacin, azithromycin/methylene blue, rifampin/ciprofloxacin, rifampin/methylene blue) completely eradicated the biofilm B. henselae after treatment for 6 days.

CONCLUSIONS

These findings may facilitate development of more effective treatment of persistent Bartonella infections in the future.

Management of Intraocular Infections in HIV

Purpose: Overview of treatment options for the most common intraocular opportunistic infections in patients with acquired immunodeficiency syndrome (AIDS), including ocular syphilis, ocular tuberculosis, toxoplasmic chorioretinitis, and viral retinitis. Method: Narrative Review. Results: Despite the huge advances in the development of combined antiretroviral therapy (cART) for the management of patients with human immunodeficiency virus (HIV) infection, opportunistic infections still represent a significant diagnostic dilemma and cause of ocular morbidity in patients with HIV. Conclusion: Although the treatment of intraocular infections in patients with AIDS may be challenging, prompt assessment of the clinical features and appropriate aggressive management of the underlying etiology are critical to avoid life and vision threatening.

Is Bartonella a Cause of Primary Sclerosing Cholangitis? A Case Study

The etiology of primary sclerosing cholangitis (PSC) is unknown. I present a case which may be indicative of a causal link between Bartonella infection and PSC. The patient presented with complaints of abdominal pain and bloody diarrhea. A colonoscopy demonstrated chronic inflammation and changes consistent with ulcerative colitis. Routine laboratory studies revealed elevated liver function tests (LFTs); ultrasound and magnetic resonance imaging (MRI) confirmed the diagnosis of PSC. Bartonella serology was positive. It is established that Bartonella infection is associated with both gastrointestinal inflammation and autoimmunity; indeed, there is an animal model for Bartonella-induced PSC. Bartonella is susceptible to treatment with vancomycin and there are case reports and small series that demonstrate that PSC responds to treatment with oral vancomycin. Because of this, it is postulated that at least some cases of PSC may be associated with Bartonella infection. The patient in this report was treated with oral vancomycin and, since then, has been in remission for both colitis and PSC. Since vancomycin is not systemically absorbed, the premise is that he suffered from Bartonella colitis and an autoimmune reaction to Bartonella causing PSC. This premise warrants further study.

Case Report: Bartonella quintana Endocarditis Outside of the Europe-African Gradient: Comprehensive Review of Cases within North America

Clinical syndromes associated with Bartonella quintana infection can be insidious and difficult to diagnose for multiple reasons. Clinically, B. quintana can manifest as asymptomatic bacteremia or with subtle subacute constitutional symptoms. Second, it is a fastidious organism that is difficult to identify using traditional culture methods. Last, the body lice vector of B. quintana transmission is likely not uncommon in most patients affected, who are homeless and of low socioeconomic status. Therefore, barriers in seeking medical care and financial constraints for medications are important considerations. The mainstay of literature surrounding B. quintana endocarditis is from Europe and the developing nations. Herein, we describe a case of native valve endocarditis secondary to B. quintana in a homeless male with preexisting valvular disease and undertake a comprehensive literature review of documented B. quintana endocarditis in North America.

Detection of Bartonella spp. in dogs after infection with Rickettsia rickettsii

Background

Dynamics of infection by Bartonella and Rickettsia species, which are epidemiologically associated in dogs, have not been explored in a controlled setting.

Objectives

Describe an outbreak investigation of occult Bartonella spp. infection among a group of dogs, discovered after experimentally induced Rickettsia rickettsii (Rr) infection.

Animals

Six apparently healthy purpose‐bred Beagles obtained from a commercial vendor.

Methods

Retrospective and prospective study. Dogs were serially tested for Bartonella spp. and Rr using serology, culture, and PCR, over 3 study phases: 3 months before inoculation with Rr (retrospective), 6 weeks after inoculation with Rr (retrospective), and 8 months of follow‐up (prospective).

Results

Before Rr infection, 1 dog was Bartonella henselae (Bh) immunofluorescent antibody assay (IFA) seroreactive and 1 was Rickettsia spp. IFA seroreactive. After inoculation with Rr, all dogs developed mild Rocky Mountain spotted fever compatible with low‐dose Rr infection, seroconverted to Rickettsia spp. within 4‐11 days, and recovered within 1 week. When 1 dog developed ear tip vasculitis with intra‐lesional Bh, an investigation of Bartonella spp. infection was undertaken. All dogs had seroconverted to 1‐3 Bartonella spp. between 7 and 18 days after Rr inoculation. Between 4 and 8 months after Rr inoculation, Bh DNA was amplified from multiple tissues from 2 dogs, and Bartonella vinsonii subsp. berkhoffii (Bvb) DNA was amplified from 4 of 5 dogs' oral swabs.

Conclusions and Clinical Importance

Vector‐borne disease exposure was demonstrated in research dogs from a commercial vendor. Despite limitations, our results support the possibilities of recrudescence of chronic subclinical Bartonella spp. infection after Rr infection and horizontal direct‐contact transmission between dogs.

B artonella endocarditis masquerading as systemic vasculitis with rapidly progressive glomerulonephritis (aka 'Löhlein nephritis')

Bartonella species are fastidious, Gram-negative aerobic rods and a well-recognised pathogen responsible for culture-negative endocarditis. The histopathological appearance of glomerulonephritis (GN) caused by Bartonella endocarditis may include a pauci-immune GN similar to that usually seen in antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis. Herein, we present an unusual case report of Bartonella endocarditis masquerading as ANCA-positive vasculitis, with crescentic GN. A 66-year-old woman, who had undergone aortic valve replacement 2 years prior to admission, presented with confusion and loss of vision in her right nasal field. Following an extensive diagnostic evaluation, the main findings were right central retinal artery occlusion, ground-glass appearance on chest CT and ANCA-positive, anti PR-3 negative, rapidly progressive GN. The patient was scheduled to start treatment with rituximab for presumed ANCA-positive GN, when a positive serological test for Bartonella henselae was received. In view of this result, a diagnosis of endocarditis was made, based on fulfilment of five Duke minor criteria, namely fever, predisposition, arterial emboli, immunological phenomena and serological evidence of active infection with an organism consistent with infective endocarditis. Immunosuppressive treatment was withheld and antibiotic treatment initiated. This case report emphasises the need for maintaining a high index of suspicion regarding the diagnosis of Bartonella infection, which might mimic ANCA-associated GN.

Essential Oils with High Activity against Stationary Phase Bartonella henselae

Bartonella henselae is a fastidious Gram-negative intracellular bacterium that can cause cat scratch disease, endocarditis in humans and animals, as well as other complications, leading to acute or chronic infections. The current treatment for Bartonella infections is not very effective due to antibiotic resistance and also persistence. To develop better therapies for persistent and chronic Bartonella infections, in this study, with the help of SYBR Green I/PI viability assay, we performed a high-throughput screening of an essential oil library against the stationary phase B. henselae. We successfully identified 32 essential oils that had high activity, including four essential oils extracted from Citrus plants, three from Origanum, three from Cinnamomum, two from Pelargonium, and two from Melaleuca, as well as frankincense, ylang-ylang, fir needle, mountain savory (winter), citronella, spearmint, elemi, vetiver, clove bud, allspice, and cedarwood essential oils. The minimal inhibitory concentration (MIC) determination of these 32 top hits indicated they were not only active against stationary phase non-growing B. henselae but also had good activity against log-phase growing B. henselae. The time-kill assay showed 13 active hits, including essential oils of oregano, cinnamon bark, mountain savory (winter), cinnamon leaf, geranium, clove bud, allspice, geranium bourbon, ylang-ylang, citronella, elemi, and vetiver, could eradicate all stationary phase B. henselae cells within seven days at the concentration of 0.032% (v/v). Two active ingredients, carvacrol and cinnamaldehyde, of oregano and cinnamon bark essential oils, respectively, were shown to be very active against the stationary phase B. henselae such that they were able to eradicate all the bacterial cells even at the concentration ≤ 0.01% (v/v). More studies are needed to identify the active components of some potent essential oils, decode their antimicrobial mechanisms, and evaluate their activity against Bartonella infections in animal models.

Bacillary angiomatosis triggered by severe trauma in a healthy Caucasian patient: A case report

Bacillary angiomatosis represents a cutaneous and systemic infection caused by Bartonella species, typically described in the past in HIV-positive patients or associated with immunodeficiencies. More recent case reports had brought into attention the probability that this entity may manifest in otherwise healthy individuals, triggered by trauma and skin burns. The physiopathology of this neoproliferative process is based on the production of angiogenetic molecules, such as vascular endothelial growth factor (VEGF) and IL-8. In case of an inadequate treatment, the evolution can be fatal, with a systemic dissemination of the abscesses within the gastro-intestinal tract, respiratory tract, brain and bones. The appropriate therapy is with oral erythromycin and doxycycline, but several treatments such as cephalosporins, penicillins, macrolides, aminoglycosides, rifampin, dapsone, ciprofloxacin, have been tried with favorable results. Herein we present the case of a Caucasian patient, seronegative for HIV, who developed multiple vascular papules and nodules on the face, after a severe trauma and which healed after an adequate antibiotic therapy with oral clarithromycin.

Multifocal pelvic osteomyelitis in a child associated with cat-scratch disease: a case report and review of the literature

Bone infections in cat-scratch disease (CSD) are uncommon and the diagnosis can be missed. A 3-year-old boy with multifocal pelvic osteomyelitis caused by Bartonella henselae is reported. Serological tests were negative but DNA was detected by polymerase chain reaction assay of a lymph node. A swift recovery followed antibiotic treatment and there was completeresolution within a few months. The literature on 64 cases of osteomyelitis owing to CSD in children and adults since 1954 is reviewed.

A "Cat"-astrophic Case of Bartonella henselae infective endocarditis followed by cardiac transplantation salvage therapy

To our knowledge, no cases of Bartonella henselae endocarditis leading to subsequent heart transplantation salvage therapy have been published. We present a case of a 29-year-old man with cat-inflicted B henselae endocarditis and concurrent worsening heart failure, who then underwent successful heart transplantation 50 days following diagnosis. Treatment and monitoring strategies used in this patient are discussed. Furthermore, we review literature related to heart transplantation salvage therapy for endocarditis due to other intracellular pathogens.

Bartonella henselae bacteremia diagnosed post-mortem in a myelodysplastic syndrome patient

This study involves a 49-year-old male, who for three years suffered with a myelodysplastic syndrome and who needed frequent blood transfusions. One day following a transfusion, he presented fever and abdominal pain. The fever became persistent and only improved temporarily with two cycles of intravenous ciprofloxacin. Nearly 120 days after beginning the second cycle of treatment, he had experienced a weight loss of 16 kg and recurring fever. Screening for fever of unknown origin was conducted, including Bartonella infection. No etiology could be found. The patient improved with an antimicrobial regimen composed of oral doxycycline and intravenous ciprofloxacin. After 15 days afebrile, the patient was discharged with a four-month oral prescription of doxycycline and ciprofloxacin. Eight months following the antibiotic treatment, the patient received an allogeneic bone marrow transplant. Five days following the transplant, the patient initiated a febrile neutropenia and died. From a blood sample collected and stored at the time of hospitalization, a microbiological and molecular study was performed again. Blood- and liquid culture-PCRs from the same blood sample were all negative, but an isolate from solid subculture was found. The molecular reactions from this isolate were all positive and the sequence was 100% homologous to Bartonella henselae . The present report points to the limitations of laboratory techniques currently available for investigation of possible cases of bartonellosis in clinical practice, and the potential risk of Bartonella spp. transmission through blood transfusions.

Cutaneous manifestations of bartonellosis

Bartonellosis are diseases caused by any kind of Bartonella species. The infection manifests as asymptomatic bacteremia to potentially fatal disorders. Many species are pathogenic to humans, but three are responsible for most clinical symptoms: Bartonella bacilliformis, Bartonella quintana, and Bartonella henselae. Peruvian wart, caused by B. bacilliformis, may be indistinguishable from bacillary angiomatosis caused by the other two species. Other cutaneous manifestations include maculo-papular rash in trench fever, papules or nodules in cat scratch disease, and vasculitis (often associated with endocarditis). In addition, febrile morbilliform rash, purpura, urticaria, erythema nodosum, erythema multiforme, erythema marginatus, granuloma annularis, leukocytoclastic vasculitis, granulomatous reactions, and angioproliferative reactions may occur. Considering the broad spectrum of infection and the potential complications associated with Bartonella spp., the infection should be considered by physicians more frequently among the differential diagnoses of idiopathic conditions. Health professionals and researchers often neglected this diseases.

An account of in silico identification tools of secreted effector proteins in bacteria and future challenges

Bacterial pathogens secrete numerous effector proteins via six secretion systems, type I to type VI secretion systems, to adapt to new environments or to promote virulence by bacterium-host interactions. Many computational approaches have been used in the identification of effector proteins before the subsequent experimental verification because they tolerate laborious biological procedures and are genome scale, automated and highly efficient. Prevalent examples include machine learning methods and statistical techniques. In this article, we summarize the computational progress toward predicting secreted effector proteins in bacteria, with an opening of an introduction of features that are used to discriminate effectors from non-effectors. The mechanism, contribution and deficiency of previous developed detection tools are presented, which are further benchmarked based on a curated testing data set. According to the results of benchmarking, potential improvements of the prediction performance are discussed, which include (1) more informative features for discriminating the effectors from non-effectors; (2) the construction of comprehensive training data set of the machine learning algorithms; (3) the advancement of reliable prediction methods and (4) a better interpretation of the mechanisms behind the molecular processes. The future of in silico identification of bacterial secreted effectors includes both opportunities and challenges.

Identification of FDA-Approved Drugs with Activity against Stationary Phase Bartonella henselae

Bartonella henselae can cause various infections in humans, ranging from benign and self-limiting diseases to severe and life-threatening diseases as well as persistent infections that are difficult to treat. To develop more effective treatments for persistent Bartonella infections, in this study, we performed a high-throughput screen of an FDA-approved drug library against stationary phase B. henselae using the SYBR Green I/propidium iodide (PI) viability assay. We identified 110 drug candidates that had better activity against stationary phase B. henselae than ciprofloxacin, and among the top 52 drug candidates tested, 41 drugs were confirmed by microscopy to have higher activity than the current frontline antibiotic erythromycin. The identified top drug candidates include pyrvinium pamoate, daptomycin, methylene blue, azole drugs (clotrimazole, miconazole, sulconazole, econazole, oxiconazole, butoconazole, bifonazole), aminoglycosides (gentamicin and streptomycin, amikacin, kanamycin), amifostine (Ethyol), antiviral Lopinavir/ritonavir, colistin, nitroxoline, nitrofurantoin, verteporfin, pentamidine, berberine, aprepitant, olsalazine, clinafloxacin, and clofoctol. Pyrvinium pamoate, daptomycin, methylene blue, clotrimazole, and gentamicin and streptomycin at their respective maximum drug concentration in serum (C_max) had the capacity to completely eradicate stationary phase B. henselae after 3-day drug exposure in subculture studies. While the currently used drugs for treating bartonellosis, including rifampin, erythromycin, azithromycin, doxycycline, and ciprofloxacin, had very low minimal inhibitory concentration (MIC) against growing B. henselae, they had relatively poor activity against stationary phase B. henselae, except aminoglycosides. The identified FDA-approved agents with activity against stationary phase B. henselae should facilitate development of more effective treatments for persistent Bartonella infections.

Disseminated Bartonella henselae disease mimicking Langerhans' cell histiocytosis

Bartonella henselae, the causative agent of cat-scratch disease, has been recognized to be responsible for a broad range of clinical syndromes. We report the case of a patient with disseminated B. henselae infection mimicking Langerhans cell histiocytosis at presentation and its successful management with neurosurgery, prolonged antibacterial therapy, and observation.