Managing iron supply during the infection cycle of a flea borne pathogen, Bartonella henselae

Blood Supplementation Enhances Bartonella henselae Growth and Molecular Detection of Bacterial DNA in Liquid Culture

Bacteria of the genus Bartonella, a member of the Alphaproteobacteria, are fastidious, Gram-negative, aerobic bacilli that comprise numerous species, subspecies, and genotypes. Bartonella henselae, with a worldwide distribution, infects cats, dogs, horses, humans, and other mammals. Diagnostically, direct detection of Bartonella henselae in patient blood specimens by culture or molecular methods is required to confirm infection with this bacterium. Enrichment blood culture combined with quantitative PCR (qPCR) or ddPCR enhances the sensitivity of direct detection. The addition of sheep blood to liquid culture media increased the Bartonella henselae DNA concentration compared to controls, additionally improving PCR direct detection sensitivity. IMPORTANCE This study aims to improve diagnostic detection of Bartonella henselae. Patient samples are combined with enriched bacterial cultures aimed at growing Bartonella henselae for the best possible chance at detection. However, current Bartonella growth methods could be improved. The DNA extraction method used by most laboratories should also be optimized. Sheep blood was added to increase the growth of Bartonella henselae and multiple DNA extraction methods were to be compared to each other.

Advancements in understanding the molecular and immune mechanisms of Bartonella pathogenicity

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

An overview of bats microbiota and its implication in transmissible diseases

Recent pandemic events have raised the attention of the public on the interactions between human and environment, with particular regard to the more and more feasible transmission to humans of micro-organisms hosted by wild-type species, due to the increasing interspecies contacts originating from human’s activities. Bats, due to their being flying mammals and their increasing promiscuity with humans, have been recognized as hosts frequently capable of transmitting disease-causing microorganisms. Therefore, it is of considerable interest and importance to have a picture as clear as possible of the microorganisms that are hosted by bats. Here we focus on our current knowledge on bats microbiota. We review the most recent literature on this subject, also in view of the bat’s body compartments, their dietary preferences and their habitat. Several pathogenic bacteria, including many carrying multidrug resistance, are indeed common guests of these small mammals, underlining the importance of preserving their habitat, not only to protect them from anthropogenic activities, but also to minimize the spreading of infectious diseases.

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.

The Detection of Hemin-Binding Proteins in Riemerella anatipestifer CH-1

Riemerella anatipestifer (R. anatipestifer) is among the most prevalent duck pathogens, causing acute or chronic septicemia characterized by serositis. Riemerella anatipestifer can be grown on blood-enriched media, in vitro, which provides a hemin source essential for the sustainment of R. anatipestifer and activation of hemin-uptake systems. However, the genes associated with hemin uptake cannot be identified exclusively through genome sequence analysis. Here, we show that R. anatipestifer encodes outer-membrane hemin-binding proteins. Hemin-binding proteins were identified in the cytoplasm with apparent molecular mass of ~45/37/33/23/20/13 kDa, and outer membrane with apparent molecular mass of ~90/70/60/50/15 kDa by batch affinity chromatography and hemin-blotting assays. Our results indicate that these proteins are involved in hemin acquisition. Finally, hemin-binding assay further showed that R. anatipestifer can bind hemin and this capability is increased in iron limited medium, indicating the hemin-uptake system of R. anatipestifer was regulated by iron.

[Bartonella henselae vertebral osteomyelitis: report of a case]

Cat scratch disease (CSD) is caused by Bartonella henselae, with unknown prevalence and incidence in the Chilean paediatric population. Regional lymphadenopathy is the most common presentation, while atypical forms constitute a diagnostic challenge.

OBJECTIVE

To report a case of CSD with osteomyelitis and present guidelines regarding treatment.

CLINICAL CASE

An eight year-old patient, with prolonged febrile illness, back pain and neck stiffness. Laboratory studies highlight positive IgG for Bartonella henselae. The abdominal ultrasound showed splenic micro-abscesses, and the MRI showing vertebral lesions suggestive of osteomyelitis.

DISCUSSION

The diagnosis of atypical forms requires a high rate of suspicion, as in this case, in which the patient manifested the musculoskeletal symptoms simultaneously with the febrile syndrome, which led us to study possible complications of the disease. Current knowledge of the treatment of atypical or complicated CSD is derived from the observation of case studies, rather than randomized trials. It is suggested that antibiotic therapy is analysed individually, with the help of a specialist.

CONCLUSION

The importance of high clinical suspicion are emphasised and discussed, as well presenting some treatment options based on the evidence from the current literature.