''Bartonella henselae'', formerly ''Rochalimæa henselae'', is a

bacterium Bacteria (; : bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among the ...

that is the causative agent of

cat-scratch disease Cat-scratch disease (CSD) is an infectious disease that most often results from a scratch or bite of a cat. Symptoms typically include a non-painful bump or blister at the site of injury and painful and swollen lymph nodes. People may feel tire ...

( bartonellosis). It primarily infects red blood cells and endothelial cells and is transmitted to humans through scratches, bites, or flea vectors associated with domestic and feral cats. ''Bartonella henselae'' is a member of the genus '' Bartonella'', one of the most common types of bacteria in the world. It is a facultative intracellular microbe that targets red blood cells. In the United States, about 20,000 cases are diagnosed each year, most under 15 years old. Most often, it is transmitted by scratches or bites from kittens. Higher prevalence is reported in warm, humid climates where flea infestations are more common.

History

The specific name ''henselae'' honors Diane Marie Hensel (b. 1953), a clinical microbiology technologist at University of Oklahoma Health Sciences Center, who collected numerous strains and samples of the infective agent during an outbreak in Oklahoma in 1985.

Etiology

Bartonella henselae is a Gram-negative, rod-shaped bacterium that invades endothelial and red blood cells. One study showed ''Bartonella henselae'' invaded the mature blood cells of humans. It infects the host cell by sticking to it using trimeric autotransporter adhesins.Angelakis E, Raoult D. Pathogenicity and treatment of Bartonella infections. Int J Antimicrob Agents 2014;44:16–25.

Diagnosis

''Bartonella henselae'' is a

Gram-negative Gram-negative bacteria are bacteria that, unlike gram-positive bacteria, do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation. Their defining characteristic is that their cell envelope consists ...

rod. It can be cultured in a lysis-centrifugation blood culture. The presence of bacteria can be detected by Warthin-Starry stain, or by a similar silver stain technique performed on infected tissue. A pan-Bartonella PCR detection is non-invasive and uses blood or biopsies to diagnose.

Symptoms

''Bartonella henselae'' infection can appear up to 10 days after exposure to the microbe. Symptoms start with a papule at the site the microbe entered, followed by

lymphadenopathy Lymphadenopathy or adenopathy is a disease of the lymph nodes, in which they are abnormal in size or consistency. Lymphadenopathy of an inflammatory type (the most common type) is lymphadenitis, producing swollen or enlarged lymph nodes. In c ...

, usually in the axillary node. Half of patients also get aches, nausea, abdominal pain, and malaise.Mazur-Melewska, Katarzyna, et al. "Cat-scratch disease: a wide spectrum of clinical pictures." Advances in Dermatology and Allergology/Postȩpy Dermatologii i Alergologii 32.3 (2015): 216. Many other complications can arise from this infection beyond the typical fever, lymphadenopathy, and general malaise. Immunocompromised people or patients who already have other conditions are at greater risk for further complications. Some cases have been found in children who had previous heart-valve disease; these children got

endocarditis Endocarditis is an inflammation of the inner layer of the heart, the endocardium. It usually involves the heart valves. Other structures that may be involved include the interventricular septum, the chordae tendineae, the mural endocardium, o ...

from ''B. henselae'' infection. Some patients had hepatosplenic involvement, myalgia, and arthritis after exposure to ''B. henselae''. In rare cases,

osteomyelitis Osteomyelitis (OM) is the infectious inflammation of bone marrow. Symptoms may include pain in a specific bone with overlying redness, fever, and weakness. The feet, spine, and hips are the most commonly involved bones in adults. The cause is ...

, an infection in the bone, can be a manifestation of ''B. henselae''.

Treatment

No definite treatment regimen is known for a patient infected with ''B. henselae''. Treatment depends on the wide range of symptoms that present. In most cases, it will resolve on its own in four to six weeks.

Aminoglycoside Aminoglycoside is a medicinal and bacteriologic category of traditional Gram-negative antibacterial medications that inhibit protein synthesis and contain as a portion of the molecule an amino-modified glycoside (sugar). The term can also refer ...

s in laboratory tests showed some bactericidal activity.

Bacteriostatic A bacteriostatic agent or bacteriostat, abbreviated Bstatic, is a biological or chemical agent that stops bacteria from reproducing, while not necessarily killing them otherwise. Depending on their application, bacteriostatic antibiotics, disinfec ...

antibiotics are not able to easily get through to intracellular ''Bartonella'', so they are not recommended. In

immunocompromised Immunodeficiency, also known as immunocompromise, is a state in which the immune system's ability to fight infectious diseases and cancer is compromised or entirely absent. Most cases are acquired ("secondary") due to extrinsic factors that affe ...

patients, pain medication is often prescribed. Nodes may need to be aspirated if painful, microabscesses often form, the abscess needs to be aspirated in many places to remove all the exudate. Because of chronic sinus tract formation risks, the nodes should not be incised to be drained.

Azithromycin Azithromycin, sold under the brand names Zithromax (in oral form) and Azasite (as an eye drop), is an antibiotic medication used for the treatment of several bacterial infections. This includes otitis media, middle ear infections, strep throa ...

can be used for lymphadenopathy, which is enlarged or swollen lymph nodes.

Prevention

Regular flea control measures, such as using flea preventatives on cats, are essential to reduce the risk of ''Bartonella henselae'' transmission. Practicing proper hygiene, including washing hands after handling cats and avoiding rough play with kittens, can further minimize exposure. Additionally, immunocompromised individuals should take extra precautions by limiting contact with young cats and avoiding direct exposure to cat saliva.

References

External links

''Bartonella henselae''
at NCBI Taxonomy Browser
Type strain of ''Bartonella henselae''
at BacDive, the Bacterial Diversity Metadatabase {{Taxonbar, from=Q140599 Bartonellaceae Bacteria described in 1992 Pathogenic bacteria