LecturePatient with cat scratch disease (Bartonella henselae) will present as → a 10-year-old girl is brought to the pediatric office by her mother with a history of fever and swelling in her right axilla for the past week. The mother mentions that their new kitten scratched the girl about two weeks ago. On physical examination, there is a 3 cm tender, enlarged lymph node in the right axilla, and a small, healed scratch on her forearm. Serological tests confirm Bartonella henselae infection. The patient is treated with azithromycin, and the mother is advised on proper wound care and flea control for their pets.
Patient with trench fever (Bartonella quintana) will present as → a 35-year-old currently experiencing homelessness presents to the clinic with a recurrent fever, severe headache, and shin pain for the past three weeks. He reports that the fever comes and goes every 5-6 days. On examination, he is febrile with a temperature of 39°C (102.2°F), and has tenderness over his tibias. He admits to living in crowded shelters with poor hygiene. Blood cultures reveal Bartonella quintana. The patient is started on doxycycline and educated on the importance of hygiene and delousing.
Patient with Bacillary angiomatosis will present as → a 45-year-old man with a history of HIV/AIDS presents with multiple red, raised, and tender lesions on his skin that have been progressively increasing in size and number over the past month. He also reports fever, weight loss, and night sweats. On examination, the lesions are nodular and highly vascular. A skin biopsy shows bacillary angiomatosis, and PCR confirms Bartonella henselae infection. The patient is started on doxycycline, and his antiretroviral therapy is reviewed and optimized to improve his immune function.
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Bartonella is a genus of gram-negative bacteria that can cause several diseases in humans, most notably cat-scratch disease (CSD)
- Trench fever (Bartonella quintana) – spread by lice, those experiencing homelessness
- Cat scratch disease (Bartonella henselae) – a lymphatic infection associated with a clawing injury by cats
- Bacillary angiomatosis – (a complication of Bartonella henselae & Bartonella quintana infection) – seen in AIDS patients, CD4 < 100
Bartonella henselae is the causative agent of cat scratch disease (CSD), the most common form of bartonellosis in the United States
- The primary agent of CSD is Bartonella henselae
- CSD is transmitted to humans through scratches or bites from infected cats (especially kittens) or via cat fleas
- CSD is characterized by low-grade fever, regional lymphadenopathy, fatigue, and a pustule or papule at the site of the scratch
- Complications can involve more severe conditions such as bacillary angiomatosis, peliosis hepatis, and endocarditis, especially in immunocompromised patients
Regional lymphadenopathy in a child with cat scratch disease
Trench fever is a louse-borne disease caused by the gram-negative bacterium Bartonella quintana and observed originally in military populations during World Wars I and II
- Symptoms are an acute, recurring febrile illness, occasionally with a rash, headache, and bone pain (especially shin bone)
- History of poor hygiene and louse infestation strongly suggests trench fever (resurgence of trench fever is being seen in those experiencing homelessness)
"Fever is a hallmark of trench fever, with a characteristic pattern of high fever for 5-6 days, followed by 5-6 days without fever, then recurrence of the fever. This is why it's called "quintan" or "five-day" fever"
Bacillary angiomatosis (BA) is a serious complication of Bartonella infection, most commonly caused by B. henselae or B. quintana, in immunocompromised individuals
- BA is characterized by the abnormal proliferation of blood vessels, leading to tumor-like masses in the skin, subcutaneous tissue, and sometimes internal organs.
- BA predominantly affects those with weakened immune systems (e.g., HIV/AIDS, organ transplant recipients), but can rarely occur in immunocompetent people.
Bartonella vs. Toxoplasmosis
Both Bartonella and Toxoplasma gondii infections can be associated with cat exposure, but there are key differences:
- Bartonella is a bacterium, while Toxoplasma gondii is a protozoan parasite
- Bartonella is typically transmitted through cat scratches, bites, or fleas, while Toxoplasma is usually acquired through ingestion of oocysts from cat feces or undercooked meat
- Bartonella commonly causes localized lymphadenopathy and skin lesions, while Toxoplasma often presents with flu-like symptoms and lymphadenopathy, and can cause severe congenital infections
| Feature | Trench fever (Bartonella quintana) | Cat scratch disease (Bartonella henselae) | Bacillary angiomatosis |
| Causative agent | Bartonella quintana | Bartonella henselae | Bartonella quintana, Bartonella henselae |
| Primary reservoir | Human body louse (Pediculus humanus corporis) | Domestic cats, especially kittens | Domestic cats (B. henselae), human body louse (B. quintana) |
| Mode of transmission | Inoculation of infected louse feces into skin lesions or mucous membranes | Cat scratches, bites, or exposure to cat fleas | Inoculation of bacteria into skin or mucous membranes |
| Risk factors | Overcrowding, poor hygiene, homelessness | Exposure to cats, especially kittens | Immunocompromised state (e.g., HIV/AIDS) |
| Incubation period | 15-25 days | 3-10 days | Variable |
| Clinical presentation | Relapsing fever, headache, myalgia, bone pain (especially shins) | Regional lymphadenopathy, fever, papule at inoculation site | Vascular skin lesions, subcutaneous nodules, osseous lesions |
| Diagnostic tests | Serology (IFA, ELISA), PCR, blood culture | Serology (IFA, ELISA), PCR of lymph node aspirate, histopathology | Histopathology, PCR, serology |
| Treatment | Doxycycline, gentamicin, azithromycin | Usually self-limited; azithromycin for severe cases | Prolonged doxycycline or erythromycin (3-4 months) |
| Complications | Chronic bacteremia, endocarditis, bacillary angiomatosis | Neuroretinitis, osteomyelitis, encephalitis | Disseminated infection, peliosis hepatis, endocarditis |
| Prevention | Improved hygiene, louse control | Avoid cat scratches and bites, flea control | Avoid exposure to lice and cats, treat underlying immunodeficiency |
Diagnosis of Bartonella infection is based on clinical presentation and confirmed through serological and molecular tests
- Serology to detect antibodies against Bartonella species using indirect fluorescence assay (IFA) or enzyme immunoassay (EIA)
- PCR (polymerase chain reaction) to detect Bartonella DNA in tissue samples, such as lymph node aspirates or skin biopsy specimens. PCR is considered the most effective diagnostic test for Bartonella
- Culture may be used, but Bartonella is fastidious and difficult to grow in standard laboratory conditions
- Histopathology can show granulomatous inflammation in a biopsy of an affected lymph node
Treatment for Bartonella infection varies based on severity and specific presentation
- Antibiotics such as azithromycin for typical cases of cat-scratch disease; doxycycline and rifampin may be used for more severe infections
- Supportive care to manage symptoms like fever and pain
- Monitoring and managing potential complications, especially in immunocompromised patients
- Preventive measures include avoiding rough play with cats and controlling flea populations
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Question 1 |
A 9-year-old boy presents with a low-grade fever and enlarged, tender lymph nodes in his neck. His mother reports he was recently scratched by their kitten. Which of the following is the most likely etiological agent responsible for his symptoms?
Borrelia burgdorferi Hint: Causes Lyme disease, which presents with erythema migrans rash, fever, fatigue, and headache. | |
Bartonella henselae | |
Rickettsia rickettsii Hint: Causes Rocky Mountain spotted fever, characterized by fever, headache, and a rash that starts on the wrists and ankles. | |
Ehrlichia chaffeensis Hint: Causes human monocytic ehrlichiosis, characterized by fever, headache, myalgia, and rash. | |
Anaplasma phagocytophilum Hint: Causes human granulocytic anaplasmosis, characterized by fever, headache, myalgia, and rarely, rash. |
Question 1 Explanation:
Bartonella henselae is the causative agent of cat scratch disease (CSD), the most common form of bartonellosis in the United States. CSD is characterized by a history of cat exposure (especially kittens), low-grade fever, and regional lymphadenopathy.
Question 2 |
A 45-year-old homeless man presents with recurrent episodes of fever, headache, and severe bone pain in his shins. He reports poor hygiene and frequent louse infestation. Which of the following is the most likely etiological agent responsible for his symptoms?
Borrelia recurrentis Hint: Causes relapsing fever, transmitted by soft-bodied ticks, and presents with recurring fevers but not the classic bone pain. | |
Bartonella quintana | |
Bartonella henselae Hint: Causes cat scratch disease. Symptoms include fever, regional lymphadenopathy, fatigue, and a pustule or papule at the site of the scratch. The patients history and severe bone pain in his shins is more consistent with trench fever. | |
Bacillary angiomatosis Hint: This is a vascular proliferative disease caused by either Bartonella henselae or Bartonella quintana. It is a disorder characterized by red or purple skin lesions that resemble Kaposi's sarcoma, as well as subcutaneous nodules and osseous lesions | |
Coxiella burnetii Hint: his bacterium causes Q fever, a zoonotic infection typically transmitted by inhalation of contaminated aerosols from infected animals, not by louse bites. |
Question 2 Explanation:
The clinical presentation of recurrent fever, headache, and bone pain (especially shin bone pain), combined with the history of poor hygiene and louse infestation, strongly suggests trench fever. This disease is specifically caused by the bacterium Bartonella quintana, which is transmitted through the bite of body lice (Pediculus humanus corporis). The bacteria multiply within the louse's gut and are excreted in their feces. When an infected louse bites, scratching the bite site inoculates the bacteria into the bloodstream. Trench fever is reappearing in the homeless population in the US.
Question 3 |
A 38-year-old man with HIV presents with multiple red-purple papules and nodules on his skin, along with fatigue and night sweats. He has several pet cats at home. Which of the following is the most likely etiological agent responsible for his symptoms?
Bartonella quintana Hint: While this bacterium can also cause bacillary angiomatosis, it is less commonly associated with cat exposure and is more prevalent in individuals experiencing homelessness. | |
Bartonella henselae | |
Borrelia burgdorferi Hint: This spirochete causes Lyme disease, which presents with erythema migrans rash, fever, fatigue, and headache. It is not associated with vascular skin lesions. | |
Brucella spp. Hint: This bacterium causes brucellosis, a zoonotic infection characterized by fever, sweating, fatigue, and musculoskeletal pain. It is not typically associated with the characteristic skin lesions seen in BA. | |
Mycobacterium avium complex (MAC) Hint: This is an opportunistic infection that can affect various organs in immunocompromised individuals, including the lungs and gastrointestinal tract, but it does not typically cause the characteristic skin lesions seen in BA. |
Question 3 Explanation:
The presentation of vascular skin lesions in an immunocompromised patient with cat exposure strongly suggests bacillary angiomatosis (BA). BA is most commonly caused by Bartonella henselae, the same bacterium responsible for cat scratch disease. The presence of multiple cats increases the likelihood of exposure.
Question 4 |
A 12-year-old boy presents with a 3-day history of fever, headache, and a tender, enlarging lymph node in his left axilla. He reports being scratched by a kitten 10 days ago. Which of the following is the most appropriate next step in the diagnosis of this patient's condition?
Bartonella henselae IgM antibody test Hint: Bartonella henselae IgM antibody test can be helpful in the diagnosis of cat-scratch disease but may not be positive in the early stages of infection and is less specific than PCR testing. | |
Blood culture for Bartonella species Hint: Blood culture for Bartonella species has low sensitivity and is not routinely recommended for the diagnosis of cat-scratch disease. | |
Chest X-ray to rule out pulmonary involvement Hint: Chest X-ray is not indicated in this patient without signs or symptoms of pulmonary involvement. | |
Lymph node biopsy for histopathologic examination Hint: Lymph node biopsy for histopathologic examination can demonstrate granulomatous inflammation suggestive of cat-scratch disease but is more invasive than PCR testing of lymph node aspirate and may not provide a definitive diagnosis. | |
PCR testing of lymph node aspirate for Bartonella DNA |
Question 4 Explanation:
In this patient with a history of cat scratch and symptoms consistent with cat-scratch disease (fever, lymphadenopathy near the site of inoculation), the most appropriate next step in the diagnosis is PCR testing of the affected lymph node aspirate for Bartonella DNA. PCR is considered the most sensitive and specific test for confirming the diagnosis of cat-scratch disease. It can detect Bartonella DNA in tissues, such as lymph node aspirates, even before the development of detectable antibodies. A positive PCR result, along with the clinical presentation and exposure history, is sufficient to establish the diagnosis and guide treatment decisions.
Question 5 |
A 25-year-old man with a history of HIV/AIDS (CD4 count: 50 cells/µL) presents with multiple red, vascular skin lesions on his lower extremities. A skin biopsy reveals bacillary angiomatosis. Which of the following is the most appropriate treatment for this patient's condition?
Azithromycin 500 mg orally on day 1, followed by 250 mg orally daily for 4 days Hint: Azithromycin for 5 days is not an adequate duration of treatment for bacillary angiomatosis in an immunocompromised patient | |
Doxycycline 100 mg orally twice daily for 3-4 months | |
Ciprofloxacin 500 mg orally twice daily for 7 days Hint: Ciprofloxacin for 7 days is not an appropriate choice for the treatment of bacillary angiomatosis and is not a sufficient duration of therapy. | |
Rifampin 300 mg orally twice daily for 2 weeks Hint: Rifampin for 2 weeks is not an appropriate choice for the treatment of bacillary angiomatosis and is not a sufficient duration of therapy. | |
Trimethoprim-sulfamethoxazole 160/800 mg orally twice daily for 6 weeks Hint: Trimethoprim-sulfamethoxazole for 6 weeks is not an appropriate choice for the treatment of bacillary angiomatosis, as it has limited activity against Bartonella species. |
Question 5 Explanation:
The most appropriate treatment for bacillary angiomatosis in this immunocompromised patient with HIV/AIDS is prolonged antibiotic therapy with doxycycline 100 mg orally twice daily for 3-4 months. Bacillary angiomatosis is a serious complication of Bartonella infection, most commonly caused by B. henselae or B. quintana, in immunocompromised individuals. Due to the potential for disseminated infection and the risk of relapse, extended treatment with antibiotics is necessary. Doxycycline is a first-line choice because of its excellent tissue penetration and activity against Bartonella species. Erythromycin is an alternative for patients who cannot tolerate doxycycline. The prolonged duration of therapy is crucial to ensure complete eradication of the bacteria and prevent relapse.
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References: Merck Manual · UpToDate