Bartonella Species

Diagnosis

Indications for Testing

  • High level of suspicion based on symptoms and exposure risk

Laboratory Testing

  • Bartonella henselae
    • Nonspecific testing
      • CBC – mildly elevated white blood cell count and elevated or diminished platelets
    • Acute and convalescent serum specimens for antibody testing – 70-90% positive in immunocompetent patients
      • Best evidence of infection is significant change on two appropriately timed specimens, where both tests are performed in same laboratory at same time
      • Confirmation requires a fourfold change in titers between acute and convalescent specimens
      • Low-positive IgG – suggests past exposure or infection
      • High positive IgG – may indicate current or recent infection (but not conclusive)
    • PCR from whole blood, tissue, or cerebrospinal fluid
      • Rapid test
      • Relatively sensitive, very specific
    • Culture of involved nodes – difficult; long incubation periods with poor yield
      • Not recommended – sensitivity ~20%
  • Bartonella quintana
    • Trench fever – may require culture, PCR, or serology
    • Endocarditis – blood cultures may be negative

Histology

  • Warthin-Starry silver stain 
    • B. henselae – pathologic examination of involved nodes
    • B. quintana – diagnosis of bacillary angiomatosis based on histopathologic findings of angiomas associated with tiny clumps of bacilli

Differential Diagnosis

Clinical Background

Bartonella spp cause several different diseases, including cat scratch disease (CSD).

Epidemiology

  • B. henselae
    • Incidence – 22,000 infections annually in the U.S. (~9/100,000)
    • Age – children <1 year have the greatest rate of infection
    • Occurrence – most common in warm, humid climates during autumn and winter months
    • Transmission – usually by cats to humans (fleas mainly transmit the disease directly through a cat scratch; flea-borne transmission to humans may also occur)
      • Most affected patients do not recall being scratched by a cat
  • B. quintana
    • Incidence – generally low; however, increasing prevalence in homeless populations in U.S. and Europe
    • Transmission – body louse (Pediculus humanus corporis)

Organism

  • Genus Bartonella contains aerobic, fastidious, gram-negative bacillus
  • Associated with four primary clinical syndromes
    • CSD – B. henselae and B. clarridgeiae
    • Bacillary angiomatosis – B. quintana and B. henselae
    • Bacillary peliosis hepatitis – B. henselae
    • Relapsing fever with bacteremia (trench fever) – B. quintana

Risk Factors

  • B. henselae
    • Cats with fleas – ~60% of strays and 40% of domestic cats are bacteremic for B. henselae
    • Rough play with cats – especially kittens
    • Unwashed bites and scratches from cats or allowing cats to lick open wounds
  • B. quintana
    • Immunocompromised persons – especially those with HIV
    • Homelessness
    • Alcoholism

Clinical Presentation

  • B. henselae
    • Immunocompetent host
      • Common presentations – CSD
        • Localized papule progressing to a pustule develops 3-5 days after cat scratch
          • Initial lesion heals uneventfully
        • Tender, unilateral regional lymphadenopathy develops 1-2 weeks later – 90% of cases
          • Generally persists for 2 weeks to 3 months before resolving spontaneously
          • Cervical and axillary – most common
          • Secondary bacterial superinfection of involved nodes – ~10% of cases
      • Other manifestations – 5-15% of cases
      • Uncommon presentation
        • Conjunctival inoculation may cause Parinaud oculoglandular syndrome with conjunctivitis and periauricular lymphadenopathy
    • Immunocompromised host
      • Bacillary angiomatosis
        • Nontender, firm, red-purple colored skin lesions
          • Dissemination to organs – pseudo neoplastic vasculitis proliferation
          • Potentially fatal if not treated
      • Bacillary peliosis
        • Vasoproliferation within the liver and spleen
          • Blood-filled cysts with possible organisms in the cysts
  • B. quintana
    • Trench fever
      • Sudden onset headache, meningitis, relapsing fever
      • Relapsing fever with bacteremia
        • Relapses common when short-course antibiotics are used
      • May cause endocarditis  
      • No fatalities reported
    • Bacillary angiomatosis
      • Many organs may be affected –  bone marrow, lymph nodes, liver, spleen
      • Hallmark symptoms – vascular nodules, papules, or tumors with proliferation of new blood vessels (angiogenesis)
      • Lesions, termed epithelioid angiomatosis, resemble Kaposi sarcoma

Indications for Laboratory Testing

  • Tests generally appear in the order most useful for common clinical situations
  • Click on number for test-specific information in the ARUP Laboratory Test Directory
Test Name and Number Recommended Use Limitations Follow Up
CBC with Platelet Count and Automated Differential 0040003
Method: Automated Cell Count/Differential

Order to differentiate between bacterial and viral etiology

    
Bartonella Species by PCR 0093057
Method: Qualitative Polymerase Chain Reaction

Use for rapid diagnoses of disease caused by Bartonella spp (used for serum, plasma, cerebrospinal fluid, or tissue)

May be useful in epidemiological situations to determine Bartonella species (sequencing of PCR product)

Negative result does not rule out the presence of Bartonella spp DNA in quantities below the sensitivity of assay or the possibility of PCR inhibitors in samples

Unidentified sequence variations may lead to a false-negative result

  
Bartonella Species by PCR, Whole Blood 0060762
Method: Qualitative Polymerase Chain Reaction

Use for rapid diagnosis of disease caused by Bartonella spp (used for whole blood)

May be useful in epidemiological situations to determine Bartonella species (sequencing of PCR product)

Negative result does not rule out the presence of Bartonella spp DNA in quantities below the sensitivity of assay or the possibility of PCR inhibitors in samples

Unidentified sequence variations may lead to a false-negative result

  
Bartonella henselae & B. quintana Antibodies, IgG & IgM 2002280
Method: Semi-Quantitative Indirect Fluorescent Antibody

Order when current or past exposure to B. henselae or B. quintana suspected

 Antibodies take up to 10 days to develop

While IgM antibodies suggest recent infection, low levels may occasionally persist >12 months postinfection

If test results are equivocal, repeat testing in 10-14 days
Blood Culture 0060102
Method: Continuous Monitoring Blood Culture/Identification
 Use in patients with endocarditis to detect if Bartonella spp are etiology

Less sensitive than PCR

Limited to the University of Utah Health Sciences Center only

  
Additional Tests Available
 
 
Click the plus sign to expand the table of additional tests.
Test Name and NumberComments
Bartonella henselae (Cat Scratch) Antibodies, IgG & IgM by IFA 0050108
Method: Semi-Quantitative Indirect Fluorescent Antibody

May take up to 10 days for antibodies to develop; titers may be elevated for years
Bartonella quintana Antibodies, IgG & IgM by IFA 0050106
Method: Semi-Quantitative Indirect Fluorescent Antibody

May take up to 10 days for antibodies to develop; titers may be elevated for years
Bartonella henselae Antibody, IgG by IFA 0050091
Method: Semi-Quantitative Indirect Fluorescent Antibody
Bartonella henselae Antibody, IgM by IFA 0050092
Method: Semi-Quantitative Indirect Fluorescent Antibody
Bartonella quintana Antibody, IgG by IFA 0050094
Method: Semi-Quantitative Indirect Fluorescent Antibody
Bartonella quintana Antibody, IgM by IFA 0050093
Method: Semi-Quantitative Indirect Fluorescent Antibody