Diagnosis>Opportunistic Infections>

PATHOGENS

• Definition: blood filled cavities (lakes) in liver that develop through Bartonella-induced neo-angiogenesis. Often accompanied by peliosis in the spleen.
• Causes: in HIV+ pts usually caused be infection by Bartonella spp. In HIV-negative (and some HIV+) pts, caused by anabolic steroids, Castleman's disease, Hodgkin's lymphoma, leukemia, other malignancies including hepatic tumors
• Pathogens: Bartonella henselae and B. quintana (formerly known as Rochalimea henselae and R. quintana)
• B. henselae: linked to cat and flea exposure
• B. quintana: linked to homelessness, low-income, and lice exposure
• Small, fastidious, gram-negative aerobic bacilli

CLINICAL

• Occurs at low CD4 counts; usually <100 
• May be associated with immune reconstitution inflammatory syndrome (IRIS) and higher CD4 count during reconstitution 
• Characterized by multiple, small, dilated blood-filled cavities in hepatic & splenic parenchyma.
• Sx: indolent course of fevers, nausea, abdominal pain, & malaise.
• PE: hepatosplenomegaly, 10-30% may also have bacillary angiomatosis
• Lab: alk phos 5-10 x ULN, ALT & AST may be 2x ULN; thrombocytopenia & pancytopenia have been reported
• Rarely may cause hypovolemic shock in HIV+ pts due to hepatic hemorrhage.

DIAGNOSIS

• Blood Cxs rarely positive for Bartonella, Cx sensitivity increases with use of isolator tubes or tubes containing EDTA; specific lab conditions required to enhance yield, so notify lab of suspicion for Bartonella infection.
• Definitive Dx by isolating organism from Cx of blood or tissue. Warthin-Starry silver staining shows masses of small, dark staining bacteria. staining, PCR, and serology findings.
• Abdominal CT: hepatomegaly +/- splenomegaly with hypodense lesions scattered throughout liver parenchyma. Other conditions producing similar radiographic findings: lymphoma, disseminated MAC, hepatic KS, and extrapulmonary pneumocystosis.
• Serologic methods (based on studies of cat scratch disease [CSD]): IFA and EIA. IFA IgG titer <1:64 suggests no infection;1:64 - 1:256 suggests possible infection;>1:256 suggests active or recent infection. Repeat testing in 10-14 days for titers suggesting possible infection. HIV and low CD4 associated with decreased probability of seropositivity. Anti-B. henselae IgM recently shown to be useful in Dx of CSD.
• Given presence of Ab titers to B. henselae of >1:256 in 4.8% of healthy controls (Sander Aet al. ref.) and lower likelihood of detectable Abs with low CD4 (Mohle-Boetani JC et al. ref.), PCR may be more useful in pts with AIDS. Can distinguish between Bartonella spp.   

TREATMENT

• Erythromycin 500 mg PO 4 times daily or doxycycline 100 mg PO twice-daily > 4 mos.
• Rifampin 300 mg IV or PO twice-daily may be added to erythromycin or doxycycline for severe disease.
• Many drug interactions with rifampin and erythromycin.
• Anecdotal evidence of success with other macrolides, including azithromycin.
• Anecdotal evidence of success with fluoroquinolones

Drug Comments

Pathogen Specific Therapy

Basis for Recommendations

• Koehler JE; Bartonella-associated infections in HIV-infected patients.; AIDS Clin Care; 1995; Vol. 7; pp. 97-102;
  ISSN: 1043-1543;
  PUBMED: 11362939
  Rating: Basis for recommendation
  Comments:Supports use of long courses of erythromycin and doxycycline as well as the use of rifampin in severely ill patients.
  
  

REFERENCES