BA and PH.
Severe, progressive, disseminated disease may occur in immunocompromised patients, especially those with HIV infection. Without appropriate therapy, infection spreads systemically and can involve virtually any organ, and the outcome is sometimes fatal (
9).
BA is a vascular proliferative disease most often involving the skin, but it may involve other organs. The disease was first described in HIV-infected patients (
102) and organ transplant recipients (
50), but it can also rarely affect immunocompetent patients (
105). The clinical differential diagnosis includes pyogenic granuloma, hemangioma, subcutaneous tumors, and Kaposi's sarcoma (
76). The skin lesions are very similar to those reported for verruga peruana, the chronic form of Carrion's disease. BA lesions can also involve the bone marrow, liver, spleen, or lymph nodes (
24,
54,
69,
77).
PH is defined as a vascular proliferation of sinusoidal hepatic capillaries resulting in blood-filled spaces in the liver. This disease was first described in patients with tuberculosis and advanced cancers and in association with the use of drugs such as anabolic steroids (
53).
B. henselae is now recognized as an infectious cause of PH in HIV-infected patients (
73,
80). PH has also been reported in organ transplant recipients (
1). PH can occur simultaneously with peliosis of the spleen, as well as BA of the skin, in HIV-infected patients (
58,
64).
Antibiotic treatment of BA and PH has never been studied systematically. Two criteria must be met to achieve successful eradication of
Bartonella infections in the immunocompromised patient: first, the specific strain of
B. henselae and
B. quintana infecting the patient must have excellent in vivo susceptibility to the prescribed antibiotic, and second, the treatment must be of sufficient duration to prevent relapse. The first patient with BA to be described was treated empirically with erythromycin, and the lesions resolved completely (
102). Subsequently, erythromycin has become the drug of first choice and has successfully been used to treat many patients with BA (Table
4) (
58,
105). Treatment of BA and PH with oral doxycycline (100 mg twice daily) has also been consistently successful (
58). Lesions resolved in several patients treated with ceftriaxone or fluoroquinolone compounds (
65,
96), but the progression of BA lesions in patients has been observed during treatment with ciprofloxacin (
104). Additionally, a
Bartonella species has been isolated from the blood or BA lesions of patients being treated with narrow-spectrum cephalosporins (
55), nafcillin, gentamicin, and trimethoprim-sulfamethoxazole (but never from patients being treated with a macrolide, rifamycin, or a tetracycline) (
57). We therefore do not recommend fluoroquinolones, trimethoprim-sulfamethoxazole, or narrow-spectrum cephalosporins for the treatment of BA or PH (
58). Treatment failures have been reported with many different antibiotics, and these are usually attributable to a lack of susceptibility of
Bartonella in vivo and/or an insufficient duration of therapy (
58,
75).
The drug of choice for the treatment of BA is erythromycin given p.o. (500 mg p.o. four times daily) for 3 months (Table
6, recommendation AII), but i.v. administration should be used in patients with severe disease (
58). Patients intolerant of erythromycin can be treated with doxycycline (100 mg p.o. or i.v. twice daily) (Table
6, recommendation AII) (
52,
58,
81). The response to treatment appears to be equivalent whether erythromycin or doxycycline is prescribed (
56). Combination therapy, with the addition of rifampin (300 mg p.o. twice daily) to either erythromycin or doxycycline, is recommended for immunocompromised patients with acute, life-threatening
Bartonella infection. The intravenous route is especially important in cases of gastrointestinal intolerance or poor absorption. The combination of doxycycline and rifampin is preferred for the treatment of patients with CNS
Bartonella infection because of the superior CNS penetration of doxycycline compared with those of the other first-line antibiotics.
The response to treatment can be dramatic in immunocompromised patients. In one patient who received a single 250-mg oral dose of erythromycin, blood cultures became sterile and a palpable subcutaneous lesion disappeared within hours (but recurred months later). More chronic lesions resolve more slowly, but after approximately 4 to 7 days of therapy, cutaneous BA lesions usually improve and resolve completely after 1 month of treatment (
11). Bacillary PH responds more slowly than cutaneous BA, but hepatic lesions should improve after several months of treatment.
Relapses of PH and BA lesions in bone and skin have been reported frequently (
38,
55,
62,
103). Relapses occur when antibiotics are given for a shorter duration (<3 months), especially in severely immunocompromised HIV-infected patients (
58,
96). For this reason and from our extensive experience treating patients with BA and PH, we recommend that treatment be given for at least 3 months for BA and 4 months for PH (Table
6, recommendation AII) (
25,
56). All immunocompromised patients with a
Bartonella infection should receive antibiotic therapy (erythromycin 500 mg p.o. four times daily or doxycycline 100 mg p.o. twice daily); patients who have relapses after the recommended treatment should then receive secondary prophylactic antibiotic treatment with erythromycin (500 mg p.o. four times daily) or doxycycline (100 mg p.o. twice daily) as long as they are immunocompromised (
56). Of note, AIDS patients receiving prophylaxis with a macrolide or rifamycin antibiotic for
Mycobacterium avium complex infection appear to be protected from developing infections with
Bartonella species (
57). Some immunocompromised patients develop a potentially life-threatening Jarisch-Herxheimer-like reaction within hours after institution of antibiotic therapy (
55). Physicians should advise patients of this possible treatment complication, and patients with severe respiratory and/or cardiovascular compromise should be monitored carefully following institution of antimicrobial therapy (
56).
Endocarditis.
Evidence of
Bartonella infection was found in 3% of all patients diagnosed with endocarditis tested at reference centers in three different countries (
73).
B. quintana (
32,
37,
82,
83,
98,
99),
B. henselae (
31,
37,
41,
82,
83), and other species, such as
Bartonella elizabethae (
27) and
Bartonella vinsonii subsp.
berkhoffii (
92), have been isolated from individual patients with bacterial endocarditis. Of the
Bartonella species,
B. quintana is the one that most commonly causes endocarditis, followed by
B. henselae. The first case of
Bartonella endocarditis was reported in an HIV-infected homosexual man in 1993 (
98).
B. quintana endocarditis has subsequently been reported in three non-HIV-infected, homeless men in France (
32). All three patients required valve replacements because of extensive valvular damage, and pathological investigation confirmed the diagnosis of endocarditis.
B. quintana endocarditis is most often observed in homeless people with chronic alcoholism and exposure to body lice and in patients without previously known valvulopathy.
B. henselae endocarditis most often occurs in patients with known valvulopathy who have contact with cats or cat fleas (
37).
Bartonella endocarditis is usually indolent and culture negative, and thus, diagnosis is often delayed, resulting in a mortality rate higher than that for some other forms of endocarditis. It was previously demonstrated (
37) that patients with
Bartonella endocarditis have a higher death rate and undergo valvular surgery more frequently than patients with endocarditis caused by other pathogens. Selection of an adequate treatment regimen is critical, even when
Bartonella infection is suspected but not yet documented. Among 101 patients with
Bartonella endocarditis recently described in a retrospective study (
83), 82 received aminoglycosides for a mean of 15 ± 11 days with either a beta-lactam (64 cases) or other antibiotics (vancomycin, doxycycline, rifampin, or co-trimoxazole). Seventy-four of the 82 patients who received an aminoglycoside recovered, whereas 13 of 19 of those who received no aminoglycoside recovered (
P = 0.02) (
84). Among the patients treated with aminoglycosides, 65 of the 69 who recovered had received aminoglycosides for 14 or more days, whereas 9 of the 13 patients who recovered had been treated for less than 14 days (
P = 0.02). Patients receiving an aminoglycoside were more likely to recover fully and, if they were treated for at least 14 days, were more likely to survive, confirming the important role of this antibiotic in the treatment of
Bartonella endocarditis (
83). These data strongly support the use of aminoglycoside therapy for at least 14 days for patients with suspected
Bartonella sp. endocarditis (Table
6, recommendation AII). Aminoglycoside therapy should be accompanied by treatment with a beta-lactam compound, preferably ceftriaxone (which is especially important for patients for whom blood cultures are negative, to adequately treat other potential bacteria that cause culture-negative endocarditis, e.g., β-lactamase-producing
Haemophilus spp.). Thus, we recommend that patients with suspected (but culture-negative)
Bartonella endocarditis receive treatment with gentamicin for the first 2 weeks and ceftriaxone (Table
6, recommendation BII) with or without doxycycline (Table
6, recommendation BII) for 6 weeks (
83).
Because chronic
B. quintana bacteremia has been shown to be optimally treated with doxycycline plus gentamicin (
36), in the absence of any prospective study for the treatment of documented
Bartonella endocarditis, it is logical that the same regimen should be used for endocarditis when a
Bartonella sp. has been identified as the causative agent. It is important that no difference in the frequency of surgery was observed in patients whether or not they were treated with aminoglycosides. This may be explained by the severity of valvular lesions at the time when the diagnosis of endocarditis is made (
37,
83). Patients should be monitored closely, and the dose of gentamicin should be chosen and adjusted according to the renal function of the patient, with a twice-daily dosing schedule for patients with renal insufficiency or those at risk for the development of aminoglycoside-induced renal failure. If renal dysfunction precludes the use of gentamicin for documented
Bartonella endocarditis, rifampin could be considered as the second drug to be added to doxycycline.