Patients included four females and two males, ranging in age from 14 to 54 years (Table ). Substantial animal contact or recent arthropod exposure was a potential risk factor for Bartonella infection.
Ages, genders, and neurological abnormalities of immunocompetent patients in this study and Bartonella species detected in the blood samples
Patient 1 was a college student who received a severe cat scratch on her right hand that resulted in raised, red, nodular lesions which were diagnosed as CSD by a dermatologist. Approximately 1 year later, she developed fatigue, headaches, memory loss, disorientation, insomnia, poor coordination, tremors, and infrequent petit mal seizures. During the subsequent 2-year period, she experienced two grand mal seizures and was treated with gabapentin for epilepsy.
Patient 2, a golf coach, traveled extensively throughout the United States and other countries, had frequent arthropod exposure, and had lived on a farm as a teenager, during which time she had been bitten by a pig and pecked frequently by roosters, turkeys, and pheasants. Her illness was characterized by severe bouts of fatigue, accompanied by subtle neurological abnormalities (Table ).
Patient 3 owned a horse farm, had frequent arthropod exposure, and reported at least yearly cat scratches. At the time of her initial blood sample, she had been ill approximately 4 years. She had been diagnosed previously with Lyme disease and babesiosis and had been treated with long courses of oral and intravenous antibiotics.
Patients 4 and 5 were veterinarians who reported weekly bites or scratches from cats, dogs, rodent pocket pets, and an assortment of wild and zoo animals. In association with a period of work-related stress, patient 4 developed debilitating depression, insomnia, fatigue, loss of coordination, memory loss, disorientation, and headaches of fluctuating severity that continued for over a year. Patient 4 maintained cats, chickens, cattle, dogs, and horses as pets.
One year prior to testing in our laboratory, patient 5 developed an acute febrile illness and malaise, which abated over the next week. In the subsequent months, neurological symptoms consisted of stumbling during jogging, muscle weakness, and fatigue, which was thought to be associated with viral neuropathy. During the next year, symptoms worsened to the extent that running was no longer possible and he could not walk unaided any distance; leg myoclonus worsened, hand numbness became problematic, and resting three to four times a day was a necessity. Multiple sclerosis was diagnosed, and treatment with intravenous interferon, intravenous immunoglobulin G, and glucocorticoids was initiated.
Patient 6 was the 14-year-old son of a veterinarian, and although exposed to both cats and dogs, the boy did not report previous scratches or bites. Ten days after an attached tick was removed from his left ankle, the boy developed severe debilitating migraine headaches, which required him to be hospitalized. Because of the more rapid turnaround time of PCR than of serological testing, PCR testing was used initially to screen an extracted blood sample for Anaplasma, Bartonella, Ehrlichia, and Rickettsia DNA. Only Bartonella DNA was detected in the child's blood sample, and subsequently, sequential serological testing demonstrated seroreactivity to B. henselae and B. quintana and seroconversion to B. vinsonii subsp. berkhoffii. Despite multiple attempts, cloning and sequencing of the initial Bartonella amplicon were not successful; however, B. henselae DNA from an agar plate isolate obtained after BAPGM preenrichment culture was sequenced. Based upon seroconversion, infection with B. vinsonii subsp. berkhoffii was implicated; however, based upon culture results, the boy was infected with B. henselae.
Fatigue, insomnia, memory loss and/or disorientation, blurred vision and loss of coordination, headaches, and depression were the most commonly reported symptoms (Table ). Seizures, severe paresis, and debilitating migraines were the predominant neurological abnormalities in patients 1, 5, and 6, respectively. Patients 2 to 4 each reported fatigue with accompanying neurological abnormalities that persisted for 3 to 5 years (Table ).
Medical care, diagnostic evaluations, the timing of sample collection for Bartonella testing, and treatment interventions, including plasmapheresis, antibiotics, corticosteroids, intravenous immunoglobulin, anticonvulsants, and other drugs, were extensive and varied among patients. In all instances, there was an evaluation by one or more neurologists. In addition to receiving other symptomatic treatments, patients 1, 5, and 6 were treated specifically for their Bartonella infections and experienced progressive improvement (patients 1 and 5) or the resolution of disease manifestations (patient 6). Patient 1 was treated with doxycycline for 6 weeks, remains healthy, and has experienced no seizures during a 36-month follow-up period while receiving an anticonvulsant medication. Patient 5 was initially treated with doxycycline for 5 weeks, followed by azithromycin for 6 weeks and then by levofloxacin for 9 weeks. There was a progressive improvement in neurological status (improved muscle strength and coordination accompanied by a return to work as a veterinary surgeon). During the past year, this individual received doxycycline and rifampin, in conjunction with other treatments, which resulted in continued improvement in muscle strength, improved coordination when walking, less myoclonus, and no relapses, which typically occurred prior to the addition of antibiotics to the treatment regimen. Patient 6 was treated with azithromycin for 6 weeks, with a rapid and progressive decrease in the severity of migraines following the initiation of antibiotics. The boy gradually returned to all preillness activities with no residual neurological abnormalities. Patients 2 and 3 were treated with doxycycline without obvious long-term benefits. Patient 4 has received continuous doxycycline treatment for the past 2 years for rosacea and has experienced a decrease in headaches, back pain, and joint pain, although there are still occasional flare-ups of pain in the joints.
Serological testing at the Centers for Disease Control and Prevention identified antibodies to Bartonella spp. (IFA reciprocal titers of 64 or greater) in samples from three of six patients (patients 1, 2, and 6). Antibodies were not detected in samples from patients 3 (six serum samples spanning July 2005 to 14 September 2006), 4 (three serum samples spanning June to November 2006), and 5 (one serum sample). For patient 1, IFA titers of antibodies to B. henselae, B. quintana, and B. vinsonii subsp. berkhoffii in samples spanning a 4-month period remained stable and were decreased but still detectable 1 year later, following antibiotic treatment (Table ). Patient 2 had reciprocal titers of antibodies to B. henselae, B. quintana, and B. vinsonii subsp. berkhoffii of 256, 128, and 128, respectively, when initially tested on 4 January 2005, after which a significant drop in antibodies occurred following antibiotic treatment, with reciprocal titers of less than 64 for all three test antigens in samples collected on 12 May 2005 and 11 September 2006. Patient 6 seroconverted to B. vinsonii subsp. berkhoffii antigens, developed the highest IFA titers of antibodies to this organism, and had a decremental decrease in titers following treatment with azithromycin (Table ).
Serological, PCR, and culture results for a 23-year-old woman with progressive neurological dysfunction, seizures, and persistent B. henselae infection
Serological, PCR, and culture results for a 14-year-old boy with migraine headaches following recent tick exposure
Based upon DNA sequencing of the ITS region, B. henselae was detected in blood samples from five individuals and coinfection with B. vinsonii subsp. berkhoffii and B. henselae was found in patient 3 (Table ). Considering only the initial BAPGM blood culture results, Bartonella DNA was detected following direct extraction from the blood samples of four patients whereas Bartonella DNA was amplified only following BAPGM enrichment culture of samples from patients 2 and 5. Following the subculture of aliquots from the liquid BAPGM enrichment cultures, isolates (B. henselae) were obtained from samples from patients 1, 2, 3, 4, and 6. Based upon sequential enrichment culture attempts, five individuals were found to be infected at more than one testing time point, as illustrated for patient 1 in Table . For this patient, the same Bartonella species and strain was detected in blood and cerebrospinal fluid samples obtained 9 months apart. Patient 6 had the shortest duration of symptoms and was assumed to have a recently acquired infection; seroconversion was documented, and after treatment with azithromycin, Bartonella bacteremia was not detected by blood culture or PCR (Table ). For patient 2, an isolate of B. henselae (San Antonio 2 [SA2] like) was initially identified by sequencing, whereas B. henselae (Houston-1 [H1]-like) sequences were obtained only from blood extracted 6 months later, following the administration of clindamycin for gingivitis and a tooth root abscess. The B. henselae reciprocal IFA titer decreased from 128 to 32 during this same time interval. Patient 3 was coinfected with B. vinsonii subsp. berkhoffii and B. henselae, and patients 4, 5, and 6 were infected with B. henselae (H1 or SA2). At no time during this study was DNA amplified from an extraction control or from an uninoculated BAPGM culture control.