Volume 18, Number 11—November 2012
Bartonella spp. Bacteremia and Rheumatic Symptoms in Patients from Lyme Disease–endemic Region
To the Editor: We believe the recent article by Maggi et al. (1) contains serious flaws in content and underlying message, including a poorly defined study population, lack of appropriate controls, improper use of the term bacteremia, and incongruent laboratory findings. Selection criteria were vague: the authors state only that participants were a “biased” collection of “patients selected by a rheumatologist,” with no control population included for comparison. The diagnosis of Lyme disease and other previously diagnosed conditions was solely by self-report. Although blood samples were collected from every participant, the authors apparently neglected to perform standardized testing for Borrelia burgdorferi or other conditions.
The term “bacteremia” signifies presence of viable bacteria in the bloodstream, which is not substantiated solely by a positive PCR result. True bacteremia was documented in only 1.7% of participants from whom a viable Bartonella species isolate was cultured, rather than the purported 41.1% of participants.
Surprisingly, many participants whose PCR results were positive for Bartonella spp. had no serologic evidence of infection (e.g., 82.5% of samples that had positive PCR results for Bartonella henselae were not seroreactive). Although anergy has been reported, samples from most immunocompetent and immunocompromised patients infected with Bartonella spp. are seroreactive (2–4), calling into question the authors’ findings. Furthermore, 24% of samples that were positive by PCR revealed no identifiable Bartonella spp. by DNA sequencing; these participants should have been excluded from analysis.
Maggi et al. hypothesize that Bartonella spp. infection is causally related to a variety of chronic ailments. In fact, there was no association within the study population between positive Bartonella spp. PCR results and chronic illness, self-reported Lyme disease, or even a prior diagnosis of bartonellosis.
Efforts to define the clinical and public health importance of Bartonella spp. require scientific rigor. The above issues challenge the validity of the study, and results should be interpreted with caution.
- Maggi RG, Mozayeni BR, Pultorak EL, Hegarty BC, Bradley JM, Correa M, Bartonella spp. bacteremia and rheumatic symptoms in patients from Lyme disease–endemic region. Emerg Infect Dis. 2012;18:783–91.
- Dalton MJ, Robinson LE, Cooper J, Regnery RL, Olson JG, Childs JE. Use of Bartonella antigens for serologic diagnosis of cat-scratch disease at a national referral center. Arch Intern Med. 1995;155:1670–6.
- Zangwill KM, Hamilton DH, Perkins BA, Regnery RL, Plikaytis BD, Hadler JL, Cat scratch disease in Connecticut. Epidemiology, risk factors, and evaluation of a new diagnostic test. N Engl J Med. 1993;329:8–13.
- Koehler JE, Sanchez MA, Tye S, Garrido-Rowland CS, Chen FM, Maurer T, Prevalence of Bartonella infection among human immunodeficiency virus–infected patients with fever. Clin Infect Dis. 2003;37:559–66.