Tuesday, December 5, 2023
| Variable | No. patients† | B. henselae, n = 338 | B. quintana, n = 54 | Other Bartonella spp.,‡ n = 28 |
|---|---|---|---|---|
| Age, y, median (range) | 415 | 32 (1–79) | 52 (9–76) | 30 (1–77) |
| <18 | NA | 122/335 (36) | 2/52 (4) | 10/28 (36) |
| 18–65 | NA | 182/335 (54) | 43/52 (83) | 11/28 (39) |
| ≥65 | NA | 31/335 (9) | 7/52 (13) | 7/28 (25) |
| Sex | 397 | NA | NA | NA |
| M | NA | 187/321 (58) | 41/50 (82) | 17/26 (65) |
| F | NA | 134/321 (42) | 9/50 (18) | 9/26 (35) |
| Specimen origin§ | 361 | NA | NA | NA |
| Texas | 48 | 38/48 (79) | 4/48 (8) | 6/48 (13) |
| Washington | 46 | 34/46 (74) | 8/46 (17) | 4/46 (9) |
| Ohio | 40 | 36/40 (90) | 0/40 (0) | 4/40 (10) |
| California | 40 | 22/40 (55) | 16/40 (40) | 2/40 (5) |
| Michigan | 30 | 27/30 (90) | 3/30 (10) | 0/30 (0) |
| Florida | 27 | 26/27 (96) | 0/27 (0) | 1/27 (4) |
| Oregon | 21 | 17/21 (80) | 2/21 (10) | 2/21 (10) |
| Pennsylvania | 11 | 10/11 (91) | 0/11 (0) | 1/11 (9) |
| Other¶ | NA | 78/98 (80) | 15/98 (15) | 5/98 (5) |
Table 1. Demographic characteristics and specimen origin for patients who had Bartonella spp. detected by PCR in study of Bartonella spp. infections identified by molecular methods, United States*
*Values are no./total no. (%) unless otherwise indicated. NA, not applicable.
†Total number of patients for each indicated variable.
‡Includes B. vinsonii (n = 2), B. clarridgeiae (n = 4), B. washoensis (n = 1), and Bartonella sp. not otherwise specified (n = 21).
§Restricted to states with ≥10 patients who were infected with an identified Bartonella spp. to preserve anonymity.
¶Alaska (n = 4), Alabama (n = 5), Arkansas (n = 5), Colorado (n = 5), Connecticut (n = 3), District of Columbia (n = 2), Georgia (n = 5), Hawaii (n = 2), Iowa (n = 3), Idaho (n = 1), Illinois (n = 3), Indiana (n = 6), Kentucky (n = 2), Louisiana (n = 1), Massachusetts (n = 5), Maine (n = 1), Montana (n = 5), Mississippi (n = 1), North Carolina (n = 8), Nebraska (n = 5), New Hampshire (n = 2), New Jersey (n = 1), New York (n = 3), Oklahoma (n = 1), South Carolina (n = 3), Tennessee (n = 5), Utah (n = 1), Virginia (n = 5), and Wisconsin (n = 5).
| No. (%) specimens | |||||
|---|---|---|---|---|---|
| Variable | p value† | Cardiac, n = 140 | Lymph node, n = 122 | Other,* n = 158 | |
| Age, y | <0.0001 | ||||
|
<18, n = 134 |
5 (4) | 52 (39) | 77 (57) | ||
|
18–65, n = 236 |
106 (45) | 66 (27) | 64 (27) | ||
|
≥65, n = 45 |
27 (60) | 3 (7) | 15 (33) | ||
| Sex | <0.0001 | ||||
|
M, n = 245) |
107 (44) | 61 (25) | 77 (31) | ||
|
F, n = 152) |
24 (16) | 57 (38) | 71 (47) | ||
Table 2. Categorical age and sex of infected persons grouped by specimen type in study of Bartonella spp. infections identified by molecular methods, United States
*Abscess (n = 38), tissue (n = 32), neck/face/arm (n = 25), liver (n = 15), leg/hip (n = 14), breast/chest wall (n = 6), skin (n = 5), lung (n = 4), aorta (n = 2), vascular (n = 2), body fluid NOS (n = 4), bone (n = 4), spleen (n = 4), synovial fluid (n = 2), and dura mater (n = 1).
†By χ2 test.
Physicians - maximum of 1.00 AMA PRA Category 1 Credit(s)™
ABIM Diplomates - maximum of 1.00 ABIM MOC points
This activity is intended for infectious disease clinicians, internists, intensivists, cardiologists, laboratory specialists, and other clinicians who treat and manage patients with Bartonella spp. Infection.
The goal of this activity is for learners to be better able to describe the demographic, clinical, and microbiologic characteristics of patients with Bartonellosis diagnosed by both broad-range and organism-specific molecular assays (ie, polymerase chain reaction) targeting bacterial 16S rDNA hypervariable V1-V2 regions only or in parallel with Bartonella-specific ribC, at a large clinical reference laboratory.
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Molecular methods can enable rapid identification of Bartonella spp. infections, which are difficult to diagnose by using culture or serology. We analyzed clinical test results of PCR that targeted bacterial 16S rRNA hypervariable V1–V2 regions only or in parallel with PCR of Bartonella-specific ribC gene. We identified 430 clinical specimens infected with Bartonella spp. from 420 patients in the United States. Median patient age was 37 (range 1–79) years; 62% were male. We identified B. henselae in 77%, B. quintana in 13%, B. clarridgeiae in 1%, B. vinsonii in 1%, and B. washoensis in 1% of specimens. Eighty-three percent of specimens with B. quintana were cardiac specimens; 34% of specimens with B. henselae were lymph nodes. We detected novel or uncommon Bartonella spp. in 9 patients. Molecular diagnostic testing can identify Bartonella spp. infections, including uncommon and undescribed species, and might be particularly useful for patients who have culture-negative endocarditis or lymphadenitis.
Bartonella spp. are fastidious, gram-negative intracellular bacteria that are transmitted to humans by insect vectors. The genus includes 12 species associated with human infection: B. henselae, B. quintana, B. bacilliformis, B. elizabethae, B. vinsonii, B. koehlerae, B. clarridgieae, B. alsatica, B. doshiae, B. grahamii, B. rattimassiliensis, and B. tribocorum[1,2]. Bartonellosis cases are not nationally notifiable in the United States, limiting knowledge of disease epidemiology.
In the United States, B. henselae is the most common pathogenic Bartonella spp.; ≈12,500 cases of infection and 500 hospitalizations occur annually[3]. The most common clinical manifestation of B. henselae infection is cat-scratch disease (lymphadenopathy and fever after a cat scratch or bite), although infection can also cause hepatic lesions, ocular disease, osteomyelitis, and endocarditis[4,5]. B. quintana infection is uncommon and incidence is unknown. Clinically, B. quintana infection can manifest as acute febrile illness or subacute endocarditis. B. quintana is transmitted by body lice and causes the most frequently reported vector-borne disease among persons experiencing homelessness (PEH); seroprevalence in the PEH population is 5%–15%[6–8]. Manifestations of other Bartonella spp. infections are sporadically described in case reports, often as culture-negative endocarditis.
Serology is the diagnostic tool most frequently used to identify Bartonella spp. infections. However, serologic diagnosis is complicated by lack of species-specific results, differences in use and interpretation of serologic assays among laboratories, and cross-reactivity with other pathogens, including Chlamydia spp. and Coxiella burnettii[9–15], which can lead to misdiagnosis and insufficient treatment. Bacterial cultures of blood or tissue can establish the diagnosis, but sensitivity of cultures is low because of the fastidious nature of Bartonella spp. and might result in underdiagnosis of infection. Combining enrichment culture techniques with molecular methods might increase detection of Bartonella spp. in blood or other clinical specimens[16].
Molecular detection of bacterial pathogens has emerged as an important clinical tool that can increase diagnostic yield compared with culture alone, particularly for detection of fastidious organisms[17]. Bartonella spp. have been detected by using broad-range PCR-based assays that target conserved binding sites flanking regions of the rRNA gene and have species-specific variations[18] or by using organism-specific gene targets, such as gltA[19] and ribC[20]. We describe the demographic, clinical, and microbiologic characteristics of patients with bartonellosis diagnosed by both broad-range and organism-specific molecular assays at a large clinical reference laboratory in Washington, USA.
