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Introduction

  1. Top of page
  2. Introduction
  3. Bartonella pre-enrichment culture
  4. Animal and human health implications
  5. References

Bartonella species are increasingly recognised as important bacterial pathogens in veterinary and human medicine. These organisms can be transmitted by an arthropod vector or alternatively by animal scratches or bites. Among the 22 species or subspecies known today, seven species, including three subspecies of Bartonella henselae, and four genotypes of Bartonella vinsonii subsp. berkhoffii, have been detected in or isolated from pet dogs, thereby highlighting the zoonotic potential of these bacteria [1–4].

Bartonella vinsonii subsp. berkhoffii

Since the isolation of B. vinsonii subsp. berkhoffii from the blood of a dog with intermittent epistaxis and endocarditis in 1993, this organism has become an important pathogen in dogs and is an emerging pathogen in people [1,2]. Current evidence indicates that canids, including coyotes, dogs and grey foxes, potentially serve as reservoir hosts. In dogs, B. vinsonii subsp. berkhoffii has been identified as an important cause of endocarditis and has been associated with cardiac arrhythmias, myocarditis, granulomatous rhinitis, anterior uveitis and chorioretinitis. More recently, this species has been detected in a dog with systemic granulomatous disease involving the spleen, heart, lymph nodes, liver, kidney, lung, mediastinum and salivary glands, and also in the blood and lymph nodes of dogs with lymphoma, and in the saliva of healthy dogs [3–5]. In addition, co-infection with two of the four previously described B. vinsonii subspecies berkhoffii genotypes was identified in the same dog.

Bartonella henselae

Based upon molecular evidence, B. henselae has been implicated in several pathological conditions in dogs, including peliosis hepatis, granulomatous hepatitis, generalised pyogranulomatous lymphadenitis, and endocarditis. It is unclear as to how dogs become infected and whether dogs serve as accidental hosts or as chronically bacteraemic reservoirs for B. henselae. More recently, Bartonella spp. were detected in the blood and lymph nodes of healthy golden retrievers and in golden retrievers with lymphoma [3,4]. Molecular prevalence of Bartonella spp. infection was 18% in both study populations.

Other Bartonella species

Similar to people, dogs can develop endocarditis and presumably other serious disease manifestations when infected with both reservoir and non-reservoir Bartonella species. Non-reservoir Bartonella species, including Bartonella clarridgeiae, Bartonella washoensis and Bartonella elizabethae, have been associated with endocarditis, hepatic disease and sudden death in dogs. More recently, Bartonella quintana DNA has been detected in two dogs with endocarditis, and in the blood and lymph nodes of dogs with lymphoma, and in the blood, lymph nodes and saliva of healthy dogs [4,5].

Bartonella pre-enrichment culture

  1. Top of page
  2. Introduction
  3. Bartonella pre-enrichment culture
  4. Animal and human health implications
  5. References

When testing cat blood samples, B. henselae and B. clarridgeae can be isolated effectively using agar plates; however, isolation from dog or human blood samples using the same approach is very insensitive [3] In 2005, we described a novel, chemically modified, insect-based liquid culture medium (Bartonella/alpha-Proteobacteria growth media, BAPGM) that supports the growth of at least seven Bartonella species. This medium also supported co-cultures consisting of different Bartonella species. This unique approach, which combines pre-enrichment culture utilising BAPGM, followed by a highly sensitive PCR assay targeting the 16S–23S ITS region, was developed to characterise and quantify Bartonella infection in blood samples. The combined BAPGM culture/PCR assay has become the main diagnostic testing format utilised by the Intracellular Pathogen Research Laboratory (IPRL), North Carolina State University, to document Bartonella infection in animals and in immunocompetent humans [2,3] When compared with more traditional methods, this combinational approach has facilitated the detection of active infection by four Bartonella species (Table 1) in dogs (B. henselae, B. quintana, B. vinsonii berkhoffii and B. bovis), but of perhaps greater comparative microbiological importance, this approach has resulted in the successful isolation of B. henselae from several dogs [3–5].

Table 1.   Detection and isolation of Bartonella species by blood pre-enrichment and PCR
No.Breed, sex, age (year)B. henselae IFA titreB. vinsonii (berkhoffii) IFA titrePCR on bloodPCR on 7-day liquid culture aliquotBartonella colonies on subcultured blood agar plate
 1English Springer spaniel, MN, 712864(−)B. vinsonii (berkhoffii)B. henselae
 2Boston terrier, MN, 5<16<16(−)B. henselaeB. henselae
 3Belgian malinois, MN, 71024256(−)B. henselaeB. henselae &  B. vinsonii berkhoffii
 4Weimaraner, FS, 4<16<16B. henselae(−)No
 5German shepherd, MN, 8<16<16(−)B. henselaeB. henselae
 6Golden retriever, FS, 464<16(−)B. henselaeNo
 7Komondor, M, 8<16<16(−)B. henselaeB. henselae & B. vinsonii berkhoffii
 8Italian greyhound, FS, 2<16<16B. henselae(−)No
 9Golden retriever, FS, 864<16B. henselae(−)No
10Golden retriever, FS, 9<16<16(−)B. vinsonii (berkhoffii)No
11Golden retriever, FS, 9<16<16(−)B. henselaeNo
12Belgian tervuren, M, 6<16<16(−)(−)B. henselae
13Lab mix, MN, 115128192(−)(−)No
14Golden retriever, FS, 2512<16(−)(−)No
15Schipperke, FS, 61024<16(−)(−)No
16American bulldog, MN, 7128512(−)(−)No

Animal and human health implications

  1. Top of page
  2. Introduction
  3. Bartonella pre-enrichment culture
  4. Animal and human health implications
  5. References

Based upon the annual increase in publications related to Bartonella infections in animals and people during the past decade, it is obvious that members of this genus are gaining increased international scrutiny by the medical and scientific communities. Animals function as blood reservoirs for various Bartonella spp., a process that facilitates a continued transmission cycle via arthropod or animal bites or scratches. A recent report describing the detection of four Bartonella species in dog saliva, in conjunction with previous case reports of sporadic Bartonella transmission by dogs, suggests that Bartonella infection may represent an occupational risk for veterinary professionals and others with extensive animal contact [2,4] The overall implications of these very recent observations for pets, pet owners, veterinarians and others with animal contact require systematic prospective studies.

References

  1. Top of page
  2. Introduction
  3. Bartonella pre-enrichment culture
  4. Animal and human health implications
  5. References
  • 1
    Breitschwerdt EB, Kordick DL, Malarkey DE. Endocarditis in a dog due to infection with a novel Bartonella subspecies. J Clin Microbiol 1995; 33: 154160.
  • 2
    Breitschwerdt EB, Maggi RG, Duncan AW, Nicholson WL, Hegarty BC, Woods CW. Bartonella species in blood of immunocompetent persons with animal and arthropod contact. Emerg Infect Dis 2007; 13: 938941.
  • 3
    Duncan AB, Maggi RG, Breitschwerdt EB. A combined approach for the enhanced detection and isolation of Bartonella species in dog blood samples: pre-enrichment liquid culture followed by PCR and subculture onto agar plates. J Microbiol Methods 2007; 69: 273281.
  • 4
    Duncan AW, Maggi RG, Breitschwerdt EB. Bartonella DNA in dog saliva. Emerg Infect Dis 2007; 13: 19491950.
  • 5
    Duncan AW, Marr HS, Birkenheuer AJ et al. Bartonella DNA in the blood and lymph nodes of golden retrievers with lymphoma and in healthy controls. J Vet Intern Med 2008; 22: 8995.