Blood Supplementation Enhances Bartonella henselae Growth and Molecular Detection of Bacterial DNA in Liquid Culture

Bacteria of the genus Bartonella, a member of the Alphaproteobacteria, are fastidious, Gram-negative, aerobic bacilli that comprise numerous species, subspecies, and genotypes. Bartonella henselae, with a worldwide distribution, infects cats, dogs, horses, humans, and other mammals. Diagnostically, direct detection of Bartonella henselae in patient blood specimens by culture or molecular methods is required to confirm infection with this bacterium. Enrichment blood culture combined with quantitative PCR (qPCR) or ddPCR enhances the sensitivity of direct detection. The addition of sheep blood to liquid culture media increased the Bartonella henselae DNA concentration compared to controls, additionally improving PCR direct detection sensitivity. IMPORTANCE This study aims to improve diagnostic detection of Bartonella henselae. Patient samples are combined with enriched bacterial cultures aimed at growing Bartonella henselae for the best possible chance at detection. However, current Bartonella growth methods could be improved. The DNA extraction method used by most laboratories should also be optimized. Sheep blood was added to increase the growth of Bartonella henselae and multiple DNA extraction methods were to be compared to each other.

Low occurrence of Bartonella in synanthropic mammals and associated ectoparasites in peri-urban areas from Central-Western and Southern Brazil

Worldwide, Bartonella species are known to infect a wide range of mammalian and arthropod hosts, including humans. The current study aimed to investigate the prevalence of Bartonella spp. in synanthropic mammals captured in peri-urban areas from Central-Western and Southern Brazil and their ectoparasites. For this aim, 160 mammals belonging to four species, and 218 associated arthropods were sampled. DNA was extracted and subjected to different Bartonella screening assays. Additionally, blood samples from 48 small rodents were submitted to liquid BAPGM culture followed by qPCR assay and solid culture. Two out of 55 Rattus captured in Santa Catarina state were PCR-positive for Bartonella when targeting the nuoG, 16S, and ITS loci. Sequences showed high homology with Bartonella coopersplainsensis. Conversely, all 48 small rodents, 14 capybaras and 43 opossum DNA samples from animals trapped in Mato Grosso do Sul were Bartonella negative in the HRM real time PCR assays targeting the ITS locus and gltA gene. Additionally, all mammal-associated ectoparasites showed negativity results based on HRM real time PCR assays. The present study showed, for the first time, the occurrence of B. coopersplainsensis in Brazil, shedding some light on the distribution of rats-related Bartonella in South America. In addition, the majority of rodents and marsupials were negative for Bartonella spp. Since B. coopersplainsensis reservoirs - Rattus spp. - are widely dispersed around the globe, their zoonotic potential should be further investigated.

Evaluation of cell culture-grown Bartonella antigens in immunofluorescent antibody assays for the serological diagnosis of bartonellosis in dogs

BACKGROUND

Because of poor sensitivity and questionable specificity of immunofluorescent antibody assays (IFAs), serological diagnosis of Bartonella species infections in dogs remains challenging. Despite limitations, IFA testing is the historical "gold standard" for Bartonella serodiagnosis in animals and humans. Because most diagnostic laboratories test against only 1 or 2 Bartonella spp., testing against a broader panel of Bartonella antigens may enhance diagnostic sensitivity and specificity.

OBJECTIVE

To evaluate the sensitivity and specificity of Bartonella IFA using 8 cell culture-grown Bartonella spp. isolates.

ANIMALS

Archived serum samples from 34 Bartonella spp. naturally exposed, polymerase chain reaction (PCR)-positive dogs and from 26 PCR-negative and IFA-negative dogs.

METHODS

Bartonella IFA sensitivity and specificity were assessed using cell culture-grown whole cell antigens derived from 3 Bartonella henselae (Bh) strains (Bh Houston 1, Bh San Antonio Type 2, Bh California 1), 3 Bartonella vinsonii subsp. berkhoffii genotypes (Bvb I, II, and III), Bartonella koehlerae (Bk), and Bartonella quintana (Bq).

RESULTS

Only 62% of 34 Bartonella spp. PCR-positive dogs were seroreactive to any of the 8 Bartonella IFA antigens, indicating low IFA sensitivity. PCR-positive dogs were most often IFA seroreactive to Bq (n = 15), to Bvb II (n = 13), or to both (n = 9) antigens. Of the 26 previously IFA-negative/PCR-negative dogs, 4 (15%) were seroreactive using the expanded antigen panel.

CONCLUSION AND CLINICAL IMPORTANCE

Despite IFA testing of dogs against 8 different Bartonella isolates, IFA sensitivity remained poor, and specificity was only 85%. Development of a reliable serological assay is needed to facilitate the diagnosis of Bartonella infection in dogs.

Infective endocarditis in 13 cats

INTRODUCTION

To describe the clinical presentation, clinicopathological abnormalities and outcomes of a series of cats diagnosed with infective endocarditis (IE) at two tertiary care referral institutions.

ANIMALS

Thirteen client-owned cats presenting to the cardiology or emergency services of tertiary referral institutions with a diagnosis of endocarditis based on the modified Duke criteria.

MATERIALS AND METHODS

Retrospective case series. Medical records were reviewed to extract relevant data. In addition, cases that had cardiac tissue available were evaluated by polymerase chain reaction for the presence of Bartonella DNA.

RESULTS

Prevalence of feline IE was 0.007%. Cats with endocarditis tended to be older (median age: 9 years, range: 2-12 years) and no sex or breed was overrepresented. Commonly encountered clinical signs included respiratory distress (n = 5) and locomotor abnormalities of varying severity (n = 5). Echocardiographic examination detected valvular lesions consistent with endocarditis on the aortic (n = 8) or mitral (n = 5) valves. Nine cats were diagnosed with congestive heart failure at the time of endocarditis diagnosis. Overall, prognosis was grave with a median survival time of 31 days.

CONCLUSIONS

In contrast to dogs, cats with IE typically present with clinical signs consistent with cardiac decompensation and locomotor abnormalities suggestive of either thromboembolic disease or inflammatory arthritis. Given the advanced state of disease when diagnosis typically occurs, prognosis is grave.