Page 1487 - Small Animal Internal Medicine, 6th Edition

CHAPTER 94 Polysystemic Bacterial Diseases 1459

Bartonella henselae survives in flea feces for days after and antibody-positive are probably not a source of flea, cat,
being passed by infected C. felis. Infected flea feces are likely or human infection. However, bacteremia can be intermit-
VetBooks.ir to contaminate cat claws during grooming, and then Barton- tent, and false-negative culture or PCR results can occur,
limiting the predictive value of a single battery of tests.
ella species are inoculated into the person when scratched.
Open wounds may also be contaminated with infected flea
results do not necessarily indicate that the organism is alive.
feces. However, Bartonella spp. DNA can also be amplified With PCR, false-positive results can occur, and positive
from the mouths of healthy cats and those with gingivosto- Although serologic testing can be used to determine whether
matitis, so bites and scratches should always be avoided an individual cat has been exposed, both seropositive and
(Quimby et al., 2008; Lappin and Hawley, 2009). Whether seronegative cats can be bacteremic, limiting the diagnostic
clinical disease occurs from Bartonella spp. infection depends utility of serologic testing when used alone. Thus testing
on a complex interaction of host and organism effects. In healthy, client-owned cats for Bartonella spp. infection is not
general, Bartonella spp.-associated illness is not identified in currently recommended in the United States (Kaplan et al.,
the host-adapted species (e.g., B. henselae, B. clarridgeiae, 2009). Testing should be reserved for cats with suspected
and B. koehlerae infections in cats) even though large clinical bartonellosis.
numbers of the organism are detected in blood. In contrast, The combination of serology and PCR assay or culture
when Bartonella spp. infect non–host-adapted species like is available in some laboratories like Antech Diagnos-
dogs and people, illness can occur with extremely low levels tics, North Carolina State University, Galaxy Diagnos-
of bacteremia. tics (www.galaxydx.com), and Colorado State University
(www.dlab.colostate.edu/). Some cats can have low-level
Clinical Features bacteremia, and specialized media combined with PCR may
Most cats with serologic evidence of exposure to Barton- be required to identify the organism (Drummond et al.,
ella spp., Bartonella spp. cultured from blood, or micro- 2018). If the results of Bartonella tests are negative in a clini-
bial DNA amplified from blood by PCR assay are clinically cally ill cat, the organism is not likely the cause of the clinical
normal. However, Bartonella spp. infection of cats has also syndrome unless the infection was peracute and serologic
been associated directly or indirectly with a variety of clini- testing was used as the diagnostic test. If the results of Bar-
cal manifestations like fever, lethargy, lymphadenopathy, tonella tests are positive, the agent remains on the list of dif-
uveitis, gingivitis, endocarditis, myocarditis, hyperglobu- ferential diagnoses, but other causes of the clinical syndrome
linemia, osteomyelitis, cutaneous vasculitis, and neuro- must also be excluded.
logic diseases. Fever and cardiac abnormalities are the most The American Association of Feline Practitioners (AAFP)
common manifestations in cats infected with B. henselae Bartonella Panel Report suggests that the diagnosis of clini-
by experimental exposure to infected C. felis (Bradley and cal bartonellosis include the following combination of find-
Lappin, 2010). How often cats become ill from Barton- ings (Brunt et al., 2006):
ella spp. infections is unknown, and more information is
necessary. • Presence of a syndrome reported to be associated with
It can be difficult to determine which cats have been Bartonella spp. infection
exposed, and which cats are diseased. Bartonella spp. serop- • Exclusion of other causes of the clinical syndrome
revalence rates in shelter cats can be as high as 93% (Nutter • Detection of a positive Bartonella spp. test (culture, PCR
et al., 2004). In another study, the presence of Bartonella assay, or serology)
species antibodies failed to correlate to the presence of most • Response to administration of a drug with presumed anti-
clinical syndromes in ill cats (Breitschwerdt et al., 2005b). In Bartonella activity
recent studies in the author’s laboratory, the prevalence rates
for Bartonella species antibodies in feline sera were not sig- However, fulfillment of these criteria does not always
nificantly different for cats with or without seizures (Pearce prove a definitive diagnosis. The antibiotics used for the
et al., 2006), cats with or without stomatitis (Dowers and treatment of bartonellosis in cats generally have a broad
Lappin, 2005), or cats with or without elevations in feline spectrum, are effective for other infecting organisms that can
pancreatic lipase immunoreactivity (Bayliss et al., 2009). cause syndromes resembling bartonellosis, and can also have
Why some cats develop Bartonella-associated illness and antiinflammatory properties.
others do not is still not clear. For example, Powell et al.
(2002) failed to induce Toxoplasma gondii or Bartonella Treatment
species uveitis when Bartonella was intravenously inoculated In experimental studies, administration of doxycycline, tet-
into cats with chronic toxoplasmosis. racycline, erythromycin, amoxicillin-clavulanate, or enro-
floxacin can limit bacteremia but does not cure infection
Diagnosis in all cats. To date, use of antibiotics in healthy cats has not
Blood culture, PCR assay on blood, and serologic testing can been shown to lessen the risk of cat scratch disease. Thus
be used to assess individual cats for Bartonella infection. Cats in the United States, treatment is generally recommended
that are culture-negative or PCR-negative and antibody- for clinically ill cats (Kaplan et al., 2009). If clinical barton-
negative, and cats that are culture-negative or PCR-negative ellosis is suspected, the AAFP Panel Report recommends