Introduction
Infective endocarditis (IE) is a severe and life-threatening disease
worldwide (1). However, because of non-specific clinical presentations,
confirmation and prescription of effective treatment are sometimes not
simple tasks. History may help significantly in the diagnosis of IE; for
example, it is more common among drug addicts, particularly Intravenous
drug users (2, 3).
Approximately 5% of IE cases have negative blood cultures (4, 5), and
its risk factors are exposure to slow-growing bacteria such as
Bartonella species, fastidious nonbacterial organisms, previous
antibiotic use, underlying valvular heart disease, and intracardiac or
vascular device or other foreign bodies in contact with the blood (6).
Most patients have nonspecific symptoms such as fever, fatigue, and
weight loss. In a case series comprising 348 blood culture-negative
endocarditis cases from France, almost all the patients had a fever as a
presenting symptom. In contrast, about 50 to 70% had symptoms of heart
failure, such as exertional dyspnea, and about 50% had insidious weight
loss(9).
Bartonella spp. is a small, intracellular, gram-negative, and very
fastidious rod mainly transmitted by vectors; they are the second most
common cause of culture-negative endocarditis. Among the cases of
Bartonella endocarditis, two species predominantly implicated in causing
culture-negative endocarditis are B. henselae and B. quintana(7).
These bacteria have been isolated from many mammalian species, including
cats and dogs. It can cause mild infection to severe and
life-threatening endocarditis in humans and dogs. In dogs, several
Bartonella species have been identified; one of the most common ones is
B. henselae.
It should be mentioned that in recent years, more cases of
culture-negative endocarditis have been reported from developing
countries(8).
This report presents a case of a patient with culture-negative B.
henselae endocarditis from Iran, diagnosed using a combined diagnostic
approach that included clinical evaluation, imaging, epidemiology,
serology, echocardiography, and transthoracic echocardiography (TTE).
Patient Information
The patient was a 38 years old male, single and unemployed with a
history of addiction, who had received care from a treatment camp for
six months. He was discharged when he was on methadone maintenance
therapy just before his first hospital admission. He was an IV drug
abuser with a history of regularly using amphetamine, cocaine, and
heroin. He also smoked cigarettes for 20 years. He also exposed that he
had unsafe sex and lost contact with dogs and cats.
Clinical Findings Timeline
The symptoms onset was 20 days before admission when he had fever and
chills besides shortness of breath in the camp. The patient was
hospitalized in another care center for five days as a suspected
COVID-19 case and he was treated with Remdesivir, but his nasopharyngeal
and oropharyngeal COVID-PCR tests were negative. Having been discharged
from the hospital, he started using amphetamine again, which
deteriorated his condition.
This time he was admitted to our center, as a referral center, with
severe dyspnea, high fever (40), chills, chest pain, myalgia, and
hemoptysis. The patient was ill and, on physical examination, he had
tachycardia (Heart rate=107) and tachypnea (Respiratory rate=28), with
low blood pressure (90/60), fluctuated oxygen saturation which was less
than 92%, normal heart auscultation, no clubbing, no splenomegaly, and
no lymphadenopathy. Table 1 summarizes the lab results.