2019 Jul 11. pii: S1875-2136(19)30078-6. doi: 10.1016/j.acvd.2019.02.005. [Epub ahead of print]

Infective endocarditis without biological inflammatory syndrome: Description of a particular entity.



Bacterial infective endocarditis (IE) is rarely suspected in patients with a low C-reactive protein (CRP) concentration.


To address the incidence, characteristics and outcome of left-sided valvular IE with low CRP concentration.


This was a retrospective analysis of cases of IE discharged from our institution between January 2009 and May 2017. The 10% lowest CRP concentration (<20mg/L) was used to define low CRP concentration. Right-sided cardiac device-related IE, non-bacterial IE, sequelar IE and IE previously treated by antibiotics were excluded.


Of the 469 patients, 13 (2.8%; median age 68 [61-76] years) had definite (n=8) or possible (n=5) left-sided valvular IE with CRP<20mg/L (median 9.3 [4.7-14.2] mg/L). The median white blood cell count was 6.3 (5.3-7.5) G/L. The main presentations were heart failure (n=7; 54%) and stroke (n=3; 23%). Transthoracic echocardiography (TTE) showed vegetations (n=5) or isolated valvular regurgitation (n=4). Overall, eight patients (62%) had severe valvular lesions on transoesophageal echocardiography (TOE), and nine patients (69%) underwent cardiac surgery. All patients survived at 1-year follow-up. Bacterial pathogens were documented in eight patients using blood cultures, serology or valve culture and/or polymerase chain reaction analysis.

  • streptococci
  • coagulase-negative Staphylococcus
  • Corynebacterium jeikeium
  • HACEK group (Haemophilus, Aggregatibacter, Cardiobacterium, Eikenella, Kingella)
  • Coxiella burnetii
  • Bartonella henselae


Left-sided valvular IE with limited or no biological syndrome is rare, but is often associated with severe valvular and paravalvular lesions. TOE should be performed in presence of unexplained heart failure, new valvular regurgitation or cardioembolic stroke when TTE is insufficient to rule out endocarditis, even in patients with a low CRP concentration.



A low CRP concentration means there isn’t inflammation. Typically, bacterial infections raise CRP, so this study is important because it shows that patients can be infected but NOT have a high CRP. 

For more on Baronella and Heart issues:

Regarding Coxiella burnetti, or Q-Fever:

The brown dog tick, Rocky Mountain Wood tick, and the Lone Star Tick are all vectors and Q-fever is endemic throughout the U.S.  Treatment is doxycycline.  This document states Q-Fever is a category B agent (moderately easy to disseminate).

Humans are very susceptible to the disease and few organisms are required to cause
infection. In rare instances, people may acquire Q fever via the ingestion of raw milk or eggs, by tick bites, or by human-to-human transmission.  Interestingly, even as far back as the 30’s, Q-fever was noted to have properties of both viruses and rickettsiae. This document states Q fever may occur in patients without any animal contact due to it’s ability to be spread by wind.  The same document states human Q-fever cases have occurred in the following:

  • An OB after an abortion on an infected woman
  • transplacental transmission
  • autopsies
  • intradermal inoculation
  • blood transfusion
  • tick bite
  • sexually in infected mice
  • possibly from infected dogs
  • infected cats

The real kicker on that last one was the 1984 report of 13 people who developed febrile respiratory disease by playing poker in a room where a cat had delivered kittens.  Abstract here:

Kosatsky T. Household outbreak of Q-fever pneumonia related to a parturient cat. Lancet. 1984;ii:1447–1449. [PubMed]

Symptoms were:

  • bradycardia (slow heart rate)
  • fever
  • palatal petechiae (red or purple spots on mouth palate)
  • rapidly enlarging bilateral pulmonary infiltrates (fluid in both lungs)