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Infective Endocarditis

Infective endocarditis (IE) is a rare, life-threatening disease that occurs when pathogens enter the bloodstream and infect the heart lining, or the endocardium. IE is generally caused by bacteria, but fungal endocarditis does occur and is the more fatal of the two conditions.1 This article reviews the disease, including its symptoms, risk factors, and causes, and discusses how a syndromic approach to blood culture testing can help improve IE diagnostics.

 

What Causes IE?

Infective endocarditis, commonly referred to as bacterial endocarditis, is caused by bacteria that enter the bloodstream and infect the lining of a heart valve or blood vessel. Infection can occur in native or prosthetic valves, with the latter accounting for 20% of endocarditis cases.2

Severity of IE is categorized as either acute or subacute—the latter form progresses rapidly over days or weeks, while the former condition develops over weeks or months and does not require immediate care.3

Risk Groups & Risk Factors

It is rare for the heart to become infected with bacteria, so people who have a damaged or diseased heart, either due to a pre-existing condition or past surgeries, are most at risk of getting IE.4 For these individuals, the bacteria can more easily enter the heart, and since white blood cells do not reach heart valves, the body cannot fight off the infection.

The demographic that's been found to be the most vulnerable is older males.5 The most common risk factors (i.e., how IE-causing bacteria enter the bloodstream) include:3,6

  • Poor dental hygiene
  • Dental procedures
  • Implanted cardiovascular devices
  • Congenial heart disease
  • Heart transplant
  • Previous surgeries on the heart valve
  • Chronic skin disorders and infections
  • Illicit drug use

In-hospital morality in IE patients who receive treatment is around 20% to 24%, while one-year mortality is estimated between 29% and 31%.5,7 Without surgical intervention, mortality can be as high as 37%.5

Symptoms & Causes

According to the American Heart Association, symptoms for IE can include:4

  • Fever and chills
  • Fast heart rate
  • Fatigue
  • Night sweats
  • Aching joints and muscles
  • Persistent cough
  • Swelling in the feet, legs, or joints

Bacteria from the Staphylococcus family, in particular Staphylococcus aureus and coagulase-negative staphylococci, are the most common causes of bacterial endocarditis.7 When looking at fungal endocarditis, Candida and Aspergillus are the species most commonly found in patients, with Candida albicans infections accounting for up to 46% of all cases.1

Blood Culture is Key

Blood culture is essential for diagnosing IE. But because bloodstream infections like IE are associated with high mortality, clinicians typically start patients on empiric antimicrobial therapy while awaiting lab results. Unfortunately, standard-of-care testing can take days to return results—labs must first identify an organism in positive blood culture before then conducting susceptibility testing to determine if the organism is resistant to any antimicrobials.

Meanwhile, the patient may be receiving inappropriate or unnecessary antimicrobials that may derail their recovery and further treatment.

The Syndromic Approach With the BIOFIRE® Blood Culture Identification 2 (BCID2) Panel

Syndromic testing offers a better way to approach blood infection diagnostics. Unlike traditional blood culture tests, the BIOFIRE® BCID2 Panel is both fast and comprehensive, returning results in about an hour from positive blood culture. The panel detects a broad menu of 43 possible targets, including S. aureus and Candida albicans among other Gram-positive bacteria, Gram-negative bacteria, and yeast. The single test also includes 10 antimicrobial resistance genes.

Multiplex PCR testing with the BIOFIRE® BCID2 Panel can shorten the time to pathogen identification, giving clinicians the information they need to make timely and optimal treatment decisions. Compared to traditional blood culture testing, the original BIOFIRE® FILMARRAY® Blood Culture Identification Panel demonstrated a 1.7-day reduction in time from blood culture collection to organism identification.8

References:

  1. Yuan S, et al. Fungal Endocarditis. Braz J Cardiovasc Surg. 2016 May-Jun;31(3):252-255.
  2. Wang A, et al. Contemporary clinical profile and outcome of prosthetic valve endocarditis. JAMA. 2007 Mar;297(12):1354-61.
  3. Heart Valves and Infective Endocarditis. Accessed 16 Feb. 2023. Retrieved from: https://www.heart.org/en/health-topics/heart-valve-problems-and-disease/heart-valve-problems-and-causes/heart-valves-and-infective-endocarditis
  4. Heart conditions - endocarditis. Accessed 16 Feb. 2023. Retrieved from: https://www.betterhealth.vic.gov.au/health/conditionsandtreatments/heart-conditions-endocarditis
  5. Sunder S, et al. Incidence, characteristics, and mortality of infective endocarditis in France in 2011. PLOS ONE. 2019;14(10)
  6. Endocarditis. Accessed 16 Feb. 2023. Retreived from: https://www.mayoclinic.org/diseases-conditions/endocarditis/symptoms-causes/syc-20352576
  7. Cresti A, et al. Epidemiological and mortality trends in infective endocarditis, a 17-year population-based prospective study. Cardiovasc Diagn Ther. 2017 Feb;7(1):27-35.
  8. MacVane SH, et al. J Clin Microbiol. 2016;54:2476-2484.

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