*2.2.5 Treatment and prognosis*

*Advanced Concepts in Endocarditis - 2021*

*2.2.2 CIED infection risk factors*

*2.2.3 Pathogenesis and microbiology*

Almqvist et al., further divides the spectrum of CIED infections into six different categories: early post-implantation inflammation, uncomplicated pocket infection, complicated pocket infection, definite CIED lead infection, possible CIED lead infection, CIED-associated endocarditis, and probable CIED infection [26].

Patients with chronic kidney disease, long-term corticosteroid use, presence of more than 2 pacing leads, diabetes mellitus, heart failure and oral anticoagulation are at higher risk for CIED infection [25, 26]. Use of preprocedural temporary pacing, fever within 24 hours prior to implantation, blood stream infections, and early reintervention were also associated with higher risk of CIED infection [25]. Lower rates of CIED infection was associated with antibiotic perioperative prophylaxis new device placement, use of pectoral approach rather than abdominal or transtho-

Source of microorganisms often originate from the skin during the implantation of the electrical agent in the subcutaneous tissue, from the pocket in which the electrical agent is placed, the tunnel that forms around the lead before its point of entry into the blood vessel or from bacteria unrelated to the CIED, which may be present in the form of a foreign body placed on or in contact with the endocardial tissue, or that applies pressure to the endocardial tissue and tricuspid valve [23, 27]. Alternatively, contamination of the CIED can occur at different stages or from various causes. This includes but is not limited to manufacturing or packaging, infection prior to or during implantation, secondary to surgical site infection or via hematogenous seeding

Physical and chemical properties such as electrostatic charge, surface tension and hydrophobicity of each device plays an important role in the interaction with bacteria and development of bacterial attachment and biofilm formation [23]. More hydrophobic surfaces such as polyvinyl chloride, polyethylene, silicone, latex and stainless steel are associated with higher microbial adherence [24]. Pathogens are more likely to adhere to irregular surfaces and may also adhere to the patient's matrix proteins (fibrinogen, fibronectin and collagen) that coat the surface of an implanted device [25]. CIED infections are more likely to occur due to gram positive bacteremia than gram negative bacteremia [25]. Staphylococci species, especially coagulase negative staph, have a knack for adhesion to CIEDs via host matrix proteins and to each other thus forming biofilms [24, 25]. Coagulase negative staphylococci comprise 42% of all PPM and ICD infections, followed by oxacillin sensitive *S. aureus* (25%), oxacillin resistant *S. aureus* (4%), with the remaining causative organisms being other gram positive cocci (4%), gram negative bacilli (9%), fungal

racic approach, and device placement by a high-volume physician [25].

from a distant site or after erosion through the skin [24, 25, 27].

(2%), polymicrobial (7%), and unidentified/culture negative (7%) [28].

Biofilm is a group of one or more microbial species firmly attached to a device surface and each other and covered by extracellular polymeric matrix [24, 25]. This matrix provides a protective barrier and results in antibiotic resistance and extreme difficult of bacterial irradiation that frequently requires device explanation [24, 25]. Some bacteria are more adept to adhering to non-biological materials such as staphylococci.

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*2.2.4 The role of biofilm*

Antibiotics are generally empirically initiated after obtaining at least three sets of blood cultures. These usually consists of broad-spectrum intravenous antibiotics covering both gram-positive and gram-negative bacteria, including methicillin/oxacillin-resistant *Staphylococcus aureus* [29]. Antibiotic therapy alone without device removal, however, is associated with a 7 times increase in 30-day mortality [28]. Treatment of CIDE as recommended per the 2017 HRS Consensus Document include complete device and lead removal in addition to antibiotics [29]. Immediate system removal is associated with a 3 times decrease in 1-year mortality as compared to preliminary antibiotic treatment and delayed system removal [30]. Mortality rates in patients with endocarditis who had systems removed and antimicrobial therapy are 18% or less compared with up to 66% on antibiotic therapy alone [27]. Multiple clinical studies have now demonstrated a 97.7% clinical success rate with hardware removal in addition to antibiotic therapy [30].
