Background: Infection of cardiac implantable electronic device including wound and pouch infection, bacteraemia and endocarditis is a common complication of device insertion. The role of antibiotic prophylaxis in prevention of this complication is well established. Most centres in Israel currently prescribe antibiotics about 5 days following the procedure as well, though clear clinical evidence warranting this practise is lacking. Unnecessary antibiotic treatment can lead to adverse events including allergy, undesirable effects of the antibiotics, establishment of resistance to antibiotics among bacteria and further infections with resistant strains.

Objective: The investigators hope to either establish evidence warranting use of post-procedural antibiotic treatment or refuting it.

Methods: The investigators intend to recruit about 400 patients a year into both trial group and control group. The trial group will be treated with post-procedural antibiotics during 5 days, while the control group will receive no post-procedural antibiotics. The endpoints of the study will include infections related to the implantable device and proposed adverse effects of the antibiotics. The t-test will be performed in order to evaluate whether benefit exists concerning one of the groups.

The infection of cardiac implantable electronic device site (including both pocket infection and deeper infections) is a common complication of electronic device insertion. Its incidence is estimated in different series as 0.2-0.7 per 100 device-years. The risk factors that raise the incidence of this complication are in the first place lack of or inappropriate antibiotic prophylaxis and repeated or recurrent manipulations with the device. Several comorbidities such as diabetes, renal insufficiency, heart failure, malignancy, anticoagulation treatment, and, non-surprisingly glucocorticoid treatment are the remaining risk factors for the infection. It is worth mentioning that over half of all cases of infection occur during the first year past implantation.

About 75% of all device infections are caused by staphylococci (both S. aureus and coagulase negative staphylococci). The other causative organisms are streptococci, Corynebacterium species, Propionibacterium, gram-negative bacilli and fungi. Main source of infection appears to be pocket contamination by skin flora. In one study the swab specimens obtained from device pockets during the procedure rendered positive culture for coagulase-negative staphylococci in up to one half of the specimens even despite observant aseptic technique and appropriate antibiotic prophylaxis.Thus, the contamination leading to infection of the implantation site can occur during the procedure. Other possible paths for infection include erosion of the device or its leads through the skin and seeding of the device and its leads by systemic bacteremia. The treatment of this complication usually requires explantation of the infected device, intravenous antibiotic treatment and then implantation of a new device through the non-infected route.

The principal approach to prevent device infection remain aseptic technique during the procedure and appropriate antibiotic prophylaxis. Different clinical trials showed that pre-treatment of elective patients before the device implantation with anti-staphylococcal penicillins or with first generation cephalosporins results in decrease in rate of infection with odds ratio about 0.2-0.25.Therefore, current recommendation is to pre-treat patients before implantation of the device with 2-3 gram cefazolin or 1.5 gram cefuroxime, or 15 mg/kg vancomycin or clindamycin 900 mg IV within 4 hours before the procedure. Currently there is no evidence regarding adjuvant antibiotic treatment after the implantation. In the face of lack of evidence, several medical centres in Israel either non-uniformly administer different antibiotic regimens following the implantation or refrain from routinely prescribing any antibiotics to the patients following the implantation.

Objective:

The investigators suppose that non-necessary antibiotic treatment entails several adverse outcomes including direct adverse effects of the antibiotics (e.g. allergy, gastrointestinal effects, QT-prolongation), and induction of resistance to antibiotics among the patient's microflora entailing further infections with resistant bacteria (e.g. urinary tract infections, diarrhea). Therefore, an evidence either warranting use of antibiotics following the implantation of implantable electronic device or refuting it should be established.

Medications:

1. cefalexin 500 mg qid,
2. roxithromycin 150 mg bid Both medications are authorized in Israel for a variety of infections or infection prevention including prevention of implantable cardiac electronic device infection. Both medications are routinely prescribed in medical centres in Israel following implantation of cardiac electronic devices.

Inclusion Criteria:

• patients undergoing de novo implantation or replacement of cardiac implantable devices (single-chamber, dual-chamber and biventricular pacemakers and defibrillators) in our institution.

Exclusion Criteria:

• procedure during which, according to the opinion of the operator, the risk of the contamination would be unusually high (for ex. due to prolonged duration) so that obligatory post-operative use of antibiotics should be warranted,
• patients with any immunosuppressive condition (including cytotoxic chemotherapy, chronic use of glucocorticoids, however excluding diabetes mellitus, renal failure and heart failure);
• malignancy,
• pregnancy and breastfeeding;
• hepatic cirrhosis;
• end stage renal disease (GFR<10 mL/min);
• known allergy to both antibiotic medications used in the study.

The random assignment will be performed by a researcher from the cardiologic team performing the implantation by means of choosing one of two closed envelopes. The treatment will not be placebo-controlled, and therefore the neither the patients nor the attending physicians will not be blinded to the final results of the assignment.