Specific Aim : The specific aim is to conduct a randomized prospective clinical trial to determine whether no antibiotics in OHCA patients in the ED with very low likelihood of infection is non-inferior to early antibiotic treatment. Hypothesis a: 28-day all-cause mortality will be non-inferior in OHCA patients with very low likelihood of infection who do not receive antibiotic therapy compared with those who receive early antibiotic therapy Hypothesis b: There will be no difference in subsequent incidence of proven infections in the no antibiotics vs, early antibiotics groups Hypothesis c: There will be no difference in the length of ICU stay and overall hospital stay in the early antibiotics vs. no antibiotics groups

As above

Inclusion Criteria:

• ● Adults aged >18 years, presenting to HGH ED after out-of-hospital cardiac arrest

  • Patients with low likelihood of infection as per the definitions provided above
  • Ability to obtain informed consent from the subjects or their next of kin/family member/legal surrogate in case of incapacitation due to sedation, mechanical ventilation, etc. In case the next of kin is not available, an independent physician who is not a part of the investigative team will complete and sign the checklist as per HMC Policy "RES 11026_Appendix 6.5". (see section 4.1.3 for details) A member of the investigative team and a witness will also sign this form before the potential subject is enrolled in the study.

Exclusion Criteria:

• Patients who have clear evidence of infection, as defined by criteria for the study.

  • Patients who have received antibiotics within the last 1 week prior to admission.
  • Patients with malignancy, except those who have been cured or in complete remission.
  • Females with known pregnancy.
  • Known immunocompromised states (including HIV/AIDS, transplant recipients on immunosuppressant drugs, long-term [> 3 weeks of prednisone >5mg/day equivalent] steroid therapy).
  • Patients on immunologic disease modifying agents (commonly known as "biologics")
  • Patients considered "brain-dead" or "vegetative state"
  • Patients transferred from another hospital, long term care facility or institution
  • Neutropenia (total WBC <1,500/mm3 or absolute neutrophil count of <1,000/mm3)