Cardiac surgery is reasonable in combination with prolonged courses of combined antibiotic therapy for most patients with IE caused by non-HACEK Gram-negative aerobic bacilli, particularly P aeru- ginosa (Class IIb; Level of Evidence B). Table 16. Therapy for Endocarditis Involving a Native or Prosthetic Valve or Other Prosthetic Material Caused by HACEK Microorganisms Regimen Dose and Route Duration, wk Strength of Recommendation Comments Ceftriaxone sodium* 2 g/24 h IV or IM in 1 dose 4, NVE; Class IIa; Level of Evidence B Preferred therapy: cefotaxime or another third- or fourth-generation cephalosporin may be substituted. Or Ampicillin sodium 2 g IV every 4 h Class IIa; Level of Evidence B Ampicillin sodium may be an option if the growth of the isolate is sufficient to permit in vitro susceptibility results. Or equally divided doses Class IIb; Level of Evidence C Fluoroquinolone therapy may be considered for patients unable to tolerate cephalosporin and ampicillin therapy; levofloxacin or moxifloxacin may be substituted; fluoroquinolones generally is not recommended for patients <18 y old. Treatment for 6 wk is reasonable in patients with PVE (Class IIa; Level of Evidence C). HACEK indicates Haemophilus species, Aggregatibacter species, Cardiobacterium hominis, Eikenella corrodens, and Kingella species; IM, intramuscular; IV, intravenous; NVE, native valve infective endocarditis; and PVE, prosthetic valve infective endocarditis. *Patients should be informed that intramuscular injection of ceftriaxone is painful. Dose recommended for patients with normal renal function. Fluoroquinolones are highly active in vitro against HACEK microorganisms. Published data on the use of fluoroquinolones for endocarditis caused by HACEK are minimal. Baddour et al Infective Endocarditis in Adults 1463 2. Combination antibiotic therapy with a -lactam (penicillins, cephalosporins, or carbapenems) and either an aminoglycoside or fluoroquinolone for 6 weeks is reasonable (Class IIa; Level of Evidence C). 3. 