HACEK Group Infections Treatment & Management

Updated: Sep 27, 2018
  • Author: Zartash Zafar Khan, MD, FACP; Chief Editor: Pranatharthi Haran Chandrasekar, MBBS, MD  more...
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Medical Care

Appropriate antibiotic therapy is key to the management of infective endocarditis (IE) caused by the HACEK organisms (see Medications). The Infectious Disease Society of America (IDSA) recommends the following: [28]

  • Unless in vitro growth is adequate to obtain susceptibility testing results, HACEK microorganisms are considered ampicillin-resistant, and penicillin and ampicillin should not be used for the treatment of IE. Ampicillin sodium may be an option if the growth of the isolate is sufficient to permit in vitro susceptibility results.
  • Ceftriaxone is reasonable for treatment of HACEK IE.
  • Four weeks of therapy for HACEK native-valve endocarditis is reasonable; for HACEK prosthetic valve endocarditis, a therapy duration of 6 weeks is reasonable.
  • Gentamicin is not recommended because of its nephrotoxicity risks.
  • A fluoroquinolone (ciprofloxacin, levofloxacin, or moxifloxacin) may be considered an alternative agent in patients who are unable to tolerate ceftriaxone (or other third- or fourth-generation cephalosporins).
  • Patients with HACEK IE who cannot tolerate ceftriaxone therapy should be treated in consultation with an infectious diseases specialist.

Antibiotic therapy may be fine-tuned when susceptibility data for the causative organism are available. [29]

Complications that arise (eg, heart failure, embolic complications) also require supportive medical therapy.

When treating a clenched fist injury or bite wound infection, HACEK organisms should be kept in consideration. E corrodens is resistant to macrolides, clindamycin, and metronidazole. H aphrophilus is also typically resistant to clindamycin.


Surgical Care

The decision to consider surgical therapy in patients with IE is often challenging and must be made on an individual basis. The following are several accepted indications for surgery in IE: [9]

  • Refractory CHF

  • One or more embolic episode

  • Uncontrolled infection (persistently positive blood cultures after 1 week of therapy)

  • Physiologically significant valve dysfunction as demonstrated by echocardiography: According to the American Heart Association Committee on IE, criteria associated with an increased need for surgical intervention include (1) persistent vegetations after a major systemic embolic episode; (2) anterior mitral valve vegetations larger than 1 cm in diameter; (3) increase in size of vegetations after 1 month of therapy; (4) periannular extension of infection; and (5) valvular dysfunction, perforation, or rupture. [30]

  • Ineffective antimicrobial therapy (usually not the case with HACEK organisms)

  • Resection of mycotic aneurysms

  • Most cases of prosthetic valve endocarditis caused by more resistant organisms (eg, methicillin-resistant S aureus [MRSA], vancomycin-resistant enterococci [VRE], enteric gram-negative bacilli)

  • Local suppurative complications including perivalvular or myocardial abscess



Treatment of HACEK endocarditis requires a multidisciplinary approach.

Consultation with an infectious disease specialist may be helpful for selecting antibiotics, monitoring therapy, and selecting the duration of therapy.

Consultation with a cardiologist may be helpful, especially if transesophageal echocardiography is needed or if CHF develops.

Management of large vegetations or mechanical complications warrants a cardiovascular surgeon's advice.

Consultation with a dentist is indicated if periodontal disease is present.



No special diet is necessary in patients with HACEK group infections.



Although there is no evidence-based recommendation for activity levels in patients with endocarditis, it is prudent to keep activity light in the initial phase of treatment.



The risk of endocarditis due to HACEK organisms may be reduced by maintenance of good dental hygiene.

Guidelines for infective endocarditis (IE) prophylaxis prior to dental procedures were updated in 2007. Current recommendations support the use of prophylactic antibiotics for high-risk lesions only.

Antibiotic prophylaxis should be considered before oral/dental procedures in patients with high-risk cardiac conditions. [31]

High-risk conditions include the following:

  • Prosthetic valves

  • Previous bacterial endocarditis

  • Complex cyanotic congenital heart disease

  • Surgically constructed systemic pulmonary shunts or conduits

  • Valvulopathy in cardiac transplantation recipients


Long-Term Monitoring

Relapse may occur during the first 6 months following the end of treatment. Patients should be counseled and observed regarding relapse.


Further Inpatient Care

Careful clinical observation is the most important aspect of monitoring adequacy of therapy in HACEK group infections. Persistent or recurrent fever may be a sign of treatment failure, but it also may be due to hypersensitivity reactions, thrombophlebitis, or sterile embolization. Observe patients closely for signs of complications, such as embolic events or CHF.

Repeat blood cultures every 48 hours until they become negative.

Fever that lasts longer than 10 days after starting appropriate antibiotics should cause concern.

Causes of persistent fever include drug fever, antibiotic resistance, myocardial or septal abscesses, large vegetations that are difficult to sterilize, and metastatic infection (intracerebral mycotic aneurysms).


Inpatient & Outpatient Medications

In general, the entire course should be with intravenous antibiotics. Once the patient is stable and cultures are negative, completing intravenous therapy on an outpatient basis is reasonable. However, even in the outpatient setting, frequent evaluations are necessary to assess for response to therapy and for drug toxicity.

Although little evidence exists to support its use in this setting, ciprofloxacin could be used in oral form in certain circumstances. However, given the lack of evidence, this be reserved for special circumstances and in consultation with an infectious disease specialist. [9]



If HACEK infection is diagnosed early, managing the infection in a center that does not offer cardiovascular surgery services may be possible. However, consider transfer to a health center with complete cardiac and neurological care for any patient at high risk for complications.

If the patient is stable, has good social support, and is afebrile with negative blood cultures, outpatient therapy can then be offered for the remainder of the treatment course.