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Anaerobic Infections, Head & Neck

For further information, see CMDT Part 35-31: Anaerobic Infections

KEY FEATURES

  • Prevotella species and anaerobic spirochetes are commonly involved in periodontal infections

  • These organisms, fusobacteria, and peptostreptococci may cause

    • Chronic sinusitis

    • Peritonsillar abscess

    • Chronic otitis media

    • Mastoiditis

  • Fusobacterium necrophorum has been recognized as a cause of pharyngitis in adolescents and young adults

  • F necrophorum infection has been associated with septic internal jugular thrombophlebitis (Lemierre syndrome) and can cause septic pulmonary embolization

CLINICAL FINDINGS

  • Related to infected organ

DIAGNOSIS

  • Culture

  • CT scan

TREATMENT

  • Tables 32–1 and 32–5

  • Penicillin alone is inadequate for infections caused by oral anaerobic organisms because of increasing penicillin resistance, usually due to β-lactamase production; therefore, the following can be used for coverage of oral anaerobes:

    • Ampicillin/sulbactam, 1.5–3 g intravenously every 6 hours (if parenteral therapy is required), or

    • Amoxicillin/clavulanic acid, 875 mg/125 mg orally twice daily

  • Antimicrobial treatment is continued for a few days after symptoms and signs of infection have resolved

  • Indolent, established infections (eg, mastoiditis or osteomyelitis) may require prolonged courses of therapy (eg, 4–6 weeks or longer), using antimicrobials that penetrate bone

  • Hygiene, drainage, and surgical debridement are as important in treatment as antimicrobials

Table 32–1.Examples of initial antimicrobial therapy for acutely ill, hospitalized adults pending identification of causative organism (listed in alphabetical order by suspected clinical diagnosis).
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Table 32–1. Examples of initial antimicrobial therapy for acutely ill, hospitalized adults pending identification of causative organism (listed in alphabetical order by suspected clinical diagnosis).
...
Suspected Clinical Diagnosis Likely Etiologic Diagnosis Medication of Choice
Brain abscess Mixed anaerobes, pneumococci, streptococci Ceftriaxone, 2 g intravenously every 12 hours plus metronidazole, 500 mg orally/intravenous every 8 hours, plus vancomycin, 15–20 mg/kg intravenously every 8–12 hours1
Endocarditis, acute (including injection drug user) Staphylococcus aureus, Enterococcus faecalis, viridans streptococci Vancomycin, 15–20 mg/kg/dose intravenously every 8-12 hours1
Fever in neutropenic patient receiving cancer chemotherapy S aureus, Pseudomonas, Klebsiella, Escherichia coli Cefepime, 2 g intravenously every 8 hours. If concerned for MRSA infection, add vancomycin 15–20 mg/kg intravenously every 8–12 hours1
Intra-abdominal sepsis (eg, postoperative, peritonitis, cholecystitis) Gram-negative bacteria, Bacteroides, anaerobic bacteria, enterococcus Piperacillin-tazobactam, 4.5 g intravenously every 6–8 hours, or ertapenem, 1 g every 24 hours
Meningitis, bacterial, age > 50 years, community-acquired Pneumococcus, meningococcus, Listeria monocytogenes,2 gram-negative bacilli, group B streptococcus Ampicillin, 2 g intravenously every 4 hours, plus ceftriaxone, 2 g intravenously every 12 hours, plus vancomycin, 15–20 mg/kg intravenously every 8–12 hours1
Meningitis, bacterial, community-acquired Streptococcus pneumoniae (pneumococcus),3 Neisseria meningitidis (meningococcus) Ceftriaxone, 2 g intravenously every 12 hours,3 plus vancomycin, 15–20 mg/kg intravenously every 8–12 hours1
Meningitis, postoperative (or posttraumatic) S aureus, gram-negative bacilli, coagulase-negative staphylococci, diphtheroids (eg, Propionibacterium acnes) (uncommon) pneumococcus (in posttraumatic)

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