Abstract
Question A 2-year-old patient in my practice with acute otitis media that has progressed to mastoiditis with a high fever returns with positive culture results for Fusobacterium. What should I do next?
Answer Fusobacterium is a genus of anaerobic bacteria. Although Fusobacterium infections are rare, they can become severe if not treated promptly. Appropriate treatment is combination antibiotic therapy consisting of a β-lactam (penicillin, cephalosporin) and an anaerobic antimicrobial agent (metronidazole, clindamycin). At times surgical involvement is required for mastoiditis such as drainage of abscesses or insertion of a ventilation tube. Delayed treatment of an infection caused by Fusobacterium can lead to serious complications, including Lemierre syndrome. Children should be seen in a hospital for close monitoring.
Fusobacterium is a family of obligate anaerobic Gram-negative bacilli that comprise the normal flora of the oral cavity, gastrointestinal tract, and female genital tract. As early as 1936, André Lemierre associated Fusobacterium infections with thrombophlebitis of the jugular vein.1 More recently the incidence of Fusobacterium infections has increased. Although the reason for this increase is unknown, theories related to decreases in antibiotic use and improved detection techniques might account for the change.2–5 It is crucial that clinicians can detect the early signs of Fusobacterium infection, as a series of complications, such as Lemierre syndrome (postanginal sepsis), bacteremia, osteomyelitis, and septic shock, can quickly arise.6
Clinical characteristics
Fusobacterium infections in the pediatric population primarily affect the head and neck region, as the bacteria predominantly reside within the oral cavity. Acute otitis media is the most common site of infection, especially among children 2 years of age and younger.3,4,6,7 In immunocompetent patients, incidence is equal among males and females.3,7 Initial symptoms include fever (38°C to 39°C) with acute otitis media that has often progressed to mastoiditis. Laboratory evaluation reveals elevated inflammatory markers: C-reactive protein level, white blood cell count, and absolute neutrophil count.3,4,6–9 Mastoiditis is diagnosed with clinical and otoscopic evidence of swelling, erythema, and tenderness of the retroauricular area or displacement of the auricle anteroinferiorly.3,4,8 Megged et al7 focused on neurologic manifestations of Fusobacterium infections among 27 children with a median age of 3.5 years and found that 5 of them presented with decreased levels of consciousness and 7 had seizures before treatment was initiated.
Anaerobic bacteria cause less than 1% of middle ear infections; however, if left untreated serious complications such as subperiosteal and epidural abscesses might occur.4,6 Bacteremia is a severe complication that commonly arises and has been seen in up to 77% of Fusobacterium cases in children, potentially caused by the proximity of intracranial sinuses to the mastoid bone.6,8 Osteomyelitis was also observed in 40% of patients and often was multifocal, requiring prolonged intravenous antibiotic therapy.4,6 Meningitis caused by Fusobacterium is rare and has been described fewer than 20 times; however, it is often noted to cause severe morbidity and mortality.7,10
It has been suggested that owing to immunological immaturity in young age, development of Lemierre or Lemierre-like syndrome commonly occurs following middle ear infections with Fusobacterium.6 This is caused by an extension of middle ear infection into a venous sinus thrombosis. Lemierre syndrome is a serious complication of Fusobacterium infection, and in a study of 12 patients with the infection, 58% developed Lemierre or Lemierre-like syndrome.6 The syndrome is characterized by internal jugular vein septic thrombophlebitis or thrombosis and can cause septic embolic lesions in the lungs or other sterile sites.11
Diagnosis
Before confirmatory culture results are completed, clinical characteristics are important to consider in the diagnosis of Fusobacterium infection. For patients younger than age 3 with suspected Fusobacterium infection, clinical characteristics include high fever, a toxic appearance, and increased inflammatory markers. Mastoid involvement is common and can be diagnosed with a computed tomographic scan.
Confirmatory diagnosis is often done by blood or tissue culture. Anaerobic cultures tend to be more difficult to grow and previous antibiotic use can yield false-negative results.9 Polymerase chain reaction assay is a simple, quick, and quantitative detection technique that can identify levels much lower than cell culture; however, its cost prevents widespread use of the assay as a diagnostic tool.2,9
Treatment
The severity and spread of Fusobacterium determines the extent of treatment needed. All Fusobacterium infections must be treated with antibiotics and are generally susceptible to β-lactams such as penicillin or cephalosporin or their derivatives.12 A few strains of Fusobacterium were found to have β-lactamase enzymes, and therefore it is recommended to include a specific anaerobic antibiotic such as metronidazole or clindamycin.4,6 Antibiotic treatment is often administered parenterally for 1 to 2 weeks followed by approximately 10 days of oral treatment.3,6–9 Some children will need removal of necrotic tissue or surgical drainage.3,4,6,9
In a surveillance study of 7 patients younger than 2.2 years of age with Fusobacterium infection, all required a ventilation tube in addition to mastoidectomy.4 In a 14-year study from Israel with 22 children with Fusobacterium infection, 3 of the 5 patients who developed Lemierre syndrome were treated with low-molecular-weight heparin to alleviate symptoms of a cerebral sinus venous thrombosis8—treatment that is still considered controversial.3,6
A 40-year literature review by Stergiopoulou et al6 identified 12 cases of Fusobacterium infections in children younger than age 2; all the children developed mastoiditis and underwent mastoidectomy and antibiotic treatment, which led to successful outcomes, regardless of severity. The combination of appropriate antibiotic treatment with surgical debridement was shown to prevent complications. In a retrospective study by Shamriz et al,8 of the 22 patients analyzed there was only 1 patient who had a fatal outcome from overwhelming sepsis and all other patients fully recovered after treatment. While a mortality rate of up to 40% of Fusobacterium infections has been reported, early detection and proper treatment can effectively halt and reverse the progression of infection.9,13
Conclusion
Fusobacterium infection can clinically present as acute otitis media in children 2 years of age and younger, but if left untreated it will progress to mastoiditis and more severe symptoms of bacteremia, osteomyelitis, and potentially Lemierre syndrome and septic shock. The use of proper antimicrobial detection techniques along with the appropriate imaging procedures should allow for the prompt use of antibiotics and surgical involvement to prevent further dissemination of the infection. While research and analysis on Fusobacterium infections is limited, important awareness of symptomatology and severity of the infection can help clinicians detect early onset of infections and direct patients to appropriate specialists.
Notes
PRETx Pediatric Research in Emergency Therapeutics
Child Health Update is produced by the Pediatric Research in Emergency Therapeutics (PRETx) program (www.pretx.org) at the BC Children’s Hospital in Vancouver, BC. Ms Arane is a member and Dr Goldman is Director of the PRETx program. The mission of the PRETx program is to promote child health through evidence-based research in therapeutics in pediatric emergency medicine.
Do you have questions about the effects of drugs, chemicals, radiation, or infections in children? We invite you to submit them to the PRETx program by fax at 604 875–2414; they will be addressed in future Child Health Updates. Published Child Health Updates are available on the Canadian Family Physician website (www.cfp.ca).
Footnotes
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La traduction en français de cet article se trouve à www.cfp.ca dans la table des matières du numéro d’octobre 2016 à la page e586.
Competing interests
None declared
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