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Retropharyngeal abscess in children: the emerging role of group A beta hemolytic Streptococcus.

Article Excerpt
Background: Because of a recent increase in the number of cases of retropharyngeal abscess (RPA) admitted to our hospital, we reviewed the incidence, microbiology, and treatment outcome of RPA during an 11-year period (1993-2003).

Methods: A retrospective review of medical records of children with RPA.

Results: Sixty-seven children (46 males) with RPA were identified, representing a 4.5-fold increase in incidence over a previous 12-year period. The majority (66%) of patients presented during the last 4 years. Computed tomography revealed inflammatory or ring enhancing lesion in all patients. Abscess drainage was performed in 51 (76%) patients. A total of 101 isolates (84 aerobes, 17 anaerobes) were recovered from 41 specimens (a mean of 2.5 isolates per specimen). Group A beta hemolytic streptococcus (GABHS) was recovered from 22 (54%) of 41 specimens compared with 6 (35%) of 17 over the previous 12 years. Treatment included IV antibiotics: ampicillin/sulbactam or clindamycin plus either cefuroxime or ceftri-axone, followed by oral amoxicillin/clavulanate or clindamycin. All patients recovered.

Conclusions: RPA, an aerobic/anaerobic polymicrobial infection, is increasing in frequency and is associated with increased recovery of GABHS in our patients. Whether this rise in incidence is due to increased invasiveness of GABHS strains is to be determined.

Key Words: retropharyngeal abscess, group A streptococcus, pharyngitis

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Deep neck infections include those involving the retropharyngeal and parapharyngeal spaces. Retropharyngeal abscess (RPA) is a relatively uncommon infection found more frequently in children and has potential serious complications. Abscess formation usually follows upper respiratory tract infection with subsequent suppuration of the lymph nodes in the retropharyngeal space. These nodes usually atrophy by 4 years of age. (1) In children, retropharyngeal lymphadenitis and RPA occur secondary to an adjacent focus of infection such as pharyngitis, tonsillitis, dental infection and adenitis. Other, less frequent causes include penetrating trauma, vertebral osteomyelitis, parotitis, mastoiditis and sinusitis. (2-4) RPA in children is polymicrobial and isolated organisms usually reflect mouth and nasopharyngeal flora. (5-7)

During the last 2 years, we noted an increase in the number of cases of RPA in children at our institution. This study was undertaken to identify the incidence of RPA among children in our institution, to identify the predisposing factors and the microbiology of RPA and to evaluate the treatment and clinical outcome. We present the results of a retrospective investigation of children with retropharyngeal abscess during 11 consecutive years.

Patients and Methods

Children admitted to our hospital with the diagnosis of RPA between February 1993 and December 2003 are the subjects of this study. Children's Hospital of Michigan is a tertiary care teaching pediatric institution with a 220-bed capacity. For this study, we examined the patient's demographic data, laboratory characteristics including microbiologic and radiographic data, clinical course and response to treatment.

Purulent material obtained at surgery from the retropharyngeal abscess was transported anaerobically to the microbiology laboratory within 30 minutes and inoculated onto plates supportive for aerobic and anaerobic growth. Gram-stained smears were obtained on all specimens. For aerobic growth, the material was plated onto sheep blood agar plates, colistin-nalidixic acid (CNA) plates, chocolate agar plates and MacConkey agar plates. All plates were incubated at 37[degrees]C, the MacConkey plates aerobically and the other plates under 5% C[O.sub.2]. All plates were examined at 24 and 48 hours. Aerobes were...