The aims of the study are:

1. Explore the bacteriology of para- and retropharyngeal abscess.
2. Validate the bacterial findings by exploring antibody development against F. necrophorum, F. nucleatum and S. pyogenes.
3. Compare bacteriologic findings in concomitant peritonsillar and parapharyngeal abscesses.
4. Characterize patients with para- and retropharyngeal abscess.
5. Compare the concentration of amylase in para- and retropharyngeal abscesses and neck abscesses without relation to the pharynx or salivary glands.
6. Perform gene-sequencing of F. Necrophorum strains, and compare these with strains recovered from patients with acute tonsillitis, peritonsillar abscess, and Lemierre´s syndrome.

Patients:

Sixty patients aged 18 years or older with para- or retropharyngeal abscess and 12 patients with neck abscess without relation to the pharynx or salivary glands (controls) will be included at five Danish centers. Estimated time of inclusion: Four years.

Data:

Symptoms, findings, and other relevant information will be obtained at admission. Data regarding treatment and complications will be obtained after discharge.

Samples:

1. Tonsillar surface swabs (bilaterally)
2. Pus aspirate from para- or retropharyngeal abscess
3. Pus aspirate from peritonsillar abscess, if present
4. Biopsy or the entire tonsil (bilaterally)
5. Blood samples (acute and convalescent)

Investigations:

1. Bacterial cultures from tonsillar surface swabs, pus aspirates, and tonsillar tissues.
2. Antibody development against F. necrophorum, F. nucleatum and S. pyogenes from the two sera.
3. Gene-sequencing of F. Necrophorum strains.
4. Measurement of amylase concentrations in pus aspirates.

Power calculations:

Patients needed to show significant increase in anti-F. necrophorum antibody development.

Assumptions:

1. The found anti-F. necrophorum antibody levels will be compared to previous findings in electively tonsillectomized patients (9 of 47 patients had two-fold or higher increase in anti-F. necrophorum antibody levels).
2. Level of statistical significance: P = 0.05
3. Power: 90%.
4. Part of F. necrophorum-positive para- or retropharyngeal patients WHO develop two-fold or higher anti-F. necrophorum antibody levels: 73%.
5. Part of para- or retropharyngeal patients with F. necrophorum: 20%. Number of para- or retropharyngeal patients needed: 60.

Concerning comparison of amylase concentrations between patients with para- or retropharyngeal abscess and patients with neck abscesses without relation to the pharynx or salivary glands:

Assumptions:

1. Amylase concentration > 20 U/L in 0% of controls.
2. Amylase-concentration > 20 U/L in 50% af patients with para- or retropharyngeal abscess .
3. Inclusion of controls 1:3 compared to patients with para- or retropharyngeal abscess .
4. Level of statistical significance: P = 0.05
5. Power: 90%. Number of para- or retropharyngeal patients needed: 36. Number of controls needed: 12.

Inclusion Criteria:

• para- or retropharyngeal abscess

Exclusion Criteria:

• refuse to participate

Sixty patients with para- or retropharyngeal abscess. Twelve patients with neck abscess without relation to the pharynx or salivary glands (controls).