What are the most prevalent pathogens in deep neck infections?

Updated: Apr 30, 2020
  • Author: Alan D Murray, MD; Chief Editor: Arlen D Meyers, MD, MBA  more...
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The microbiology of deep neck infections usually reveals mixed aerobic and anaerobic organisms, [17] often with a predominance of oral flora. Both gram-positive and gram-negative organisms may be cultured. Group A beta-hemolytic streptococcal species (Streptococcus pyogenes), alpha-hemolytic streptococcal species (Streptococcus viridans, Streptococcus pneumoniae), Staphylococcus aureus, Fusobacterium nucleatum, Bacteroides melaninogenicus, Bacteroides oralis, and Spirochaeta, Peptostreptococcus, and Neisseria species often are found together in various combinations. Pseudomonas species, Escherichia coli, and Haemophilus influenzae are occasionally encountered.

A German study, by Cordesmeyer et al, of 63 patients with deep neck space infections, found Streptococcus viridans to be the most prevalent aerobic gram-positive pathogen to be isolated (26.7% of infections), with Staphylococcus epidermidis and Staphylococcus aureus each being isolated in 16.7% of infections. Among the aerobic gram-negative pathogens, Escherichia coli, Klebsiella oxytoca, and Haemophilus influenzae were the most frequently isolated. Malignancy was found in 1.6% of patients. [18]

In a retrospective study by Shimizu et al of patients with deep neck infection, bacterial cultures revealed Staphylococcus species in 60% of pediatric patients but in only 9% of adults, with Streptococcus species, on the other hand, being more common in adults (56%) than in children (27%). [19]

A study by Asmar of retropharyngeal abscess microbiology demonstrated polymicrobial culture results in almost 90% of patients. [20] Aerobes were found in all cultures, and anaerobes were found in more than 50% of patients. Other studies have shown an average of at least 5 isolates from cultures.

May et al found evidence that biofilm phenotypes may be associated with the pathogenesis of deep neck infections, as well as with the recalcitrance to treatment experienced with larger deep neck abscesses. The investigators obtained biopsy samples from abscess walls located in the deep neck spaces of 14 patients undergoing surgical drainage. Scanning electron microscopy revealed that 12 of the 14 tissue samples contained biofilm imbedded with rod- and cocci-shaped bacteria. [21]

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