Bacteria, Antibiotics and Resistance: Odontogenic Infections Revisited
Method: This study is a seven year retrospective study of 78 consecutive patients at Kings County Hospital Center with major odontogenic space infections who required admission for intravenous antibiotics and incision and drainage under general anesthesia. Orofacial spaces involved included submandibular, sublingual, submental, buccal, pterygomandibular, lateral pharyngeal and retropharyngeal spaces. Implicated bacteria isolated via standard aerobic and anaerobic culture technique are listed as well as antibiotic resistance and sensitivity. Exclusion criteria were non-odontogenic etiology such as sinusitis, sialodenitis, osteomyelitis and peritonsilar abscess.
Results: Only 77% of the patients in this study were culture positive with 23% showing no growth. Most (69%) of the 78 orofacial infections involved one space, 21% involved two spaces and 10% involved 3 or more spaces. Consistent with previous studies Streptococus viridans, isolated in 54% of patients with positive cultures, continues to be the most frequently isolated organism. Streptococcus species as a group was isolated in 70% of patients. Most (68%) infections were polymicrobial with the remainder (32%) being unimicrobial. While 42% of infections grew anaerobic gram negative bacilli in a polymicrobial flora only 5% grew gram negative bacilli in a unimicrobial flora with those cultures growing either Eikenella, Actinobacter or Fusobacterium. This study found 26% of patients had at least one microbe showing antibiotic resistance to one front line antibiotic. It also showed penicillin resistance to be 23% amongst microbes typically sensitive to penicillin (eg Streptococcus) and clindamycin resistance was found to be less than 5% amongst microbes typically sensitive to clindamycin (eg Streptococcus and Prevotella). All microbes resistant to clindamycin were also resistant to penicillin. Only 5 patients had resistance to multiple front line drugs; those patients grew MRSA, Staphylococcus epidermidis, Gardnerella vaginalis, Pseudomonas and Acinetobacter.
Discussion/Conclusion: Clearly the high rate of cultures yielding no growth must be addressed in the future by the surgeons and microbiology lab. Like Flynn and others who reported about 19% penicillin resistance rate we encountered resistance of 23% to penicillin but only 5% to clindamycin. It is still important to recognize that most of the severe odontogenic orofacial infections seen by oral maxillofacial surgeons are polymicrobial and will require empiric antibiotics that are initially broad spectrum to cover all commonly involved organisms including gram positive cocci and anaerobic gram negative bacilli until sensitivity results are available to tailor treatment. Clindamycin remains an excellent empiric first choice to cover both gram positive cocci and anaerobic gram negative bacilli most commonly isolated from severe odontogenic orofacial space infections.
References:
- Flynn, TR et al. Severe odontogenic infections. J Oral Maxillofac Surg 64:1093-1113, 2006.
- Lazow, SK. Orofacial infections in the 21st Century. NY State Dent J. 2005 Nov;71(6):36-41.