Objectives: The purpose of this prospective clinical study was to identify the bacterial spectra on the surface of oral squamous cell carcinomas (OSCC) in comparison to oral mucosa of patients with a higher risk to emerge an OSCC and a control group to determine their susceptibility to various common antibiotics.
Material and methods: Swabs from 90 patients, 30 patients of each group, were cultured on media for aerobes and anaerobes and tested with agar diffusion and Etest.
Results: The predominant pathogens of the normal healthy oral mucosa were aerobes. The ratio between aerobes and anaerobes was 2:1, balanced in risk patients and inverted in the OSCC group. Altogether, 1,006 isolates were cultured. The most frequent strains were 47 viridans streptococci, 30 Staphylococcus species, 14 Enterococcus faecalis, 36 Neisseria species, 14 Escherichia coli, and 23 other aerobes, 66 Peptostreptococcus species, 39 Fusobacterium species, and 34 Prevotella species. The resistance rates in the OSCC group were penicillin 40%, ampicillin 57%, doxycycline 23%, clindamycin 47%, and amoxicillin/clavulanic acid 20%, but up to 100% of pathogens were susceptible to azithromycin, telithromycin, levofloxacin, and moxifloxacin.
Conclusion: Gram-negative anaerobes play a decisive role in the development of postoperative infections in patients with OSCC. This tumor special type of colonization does not agree with the normal flora of the oral cavity.
Clinical relevance: Biofilms on OSCC surfaces provide an important reservoir for anaerobic bacteria. As a consequence, a proposal for an antibiotic prophylactic regime should be given.