Background & Objectives: Administration of antibiotics is an essential modality to treat acute rhinosinusitis. Although intranasal inoculation of antibiotics does not have definite bioavailability, it is a very effective method to treat acute rhinosinusitis. We made a mouse model of rhinosinusitis by inoculation of Streptococcus pneumoniae and administrated time-dependent antibiotics or concentration-dependent antibiotics as a topical manner and investigated their effectiveness.
Subjects & Methods: Fifty 10-week old male C57BL/6 mice were employed for acute rhinosinusitis model. Mice were inoculated with Streptococcus pneumoniae, and from the 6th to 10th day, we made the negative control group by inoculation of normal saline (Group I), the antibiotics group by inoculation of cefmenoxime & vancomycin (Group II), the ofloxacin & tobramycin group (Group III), and the positive control group (Group IV). On the 11th day, all mice were sacrificed and the effectiveness of antibiotics was evaluated by comparison of nasal lavage colony count and neutrophil count of the sinonasal tissue.
Results: Minimum bactericidal concentration (MBC) of each antibiotics was cefmenoxime 20 microgram/ml, ofloxacin 80 microgram/ml, tobramycin 25 microgram/ml, vancomycin 12.5 microgram/ml. By nasal lavage, antibiotics inoculation group (Group II, III) had more decreased bacterial growth than the positive control, and it was statistically significant (p=0.037). Comparision between the group administrated with concentration-dependent antibiotics and time-dependent antibiotics, clusters of neutrophil decreased in two groups compared to positive control revealed that the group administered with concentration-dependent antibiotics had fewer clusters of neutrophil than the group administered with time-dependent antibiotics, and it was statistically significant.
Conclusion: Local inoculation of concentration dependent antibiotics could be a more effective way to treat acute rhinosinusitis induced by Streptococcus pneumoniae than time dependent antibiotics.
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