Background In the recently performed studies, various investigators have shown considerable interest in the immunomodulatory and anti-inflammatory action of the macrolide antibiotics for long-term low-dose treatment of chronic rhinosinusitis and nasal polyposis. Previous investigations regarding the results of bacterial cultures (Streptococcus pneumoniae, Haemophillus influenzae) suggest that the risk of selecting resistant bacteria is low. In a small number of patients the cultures were positive, but this was not always linked with an increase in symptoms, which could be due to the fact that in addition to the direct bacteriostatic effects of macrolides, they may in some cases reduce the virulence of bacteria without eradicating them.

Purpose The present study was designed to investigate the anti-inflammatory and clinical effects of long-term low-dose clarithromycin (CAM) treatment of non-atopic and atopic patients with nasal polyposis.

Materials and methods Forty (n=40) nasal polyp patients, 22 non-allergic and 18 allergic were administered CAM 500 mg/day single oral dose for eight weeks. Nasal secretion samples were collected from nasal cavities of all 40 subjects before and after CAM treatment by absorption technique. The authors measured the levels of myeloperoxidase (MPO), a neutrophil activation marker, before and after therapy, using an enzyme-linked immunosolvent assay (ELISA) kit. Eosinophil cationic protein (ECP), an eosinophil activation marker, and tryptase (TRY), a mastocyte activation marker were measured in nasal secretions by fluoroenzyme assay. The authors also scored each of the forty patients before and after therapy according to nasal symptom score and endoscopic score.

Results Following treatment, The authors found significantly reduced levels of MPO in nasal secretions in both non-atopic and atopic patients (p<0.05). Treatment by CAM decreased the levels of ECP only in non-atopic nasal polyp patients (p<0.05). Macrolide therapy decreased the size of nasal polyps in 45.45% non-allergic and in 50% allergic patients. After CAM administration, The authors found 67.83% patients in non-atopic group and 55.55% patients in atopic group with improved nasal symptoms.

Conclusions Long-term low-dose treatment by CAM was effective in the management of nasal polyposis. Our results showed that macrolide administration have different anti-inflammatory and similar clinical effects in non-allergic and allergic subjects.