Molecular investigation of macrolide and Tetracycline resistances in oral bacteria isolated from Tunisian children

Objective: This study aims to investigate the antibiotic susceptibility of strains isolated from the oral cavity of Tunisian children. Design: Strains were isolated from the oral cavity of Tunisian children (60 caries-actives and 30 caries-free). Molecular characterization was assessed by PCR assay to detect erythromycM methylase gene (ermB), macrolide efflux (mefl) and tetracycline resistance genes (tetM and tetO). Results: A total of 21 species were isolated and identified. Antimicrobial susceptibility revealed that the resistance rate to antibiotics was as follow: erythromycin (22%), tetracycline (15.6%), cefotaxim, (7.3%), trimethoprim-sulfamethoxazol (37.6%), nitrofurantoine (2.8%), pristinamycin (17.4%), quinupristin-dalfopristin (15.6%), and rifampicin (3.7%). The majority of mefl positive strains (31.2%) were isolated from the carious children (n = 34) in comparison with 8.25% from the control group (n = 9). In addition, frequency of strains caring resistance genes were as follow: 12.84% for ermB, 9.17% for tetM and 27.52% for tetO from the carious children in comparison to 0.092%, 3.67% and 3.67% from the caries free group respectively. Conclusion: Multi-resistance strains towards macrolides and tetracycline were recorded. The majority of strains carrying antibiotics resistance genes were isolated from the caries active children. The presence of multi-resistant bacteria in the oral cavity can be the major cause of antibiotic prophylaxis failure in dental practise. (C) 2010 Elsevier Ltd. All rights reserved.