RESISTANCE TO SEVERAL ANTIBIOTICS IN HAEMOPHILUS INFLUENZAE STRAINS

Mzilem S, Boukhchina S

LR18ES03. Laboratory of Neurophysiology, Cellular Physiopathology and Biomolecules Valorisation.   Faculty of Sciences of Tunis. University of Tunis El Manar 2092. Tunis. Tunisia

Introduction: H. influenzae is a bacterium that causes respiratory diseases principally in children. In this report, we determined the antibiotic susceptibilities of 200 H. influenzae strains isolated from children in Tunisia between 2010 and 2011. 

Materials and methods: All strains were investigated by PCR to identify the resistance genes (bla_TEM-1, bla_ROB-1, and ftsI). Antibiotic susceptibility was controlled by disc diffusion. The antibiotics tested were ampicillin, amoxicillin-clavulanate, cefotaxime, kanamycin, gentamycin, rifampicin, pristinamycin, and nalidixic acid. 

Results: Two hundred strains of H.influenzae were analyzed: 91 (were resistant to ampicillin (66 were beta-lactamase positive), 43 to kanamycin (39 were β-lactamase positive), 6 to gentamycin (all were β-lactamase positive), 23 to rifampicin (20 were β-lactamase positive) and 11 to pristinamycin (9 were β-lactamase positive). Strains demonstrating resistances to many antibiotics, according to their mechanism of resistance have been detected in this work: 24 strains were ampicillin- kanamycin resistant, 2 were ampicillin - gentamycin resistant, 5 were ampicillin - rifampicin resistant, 3 were ampicillin - pristinamycin resistant, 3 were kanamycin - pristinamycin resistant and 8 strains were kanamycin - rifampicin resistant. Cefotaxime and nalidixic acid were the most intense agents against our strains. 

Conclusion: This work demonstrates an unexpected rise of resistances to several antibiotics in H. influenzae strains which show different mechanisms of resistance in children. Thus, the evaluation of new antibiotics for the treatment of multiply resistant Haemophilus influenzae diseases seems necessary.