The determination of antibiotics resistance rate and genotypic ampicillin resistance in haemophilus influenzae strains

Aim and hypothesis: Haemophilus influenzae is one of the most frequent agents of acute otitis media, sinusitis, conjunctivitis, pneumonia and childhood infections such as meningitis other than to its presence of in normal respiratory flora. The purpose of the study is to determine the rate of ampicillin and various antibiotics resistance as well as ampicillin resistance mechanisms in clinical isolates of H. influenzae strains.Methods: This study was conducted between December 2008 and March 2011 at department of Medical Microbiology of Faculty of Medicine of Adnan Menderes University. 56 Haemophilus influenzae strains isolated from various clinical samples coming to the laboratory were included in the study. In identification of the strains, X, V, XV discs, semi-automatic identification system and PCR were used. Antimicrobial susceptibilities of strains defined as Haemophilus influenzae were investigated by disk diffusion and microdilution methods. The presence of Haemophilus influenzae serotype b, beta-lactamase production and the presence of beta-lactamase-negative ampicillin-resistant strains were investigated by PCR.Results: Haemophilus influenzae serotype b has not been detected in any of the tested strains. All of the strains were susceptible to amoxicillin clavulanic acid, ampicillin sulbactam, cefepime, cefixime, ceftriaxone, cefuroxime sodium, imipenem, chloramphenicol, levofloxacin, meropenem, sparfloksasin and tetracycline. The tested strains were 92.8% susceptible, 5.4% intermediate susceptible, 1.8% resistant to ampicillin; 94.6% susceptible, 5.4% intermediate susceptible to cefaclor; 71.4% susceptible, 23.2% intermediate susceptible, 5.4% resistant to clarithromycin; 50% susceptible, 14.3% intermediate susceptible and 35.8% resistant to co-trimaksazole. In one of the ampicilin resistant strains (1.8%) the production of beta-lactamase were found positive. In 11 strain (19.6%), which ftsI-S gene was not detected, there was no Group III ftsI-BLN gene too. The strains which do not have ftsI-S and Group III ftsI-BLN genes were defined as weak BLNAR (Group I and/or Group II).Conclusion: There were no H. influenzae serotype b and Group III BLNAR in this study. Beta-lactamase production was detected low rate (1.8%). The ampicillin MIC of 11 strains defined as weak BLNAR were higher than susceptible strains. In BLNAR strains, an increase in the MIC of the other antibiotics (ampicillin-sulbactam, amoxicillin/clavulanic acid, cefaclor, cefixime, cefuroxime, imipenem, meropenem) was observed. It has been thought that could prescribe amoxicillin clavulanic acid, ampicillin sulbactam, cefepime, cefixime, ceftriaxone, cefuroxime sodium, imipenem, chloramphenicol, levofloxacin, meropenem, sparfloksasin and tetracycline antibiotics in empiric treatment. Although there was no a high rate of resistance in H. influenzae strains, the presence of weak BLNARs suggest that surveillance studies of this strains should be done regularly.Keywords: Haemophilus influenzae, BLNAR, PCR, MIC