Present status of antimicrobial susceptibility of haemophilus influenzae isolates in Kuwait as determined by E - test

ABSTRACT

To study antimicrobial susceptibility pattern of clinical isolates of Haemophilus influenzae using E-test and compare the results with those of a study done in 1983. The antimicrobial susceptibility of 196 isolates of H. influenzae against nine antimicrobial agents [amoxicillin-clavulanic acid, ampicillin, cefaclor, cefotaxime, ceftriaxone, chloramphenicol, ciprofloxacin, clarithromycin, and trimethoprim-sulfamethoxazole] was performed by E-test on Haemophilus test medium. The results obtained were compared with those from an earlier study conducted here on 108 strains collected between October and December 1983. Except for cefotaxime, which consistently showed an excellent in vitro activity [MIC90 = 0.047 mg/l], other antimicrobial agents presented a decline in their effectiveness. Among the newer antibiotics tested, all the strains were found to be sensitive to ciprofloxacin [MIC range = 0.004-0.0094 mg/l] whereas clarithromycin showed high MIC of 12 mg/l for 90% of the strains. There was a marked increase in the number of beta-lactamase-producing isolates from 4.6% in 1983 to 31.6% in the present study. Amongst 62 beta-lactamase-producing strains 14.5% exhibited resistance to amoxicillin-clavulanic acid [MIC >8 mg/l]. Only 3.1% isolates were found to be of capsular type b in 1998 compared to 9.2% in 1983. No beta-lactamase-negative ampicillin-resistant [BLNAR] strain was isolated during the present study whereas only one strain [0.9%] was isolated in 1983. This study shows that despite a decrease in the number of type b and BLNAR H. influenzae isolates, there is an apparent increase in the trend to acquire resistance to several antimicrobial agents