HAEMOPHILUS INFLUENZAE FROM PATIENTS AT THE LARGEST UNIVERSITY TERTIARY CARE CENTER, THAILAND 2012 - 2015.

Haemophilus influenzae was isolated from 556 different patients, mostly 10 years or under, at a tertiary referral hospital in Bangkok, Thailand during 2012 - 2015. Peak period of detection was from January to March. Thirty-nine percent of the isolates were β-lactamase positive. β-Lactamase-negative ampicillin-resistant H. influenzae (BLNAR) constituted 2% of β-lactamase-negative cases. H. influenzae was susceptible to ampicillin (58%), amoxicillin/clavulanate (99%), cefotaxime (100%), ceftriaxone (100%), cefuroxime (99%), ciprofloxacin (99%), chloramphenicol (86%), tetracycline (75%), and trimethoprim-sulphamethoxazole (52%). β-Lactamase-producing isolates (72%) showed high minimal inhibitory concentration (MIC) to ampicillin (128-516 μg/ml) and all BLNAR isolates low ampicillin MIC (2-16 μg/ml). These findings indicate that the level of ampicillin resistance in H. influenzae depended on differences in resistance mechanism.