Prevalence of macrolide-non-susceptible isolates among β-lactamase-negative ampicillin-resistant Haemophilus influenzae in a tertiary care hospital in Japan

Clarithromycin Resistance Mechanisms of Epidemic β-Lactamase-Nonproducing Ampicillin-Resistant Haemophilus influenzae Strains in Japan

“…However, many pathogens have become macrolide resistant (6)(7)(8). We reported previously that clarithromycin susceptibility has decreased among clinically isolated BLNAR H. influenzae, suggesting the occurrence of multidrugresistant BLNAR H. influenzae (9).…”

“…We collected BLNAR H. influenzae isolates from patients with respiratory infections at the Tokyo Medical University Hachioji Medical Center between 2010 and 2012 (9). Among them, all clarithromycin-resistant BLNAR H. influenzae isolates (n ϭ 7; clarithromycin MIC, Ն32 g/ml) were used in this study.…”

Amino Acid Substitution in the Major Multidrug Efflux Transporter Protein AcrB Contributes to Low Susceptibility to Azithromycin in Haemophilus influenzae

“…M acrolide-, ␤-lactam-, and fluoroquinolone-resistant Haemophilus influenzae strains have been isolated worldwide (1)(2)(3)(4). In particular, clarithromycin (CLR)-resistant strains have been increasing in Japan (1).…”

“…In particular, clarithromycin (CLR)-resistant strains have been increasing in Japan (1). We reported previously that these strains harbored a nonsense mutation in the negative regulator gene acrR that resulted in overexpression of the chromosomal efflux pump AcrAB, which likely contributed to the CLR resistance (MICs of Ն32 g/ml) (5).…”

“…These two strains have the same genetic background of sequence type 156 (ST156), as determined by multilocus sequence typing (1). H. influenzae ATCC 49247 and H. influenzae Rd were used as control strains in the antimicrobial susceptibility tests, and H. influenzae Rd was also used as a recipient for transformation.…”