Objectives: To determine antibiotic susceptibility of Streptococcus pneumoniae and Haemophilus influenzae isolates from community-acquired respiratory tract infections (CA-RTIs) collected in 2016-17 from Ukraine.
Methods: MICs were determined by CLSI broth microdilution and susceptibility was assessed using CLSI, EUCAST (dose-specific) and pharmacokinetic/pharmacodynamic (PK/PD) breakpoints.
Results: A total of 177 viable clinical isolates, including 78 S. pneumoniae and 99 H. influenzae, were collected. Overall, ∼98% of S. pneumoniae isolates were susceptible to penicillin by CLSI IV or EUCAST high-dose breakpoints and 73.1% were susceptible by CLSI oral or EUCAST low-dose IV breakpoints. Susceptibility rates of 76.9%-100% were observed for most antibiotics by all breakpoints except trimethoprim/sulfamethoxazole (41%-69.2%) and cefaclor, which showed the greatest difference between breakpoints: 0% by EUCAST, 28.2% by PK/PD and 73.1% by CLSI. All S. pneumoniae isolates were susceptible to amoxicillin/clavulanic acid by CLSI and PK/PD breakpoints. H. influenzae isolates were almost all β-lactamase negative (90.9%). One isolate was β-lactamase negative and ampicillin resistant (BLNAR) by CLSI and four isolates were BLNAR by EUCAST criteria. Susceptibility of isolates was high (≥90.9%) by CLSI breakpoints for all antibiotics tested except trimethoprim/sulfamethoxazole (61.6%). Susceptibility using EUCAST breakpoints was similar for ampicillin (90.9%) and amoxicillin/clavulanic acid (95%) but was low for cefuroxime (oral), where only 10.1% of isolates were susceptible. All S. pneumoniae and H. influenzae isolates were susceptible to the fluoroquinolones by all breakpoints. Susceptibility to ceftriaxone was also 100% for H. influenzae and ≥91% for S. pneumoniae isolates by all breakpoints. The application of different EUCAST breakpoints for low and higher doses for some of the antibiotics (amoxicillin, amoxicillin/clavulanic acid, ampicillin, penicillin, ceftriaxone, clarithromycin, erythromycin, levofloxacin and trimethoprim/sulfamethoxazole) allowed, for the first time in a SOAR study, the effect of raising the dosage on susceptibility to be quantified.
Conclusions: Antibiotic susceptibility in these respiratory tract pathogens was generally high in Ukraine. These data are important for empirical therapy choices in the treatment of CA-RTIs.
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