Surveillance of antibiotic resistance of Streptococcus pneumoniae in the Czech Republic, respiratory study results, 2010-2017

Aim: The purpose of the surveillance performed from October to December in 2010-2017 was to monitor the trends in the susceptibility to beta lactam and macrolide antibiotics in Streptococcus pneumoniae isolates from respiratory tract infections in the Czech Republic. Material and methods: Between 42 and 55 laboratories participated in the study every year. Consecutive non-duplicate pneumococcal isolates from relevant microbiological specimens from patients with community-acquired bacterial respiratory tract infection were sequentially included in the study. Laboratories recorded qualitative results of penicillin and erythromycin susceptibility testing; susceptibility to antibiotics was determined by the disk diffusion method. Penicillin non-susceptible and/or erythromycin resistant isolates were referred to the National Reference Laboratory for Antibiotics, where the minimum inhibitory concentration of each antibiotic was tested using the broth microdilution method, and their serotyping was performed in the National Reference Laboratory for Streptococcal Infections. Twenty-six isolates from 2017 were analysed by the multilocus sequence typing method. Results: In total, 7 491 pneumococcal strains were examined, of which 53.7% (4 023) were from the upper respiratory tract and 47.7% (3 573) from children under 15 years of age. Non-susceptibility to penicillin decreased from 2.6% in 2010 to 1.2% in 2017, while resistance to erythromycin increased from 7.4% to 9.7% over the same period. Penicillin non-susceptible isolates were mostly of serotypes 19A, 19F, and 15A. Macrolide resistant but penicillin susceptible isolates were predominantly represented by serotypes 19A and 3. The presence of the Taiwan(19F)-14 clone was confirmed in penicillin non susceptible isolates by MLST, and the most frequently identified sequence type (ST) in macrolide resistant isolates was ST416 classified into the Netherlands(15B)-37 clone. Conclusions: The respiratory study of antibiotic resistance in S. pneumoniae confirmed the decreasing trend of resistance to penicillin but revealed a growing resistance to macrolide antibiotics in the Czech Republic.The results of our study confirm that antibiotic resistance in the vaccination era is associated primarily with the non-vaccine serotypes, and the clonal expansion of rnacrolide resistant serotype 19A was apparently supported by the growing prescription of macrolide antibiotics.