Serotype distribution and antimicrobial resistance of invasiveStreptococcus pneumoniaeisolates in Bulgaria before the introduction of pneumococcal conjugate vaccine

Abstract

The 10-valent pneumococcal conjugate vaccine (PCV10) was introduced as a mandatory vaccine in Bulgaria in April 2010. We report on the serotype distribution and the antimicrobial resistance of 222 invasive Streptococcus pneumoniae isolates collected from all age groups before the introduction of PCV10. PCV7, PCV10, and PCV13 covered 43.7, 59.9, and 78.8% of all invasive pneumococcal strains, and 64.2, 79.1, and 89.6% of isolates involving children less than 5 years of age. Penicillin resistance was found in 30.1% of the isolates responsible for meningitis and in 5.0% of isolates responsible for other invasive infections. Overall, erythromycin resistance was found in 19.4% of all invasive strains. The erm(B) was the most prevalent pneumococcal macrolide resistance genotype (63.2%) and dual mechanisms of both genes the erm(B) and mef(E) were detected in 15.8% of 19 erythromycin resistant isolates during the period 2006-2010. The prevalence and spread of serotypes 19F, 6B, and 19A during the last period may have contributed to the high predominance of erm(B) genotype in comparison of mef genotype, which was predominant in our country among erythromycin-resistant isolates before 2005. Continuing surveillance is required after the recent introduction of PCV10 in order to observe future developments of any serotype changes in the Bulgarian population, as well as surveillance of antimicrobial susceptibility of invasive S. pneumoniae isolates.

Microbiological characterization of Streptococcus pneumoniae and non-typeable Haemophilus influenzae isolates as primary causes of acute otitis media in Bulgarian children before the introduction of conjugate vaccines

“…Serotypes 6B and 19A were next most prominent, each comprising about 16% and 11%, respectively of the overall data set. The coverage calculations for the serotypes included in PCV7 without cross-protection was 63.6% in children with AOM aged < 5 years, which is almost the same as was the serotype coverage previously reported for invasive pneumococcal disease (IPD) for the same age group in Bulgaria [23]. The PCV10 increase the coverage by 2.8% of pneumococcal AOM (66.4%).…”

“…These rates are more than twice as high as previously recorded with IPD isolates in Bulgaria studied during the same year period [23]. These high resistance rates may be due to clonal spread of certain MDR pneumococcal serotypes such as 6B, 19 F and 19A.…”

Microbiological Features of Upper Respiratory Tract Infections in Bulgarian Children for the Period 1998-2014

“…After the introducing of the new macrolides, suitable for respiratory infection therapy in childhood and their uncontrolled use for 10 years, now more than 1/3 from isolates are resistant to macrolides mainly due to prevail of the induced mechanism of resistance to lincosamides. In recent years similar alarming data have been reported in many other European and non-European countries (6,7,9,16,17,19,24). This fast growing resistance Balkan Med J, Vol.…”

“…33, No. 6,2016 due to the change of the action target in the last ten years has become a serious problem for therapy, particularly in combination with a change in penicillin-binding proteins because they are major classes of antimicrobial agents for the treatment of respiratory infections in children, and nowadays there has been reports for failures in the treatment of serious infections caused by multidrug-resistant strains (6,9,15,19,20).…”

“…The rapid development of bacterial resistance in recent years to the most popular antimicrobial agents has affected the etiology of respiratory infections, as well as recommendations regarding the initial approach to therapy (6)(7)(8)(9)(10).…”