Opavski Natasa, Jovicevic Milos, Kabic Jovana, Kekic Dusan, Vasiljevic Zorica, Tosic Tanja, Medic Deana, Laban Suzana, Ranin Lazar, Gajic Ina
Faculty of Medicine, Institute of Microbiology and Immunology, University of Belgrade, Belgrade, Serbia.
Department of Clinical Microbiology, Mother and Child Health Care Institute of Serbia "Dr. Vukan Cupic", Belgrade, Serbia.
Front Microbiol. 2023 Aug 21;14:1244366. doi: 10.3389/fmicb.2023.1244366. eCollection 2023.
is one of the leading bacterial pathogens that can cause severe invasive diseases. The aim of the study was to characterize invasive isolates of obtained during the nine-year period in Serbia before the introduction of the pneumococcal conjugate vaccines (PCVs) into routine vaccination programs by determining: serotype distribution, the prevalence and genetic basis of antimicrobial resistance, and genetic relatedness of the circulating pneumococcal clones. A total of 490 invasive isolates were included in this study. The serotype, antimicrobial susceptibility, and ST of the strains were determined by the Quellung reaction, disk- and gradient-diffusion methods, and multilocus sequence typing (MLST), respectively. The most common serotypes in this study were 3, 19F, 14, 6B, 6A, 19A, and 23F. The serotype coverages of PCV10 and PCV13 in children less than 2 years were 71.3 and 86.1%, respectively, while PPV23 coverage in adults was in the range of 85-96%, depending on the age group. Penicillin and ceftriaxone-non-susceptible isolates account for 47.6 and 16.5% of all isolates, respectively. Macrolide non-susceptibility was detected in 40.4% of isolates, while the rate of multidrug- and extensive-drug resistance was 20.0 and 16.9%, respectively. The MLST analysis of 158 pneumococci identified 60 different STs belonging to the 16 Clonal Complexes (CCs) (consisting of 42 STs) and 18 singletons. The most common CC/ST were ST1377, CC320, CC15, CC273, CC156, CC473, CC81, and CC180. Results obtained in this study indicate that the pre-vaccine pneumococcal population in Serbia is characterized by high penicillin and macrolides non-susceptibility, worrisome rates of MDR and XDR, as well as a high degree of genetic diversity. These findings provide a basis for further investigation of the changes in serotypes and genotypes that can be expected after the routine introduction of PCVs.
是能够引发严重侵袭性疾病的主要细菌病原体之一。本研究的目的是通过确定血清型分布、抗菌药物耐药性的流行情况和遗传基础以及循环肺炎球菌克隆的遗传相关性，来描述在塞尔维亚将肺炎球菌结合疫苗（PCV）引入常规疫苗接种计划之前的九年期间分离出的侵袭性菌株。本研究共纳入490株侵袭性菌株。分别通过荚膜肿胀反应、纸片扩散法和梯度扩散法以及多位点序列分型（MLST）来确定菌株的血清型、抗菌药物敏感性和序列型（ST）。本研究中最常见的血清型为3、19F、14、6B、6A、19A和23F。2岁以下儿童中PCV10和PCV13的血清型覆盖率分别为71.3%和86.1%，而成人中PPV23的覆盖率在85%至96%之间，具体取决于年龄组。青霉素和头孢曲松不敏感菌株分别占所有分离株的47.6%和16.5%。在40.4%的分离株中检测到大环内酯类不敏感，而多重耐药和广泛耐药率分别为20.0%和16.9%。对158株肺炎球菌的MLST分析确定了60种不同的ST，它们属于16个克隆复合体（CCs）（由42个ST组成）和18个单态型。最常见的CC/ST为ST1377、CC320、CC15、CC273、CC156、CC473、CC81和CC180。本研究获得的结果表明，塞尔维亚疫苗接种前的肺炎球菌群体具有青霉素和大环内酯类不敏感率高、多重耐药和广泛耐药率令人担忧以及高度遗传多样性的特点。这些发现为进一步研究常规引入PCV后血清型和基因型的变化提供了依据。
