Department of Microbiology, All India Institute of Medical Sciences, New Delhi, India.
Department of Paediatrics, All India Institute of Medical Sciences, New Delhi, India.
Indian J Med Microbiol. 2020 Jan-Mar;38(1):78-86. doi: 10.4103/ijmm.IJMM_20_111.
The purpose of this study is to determine the antimicrobial susceptibility pattern, serotype distribution and sequence type (ST) of Streptococcus pneumoniae isolates from invasive and non-invasive infection and correlate it with isolates from commensal nasopharyngeal flora to ascertain their role in infection.
S. pneumoniae isolates from blood, cerebrospinal fluid, pleural fluid and respiratory secretions (sputum, bronchoalveolar lavage and nasopharyngeal swab/throat swab) were analysed to determine ST, serotype and antimicrobial susceptibility pattern. Serotyping was performed by multiplex polymerase chain reactions as well as by quellung reaction. Antimicrobial susceptibility testing was determined using Kirby Bauer's disc diffusion method as per the Clinical Laboratory Standards Institute guidelines. Minimum inhibitory concentration was determined using E-test for penicillin. Multilocus sequence typing (MLST) was done to understand genetic relatedness and evolutionary relationship among strains.
A total of 125 S. pneumoniae isolates were collected, including 25 from invasive pneumococcal disease, 25 from non-invasive and 75 from nasopharyngeal swab of healthy children (Commensal). Resistance to penicillin, erythromycin, and co-trimoxazole was observed in 14.4%, 12% and 81.6% of the isolates, respectively, by KirbyBauer's disc diffusion method. Serotype 14 was found to be the most prevalent in invasive and non-invasive isolates, while serotype 6 was the most common in commensal isolates. New STs were found among invasive (ST13826, ST13827), non-invasive (ST13823, ST13824, and ST13961) and commensal (ST13825) isolates.
MLST sequence analysis shows that invasive isolates were found to be clustered with non-invasive and commensal isolates. Analysis of MLST suggests the possibility of genetic relatedness and exchange of genetic material between invasive, non-invasive and commensal isolates.
本研究旨在确定来自侵袭性和非侵袭性感染的肺炎链球菌分离株的抗菌药敏模式、血清型分布和序列型（ST），并将其与来自共生鼻咽菌群的分离株进行比较，以确定其在感染中的作用。
分析血、脑脊液、胸腔积液和呼吸道分泌物（痰、支气管肺泡灌洗液和鼻咽拭子/咽拭子）中的肺炎链球菌分离株，以确定 ST、血清型和抗菌药敏模式。血清型通过多重聚合酶链反应和胶乳反应进行检测。抗菌药敏试验采用 Kirby Bauer 纸片扩散法，根据临床实验室标准化研究所指南进行。采用 E 试验法测定青霉素的最低抑菌浓度。采用多位点序列分型（MLST）了解菌株之间的遗传关系和进化关系。
共收集了 125 株肺炎链球菌分离株，其中 25 株来自侵袭性肺炎球菌病，25 株来自非侵袭性感染，75 株来自健康儿童的鼻咽拭子（共生）。 KirbyBauer 纸片扩散法检测发现，14.4%、12%和 81.6%的分离株对青霉素、红霉素和复方磺胺甲噁唑耐药。血清型 14 是侵袭性和非侵袭性分离株中最常见的血清型，而血清型 6 是共生分离株中最常见的血清型。在侵袭性（ST13826、ST13827）、非侵袭性（ST13823、ST13824 和 ST13961）和共生（ST13825）分离株中发现了新的 ST。
MLST 序列分析表明，侵袭性分离株与非侵袭性和共生分离株聚集在一起。MLST 分析表明，侵袭性、非侵袭性和共生分离株之间存在遗传相关性和遗传物质交换的可能性。
