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Abstract：
OBJECTIVE: In Morocco, 13-valent pneumococcal conjugated vaccine (PCV) was introduced in the childhood immunization program in October 2010 and changed to PCV-10 in July 2012. The purpose of this study was firstly to determine the prevalence of pneumococcus carriage in a population of febrile infants in Marrakesh and secondly, to investigate the risk factors for carriage and the distribution of circulating serotypes.
METHODS: This prospective study was conducted from February to June 2017, in the pediatric emergency department of the Mother and Child Hospital of Mohammed VI University Hospital Centre (UHC) in Marrakesh. At total of 183febrile infants, aged 2-18months, were enrolled in this study and were swabbed for nasopharyngeal carriage. Pneumococci were cultured, identified, serotyped, and tested for penicillin susceptibility. Demographic data and risk factors for carriage were collected. The statistical analyses performed were the following: the analysis of the risk factors using logistic regression, the estimation of serotype diversity with the Simpson index, and the Chi2 test to compare serotype distribution in the prevaccination (a cohort of 660 healthy children, less than 2years old, in the Marrakesh region, in 2008-2009) and postvaccination periods.
RESULTS: The prevalence of Streptococcus pneumoniae carriage was 68.3%. Of the 183infants enrolled in this study, 111 had received at least one dose of PCV-10. Colonization by vaccine serotype among febrile children was related to incomplete vaccination status. In total, vaccine serotypes accounted for 6.4% (n=8): 19F (n=2), 1 (n=2) and one strain for each of the following serotypes: 14, 23F, 6B, and 9V. Non-vaccine and nontypeable strains presented 63.2% and 23.2%, respectively, with dominance of serotypes 6A (6.4%), 15A/15F (5.6%), 20, 22F/22A, 23B, and 11A/11D with a prevalence of 3.2%. The rate of pneumococcus strains with reduced susceptibility to penicillin was 33.6%, of which 90.2% were non-vaccine serotypes and nontypeable strains. Serotype diversity increased in the postvaccination period and the effectiveness of PCV-10 against vaccine serotypes was estimated at 89.6%.
CONCLUSIONS: An important change in the distribution of vaccine and non-vaccine serotypes was observed after the introduction of the PCVs. In fact, the prevalence of vaccine serotypes decreased significantly while non-vaccine serotypes emerged. These results underscore the importance of maintaining close and prolonged surveillance of serotype distribution to monitor the dynamics of nasopharyngeal pneumococcal carriage.
METHODS: This prospective study was conducted from February to June 2017, in the pediatric emergency department of the Mother and Child Hospital of Mohammed VI University Hospital Centre (UHC) in Marrakesh. At total of 183febrile infants, aged 2-18months, were enrolled in this study and were swabbed for nasopharyngeal carriage. Pneumococci were cultured, identified, serotyped, and tested for penicillin susceptibility. Demographic data and risk factors for carriage were collected. The statistical analyses performed were the following: the analysis of the risk factors using logistic regression, the estimation of serotype diversity with the Simpson index, and the Chi2 test to compare serotype distribution in the prevaccination (a cohort of 660 healthy children, less than 2years old, in the Marrakesh region, in 2008-2009) and postvaccination periods.
RESULTS: The prevalence of Streptococcus pneumoniae carriage was 68.3%. Of the 183infants enrolled in this study, 111 had received at least one dose of PCV-10. Colonization by vaccine serotype among febrile children was related to incomplete vaccination status. In total, vaccine serotypes accounted for 6.4% (n=8): 19F (n=2), 1 (n=2) and one strain for each of the following serotypes: 14, 23F, 6B, and 9V. Non-vaccine and nontypeable strains presented 63.2% and 23.2%, respectively, with dominance of serotypes 6A (6.4%), 15A/15F (5.6%), 20, 22F/22A, 23B, and 11A/11D with a prevalence of 3.2%. The rate of pneumococcus strains with reduced susceptibility to penicillin was 33.6%, of which 90.2% were non-vaccine serotypes and nontypeable strains. Serotype diversity increased in the postvaccination period and the effectiveness of PCV-10 against vaccine serotypes was estimated at 89.6%.
CONCLUSIONS: An important change in the distribution of vaccine and non-vaccine serotypes was observed after the introduction of the PCVs. In fact, the prevalence of vaccine serotypes decreased significantly while non-vaccine serotypes emerged. These results underscore the importance of maintaining close and prolonged surveillance of serotype distribution to monitor the dynamics of nasopharyngeal pneumococcal carriage.
摘要：
目标：在摩洛哥，13价肺炎球菌结合疫苗（PCV）于2010年10月引入儿童免疫计划，并于2012年7月更改为PCV-10。这项研究的目的是首先确定在马拉喀什发热婴儿人群中肺炎球菌携带的患病率，其次，探讨携带的危险因素和循环血清型的分布。
方法：这项前瞻性研究于2017年2月至6月在马拉喀什的穆罕默德六世大学医院中心（UHC）母婴医院儿科急诊科进行。总共183名发热婴儿，年龄2-18个月，参加了这项研究，并擦拭了鼻咽部运输。培养肺炎球菌，已识别,血清分型,并检测青霉素敏感性.收集了人口统计学数据和运输的危险因素。进行的统计分析如下：使用逻辑回归分析的危险因素，用辛普森指数估计血清型多样性，和Chi2检验比较接种前血清型分布（660名健康儿童，不到2岁，在马拉喀什地区,2008-2009年）和疫苗接种后时期。
结果：肺炎链球菌携带率为68.3%。在这项研究的183名婴儿中，111已经接受了至少一个剂量的PCV-10。发热儿童疫苗血清型定植与疫苗接种不完全状态有关。总的来说,疫苗血清型占6.4%(n=8)：19F(n=2)，1（n=2）和1株以下血清型：14,23F，6B,9V。非疫苗和不可分型的菌株分别为63.2%和23.2%，分别,血清型6A占优势（6.4%），15A/15F（5.6%），20,22F/22A,23B,和11A/11D，患病率为3.2%。肺炎球菌对青霉素敏感性降低的菌株率为33.6%,其中90.2%是非疫苗血清型和不可分型的菌株。血清型多样性在疫苗接种后增加，PCV-10对疫苗血清型的有效性估计为89.6％。
结论：在引入PCV后，观察到疫苗和非疫苗血清型的分布发生了重要变化。事实上,疫苗血清型的流行率显着下降，而非疫苗血清型出现。这些结果强调了保持密切和长期监测血清型分布以监测鼻咽肺炎球菌携带动态的重要性。
方法：这项前瞻性研究于2017年2月至6月在马拉喀什的穆罕默德六世大学医院中心（UHC）母婴医院儿科急诊科进行。总共183名发热婴儿，年龄2-18个月，参加了这项研究，并擦拭了鼻咽部运输。培养肺炎球菌，已识别,血清分型,并检测青霉素敏感性.收集了人口统计学数据和运输的危险因素。进行的统计分析如下：使用逻辑回归分析的危险因素，用辛普森指数估计血清型多样性，和Chi2检验比较接种前血清型分布（660名健康儿童，不到2岁，在马拉喀什地区,2008-2009年）和疫苗接种后时期。
结果：肺炎链球菌携带率为68.3%。在这项研究的183名婴儿中，111已经接受了至少一个剂量的PCV-10。发热儿童疫苗血清型定植与疫苗接种不完全状态有关。总的来说,疫苗血清型占6.4%(n=8)：19F(n=2)，1（n=2）和1株以下血清型：14,23F，6B,9V。非疫苗和不可分型的菌株分别为63.2%和23.2%，分别,血清型6A占优势（6.4%），15A/15F（5.6%），20,22F/22A,23B,和11A/11D，患病率为3.2%。肺炎球菌对青霉素敏感性降低的菌株率为33.6%,其中90.2%是非疫苗血清型和不可分型的菌株。血清型多样性在疫苗接种后增加，PCV-10对疫苗血清型的有效性估计为89.6％。
结论：在引入PCV后，观察到疫苗和非疫苗血清型的分布发生了重要变化。事实上,疫苗血清型的流行率显着下降，而非疫苗血清型出现。这些结果强调了保持密切和长期监测血清型分布以监测鼻咽肺炎球菌携带动态的重要性。
