Department of Medical Microbiology, School of Medicine, Faculty of Health Sciences, University of Pretoria, South Africa.
S Afr Med J. 2021 Feb 1;111(2):143-148. doi: 10.7196/SAMJ.2021.v111i2.14626.
Pneumococcal carriage studies provide a baseline for measuring the impact of pneumococcal conjugate vaccines (PCVs). The advent of conjugate vaccines has led to reductions in vaccine serotypes (VTs) in pneumococcal carriage. However, increasing non-vaccine serotypes (NVTs) remain a significant concern, necessitating continued surveillance of serotypes in the 13-valent PCV vaccine (PCV13) era.
To investigate pneumococcal carriage, serotype distribution and risk factors for pneumococcal colonisation among children presenting for routine immunisation at two clinics in Gauteng Province, South Africa (SA), 10 years after PCV introduction into the SA Expanded Programme on Immunisation (EPI-SA).
Nasopharyngeal swabs were collected from 322 healthy children aged between 6 weeks and 5 years at two clinic centres in 2014 and 2016. Demographic data, risk factors for colonisation and vaccination details were recorded. The pneumococcal isolates were serotyped and tested for antimicrobial susceptibility.
Pneumococci were isolated from 138/316 healthy children (43.7%) presenting for routine immunisation at two clinics. The median age was 8.3 months and the age range 1.4 months - 5 years. Carriage varied across the age groups: 6 - 14 weeks 35.5%, 9 months 27.5%, 18 months 21.7%, and 5 years 15.2%. Risk factors significantly associated with pneumococcal colonisation included young age (9 - 18 months (odds ratio OR 3.5; 95% confidence interval (CI) 1.9 - 5.9), type of dwelling (single room (OR 8.1; 95% CI 1.3 - 52.3) or informal dwelling (OR 2.4; 95% CI 1.2 - 4.5)) and Haemophilus influenzae carriage (OR 5.6; 95% CI 0.6 - 2.5). Of the 26 serotypes detected, 19F (10/121; 8.3%) was the most frequent. The most frequent NVTs were 23B (16/121; 13.2%), 15B/C (14/121; 11.6 %) and 35B (11/121; 8.2%). Children aged 9 months carried the highest proportion of NVTs (33/101; 32.7%). Penicillin non-susceptibility was observed in 20 NVT isolates (20/36; 55.6%) and 2 VT isolates (2/36; 5.6%).
The pneumococcal carriage prevalence described in our study varied across the age groups and was lower compared with other African studies that looked at pneumococcal carriage post PCV. The study gave insight into the common NVTs encountered at two immunisation clinics in Gauteng. Given that pneumococcal carriage precedes disease, common colonisers such as 15B/C and 35B may be sufficiently prevalent in carriage for expansion to result in significant disease replacement.
肺炎球菌带菌研究为衡量肺炎球菌结合疫苗（PCV）的影响提供了基线。结合疫苗的出现导致了肺炎球菌带菌中疫苗血清型（VTs）的减少。然而，不断增加的非疫苗血清型（NVTs）仍然是一个重大问题，需要继续监测 13 价 PCV 疫苗（PCV13）时代的血清型。
调查南非夸祖鲁-纳塔尔省（SA）两个诊所儿童在 PCV 引入 SA 扩大免疫规划（EPI-SA）10 年后的常规免疫接种时，肺炎球菌带菌情况、血清型分布和肺炎球菌定植的危险因素。
2014 年和 2016 年，从两个诊所的 322 名 6 周至 5 岁健康儿童中采集鼻咽拭子。记录人口统计学数据、定植危险因素和疫苗接种详细信息。肺炎球菌分离株进行血清分型，并进行抗菌药物敏感性试验。
在两个诊所进行常规免疫接种的 316 名健康儿童中，138 名（43.7%）分离出肺炎球菌。中位年龄为 8.3 个月，年龄范围为 1.4 个月至 5 岁。带菌率随年龄组而异：6-14 周 35.5%，9 个月 27.5%，18 个月 21.7%，5 岁 15.2%。与肺炎球菌定植显著相关的危险因素包括年龄较小（9-18 个月（优势比 OR 3.5；95%置信区间（CI）1.9-5.9）、居住类型（单人间（OR 8.1；95%CI 1.3-52.3）或非正规住所（OR 2.4；95%CI 1.2-4.5）和流感嗜血杆菌定植（OR 5.6；95%CI 0.6-2.5）。在检测到的 26 个血清型中，19F（10/121；8.3%）最为常见。最常见的 NVT 是 23B（16/121；13.2%）、15B/C（14/121；11.6%）和 35B（11/121；8.2%）。9 个月大的儿童携带 NVT 的比例最高（33/101；32.7%）。20 株 NVT 分离株（20/36；55.6%）和 2 株 VT 分离株（2/36；5.6%）对青霉素不敏感。
我们的研究描述的肺炎球菌带菌率在不同年龄组之间存在差异，与其他研究非洲 PCV 后肺炎球菌带菌的研究相比，我们的研究结果较低。该研究深入了解了豪登省两个免疫接种诊所常见的 NVT。鉴于肺炎球菌带菌先于疾病发生，15B/C 和 35B 等常见定植菌的流行率可能足以在带菌中扩张，从而导致疾病的显著替代。
