Prevalence and risk factors for Staphylococcus aureus nasopharyngeal carriage during a PCV trial

Abstract

BackgroundWe conducted an ancillary study among individuals who had participated in a cluster-randomized PCV-7 trial in rural Gambia (some clusters were wholly-vaccinated while in others only young children had been vaccinated), to determine the prevalence and risk factors for Staphylococcus aureus nasopharyngeal carriage.MethodsTwo hundred thirty-two children aged 5–10 years were recruited and followed from 4 to 20 months after vaccination started. We collected 1264 nasopharyngeal swabs (NPS). S. aureus was isolated following conventional microbiological methods. Risk factors for carriage were assessed by logistic regression.ResultsPrevalence of S. aureus carriage was 25.9%. In the univariable analysis, prevalence of S. aureus carriage was higher among children living in villages wholly-vaccinated with PCV-7 [OR = 1.57 95%CI (1.14 to 2.15)] and children with least 1 year of education [OR = 1.44 95%CI (1.07 to 1.92)]. S. aureus carriage was also higher during the rainy season [OR = 1.59 95%CI (1.20 to 2.11)]. Carriage of S. pneumoniae did not have any effect on S. aureus carriage for any pneumococcal, vaccine-type (VT) or non-vaccine-type (NVT) carriage. Multivariate analysis showed that the higher prevalence of S. aureus observed among children living in villages wholly-vaccinated with PCV-7 occurred only during the rainy season OR 2.72 95%CI (1.61–4.60) and not in the dry season OR 1.28 95%CI (0.78–2.09).ConclusionsPrevalence of nasopharyngeal carriage of S. aureus among Gambian children increased during the rainy season among those children living in PCV-7 wholly vaccinated communities. However, carriage of S. aureus is not associated with carriage of S. pneumoniae.Trial registration ISRCTN51695599. Registered August 04th 2006.

Nasopharyngeal Carriage and Antimicrobial Susceptibility Profile of Staphylococcus aureus among Children under Five Years in Accra

“…The overall S. aureus nasopharyngeal carriage prevalence of 23.2% is comparable to what has been reported previously in Ghana in the nasopharynx of HIV-infected children below five years of age (22.03%) [12] and in the anterior nares of the general population (21%) [54] and children with sickle cell disease (33.3%) [14], but it is heterogeneously lower (44.9%) [13] and higher (8%) [55] than the prevalence among HIV-infected patients post-PCV introduction. It is also comparable to what has been reported for nasopharyngeal carriage in other countries: in The Gambia (20-25.9%) [56,57], Portugal (21.6%) [58], and the Netherlands (23.2%) [25]. However, the post-vaccination carriage prevalence recorded among apparently healthy children in the current study is slightly lower than what was reported in Iran (29.6%) [59], Belgium (34%) [60], Vietnam (30.6%) [61], and The Gambia (30.6%) [62], but higher than that reported in Ethiopia (10.3%) [3].…”

Staphylococcus aureus Bacteremia in Children of Rural Areas of The Gambia, 2008–2015

“…We found S. aureus bacteremia to be more common during the wet season. This seasonal variation might relate to S. aureus colonization (a prerequisite for disease), which is highest during the wet season ( 31 ), or seasonal differences in the incidence of viral infections, which are known to disrupt mucosal epithelium, thereby encouraging S. aureus invasion ( 32 ). In a study of US adults ( 33 ), the peak incidence of S. aureus infection occurred during the winter months and coincided with the peak incidence of viral infections.…”

Impact of pneumococcal conjugate vaccine on the carriage density of Streptococcus pneumoniae and Staphylococcus aureus in children living with HIV: a nested case–control study

“…45,46 Gambian children had an S. aureus carriage increase 4 months after PCV-7. 47 In South Africa, children had an initial increase in S. aureus carriage post-PCV-7 immunization that then normalized 16 months post-immunization. 33 It is difficult to make comparisons with other studies as they differ in age, size, methodology, immunization doses, and the time point postimmunization.…”