Longitudinal Population Dynamics of Staphylococcus aureus in the Nasopharynx During the First Year of Life

Shima M. Abdulgader, Lourens Robberts, Jordache Ramjith, Polite M. Nduru, Felix Dube, Sugnet Gardner-Lubbe, Heather J. Zar, Mark P. Nicol

Research output: Contribution to journalArticle

Abstract

Background: Staphylococcus aureus colonization is a risk factor for invasive disease. Few studies have used strain genotype data to study S. aureus acquisition and carriage patterns. We investigated S. aureus nasopharyngeal carriage in infants in an intensively sampled South African birth cohort.

Methods: Nasopharyngeal swabs were collected at birth and fortnightly from 137 infants through their first year of life. S. aureus was characterized by spa-typing. The incidence of S. aureus acquisition, and median carriage duration for each genotype was determined. S. aureus carriage patterns were defined by combining the carrier index (proportion of samples testing positive for S. aureus) with genotype diversity measures. Persistent or prolonged carriage were defined by a carrier index >= 0.8 or >= 0.5, respectively. Risk factors for time to acquisition of S. aureus were determined.

Results: Eighty eight percent (121/137) of infants acquired S. aureus at least once. The incidence of acquisition at the species and genotype level was 1.83 and 2.8 episodes per child-year, respectively. No children had persistent carriage (defined as carrier index of >0.8). At the species level 6% had prolonged carriage, while only 2% had prolonged carriage with the same genotype. Carrier index correlated with the absolute number of spa-CCs carried by each infant (r = 0.5; 95% CI 0.35-0.62). Time to first acquisition of S. aureus was shorter in children from households with >= 5 individuals (HR 1.06, 95% CI 1.07-1.43), with S. aureus carrier mothers (HR; 1.5, 95% CI 1.2-2.47), or with a positive tuberculin skin test during the first year of life (HR; 1.81, 95% CI 0.97-3.3).

Conclusion: Using measures of genotype diversity, we showed that S. aureus NP carriage is highly dynamic in infants. Prolonged carriage with a single strain occurred rarely; persistent carriage was not observed. A correlation was observed between carrier index and genotype diversity.

Original languageEnglish
Article number198
Number of pages10
JournalFrontiers in Genetics
Volume10
DOIs
Publication statusPublished - 15 Mar 2019

Cite this

Abdulgader, Shima M. ; Robberts, Lourens ; Ramjith, Jordache ; Nduru, Polite M. ; Dube, Felix ; Gardner-Lubbe, Sugnet ; Zar, Heather J. ; Nicol, Mark P. / Longitudinal Population Dynamics of Staphylococcus aureus in the Nasopharynx During the First Year of Life. In: Frontiers in Genetics. 2019 ; Vol. 10.
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abstract = "Background: Staphylococcus aureus colonization is a risk factor for invasive disease. Few studies have used strain genotype data to study S. aureus acquisition and carriage patterns. We investigated S. aureus nasopharyngeal carriage in infants in an intensively sampled South African birth cohort.Methods: Nasopharyngeal swabs were collected at birth and fortnightly from 137 infants through their first year of life. S. aureus was characterized by spa-typing. The incidence of S. aureus acquisition, and median carriage duration for each genotype was determined. S. aureus carriage patterns were defined by combining the carrier index (proportion of samples testing positive for S. aureus) with genotype diversity measures. Persistent or prolonged carriage were defined by a carrier index >= 0.8 or >= 0.5, respectively. Risk factors for time to acquisition of S. aureus were determined.Results: Eighty eight percent (121/137) of infants acquired S. aureus at least once. The incidence of acquisition at the species and genotype level was 1.83 and 2.8 episodes per child-year, respectively. No children had persistent carriage (defined as carrier index of >0.8). At the species level 6{\%} had prolonged carriage, while only 2{\%} had prolonged carriage with the same genotype. Carrier index correlated with the absolute number of spa-CCs carried by each infant (r = 0.5; 95{\%} CI 0.35-0.62). Time to first acquisition of S. aureus was shorter in children from households with >= 5 individuals (HR 1.06, 95{\%} CI 1.07-1.43), with S. aureus carrier mothers (HR; 1.5, 95{\%} CI 1.2-2.47), or with a positive tuberculin skin test during the first year of life (HR; 1.81, 95{\%} CI 0.97-3.3).Conclusion: Using measures of genotype diversity, we showed that S. aureus NP carriage is highly dynamic in infants. Prolonged carriage with a single strain occurred rarely; persistent carriage was not observed. A correlation was observed between carrier index and genotype diversity.",
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Longitudinal Population Dynamics of Staphylococcus aureus in the Nasopharynx During the First Year of Life. / Abdulgader, Shima M.; Robberts, Lourens; Ramjith, Jordache; Nduru, Polite M.; Dube, Felix; Gardner-Lubbe, Sugnet; Zar, Heather J.; Nicol, Mark P.

In: Frontiers in Genetics, Vol. 10, 198, 15.03.2019.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Longitudinal Population Dynamics of Staphylococcus aureus in the Nasopharynx During the First Year of Life

AU - Abdulgader, Shima M.

AU - Robberts, Lourens

AU - Ramjith, Jordache

AU - Nduru, Polite M.

AU - Dube, Felix

AU - Gardner-Lubbe, Sugnet

AU - Zar, Heather J.

AU - Nicol, Mark P.

PY - 2019/3/15

Y1 - 2019/3/15

N2 - Background: Staphylococcus aureus colonization is a risk factor for invasive disease. Few studies have used strain genotype data to study S. aureus acquisition and carriage patterns. We investigated S. aureus nasopharyngeal carriage in infants in an intensively sampled South African birth cohort.Methods: Nasopharyngeal swabs were collected at birth and fortnightly from 137 infants through their first year of life. S. aureus was characterized by spa-typing. The incidence of S. aureus acquisition, and median carriage duration for each genotype was determined. S. aureus carriage patterns were defined by combining the carrier index (proportion of samples testing positive for S. aureus) with genotype diversity measures. Persistent or prolonged carriage were defined by a carrier index >= 0.8 or >= 0.5, respectively. Risk factors for time to acquisition of S. aureus were determined.Results: Eighty eight percent (121/137) of infants acquired S. aureus at least once. The incidence of acquisition at the species and genotype level was 1.83 and 2.8 episodes per child-year, respectively. No children had persistent carriage (defined as carrier index of >0.8). At the species level 6% had prolonged carriage, while only 2% had prolonged carriage with the same genotype. Carrier index correlated with the absolute number of spa-CCs carried by each infant (r = 0.5; 95% CI 0.35-0.62). Time to first acquisition of S. aureus was shorter in children from households with >= 5 individuals (HR 1.06, 95% CI 1.07-1.43), with S. aureus carrier mothers (HR; 1.5, 95% CI 1.2-2.47), or with a positive tuberculin skin test during the first year of life (HR; 1.81, 95% CI 0.97-3.3).Conclusion: Using measures of genotype diversity, we showed that S. aureus NP carriage is highly dynamic in infants. Prolonged carriage with a single strain occurred rarely; persistent carriage was not observed. A correlation was observed between carrier index and genotype diversity.

AB - Background: Staphylococcus aureus colonization is a risk factor for invasive disease. Few studies have used strain genotype data to study S. aureus acquisition and carriage patterns. We investigated S. aureus nasopharyngeal carriage in infants in an intensively sampled South African birth cohort.Methods: Nasopharyngeal swabs were collected at birth and fortnightly from 137 infants through their first year of life. S. aureus was characterized by spa-typing. The incidence of S. aureus acquisition, and median carriage duration for each genotype was determined. S. aureus carriage patterns were defined by combining the carrier index (proportion of samples testing positive for S. aureus) with genotype diversity measures. Persistent or prolonged carriage were defined by a carrier index >= 0.8 or >= 0.5, respectively. Risk factors for time to acquisition of S. aureus were determined.Results: Eighty eight percent (121/137) of infants acquired S. aureus at least once. The incidence of acquisition at the species and genotype level was 1.83 and 2.8 episodes per child-year, respectively. No children had persistent carriage (defined as carrier index of >0.8). At the species level 6% had prolonged carriage, while only 2% had prolonged carriage with the same genotype. Carrier index correlated with the absolute number of spa-CCs carried by each infant (r = 0.5; 95% CI 0.35-0.62). Time to first acquisition of S. aureus was shorter in children from households with >= 5 individuals (HR 1.06, 95% CI 1.07-1.43), with S. aureus carrier mothers (HR; 1.5, 95% CI 1.2-2.47), or with a positive tuberculin skin test during the first year of life (HR; 1.81, 95% CI 0.97-3.3).Conclusion: Using measures of genotype diversity, we showed that S. aureus NP carriage is highly dynamic in infants. Prolonged carriage with a single strain occurred rarely; persistent carriage was not observed. A correlation was observed between carrier index and genotype diversity.

KW - Staphylococcus aureus

KW - carriage

KW - infancy

KW - genotype diversity

KW - longitudinal

KW - NASAL CARRIAGE

KW - DETERMINANTS

KW - COLONIZATION

KW - ACQUISITION

KW - PATTERNS

KW - CARRIERS

KW - SAMPLES

KW - CHILD

KW - CODY

U2 - 10.3389/fgene.2019.00198

DO - 10.3389/fgene.2019.00198

M3 - Article

VL - 10

JO - Frontiers in Genetics

JF - Frontiers in Genetics

SN - 1664-8021

M1 - 198

ER -