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Persistent Staphylococcus aureus colonization is not a strongly heritable trait in Amish families.

Roghmann MC, Johnson JK, Stine OC, Lydecker AD, Ryan KA, Mitchell BD, Shuldiner AR - PLoS ONE (2011)

Bottom Line: Twenty two per cent (8/36) of siblings of persistently colonized index cases were persistently colonized with S. aureus compared to 17% (34/196) of siblings of non-persistently colonized index cases, yielding a prevalence rate ratio of 1.28 (95% CI: 0.65-2.54, p = 0.64) and sibling relative risk of 1.25 (95% CI: 0.65-2.38, p = 0.51).The heritability of persistent colonization was 0.19±0.21 (p = 0.31).Persistent S. aureus colonization does not strongly aggregate in Amish family members in different households and heritability is low, suggesting that environmental factors or acquired host factors are more important than host genetic factors in determining persistent S. aureus colonization in this community.

View Article: PubMed Central - PubMed

Affiliation: University of Maryland School of Medicine, Baltimore, Maryland, United States of America. mroghman@epi.umaryland.edu

ABSTRACT
About 20% of adults are persistently colonized with S. aureus in the anterior nares. Host genetic factors could contribute susceptibility to this phenotype. The objective of this study was to determine whether the phenotype of persistent S. aureus colonization aggregates in family members who live in different households. Healthy adults and their eligible same sex siblings who lived in different households were recruited from the Old Order Amish of Lancaster, Pennsylvania. All participants had two cultures of the anterior nares to determine if they were persistently colonized with S. aureus. Three hundred and ninety eight participants finished the study, of whom 166 were index cases and 232 were siblings of index cases. Eighteen per cent (71/398) of all participants and 17% (29/166) of index cases were persistently colonized with S. aureus. Twenty two per cent (8/36) of siblings of persistently colonized index cases were persistently colonized with S. aureus compared to 17% (34/196) of siblings of non-persistently colonized index cases, yielding a prevalence rate ratio of 1.28 (95% CI: 0.65-2.54, p = 0.64) and sibling relative risk of 1.25 (95% CI: 0.65-2.38, p = 0.51). The heritability of persistent colonization was 0.19±0.21 (p = 0.31). Persistent S. aureus colonization does not strongly aggregate in Amish family members in different households and heritability is low, suggesting that environmental factors or acquired host factors are more important than host genetic factors in determining persistent S. aureus colonization in this community.

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Validation of two culture method to determine nasal S. aureus colonization status.Correlation between the two semi-quantitative cultures for S. aureus and the nine or more qualitative cultures for S. aureus results in study population, Spearman’s rho = 0.85, p value <0.01, EB is enrichment broth, CFU is colony forming units, SA is S. aureus.
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pone-0017368-g001: Validation of two culture method to determine nasal S. aureus colonization status.Correlation between the two semi-quantitative cultures for S. aureus and the nine or more qualitative cultures for S. aureus results in study population, Spearman’s rho = 0.85, p value <0.01, EB is enrichment broth, CFU is colony forming units, SA is S. aureus.

Mentions: We validated use of two semi-quantitative cultures to define persistent S. aureus colonization by comparing these test results against those obtained from the use of nine or more qualitative cultures. Persistent S. aureus colonization was defined as an average of ≥1000 CFU on the two cultures collected by the research nurse. [9]. Of the 16 participants having S. aureus present on ≥80% of the cultures and therefore defined as persistent S. aureus carriers, 15 of them had an average of ≥1000 CFU on the first two cultures (sensitivity 94%, 95% CI 89%–98%). Of the 84 participants who did not have S. aureus present on ≥80% of the cultures, and were therefore not persistent S. aureus carriers, 79 of them had an average of <1000 CFU on the first two cultures (specificity 94%, 95% CI 89%–99%). The 2 culture rule identified 20 participants as persistent S. aureus carriers, 15 of whom were correctly characterized (positive predictive value 75%, 95% CI 67%–83%). Figure 1 shows the strong correlation between the average of two semi-quantitative cultures and the percent positive from nine or more qualitative culture results in our validation cohort (r = 0.85, p<0.01, Spearman’s rho).


Persistent Staphylococcus aureus colonization is not a strongly heritable trait in Amish families.

Roghmann MC, Johnson JK, Stine OC, Lydecker AD, Ryan KA, Mitchell BD, Shuldiner AR - PLoS ONE (2011)

Validation of two culture method to determine nasal S. aureus colonization status.Correlation between the two semi-quantitative cultures for S. aureus and the nine or more qualitative cultures for S. aureus results in study population, Spearman’s rho = 0.85, p value <0.01, EB is enrichment broth, CFU is colony forming units, SA is S. aureus.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3046241&req=5

pone-0017368-g001: Validation of two culture method to determine nasal S. aureus colonization status.Correlation between the two semi-quantitative cultures for S. aureus and the nine or more qualitative cultures for S. aureus results in study population, Spearman’s rho = 0.85, p value <0.01, EB is enrichment broth, CFU is colony forming units, SA is S. aureus.
Mentions: We validated use of two semi-quantitative cultures to define persistent S. aureus colonization by comparing these test results against those obtained from the use of nine or more qualitative cultures. Persistent S. aureus colonization was defined as an average of ≥1000 CFU on the two cultures collected by the research nurse. [9]. Of the 16 participants having S. aureus present on ≥80% of the cultures and therefore defined as persistent S. aureus carriers, 15 of them had an average of ≥1000 CFU on the first two cultures (sensitivity 94%, 95% CI 89%–98%). Of the 84 participants who did not have S. aureus present on ≥80% of the cultures, and were therefore not persistent S. aureus carriers, 79 of them had an average of <1000 CFU on the first two cultures (specificity 94%, 95% CI 89%–99%). The 2 culture rule identified 20 participants as persistent S. aureus carriers, 15 of whom were correctly characterized (positive predictive value 75%, 95% CI 67%–83%). Figure 1 shows the strong correlation between the average of two semi-quantitative cultures and the percent positive from nine or more qualitative culture results in our validation cohort (r = 0.85, p<0.01, Spearman’s rho).

Bottom Line: Twenty two per cent (8/36) of siblings of persistently colonized index cases were persistently colonized with S. aureus compared to 17% (34/196) of siblings of non-persistently colonized index cases, yielding a prevalence rate ratio of 1.28 (95% CI: 0.65-2.54, p = 0.64) and sibling relative risk of 1.25 (95% CI: 0.65-2.38, p = 0.51).The heritability of persistent colonization was 0.19±0.21 (p = 0.31).Persistent S. aureus colonization does not strongly aggregate in Amish family members in different households and heritability is low, suggesting that environmental factors or acquired host factors are more important than host genetic factors in determining persistent S. aureus colonization in this community.

View Article: PubMed Central - PubMed

Affiliation: University of Maryland School of Medicine, Baltimore, Maryland, United States of America. mroghman@epi.umaryland.edu

ABSTRACT
About 20% of adults are persistently colonized with S. aureus in the anterior nares. Host genetic factors could contribute susceptibility to this phenotype. The objective of this study was to determine whether the phenotype of persistent S. aureus colonization aggregates in family members who live in different households. Healthy adults and their eligible same sex siblings who lived in different households were recruited from the Old Order Amish of Lancaster, Pennsylvania. All participants had two cultures of the anterior nares to determine if they were persistently colonized with S. aureus. Three hundred and ninety eight participants finished the study, of whom 166 were index cases and 232 were siblings of index cases. Eighteen per cent (71/398) of all participants and 17% (29/166) of index cases were persistently colonized with S. aureus. Twenty two per cent (8/36) of siblings of persistently colonized index cases were persistently colonized with S. aureus compared to 17% (34/196) of siblings of non-persistently colonized index cases, yielding a prevalence rate ratio of 1.28 (95% CI: 0.65-2.54, p = 0.64) and sibling relative risk of 1.25 (95% CI: 0.65-2.38, p = 0.51). The heritability of persistent colonization was 0.19±0.21 (p = 0.31). Persistent S. aureus colonization does not strongly aggregate in Amish family members in different households and heritability is low, suggesting that environmental factors or acquired host factors are more important than host genetic factors in determining persistent S. aureus colonization in this community.

Show MeSH