Staphylococcus aureus in Iowa child care facilities

Abstract

Staphylococcus aureus (S. aureus) is a ubiquitous bacterium that has the potential to cause severe disease in children and adults. Asymptomatic carriage of S. aureus is an important risk factor for developing infection, as well as a key contributor to transmission. Carriage of respiratory bacteria (mainly Streptococcus pneumoniae, Staphylococcus aureus, Haemophilus influenzae, and Moraxella catarrhalis) has been studied extensively in child care attendees. Prevalence of these pathogens and resistance rates among them vary widely, and the introduction of the pneumococcal vaccine has the potential to alter patterns of carriage in this population. Molecular characterization of bacteria in child care facilities, primarily of S. pneumoniae, has shown that each facility hosts its own bacteriological profile, but can also serve as a community reservoir for epidemic and internationally-recognized clones. Limitations in current research on this topic exist. The majority of data is cross-sectional with no comparison group, and there has been little research published since 2000 on child care employees, bacterial contamination of environmental surfaces, and bacteria causing diarrheal illness. Despite the fact that child care workers are at risk of infections, little research has focused on asymptomatic carriage in this occupational group. We collected samples from 110 employees, 81 children, and 214 surfaces at twelve child care facilities, as well as 111 age-and gender-matched adults not employed at child care centers. After adjusting for age, a household contact with a recent influenza-like illness, and a household contact with exposure to cattle, the odds ratio for S. aureus carriage in child care employees was 0.68 (95% CI 0.31-1.50, p-value 0.34). The odds of MRSA carriage was 3.28 times higher in child care employees than unexposed adults after adjusting for a history of TABLE OF CONTENTS LIST OF TABLES.

Molecular characteristics of Staphylococcus aureus isolated from employees, children, and environmental surfaces in Iowa child daycare facilities

“…Our study population was also recruited primarily in the Iowa City metropolitan area, whereas the Wardyn population was recruited in rural areas, likely resulting in different risk profiles between the 2 populations. 11,17 Daycare employees do not appear to be at increased risk of carriage of overall S aureus. 11 The carriage rates of employees and unexposed adults were very similar, possibly because we recruited unexposed adults based on frequency matching on age category and gender, 2 variables that have been associated with risk of S aureus carriage.…”

“…11,17 Daycare employees do not appear to be at increased risk of carriage of overall S aureus. 11 The carriage rates of employees and unexposed adults were very similar, possibly because we recruited unexposed adults based on frequency matching on age category and gender, 2 variables that have been associated with risk of S aureus carriage. 25,26 This strategy helped ensure that age and gender were not confounders in the assessment of daycare employment as a risk factor for carriage.…”

“…Previously published risk factor data from this study did not demonstrate an association between living on a farm or contact with animals or animal waste products and S aureus carriage, although our samples sizes were likely too small to detect any meaningful difference. 11 However, a spa type t571 isolate (identical by pulsed field gel electrophoresis to livestock-associated strain ST398) was identified in a daycare employee with no livestock exposure. 24 Our findings may have been different if more rural child-care centers had been targeted.…”

“…Comprehensive recruitment methods are published elsewhere, 11 but involved identifying child-care centers from the Johnson County list of registered and licensed facilities, as well as through personal contacts. Letters were sent to all facilities and follow-up telephone calls were conducted, with priority given to larger licensed facilities.…”

“…Nasal and throat samples were collected from adults, whereas only nasal swabs were collected from children to minimize discomfort. 11 Environmental samples were collected throughout each facility, concentrating on areas that are frequently touched (eg, doorknobs and popular toys). After immersing the swab in sterile phosphate-buffered saline, samples were obtained by rotating the swab in 3 directions across as much of the surface as possible.…”