Swine Farming Is a Risk Factor for Infection With and High Prevalence of Carriage of Multidrug-Resistant Staphylococcus aureus.
BACKGROUND
Livestock-associated Staphylococcus aureus (LA-SA) has been documented worldwide. However, much remains unknown about LA-SA colonization and infection, especially in rural environments.


METHODS
We conducted a large-scale prospective study of 1342 Iowans, including individuals with livestock contact and a community-based comparison group. Nasal and throat swabs were collected to determine colonization at enrollment, and skin infection swabs over 17 months were assessed for S. aureus. Outcomes included carriage of S. aureus, methicillin-resistant S. aureus (MRSA), tetracycline-resistant S. aureus (TRSA), multidrug-resistant S. aureus (MDRSA), and LA-SA.


RESULTS
Of 1342 participants, 351 (26.2%; 95% confidence interval [CI], 23.8%-28.6%) carried S. aureus. MRSA was isolated from 34 (2.5%; 95% CI, 1.8%-3.5%) and LA-SA from 131 (9.8%; 95% CI, 8.3%-11.5%) of the 1342 participants. Individuals with current swine exposure were significantly more likely to carry S. aureus (prevalence ratio [PR], 1.8; 95% CI, 1.4-2.2), TRSA (PR, 8.4; 95% CI, 5.6-12.6), MDRSA (PR, 6.1; 95% CI, 3.8-10.0), and LA-SA (PR, 5.8; 95% CI, 3.9-8.4) than those lacking exposure. Skin infections (n = 103) were reported from 67 individuals, yielding an incidence rate of 6.6 (95% CI, 4.9-8.9) per 1000 person-months.


CONCLUSIONS
Current swine workers are 6 times more likely to carry MDRSA than those without current swine exposure. We observed active infections caused by LA-SA. This finding suggests that individuals with livestock contact may have a high prevalence of exposure to, and potentially infection with, antibiotic-resistant S. aureus strains, including LA-SA strains.
Center for Emerging Infectious Diseases Department of Epidemiology, College of Public Health.
Shylo E
SE
Wardyn
Center for Emerging Infectious Diseases Department of Epidemiology, College of Public Health.
Brett M
BM
Forshey
Center for Emerging Infectious Diseases.
Sarah A
SA
Farina
Center for Emerging Infectious Diseases Department of Epidemiology, College of Public Health.
Ashley E
AE
Kates
Center for Emerging Infectious Diseases Department of Epidemiology, College of Public Health.
Rajeshwari
R
Nair
Center for Emerging Infectious Diseases.
Megan K
MK
Quick
Center for Emerging Infectious Diseases Department of Epidemiology, College of Public Health.
James Y
JY
Wu
Center for Emerging Infectious Diseases Department of Epidemiology, College of Public Health.
Blake M
BM
Hanson
Center for Emerging Infectious Diseases.
Sean M
SM
O'Malley
Center for Emerging Infectious Diseases.
Hannah W
HW
Shows
Department of Occupational and Environmental Health, College of Public Health, University of Iowa, Iowa City.
Ellen M
EM
Heywood
Occupational and Environmental Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Rockville, Maryland.
Laura E
LE
Beane-Freeman
Department of Epidemiology, College of Public Health.
Charles F
CF
Lynch
Department of Geographical and Sustainability Sciences, College of Liberal Arts and Sciences.
Margaret
M
Carrel
Department of Biostatistics, Environmental Health Sciences and Epidemiology, College of Public Health, Kent State University, Ohio.
Tara C
TC
Smith
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000383:Agriculture; D000818:Animals; D002353:Carrier State / Q000453:epidemiology* / Q000382:microbiology; D002648:Child; D002675:Child, Preschool; D024901:Drug Resistance, Multiple, Bacterial; D004781:Environmental Exposure; D005260:Female; D006801:Humans; D007223:Infant; D007484:Iowa / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D009296:Nasal Cavity / Q000382:microbiology; D016273:Occupational Exposure; D010614:Pharynx / Q000382:microbiology; D015995:Prevalence; D011446:Prospective Studies; D012307:Risk Factors; D012867:Skin / Q000382:microbiology; D013203:Staphylococcal Infections / Q000453:epidemiology* / Q000382:microbiology; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000302:isolation & purification; D013552:Swine; D055815:Young Adult
Staphylococcus aureus; colonization; livestock-associated Staphylococcus aureus; multidrug resistance; swine