Frequency-risk and duration-risk relations between occupational livestock contact and methicillin-resistant Staphylococcus aureus carriage among workers in Guangdong, China.
BACKGROUND
Increasing evidence indicates a strong association between occupational livestock contact and methicillin-resistant Staphylococcus aureus (MRSA) carriage. However, it remains unclear whether there are frequency-risk and duration-risk relations between occupational livestock contact and human MRSA carriage.


METHODS
A cross-sectional survey was conducted in Guangdong, China, using a multistage sampling method. Participants were interviewed and provided a nasal swab for S aureus analysis. All MRSA isolates were genotyped by multilocus sequence typing. The dose-response relation was examined using logistic regression models.


RESULTS
Among the 1,860 participants, 1.4% of controls tested positive for MRSA (characterized as sequence type [ST] 59 and ST7), and 7% of workers with livestock contact tested positive for MRSA (characterized as ST9, ST59, and ST7). There was a 5.31 times increased risk of MRSA carriage corresponding to occupational livestock contact (odds ratio = 6.31; 95% confidence interval, 3.44-11.57) using no contact as reference. We found frequency and short-term duration of occupational livestock contact were associated with increased risk of MRSA carriage in a dose-response manner. These significant trends were observed consistently among workers with occupational pig contact. However, no long-term duration-risk increasing trend was observed for occupational livestock or pig contact.


CONCLUSIONS
Our findings suggest that there may be dose-response relations between occupational livestock contact and human MRSA carriage. Nasal MRSA clonal complex 9 is not found in controls, but it is found in workers with livestock contact.
Guangdong Key Laboratory of Molecular Epidemiology, School of Public Health, Guangdong Pharmaceutical University, Guangzhou, China.
Xiaohua
X
Ye
Guangdong Key Laboratory of Molecular Epidemiology, School of Public Health, Guangdong Pharmaceutical University, Guangzhou, China.
Weidong
W
Liu
Guangdong Key Laboratory of Molecular Epidemiology, School of Public Health, Guangdong Pharmaceutical University, Guangzhou, China.
Yanping
Y
Fan
Guangdong Key Laboratory of Molecular Epidemiology, School of Public Health, Guangdong Pharmaceutical University, Guangzhou, China.
Xiaolin
X
Wang
Guangdong Key Laboratory of Molecular Epidemiology, School of Public Health, Guangdong Pharmaceutical University, Guangzhou, China.
Junli
J
Zhou
Guangdong Key Laboratory of Molecular Epidemiology, School of Public Health, Guangdong Pharmaceutical University, Guangzhou, China. Electronic address: zhjyao2001@yahoo.com.
Zhenjiang
Z
Yao
Guangdong Key Laboratory of Molecular Epidemiology, School of Public Health, Guangdong Pharmaceutical University, Guangzhou, China. Electronic address: chensidong1@126.com.
Sidong
S
Chen
D000293:Adolescent; D000328:Adult; D000818:Animals; D002353:Carrier State / Q000453:epidemiology* / Q000382:microbiology*; D002681:China; D003430:Cross-Sectional Studies; D005260:Female; D005838:Genotype; D006801:Humans; D007407:Interviews as Topic; D058751:Livestock; D008297:Male; D055624:Methicillin-Resistant Staphylococcus aureus / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D008875:Middle Aged; D058885:Multilocus Sequence Typing; D009297:Nasal Mucosa / Q000382:microbiology; D016273:Occupational Exposure; D018570:Risk Assessment; D013203:Staphylococcal Infections / Q000453:epidemiology* / Q000382:microbiology*; D055815:Young Adult
Community-acquired; Human; Livestock; Methicillin-resistant Staphylococcus aureus