Use of antimicrobials in industrial food animal production is associated with the presence of multidrug-resistant Staphylococcus aureus among animals and humans. The livestock-associated (LA) methicillin-resistant S. aureus (MRSA) clonal complex 9 (CC9) is associated with animals and related workers in Asia. This study aimed to explore the genotypic and phenotypic markers of LA-MRSA CC9 in humans. We conducted a cross-sectional study of livestock workers and controls in Guangdong, China. The study participants responded to a questionnaire and provided a nasal swab for S. aureus analysis. The resulting isolates were assessed for antibiotic susceptibility, multilocus sequence type, and immune evasion cluster (IEC) genes. Methicillin-resistant Staphylococcus aureus (MRSA) is one of the leading causes of antibiotic-resistant nosocomial infections, causing diseases ranging from minor skin infections to severe septicemia and pneumonia, and is of particular concern because few antibiotics are effective at treating infections caused by the pathogen. The epidemiology of MRSA has changed with the increasing emergence of community-associated MRSA (1, 2). Recently, another MRSA clone emerged in the community, which was observed in livestock and related workers and was referred to as livestock-associated MRSA (LA-MRSA) (3). Livestock, especially pigs, can serve as reservoirs for LA-MRSA, and the bacteria can also be transmitted to humans in close contact with MRSAcolonized animals (4, 5).LA-MRSA isolates have unique molecular characteristics that distinguish them from community-associated MRSA and health care-associated MRSA, and these characteristics vary according to the geographic area. Sequence type 398 (ST398) has been referred to as the most pandemic LA-MRSA in Europe and North America, while ST9 is the most prevalent LA-MRSA in most Asian countries (3). However, persons living in areas of high livestock density were also found to have a greater risk of LA-MRSA carriage even if they lacked direct contact with livestock (6, 7). Thus, the possibility of direct and indirect livestock contact as a potential source of human MRSA infection has become a growing public health concern.Few reports have described the epidemiology and molecular characteristics of LA-MRSA in developing countries in Asia. In China, MRSA has been isolated from pigs and pig workers (8, 9). However, there is still very limited information on LA-MRSA infection among healthy people. In addition, few studies examining human MRSA carriage have attempted to differentiate humanfrom livestock-associated isolates based on genotypic and phenotypic markers. The goals of this study, therefore, were to determine the prevalence of MRSA (including LA-MRSA) in livestock workers and control workers in Guangdong, as well as to use the multifactor dimensionality reduction method to detect the genotypic and phenotypic markers for LA-MRSA. MATERIALS AND METHODSEthics statement. This study was approved by the Ethics Committee of Guangdong Pharmaceutical Universit...

No abstract

This study aimed to explore the association of livestock-associated S. aureus with occupational pig contact and pet contact. In this cross-sectional study, 1,422 participants (including 244 pig workers, 200 pet-owning workers and 978 control workers) responded to a questionnaire and provided a nasal swab for S. aureus analysis. Resulting isolates were tested for antibiotic susceptibility, the immune evasion cluster (IEC) genes, and multilocus sequence type. Compared with controls, the pig workers demonstrated a greater prevalence of multidrug-resistant S. aureus (MDRSA) [prevalence ratio (PR) = 3.38; 95% CI: 2.07–5.53] and methicillin-resistant S. aureus (MRSA) (PR = 7.42; 95% CI: 3.71–14.83), but the prevalence of MDRSA and MRSA was similar in pet-owning workers and controls. There was a positive relation of frequency of pig contact with prevalence of MDRSA and MRSA carriage. Only pig workers carried MDRSA CC9 (16 isolates) and MRSA CC9 (16 isolates), and all of these isolates were tetracycline resistant and absent of IEC genes. These findings suggest that livestock-associated MRSA and MDRSA(CC9, IEC-negative, tetracycline-resistant) in humans is associated with occupational pig contact, not pet contact, and support growing concern about antibiotics use in pig farms and raising questions about the potential for occupational exposure to opportunistic S. aureus.

No abstract

While some studies have defined Staphylococcus aureus based on its clonal complex and resistance pattern, few have explored the relations between the genetic lineages and antibiotic resistance patterns and immune evasion cluster (IEC) genes. Our aim was to investigate the potential relationship between phenotypic and molecular characteristics so as to reveal livestock-associated S. aureus in humans. The study participants were interviewed, and they provided two nasal swabs for S. aureus analysis. All S. aureus and methicillin-resistant S. aureus (MRSA) were tested for antibiotic susceptibility, multilocus sequence type and IEC genes. Of the 1162 participants, 9.3% carried S. aureus, including MRSA (1.4%) and multidrug-resistant S. aureus (MDRSA, 2.8%). The predominant multidrug-resistant pattern among MDRSA isolates was non-susceptibility to erythromycin, clindamycin and tetracycline. The most common S. aureus genotypes were ST7, ST6, ST188, and ST59, and the predominant MRSA genotype was ST7. Notably, the livestock-associated S. aureus isolates (IEC-negative CC9, IEC-negative tetracycline-resistant CC398, and IEC-negative tetracycline-resistant CC5) were found in people with no occupational livestock contact. These findings reveal a potential relationship between S. aureus CCs and IEC genes and antibiotic resistance patterns in defining livestock-associated S. aureus in humans and support growing concern about the potential livestock-to-human transmission of livestock-associated S. aureus by non-occupational livestock contact.

BackgroundStudies conducted in the past mostly rely on models of functional health literacy in adult populations. However, such models do not satisfy the need for health intervention in adolescents. The identification of key factors influencing adolescents' health literacy is essential in developing effective prevention and intervention measures. This study aimed to test a theoretical model of predictors on health skills and health behaviors in adolescents.MethodsA cross-sectional survey was conducted in Guangdong using a multi-stage stratified cluster sample design. A representative random sample of 3821 students aged 13–25 years was selected using multi-stage stratified cluster sampling. The path analysis was used to test a hypothesized model of health literacy.ResultsThe path analysis showed that knowledge of infectious disease (β = 0.26), health skills (β = 0.22), health concept (β = 0.20), general health knowledge (β = 0.15), gender (β = 0.12), and school performance (β = 0.06) had positive direct effect on health behaviors in adolescents. The explanatory variables accounted for 43% of the variance in explaining health behaviors. Knowledge of infectious disease (β = 0.30), health concept (β = 0.17), general health knowledge (β = 0.13), and school performance (β = 0.05) had positive indirect effect on health behaviors through the impacts on health skills.ConclusionThis study identified several direct and indirect factors influencing health skills and health behaviors in adolescents. These findings will assist health professionals designing effective health interventions that aim to improve health skills and health behaviors in adolescents.

Pig farmers and veterinarians have high prevalence of methicillin-resistant Staphylococcus aureus (MRSA) due to the occupational livestock exposure, while few reported this association on slaughterhouse workers. We conducted this cross-sectional study to explore the phenotypic and molecular characteristics of S. aureus and MRSA in slaughterhouse pig-related workers and control workers in Guangdong Province, China. Participants were interviewed and provided two nasal swabs. Swabs were tested for S. aureus, and isolates were further tested for antimicrobial susceptibility, virulence genes and multi-locus sequence typing. Compared with control workers, pig-related workers have significantly higher prevalence of MRSA carriage (adjusted odd ratio (aOR) 3·70, 95% CI 1·63-8·40). The proportions of MRSA resistant to clindamycin, erythromycin, tetracycline or chloromycetin were significantly higher in pig-related workers than in control workers. The predominant phenotypes of S. aureus were resistant to penicillin, clindamycin, erythromycin and tetracycline. Three MRSA CC9 isolates with livestock-associated characteristics (resistance to tetracycline and absence of immune evasion cluster (IEC) genes) were detected in pig-related workers but not in control workers. For human-associated CCs (CC7, CC59, CC6, and CC188), there was no significant difference in IEC profile or antimicrobial resistance between the groups. These findings reveal that there may be a potential risk for livestock-to-human transmission of LA-MRSA and human-to-human transmission of human-associated MRSA.

No abstract