Genotypic and Phenotypic Markers of Livestock-Associated Methicillin-Resistant Staphylococcus aureus CC9 in Humans

Abstract

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...

Livestock-Associated, Antibiotic-Resistant Staphylococcus aureus Nasal Carriage and Recent Skin and Soft Tissue Infection among Industrial Hog Operation Workers

“…CC9 has been identified as a marker of LA- S . aureus among livestock workers in Asia [39], and has been observed among livestock herds and people in contact with these herds in the Midwestern US [7], and in the same geographic region as the present study [6,38]. …”

The Prevalence of Antibiotic-Resistant Staphylococcus aureus Nasal Carriage among Industrial Hog Operation Workers, Community Residents, and Children Living in Their Households: North Carolina, USA

“…For example, the scn gene has been shown to be highly mobile, with phage-mediated loss in an animal host and insertion in a human host potentially occurring in as little as 4 hr (McCarthy et al 2014; Thammavongsa et al 2015). S. aureus spa types that circulate in livestock also can evolve quickly and putative LA- S. aureus markers based on spa types, CCs (e.g., CC398 or CC9) and/or MLSTs may have uncertain specificity depending on regional and microbial selection factors (Bosch et al 2016; Hau et al 2015; Lahuerta-Marin et al 2016; Ye et al 2016b). …”

“…We examined prevalence of S. aureus , MRSA, and MDRSA nasal carriage outcomes, including several putative markers of LA- S. aureus — scn -negative S. aureus , S. aureus CC398, and S. aureus CC9 (Nadimpalli et al 2015; Rinsky et al 2013; Ye et al 2016a, 2016b)—among adults with occupational exposure to IHOs, adult community resident without occupational exposure to IHOs, and one child < 7 years of age living in the same household as each adult in rural southeastern North Carolina.…”

The Genomic Context for the Evolution and Transmission of Community-Associated Staphylococcus aureus ST59 Through the Food Chain

“…However, zoonotic MRSA infections are primarily livestock-associated (LA-MRSA) (Petinaki and Spiliopoulou, 2012), and these are not typically members of CC59. For example, LA-MRSA isolates from Europe and North America primarily belong to CC398, and the vast majority of LA-MRSA isolates from Asia belong to CC9 (Bens et al, 2006;Cui et al, 2009;Smith et al, 2009;Ye et al, 2016). Indeed, CC59 isolates are rarely linked to LA infections but are frequently associated with CA infections.…”