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Yanling Liu, Wenhui Li, Qian Dong, Yangqun Liu, Xiaohua Ye School of Public Health, Guangdong Pharmaceutical University, Guangzhou, People’s Republic of ChinaCorrespondence: Yangqun Liu; Xiaohua YeSchool of Public Health, Guangdong Pharmaceutical University, 283# Jianghai Dadao, Haizhu District, Guangzhou, People’s Republic of ChinaTel +862034055355Email 136437677@qq.com; smalltomato@163.comBackground: The distinction between livestock-associated and human-associated methicillin-resistant Staphylococcus aureus (MRSA) has become more and more blurred. This study aimed to reveal the transmission risk of livestock-associated and non-livestock-associated S. aureus (including MRSA and multidrug-resistant S. aureus [MDRSA]) by occupational pig exposure.Methods: A total of 591 pig-exposed workers and 1178 non-exposed workers were enrolled in this study. All nasal S. aureus isolates were tested for antibiotic susceptibility and molecular characteristics. Logistic regression models were used to examine the dose–response relationships between occupational pig exposure and S. aureus carriage.Results: Pig-exposed workers had significantly higher carriage rates of MRSA (OR=6.29, 95% CI: 3.38∼ 11.68) and MDRSA (OR=3.17, 95% CI: 2.03∼ 4.96) than non-exposed workers. Notably, we found dose–response relationships between occupational pig exposure and MRSA or MDRSA carriage. Using genotypic and phenotypic markers for differentiating livestock-associated and non-livestock-associated S. aureus, we also revealed dose–response relationships occupational pig exposure and livestock-associated or non-livestock-associated S. aureus carriage.Conclusion: Our findings provide sufficient epidemiological evidence for revealing the high transmission risk of livestock-associated S. aureus and the low transmission risk of non-livestock-associated S. aureus by occupational pig exposure.Keywords: livestock, human, methicillin-resistant S. aureus, multidrug-resistant S. aureus, transmission

Nelly Hérault, 1,* Julia Wagner, 2–4,* Sarah-Luise Abram, 1 Jérôme Widmer, 2 Lenke Horvath, 1 Dimitri Vanhecke, 5 Carole Bourquin, 2–4,* Katharina M Fromm 1,* 1Department of Chemistry, University of Fribourg, Fribourg 1700, Switzerland; 2Department of Medicine, University of Fribourg, Fribourg 1700, Switzerland; 3Institute of Pharmaceutical Sciences of Western Switzerland, University of Geneva, Geneva 1211, Switzerland; 4Department of Anaesthesiology, Pharmacology, Intensive Care and Emergency Medicine, Faculty of Medicine, University of Geneva, Geneva 1211, Switzerland; 5Adolphe Merkle Institute, University of Fribourg, Fribourg 1700, Switzerland*These authors contributed equally to this workCorrespondence: Katharina M FrommUniversity of Fribourg, PER 10 bu. 114, chemin du Musée 9, Fribourg 1700, SwitzerlandTel +41 26 300 8732Email katharina.fromm@unifr.chBackground: Joint arthroplasty has improved the quality of life of patients worldwide, but infections of the prosthesis are frequent and cause significant morbidity. Antimicrobial coatings for implants promise to prevent these infections.Methods: We have synthesized nanocapsules of titanium dioxide in amorphous or anatase form containing silver as antibacterial agent and tested their impact on bacterial growth. Furthermore, we explored the possible effect of the nanocapsules on the immune system. First, we studied their uptake into macrophages using a combination of electron microscopy and energy-dispersive spectroscopy. Second, we exposed immune cells to the nanocapsules and checked their activation state by flow cytometry and enzyme-linked immunosorbent assay.Results: Silver-containing titanium dioxide nanocapsules show strong antimicrobial activity against both E. coli and S. aureus and even against a multidrug-resistant strain of S. aureus. We could demonstrate the presence of the nanocapsules in macrophages, but, importantly, the nanocapsules did not affect cell viability and did not activate proinflammatory responses at doses up to 20 μg/mL.Conclusion: Our bactericidal silver-containing titanium dioxide nanocapsules fulfill important prerequisites for biomedical use and represent a promising material for the coating of artificial implants.Keywords: silver nanoparticles, titanium dioxide nanocapsules, antimicrobial effect, multidrug-resistant S. aureus, immune cell uptake

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 nonsusceptibility 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.

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.