Development of a skin colonization model in gnotobiotic piglets for the study of the microbial ecology of meticillin-resistant Staphylococcus aureus ST398

Abstract

Aims Meticillin‐resistant Staphylococcus aureus (MRSA) ST398 continues to spread amongst pigs and other domestic animals and man. This highlights the need for models to examine MRSA colonization and investigate control strategies. This study aimed to develop a gnotobiotic pig model and assess the potential of bacterial interference from selected coagulase‐negative staphylococci (CNS) against MRSA ST398. Methods and Results Groups of 2‐week‐old piglets were atraumatically inoculated either with MRSA and/or CNS. Skin and mucosae were swabbed, and bacterial counts compared over a period of 21 days. Piglets developed healthily, and bacterial populations increased similarly for both MRSA and CNS until day 32. On day 37, MRSA counts in groups with CNS reduced significantly compared with MRSA alone (P = 0·03). Conclusions The results showed that inoculation of piglet skin with MRSA resulted in spontaneous colonization and that MRSA ST398 has a low pathogenic potential in gnotobiotic piglets. Quantitative bacteriology indicated that initial MRSA colonization was unaffected by concurrent CNS colonization but that interference may occur over a longer period. Significance and Impact of the Study Gnotobiotic piglets provide a reproducible model suitable for bacterial interference studies, which should be further explored as an alternative to antimicrobials in the control of MRSA.

Candida auris Forms High-Burden Biofilms in Skin Niche Conditions and on Porcine Skin

“…The present study provides tools to further dissect C. auris growth and biofilm formation in the skin environment. In light of the similarities to human skin, porcine skin serves as an excellent model for studies of wound healing, infection, and skin colonization (15)(16)(17)(18)25). Growth of C. auris in this ex vivo model mimics what is observed clinically, an enhanced capacity for skin colonization.…”

Comparative Host Specificity of Human- and Pig- Associated Staphylococcus aureus Clonal Lineages

“…No antagonism between these strains (ST8, ST22, ST36 and ST398) could be detected in vitro by a) measuring inhibition zone diameters after spotting supernatant derived from an centrifuged overnight culture of one strain onto a spread plate of the other strain, and b) growing two strains together in liquid medium and measuring the CFU/mL of each strain at 1 h intervals for 6 hrs (data not shown). However, in vivo colonization could be influenced by bacterial interference with other staphylococcal species present in the normal flora of the pigs, as suggested by a recent study of MRSA ST398 colonization in gnotobiotic piglets [33]. It is also a possibility that the undetected strains could have been present at low numbers below the detection limit of the method and/or have a slower growth rate resulting in the strains being outgrown during enrichment by faster growing strains.…”

Physical stress and bacterial colonization

“…The only skin colonization model deemed to appropriately reflect human skin colonization is the pig skin model, which is only rarely used, owing to the difficult requirements for having pigs as test animals. It has been applied more recently predominantly to investigate colonization of pigs as hosts for livestockassociated methicillin-resistant S. aureus (MRSA; Moodley et al, 2011;Giotis et al, 2012). Therefore, most of what we know about the bacterial components that ascertain binding to host matrix proteins stems from in vitro tests that use matrix protein-coated abiotic surfaces, such as present in microtiter plates.…”