Multilocus sequence type-dependent activity of human and animal cathelicidins against community-, hospital-, and livestock-associated methicillin-resistant Staphylococcus aureus isolates

Abstract

Sequence type (ST) 5 methicillin-resistant Staphylococcus aureus (MRSA) with staphylococcal cassette chromosome mec (SCCmec) type II (ST5-MRSA-II) and ST72-MRSA-IV represent the most significant genotypes for healthcare- (HA) and community-associated (CA) MRSA in Korea, respectively. In addition to the human-type MRSA strains, the prevalence of livestock-associated (LA) MRSA clonal lineages, such as ST541 and ST398 LA-MRSA-V in pigs and ST692 LA-MRSA-V and ST188 LA-MRSA-IV in chickens, has recently been found. In this study, clonotype-specific resistance profiles to cathelicidins derived from humans (LL-37), pigs (PMAP-36), and chickens (CATH-2) were examined using six different ST groups of MRSA strains: ST5 HA-MRSA-II, ST72 CA-MRSA-IV, ST398 LA-MRSA-V, ST541 LA-MRSA-V, ST188 LA-MRSA-IV, and ST692 LA-MRSA-V. Phenotypic characteristics often involved in cathelicidin resistance, such as net surface positive charge, carotenoid production, and hydrogen peroxide susceptibility were also determined in the MRSA strains. Human- and animal-type MRSA strains exhibited clonotype-specific resistance profiles to LL-37, PMAP-36, or CATH-2, indicating the potential role of cathelicidin resistance in the adaptation and colonization of human and animal hosts. The ST5 HA-MRSA isolates showed enhanced resistance to all three cathelicidins and hydrogen peroxide than ST72 CA-MRSA isolates by implementing increased surface positive charge and carotenoid production. In contrast, LA-MRSA strains employed mechanisms independent of surface charge regulation and carotenoid production for cathelicidin resistance. These results suggest that human- and livestock-derived MRSA strains use different strategies to counteract the bactericidal action of cathelicidins during the colonization of their respective host species.

The current state of phage therapy in livestock and companion animals

“…Contagious mastitis, caused by pathogens like Staphylococcus aureus , Streptococcus agalactiae , and Corynebacterium bovis , can transmit from one cattle to another. Environmental mastitis is instigated by pathogens such as Escherichia coli , Klebsiella spp., Streptococcus dysgalactiae , and Streptococcus uberis [ 8 , 32 ].…”

“…Corynebacterium bovis, can transmit from one cattle to another. Environmental mastitis is instigated by pathogens such as Escherichia coli, Klebsiella spp., Streptococcus dysgalactiae, and Streptococcus uberis [8,32]. Among these pathogens, S. aureus, along with nonaureus staphylococci, is the most frequently detected contagious pathogen [33].…”