Transmission of highly virulent community-associated MRSA ST93 and livestock-associated MRSA ST398 between humans and pigs in Australia

Abstract

Pigs have been recognised as a reservoir of livestock associated methicillin-resistant Staphylococcus aureus (LA-MRSA) in Europe, Asia and North America. However, little is known about the presence and distribution of MRSA in the Australian pig population and pig industry. This study describes the presence, distribution and molecular characteristics of the human adapted Australian CA-MRSA ST93 isolated from pigs, people, and the environment within a piggery. Isolates were subjected to antibiotic susceptibility testing, DNA microarray, whole genome sequencing, multi locus sequence typing, virulence and resistance gene characterization and phylogenetic analysis. MRSA were isolated from 60% (n = 52) of farm workers where 84% of isolates returned ST93 and the rest ST398. Of the thirty-one pig isolates tested further, an equal number of ST398 and ST93 (15 each) and one as ST30-V were identified. Four of six environmental isolates were identified as ST93 and two as ST398. This study has identified for the first time in Australia the occurrence of CA-MRSA ST93 and LA-MRSA ST398 amongst farm workers, pigs, and the farm environment. Comparative genome analysis indicates that ST398 is likely to have been introduced into Australia from Europe or North America. This study also reports the first linezolid resistant MRSA isolated in Australia.

The need for efforts to obtain high quality evidence in a one health approach

“…There are many observational studies using the whole-genome sequencing tool to analyse the possibility of the transmission of genetic mobile elements or strains responsible for antibiotic resistance among human, animal, and environment ( Table 1). The whole genome sequencing studies showed that the same antibiotic-resistant foodborne and zoonotic pathogens, such as S. enterica, Staphylococcus aureus, and Campylobacter sp., are detected in both human and animals [16][17][18][19][20][21][22][23][24][25][26][27][28]. For example, cefoxitin-resistant S. enterica serovar Heidelberg strains with 0 to 4 Single Nucleotide Variations (SNVs) (i.e.…”

“…Animal and human Identification of the same antimicrobial-resistant strain β-Lactam Staphylococcus aureus [17,[19][20][21][22][24][25][26] Salmonella enterica [18,23,27] Escherichia coli [29,31,[35][36][37][38] Klebsiella pneumoniae [30] Campylobacter sp.…”

Single Nucleotide Polymorphism Analysis Indicates Genetic Distinction and Reduced Diversity of Swine-Associated Methicillin Resistant Staphylococcus aureus (MRSA) ST5 Isolates Compared to Clinical MRSA ST5 Isolates

“…Phylogenetic studies employ whole genome sequencing (WGS) technology and data analysis to better understand the epidemiology, origin, and evolution of bacteria ( Price et al, 2012 ; Uhlemann et al, 2012 ; Eppinger et al, 2014 ; Sahibzada et al, 2017 ). In the case of LA-MRSA, these techniques have been used to assess the relatedness of isolates from the ST398 lineage.…”

“…WGS analysis can be used to assess isolate relatedness or determine genetic characteristics that define subsets of isolates, including information about the MGEs harboring virulence factors or AMR genes. Through single nucleotide polymorphism (SNP) discovery within the core genome, the accuracy and resolution power is available to determine phylogenetic relationships and distinguish isolates within highly homogenous lineages, which provides insight in epidemiological investigations ( Eppinger et al, 2011 , 2014 ; Rusconi et al, 2016 ; Sahibzada et al, 2017 ).…”

<i>vicK</i> Gene as Potential Identification Marker for <i>Staphylococcus aureus</i>

“…HA-MRSA infections are usually difficult to treat due to their resistance to multiple antibiotics, contributing to a significant mortality and morbidity [7]. The worldwide concern of S. aureus infections increases with recent emergence of community-associated MRSA (CA-MRSA) and livestock-associated MRSA (LA-MRSA) which posed a significant impact and economic burden in public health and livestock industry [8] [9] [10].…”