Transmission and Persistence of Livestock-Associated Methicillin-Resistant Staphylococcus aureus among Veterinarians and Their Household Members

Abstract

Shortly after the introduction of methicillin in 1959, methicillin-resistant Staphylococcus aureus (MRSA) emerged as an important human pathogen (1). Currently, MRSA is held responsible for numerous hospital-acquired infections worldwide, such as skin infections and toxic shock syndrome (2). MRSA also emerged as a community-acquired pathogen and in recent years has increasingly been isolated from livestock (3, 4). Livestock-associated MRSA (LA-MRSA) can be separated from other MRSA strains, as all strains belong to one multilocus sequence type (MLST) clonal complex. Since the first detection of LA-MRSA in 2003, it has been found in many countries worldwide (5-7). In the Netherlands, LA-MRSA has become quite prominent, making up approximately 40% of all MRSA strains isolated from humans that were sent to the National Institute for Public Health and the Environment (RIVM) for molecular typing as part of the Dutch national MRSA surveillance.From 2002 to 2007, all Dutch MRSA isolates were typed with pulsed-field gel electrophoresis (PFGE) using SmaI, but because of its labor-intensive character and the subjectivity involved in interpretation, this method was replaced by spa typing in 2007 (8, 9). In addition, multilocus variable-number tandem-repeat analysis (MLVA) was introduced for S. aureus in 2008 (10-12), and since then all isolates have been characterized by MLVA and spa typing.Although spa and MLVA typing are very well suited for characterizing most MRSA isolates, they provide very low discriminatory power for isolates belonging to MLVA complex 398 (MC398) (10, 13). The limited differentiation of MC398 isolates, representing LA-MRSA, has impeded investigations on transmission events and possible outbreaks caused by LA-MRSA.Transmission of LA-MRSA has been described in multiple reports, suggesting that human-to-human transmission of LA-MRSA is less likely to occur than that of other MRSA lineages (14,15). However, these reports describe the transmission of the MC398 (or CC398) clade based on epidemiology and limited molecular characterization of isolates, making it difficult to interpret if actual transmission events with LA-MRSA did occur.Recently, a new high-resolution typing technique for LA-MRSA was introduced named whole-genome mapping (13). Using this method, epidemiologically unrelated LA-MRSA isolates that were previously indistinguishable by spa and MLVA typing can now be differentiated. Furthermore, the method is able to identify transmission events between livestock veterinarians and their household, showing its potential as a typing tool for LA-MRSA.In the study presented here, we further investigated the potential of whole-genome mapping to identify possible transmission of

Livestock-associated strains of methicillin resistant Staphylococcus aureus (LA-MRSA) – the current state of knowledge

“…W badaniach podjętych na szeroką skalę w Niemczech potwierdzono występowanie LA-MRSA CC398 u 86% hodowców świń oraz 45% lekarzy weterynarii oraz, odpowiednio, u 4,3% oraz 9% członków ich rodzin nie mających kontaktów ze zwierzętami (20). Podobieństwo genetyczne szczepów izolowanych od osób zatrudnionych przy hodowli zwierząt oraz szczepów izolowanych od członków ich rodzin potwierdza transmisję LA--MRSA z człowieka na człowieka, jednak zachodzi ona znacznie rzadziej niż między zwierzętami i ludź-mi (9). Ustalono również, że jednorazowy pobyt na fermie świń może skutkować nosicielstwem, lecz jest ono krótkotrwałe i na ogół zanika po 24 godzinach (13).…”

“…Tak więc utrzymywanie się kolonizacji u ludzi jest związane z powtarzalnością kontaktów ze zwierzęta-mi (15,23). Trwały charakter nosicielstwa szczepów LA-MRSA u osób z grup ryzyka stwarza możliwość dalszej transmisji gronkowców na pozostałą część społeczeństwa (9,42).…”

“…Transmisja szczepów LA-MRSA w obrębie osób nie mających kontaktów ze zwierzętami gospodarskimi może również zachodzić za pośrednictwem mięsa i innych produktów żywnościowych pochodzenia zwierzęcego (9,42,52). Tezę tę potwierdza izolacja szczepów S. aureus CC398 z mięsa.…”

Dissemination of Resistance and Virulence Determinants in Methicillin-Resistant Staphylococcus aureus During Colonization and Disease: A Review

“…Methicillin-resistant S. aureus is a major cause of severe life-threatening infection in animals (Bosch et al, 2015;El-Gendy et al, 2017). The economic implication of disease caused by MRSA is hinged on its ability to rapidly acquire resistance and virulence determinants, cost of treatment, prevention and control and production of antibiotics (Bitrus et al, 2016).…”

Whole-Genome Mapping as a Novel High-Resolution Typing Tool for Legionella pneumophila

“…WGM uses high-resolution, ordered, whole-genome restriction maps for comparative analysis. In a recent study, WGM successfully discriminated between isolates belonging to livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) and identified the transmission and persistence of this genetically homogeneous MRSA variant, where current typing techniques failed (17). Although WGM has been very successful for LA-MRSA, the number of reports in which WGM was applied for molecular typing of other bacterial pathogens is very limited (18,19).…”