Methicillin-Resistant Staphylococcus aureus (MRSA) Strain ST398 Is Present in Midwestern U.S. Swine and Swine Workers

Abstract

BackgroundRecent research has demonstrated that many swine and swine farmers in the Netherlands and Canada are colonized with MRSA. However, no studies to date have investigated carriage of MRSA among swine and swine farmers in the United States (U.S.).MethodsWe sampled the nares of 299 swine and 20 workers from two different production systems in Iowa and Illinois, comprising approximately 87,000 live animals. MRSA isolates were typed by pulsed field gel electrophoresis (PFGE) using SmaI and EagI restriction enzymes, and by multi locus sequence typing (MLST). PCR was used to determine SCCmec type and presence of the pvl gene.ResultsIn this pilot study, overall MRSA prevalence in swine was 49% (147/299) and 45% (9/20) in workers. The prevalence of MRSA carriage among production system A's swine varied by age, ranging from 36% (11/30) in adult swine to 100% (60/60) of animals aged 9 and 12 weeks. The prevalence among production system A's workers was 64% (9/14). MRSA was not isolated from production system B's swine or workers. Isolates examined were not typeable by PFGE when SmaI was used, but digestion with EagI revealed that the isolates were clonal and were not related to common human types in Iowa (USA100, USA300, and USA400). MLST documented that the isolates were ST398.ConclusionsThese results show that colonization of swine by MRSA was very common on one swine production system in the midwestern U.S., suggesting that agricultural animals could become an important reservoir for this bacterium. MRSA strain ST398 was the only strain documented on this farm. Further studies are examining carriage rates on additional farms.

Livestock-Associated MRSA and Its Current Evolution

“…Although ST398 is identified commonly in pigs and farming environments in North America [73,[92][93][94][125][126][127][128][129][130][131][132][133], there appears to be a greater diversity of molecular types found on North American farms compared with those in Europe, where ST398 remains the dominant or sole strain of MRSA identified. One study in Michigan found no ST398 present in the pigs sampled [134], whereas the bulk of studies have found a mix of Bhuman^types (such as ST8 and ST5) in conjunction with ST398.…”

Prevalence, risk factors and multidrug resistance profile of Staphylococcus aureus isolated from bovine mastitis in selected dairy farms in and around Asella town, Arsi Zone, South Eastern Ethiopia

“…Methicillin resistant S. aureus is emerging as a zoonotic and veterinary bacterial pathogen of public health importance (Smith et al, 2009;Springer et al, 2009). It is a zoonosis that has garnered the attention of scientists and the public in recent years.…”

L’histoire de Staphylococcus aureus ST398 : un paradigme médical du 21ème siècle

“…Plus de 50 % des souches sont de type SARM. Une enquête plus récente menée aux USA, en particulier dans l'Iowa et l'Illinois, principales régions américaines de production porcine, montre une prévalence de SARM de l'ordre de 49 % chez le porc, bien que variable avec l'âge, et de 45 % chez les porchers (Smith et al 2009). Le typage des souches par la technique MLST montre l'existence unique de ST398, en particulier chez ce type d'éleveur, alors que les types habituels observés chez les patients dans ce pays étaient USA100, USA300 et USA400.…”