The Emergence ofStaphylococcus aureusST398

Abstract

The epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) has changed dramatically over the past 15 years. Initially a nosocomial pathogen, newly emergent strains of MRSA have become increasingly common in the community among individuals lacking contact with healthcare. More recently, a third group of MRSA strains have been identified in association with livestock, particularly swine. These strains, termed livestock-associated MRSA, have now been identified in Europe, North America, and Asia in humans and animals. One molecular type, ST398, has been the dominant strain of livestock-associated MRSA identified to date. The emergence of this strain in animals and humans will be described in this review, including colonization and clinical infections caused by this strain. We also discuss lingering research questions and implications for controlling spread of this bacterium in an agricultural environment and beyond.

Methicillin-Resistant Staphylococcus aureus (MRSA) in Food- Producing and Companion Animals and Food Products

“…In an interesting report from the Netherlands, it was shown that farm visitors were positive for CC398 MRSA directly after a farm visit but tested MRSA negative after 24 h [19,41]. These and other studies indicate that CC398 appears to be frequently shared between animals and humans and is capable of causing infections in both species [25,70,164]. Transmission of MRSA between animals and humans is not new, but the MRSA isolates, in most cases, represent an initial human-to-animal transmission [24,49,165,166].…”

“…The emergence of LA-MRSA strains in humans [16,17,25,56] and the presence of an identical MRSA CC398 in pigs, farm workers, veterinarians who atended to the same pig farms and their nonexposed family members [47,48] suggests animal-to-human or human-to-animal transmission. In an interesting report from the Netherlands, it was shown that farm visitors were positive for CC398 MRSA directly after a farm visit but tested MRSA negative after 24 h [19,41].…”

“…An examination of livestock-associated MRSA (LA-MRSA) in human case isolates in the Netherlands indicated an increase from 0% in 2002 to greater than 21% in mid-2006 [23] and 35% in 2009 [24]. In most European countries, CC398 remains the most commonly identiied type of LA-MRSA [15,[25][26][27]. However, the epidemiology of LA-MRSA difers in other geographic areas.…”

“…In Belgium and Denmark, the prevalence of MRSA in veterinarians was 9.5% and 1.4%, respectively [47]. German researchers reported that MRSA ST398 that carried SCCmec IV or V, accessory gene regulator type I and capsule type 5 [25] in pig primary production herds was higher in their country (45-70%) than in the rest of the European Union [45,46]. In an interesting report, 12.5% of atendees at an international meeting concerning pig health carried MRSA and 91.2% (31/34) of them CC398 [50].…”

Comparative studies on the antibacterial activities of leaf extracts of Azadirachta indica and Psidium guajava and antibiotics on methicillin and vancomycin resistant Staphylococcus aureus

“…6 Over the last few decades, the number and proportion of vancomycin-resistant S. aureus (VRSA) and methicillin-resistant S. aureus (MRSA) infections in different countries has increased. 7,8 Several studies have shown that MRSA strains are highly resistant to antibiotics. [9][10][11] Despite the discovery of new drugs for the treatment of infections caused by VSRA and MRSA, outbreaks of MRSA/VRSA infections often appear in hospitals, clinics, nursing and elderly homes.…”