CA-MRSA

CA-MRSA is the acronym for "community-associated" MRSA or also "community-adapted" MRSA or "community-acquired" MRSA. CA-MRSA are to be distinguished from HA-MRSA (Hospital-acquired MRSA) and lead to infections within a group of people who are not in direct contact with healthcare facilities (e.g. hospitals). CA-MRSA have a different genetic background than HA-MRSA (Chambers et al 2009). In addition, CA-MRSA have different resistance profiles to antibiotic substances compared to HA-MRSA.

Furthermore, there are striking differences with regard to virulence characteristics. CA-MRSA often have different exotoxin profiles, such as the frequent occurrence of PVL compared to HA-MRSA (Otter et al. 2010). Other characteristics that distinguish CA-MRSA from HA-MRSA are increased transmissibility and increased virulence.

CA-MRSA infections manifest as soft tissue and skin infections as well as abscesses, endocarditis, sepsis, osteomyelitis, pulmonary embolism and necrotizing pneumonia (Linde 2008). The capacity for very rapid transmission between primarily healthy individuals is problematic (Chambers and Deleo, 2009).

The occurrence and infections associated with CA-MRSA are reported worldwide. CA-MRSA are increasingly gaining the status of a significant pathogen within society. In the past, army recruits and contact athletes, for example, were considered to be particularly affected (Cohen 2005).

Theprevalence of CA-MRSA seems to have increased significantly over the last decade (Kouyos et al. 2013). According to an American study, the proportion of CA-MRSA within the emergence of MRSA isolates in general increased from 8.7% (43 of 507 MRSA cultures) in 1996 to 39.6% (672 of 1697 MRSA cultures) in 2005 (McMullen et al. 2009). In a comparison between CA-MRSA emergence and HA-MRSA emergence in 1100 MRSA infections, CA-MRSA was detectable in 12% (n=131) of isolates investigated. They were disproportionately (75 %) associated with skin/soft tissue infections. In Europe, the incidence of CA-MRSA has so far been considered low compared to the USA. Thus, ST80-MRSA IV dominates in the EU, whereas ST8- MRSA IV ("USA300") is widespread in the USA (Otter and French 2010).

Although CA-MRSA is differentiated from HA-MRSA, CA-MRSA is also increasingly found in hospitals. As early as 10 years ago, CA-MRSA accounted for over 30% to as much as 40% of total MRSA within numerous hospitals (Salgado et al. 2003). These relatively high detection rates are also supported by comparative studies between HA-MRSA and CA-MRSA and their occurrence in hospitals (Huang et al. 2006). It is currently being discussed whether a coexistence or even an extensive exchange of HA-MRSA and CA-MRSA takes place in hospitals and what consequences this could have (Kouyos et al. 2013).

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