HA-MRSA

HA-MRSA is the acronym for "hospital-acquired" MRSA, i.e. MRSA associated with healthcare facilities. Until the end of the 1990s, MRSA were almost exclusively considered to be hospital-associated problem germs (Layer et al. 2012). Within HA-MRSA, several clonal lineages can be identified. However, with regard to data from 2005 to 2011, two clonal lineages can be considered dominant. Currently, the clonal lines ST22-MRSA IV (also called "Barnim epidemic strain") and ST5/ST225-MRSA II (also called "Rhine-Hesse epidemic strain") are the most widespread and common in German hospitals. They both show a much narrower resistance spectrum compared to older epidemic MRSA.

The general occurrence of HA-MRSA is seen in connection with certain risk factors that can be associated with hospital treatment. HA-MRSA are responsible for a wide range of serious illnesses in patients. It ranges from osteomyelitis, intra-abdominal infections/inflammation to severe wound infections, pneumonia and bacteremia (Haddadin et al. 2002). However, skin/soft tissue infections in particular are associated with MRSA. Hospital-acquired MRSA infections are considered to be one of the main causes of death and illness (Klein et al. 2007). In German hospitals, surgical wound infections, septicaemia, pneumonia and more recently a trend towards urinary tract infections are clearly in the foreground (Layer et al., 2012). High risk groups within the hospital are considered to be immunosuppressed, elderly, intensive care patients and patients who are on strong antibiotic treatment, as well as patients in contact with MRSA positive individuals (Haddadin et al 2002). Due to the enormous health risks and the difficulty in controlling infections, patient screening for MRSA in conjunction with decolonisation therapy for MRSA-positive patients has become established in many hospitals. The antibiotic mupirocin is used for nasal decolonization; it is considered an effective means of combating nasal carriers of S. aureus. When mupirocin is used, a success rate of treatment of MRSA is observed in 90% of cases and within the first week of treatment. Mupirocin treatment is therefore considered the most successful decolonization option (Ammerlaan et al. 2009).

Within hospitals, the spread of HA-MRSA via nursing staff, medical students and physicians themselves is problematic, as they could act as reservoirs (Lopez-Aguilera et al. 2013). Various studies show the relatively high rate of colonization by S. aureus in general and hereunder the occurrence of MRSA among medical professionals (Lopez-Aguilera et al. 2013). Within the group of healthcare professionals, nurses stood out with the highest MRSA colonization rate (ElieTurenne et al., 2010).

The spread of MRSA in particular has long been associated with spread via pathogen-ridden hands of nurses (Thompson et al. 1982). Worryingly, in the United States, there are concerns of increased displacement and coexistence of HA-MRSA within hospitals by and with CA-MRSA (Kouyos et al. 2013).

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