Researchers have gathered a decade’s worth of information

Scientists at the Dublin Dental University Hospital (DDUH) School of Dental Sciences have published findings that provide new intelligence on the pool of MRSA strains circulating in Irish hospitals over the last decade from which the next dominant MRSA hospital strains of the future may come.

Working in conjunction with the National MRSA Reference Laboratory (NMRSARL) at St. James’s Hospital and Alere Technologies, Germany, the DDUH researchers believe the information gathered will assist them in identifying emrging new MRSA strains at an early stage to give clinicians time to prepare to prevent the spread of the next dominant strain that arises.

The ST22-MRSA-IV strain has dominated in Irish hospitals since 2002 and since then has accounted for 70-80 per cent of life-threatening MRSA bloodstream infections each year. The pattern from the last 40 years suggests that the ST22-MRSA-IV strain may be replaced at any time by another strain which would then become the dominant strain in Irish hospitals.

However, little was known about the properties of other MRSA strains responsible for infections in Irish hospitals since the rise to predominance of the ST22 strain, making pre-planning and advance control measures very difficult.

The microbiologists from the Oral Biosciences Microbiology Unit in the Dublin Dental University Hospital and the School of Dental Science, Trinity studied a large sample of MRSA that occurred sporadically in patients with bloodstream infections in Irish hospitals between 2000-2012.

The researchers revealed that the sporadic MRSA consisted of a myriad of MRSA strains, numerous sub-types and variants. Many of the sporadic MRSA were more resistant to drugs and carried genes that made them particularly virulent and aided their spread between different MRSA samples, which in turn, created further new variants which are more difficult to treat effectively with antibiotics.

Commenting on the significance of the findings, corresponding author on the study, Professor David Coleman, professor and chair of oral and applied microbiology, said: “This study reveals the presence of a very large number of different MRSA strains in Irish hospitals that sporadically cause infection.

“Given the history of dominant MRSA strain replacement in Irish hospitals over the last 40 years, any one of these strains may become predominant. Understanding the detailed characteristics of the pool of sporadic MRSA present in Irish hospitals and ongoing surveillance will permit the early identification of emerging new MRSA strains so that appropriate control measures can be put in place to prevent their spread.”