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The drug-resistant bacÂteÂria known as MRSA, once conÂfined to hosÂpiÂtals but now wideÂspread in comÂmuÂniÂties, will likely conÂtinue to exist in both setÂtings as sepÂaÂrate strains, accordÂing to a new study.
The preÂdicÂtion that both strains will coexÂist is reasÂsurÂing because preÂviÂous proÂjecÂtions indiÂcated that the more invaÂsive and fast-growing comÂmuÂnity strains would overÂtake and elimÂiÂnate hosÂpiÂtal strains, posÂsiÂbly posÂing a threat to pubÂlic health.
Researchers at PrinceÂton UniÂverÂsity used mathÂeÂmatÂiÂcal modÂels to explore what will hapÂpen to comÂmuÂnity and hosÂpiÂtal MRSA strains, which difÂfer genetÂiÂcally.Â OrigÂiÂnally methicillin-resistant StaphyÂloÂcocÂcus aureus (MRSA)Â was conÂfined to hosÂpiÂtals. HowÂever, community-associated strains emerged in the past decade and can spread widely from perÂson to perÂson in schools, athÂletic facilÂiÂties and homes.
Both comÂmuÂnity and hosÂpiÂtal strains cause disÂeases rangÂing from skin and soft-tissue infecÂtions to pneuÂmoÂnia and sepÂticemia. HosÂpiÂtal MRSA is resisÂtant to numerÂous antibiÂotics and is very difÂfiÂcult to treat, while comÂmuÂnity MRSA is resisÂtant to fewer antibiotics.
The new study found that these difÂferÂences in antibiÂotic resisÂtance, comÂbined with more aggresÂsive antibiÂotic usage patÂterns in hosÂpiÂtals verÂsus the comÂmuÂnity setÂting, over time will perÂmit hosÂpiÂtal strains to surÂvive despite the comÂpeÂtiÂtion from comÂmuÂnity strains. Hospital-based antibiÂotic usage is likely to sucÂcessÂfully treat patients infected with comÂmuÂnity strains, preÂventÂing the newÂcomer strains from spreadÂing to new patients and gainÂing the foothold they need to out-compete the hosÂpiÂtal strains.
The researchers made their preÂdicÂtions by using mathÂeÂmatÂiÂcal modÂels of MRSA transÂmisÂsion that take into account data on drug-usage, resisÂtance proÂfiles, person-to-person conÂtact, and patient age.
PubÂlished FebÂ. 28 in the jourÂnal PLOS Pathogens, the study was conÂducted by postÂdocÂtoral researcher Roger Kouyos, now a scholar at the UniÂverÂsity of Zurich, and Eili Klein, a gradÂuÂate stuÂdent who is now an assisÂtant proÂfesÂsor in the Johns HopÂkins School of MedÂiÂcine. They conÂducted the work under the adviseÂment of Bryan GrenÂfell, Princetons Kathryn Briger and Sarah FenÂton ProÂfesÂsor of EcolÂogy and EvoÂluÂtionÂary BiolÂogy and PubÂlic Affairs at Princetons Woodrow WilÂson School of InterÂnaÂtional and PubÂlic Affairs.
Reference: Kouyos R., Klein E. & GrenÂfell B. (2013). Hospital-Community InterÂacÂtions FosÂter CoexÂisÂtence between Methicillin-Resistant Strains of StaphyÂloÂcocÂcus aureus. PLoS Pathogens, 9 (2) e1003134. PMID: 23468619
Source: Princeton University