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An observational prospective study of topical acidified nitrite for killing methicillin-resistant Staphylococcus aureus (MRSA) in contaminated wounds

Anthony D Ormerod1*, Amjad AJ Shah2, Hong Li3, Nigel B Benjamin4, Gail P Ferguson1 and Carlo Leifert5

Author Affiliations

1 Division of Applied Medicine, University of Aberdeen, Polwarth Building, Foresterhill, Aberdeen, AB24 2ZD, UK

2 Royal Lancaster Infirmary, Ashton Road, Lancaster, LA1 4RP, UK

3 Centre For Ecology & Hydrology, Lancaster Environment Centre, Bailrigg, Lancaster, LA1 4AP, UK

4 Acute Medical Unit, Level 9, Derriford Hospital, Plymouth, PL6 8DH, UK

5 Newcastle University, Nafferton Farm, Stocksfield, Northumberland, NE43 7XD, UK

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BMC Research Notes 2011, 4:458  doi:10.1186/1756-0500-4-458

Published: 27 October 2011



Endogenous nitric oxide (NO) kills bacteria and other organisms as part of the innate immune response. When nitrite is exposed to low pH, NO is generated and has been used as an NO delivery system to treat skin infections. We demonstrated eradication of MRSA carriage from wounds using a topical formulation of citric acid (4.5%) and sodium nitrite (3%) creams co-applied for 5 days to 15 wounds in an observational prospective pilot study of 8 patients.


Following treatment with topical citric acid and sodium nitrite, 9 of 15 wounds (60%) and 3 of 8 patients (37%) were cleared of infection. MRSA isolates from these patients were all sensitive to acidified nitrite in vitro compared to methicillin-sensitive S. aureus and a reference strain of MRSA.


Nitric oxide and acidified nitrite offer a novel therapy for control of MRSA in wounds. Wounds that were not cleared of infection may have been re-contaminated or the bioavailability of acidified nitrite impaired by local factors in the tissue.