The susceptibility of clinical isolates of 'Staphylococcus aureus' to chemical killing in vitro

Badyal, Rashpal Kaur (2006) The susceptibility of clinical isolates of 'Staphylococcus aureus' to chemical killing in vitro. (MSc(R) thesis), Kingston University, .


'Staphylococcus aureus' is one of the major causes of morbidity and mortality in the population; this organism causes numerous nosocomial infections leading to complications such as bacteraemia, acute endocarditis and may result in death. This situation remains one of the major challenges facing infection control teams and physicians alike. Nosocomial infections are a problem worldwide with a fifth of nosocomial infections in the UK caused by MRSA. As a consequence the control of MRS A infections are a priority. Effective decontamination procedures are necessary. It is important to clean, disinfect or sterilize medical devices as microorganisms can spread directly or indirectly within healthcare services. Bacterial antibiotic resistance is a long established problem; however, as a result of microbial contamination and infection, this has led to an increased use of disinfectants and antiseptics. Consequently, resistance to some disinfectants has been reported. The efficacies of Virkon, Hycolin and Hibiserub were tested using dilution suspension tests against a range of MRS A and MSSA clinical isolates from Malta and the UK at recommended concentrations, half and double the recommended concentrations. The most efficient disinfectants appeared to be Virkon and Hycolin. However, Hycolin was less effective compared to Virkon, and the least effective disinfectant was Hibiscrub, which produced inadequate inhibition of growth. The second part of the study mimicked surfaces found in the clinical environment; Hibiserub was not used, as it is a hand disinfectant. The remaining disinfectants, Virkon and Hycolin were highly effective in inhibiting the growth of the isolates tested. Both disinfectants were tested in Ringers solution and serum. Virkon completely inhibited bacterial growth at the recommended concentration (1 %). Hycolin (2 %) however, did not, but the growth observed was minimal. In conclusion, 1 % Virkon is effective in eradicating both MRSA and MSSA. Hycolin is also effective, but at a less extent, and Hibiserub displayed variable results against the tested isolates. However, further work is required to give more conclusive data. More strains would need to be assessed in order to find clear trends and patterns between strains of different countries and strains of different antibiotic resistance.

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