Effect of Ciprofloxacin on the Growth and Biofilm Formation Ability of Staphylococcus aureus

Abstract

Staphylococcus aureus is part of the normal bacterial flora of the skin, intestine and upper respiratory tract of both humans and animals and has the potential of causing staphylococcal infections if there is a breach in the hosts’ defense mechanism. These infections could range from mild superficial skin infections to more severe and even fatally invasive diseases such as sepsis and toxic shock syndrome. The infectivity of S. aureus is attributed to its ability to withstand extreme conditions and its possession of various virulence factors. The aim of this project was to study the effect of ciprofloxacin on the growth and biofilm forming ability of CM10 strain of Staphylococcus aureus using time kill study, resazurin and live/dead staining of biofilms and Real-time polymerase chain reaction. The identity of the given CM10 strain was confirmed when the result of the API-Staph was in total accordance with the results obtained from the colony morphology and phenotypic characterization tests (Coagulase/protein A, Gram, and Catalase tests). CM10 strain of S. aureus was not susceptible to 0.25mg/L of ciprofloxacin used for the time kill experiment but was susceptible to a minimum inhibitory concentration of 0.5mg/L. The difference between the ciprofloxacin treated biofilms of CM10 strain and the untreated biofilms was significant (P<0.05) showing that ciprofloxacin has an adverse effect on the cells in the biofilm. The results of this study provide an insight on the growth as well as the biofilm forming ability of CM10 strain of Staphylococcus aureus. Ciprofloxacin has been shown to be an effective antibacterial against this strain of S. aureus by its inhibitory effect on the growth as well as biofilm forming ability of this strain of S. aureus.  This information would assist in developing novel anti-biofilm therapies to help in the management of biofilm mediated infections thereby reducing the morbidity and mortality rate of staphylococcal infections.