Final answer:
The most suitable skin preparations for blood cultures are povidone iodine and 70% ethyl alcohol, as they are both effective antiseptics. Povidone iodine is a stable iodophor commonly used for pre-surgical skin antisepsis. 70% ethyl alcohol is preferred over higher concentrations for its efficacy in denaturing proteins and membrane disruption.
Step-by-step explanation:
The appropriate skin preparation for blood cultures involves using an antiseptic that is effective at inhibiting microbial growth without being too harsh on the skin. Among the options provided, c) with povidone iodine is a suitable choice for skin antisepsis before blood culture collection. Povidone-iodine is a type of iodophor, which is a compound of iodine complexed with an organic molecule that releases iodine relatively slowly and increases its stability and efficacy. Betadine, a common brand of povidone-iodine, is widely used for topical antisepsis on a patient's skin before surgical incisions.
Alcohols such as ethanol and isopropyl alcohol are also commonly used as antiseptics and disinfectants due to their ability to denature proteins and disrupt microbial cell membranes. Ethanol is usually used in a 70% concentration for skin antisepsis because it is more effective in aqueous solutions than at 100%, as the water content allows for better penetration and denaturation of proteins. Therefore, a) 70% ethyl alcohol is also an appropriate skin antiseptic for drawing blood cultures.