Final answer:
To eliminate contaminating bacteria at the venipuncture site for a blood culture, chlorhexidine is typically used as an antiseptic. In a related case study, failure of initial therapy was possibly due to the intravenous catheter serving as a reservoir for bacteria, which was resolved after its removal and administration of oral antibiotics.
Step-by-step explanation:
When a blood culture is ordered, the venipuncture site should be cleaned with an antiseptic to eliminate contaminating bacteria. Chlorhexidine is commonly used for this purpose and has broad-spectrum antimicrobial activity, making it an effective choice for disinfecting skin. Isopropyl alcohol may also be used, either alone or in combination with chlorhexidine, to disinfect the area. Sterile water and hydrogen peroxide are not typically used as skin antiseptics in this context, since they do not have the same level of antimicrobial efficacy.
Regarding the control of microbial growth, B is the correct answer; an antiseptic is suitable for use on tissues for microbial control to prevent infection. Disinfectants are used on non-living surfaces and sterilants are used for a complete elimination of all forms of microbial life, which is more aggressive than what is needed for skin preparation.
In the case study provided, one reason for the failure of the initial antibacterial chemotherapy could be that the intravenous catheter served as a biofilm for S. epidermidis, shielding the bacteria from the effects of the drug. An oral antibiotic regimen eventually succeeded because it likely achieved wider distribution and could address any residual bacteria after the catheter, a potential source of reinfection, was removed. This case emphasizes the importance of catheter care and prompts an evaluation of when to replace or remove an intravenous catheter as a method to prevent recurrent infections.