Drug choices and dosing may be determined by the characteristics of the SSTI and the pharmacokinetics of the drug. Once-daily dosing may be common for aminoglycosides, which appear to have a prolonged effect on bacterial growth during post-treatment phases and are concentration-dependent in their bacteriocidal effect. Beta-lactam antimicrobials (such as the penicillins, cephalosporins, or carbapenems), on the other hand, have a shorter term post-treatment effect and are time-dependent, making them more appropriate for continuous infusion. In some cases, beta-lactam drugs may have very short half-lives and can deteriorate quickly at body temperature, which requires daily mixing and frequent administration. Cephalosporins, such as ceftriaxone, have longer half lives and can be administered once daily.

Vancomycin is commonly used for cases of penicillin- or cephalosporin-resistant CSSTIs. With continued use there is some concern for additional resistance to vancomycin, requiring alternate drug choices. Several studies have compared this routine intravenous treatment with vancomycin to linezolid. Test-of-cure outcomes appeared to be superior in the linezolid-treated patients (89% cured) compared to vancomycin (67% cured) and linezolid was well-tolerated (Weigelt J et al. 2005). This result was later challenged by others who suggested that the evaluation should have included information on which patients had vancomycin-resistant infections (Howdenet al. 2005). In this case, patients with vancomycin-resistant infections would have been expected to have a less effective response to vancomycin. Thus, the results might have been reported as the importance of determination of vancomycin-resistance rather than an even comparison of vancomycin to linezolid. Additional research will be required to sort out the comparison of vancomycin to linezaolid treatment. Clinicians should be aware of case reports of serotonin toxicity associated with linezolid that suggest, while it may be rare, it will be important to closely monitor patients on serotonergic drugs that are administered at higher doses (Bergeron, Boule, & Perreault 2005). 

Both the medication and the duration of therapy have been investigated for some treatments. Short-course and longer-course antibiotic regimens have been compared in the treatment of cellulitis. In a group of 87 patients randomized to receive either 10 days of levofloxacin therapy or 5 days of therapy and 5 days of placebo, both groups achieved a 98% cure rate (Hepburn et al. 2004). In addition, there were no significant differences at day 14 and 28, suggesting that a shorter course of therapy may be as effective in cases of uncomplicated cellulitis. Complete and successful treatment is important for both the prevention of resistant strains and recurrence of infection. Repeated infections can lead to more serious effects, such as lymphadenopathy and additional tissue damage. Recommended in cases of recurrent infections, prophylactic use of antibiotics in such cases has had mixed results (Kremer et al. 1991; Wang et al. 1997).

Choice of drug regimens is driven by the susceptibility of the pathogen, history of allergic reactions to therapies, potential for other adverse events, and factors related to the ease of use by caregivers and patients in the homecare setting. Table 2 shows a listing of selected intravenous antimicrobial medications.