Evaluation of Optimal Treatment Strategy of Skin and Soft Tissue Infections with Uncomplicated Methicillin-Resistant Staphylococcal Aureus Bacteremia

Background:

Skin and soft tissue infections (SSTI) are amongst the most common causes of uncomplicated methicillin-resistant Staphylococcal aureus bacteremia (UMRSAB), with significant economical and clinical implications. There is limited clinical data to suggest optimal treatment duration and use of oral antibiotics in the management of UMRSAB due to SSTI, after appropriate surgical intervention and initial intravenous (IV) therapy. Current recommendations from IDSA suggest 14 days of IV antibiotics.

Methods:

This was a retrospective cohort study conducted in an integrated 4-hospital health system in Southeast Michigan from 2005 - 2015. Data was collected via electronic medical record. Patients were considered to have UMRSAB if they met the following criteria: absence of a positive follow up blood cultures 72 hours after the initial set, absence of endocarditis, osteomyelitis, metastatic site infection, prosthetic implants and grafts. Group I included patients treated for < 14 days and group II included patients treated for ≥14 days. Both groups received IV therapy with and without oral antibiotics. Univariate two-group comparisons were done using chi-square test or Fisher’s exact test. All analyses were performed using SAS 9.4. (SAS Institute Inc, Cary, NC, USA).

Results:

From the database 115 patients with UMRSAB secondary to SSTI were identified. Group I had 33 (29%) patients and group 2 had 82 (71%) patients. The mean age was 55.0 +17.0 years. The two treatment groups had similar baseline comorbidities. Both groups that were treated with IV antibiotics only, had higher 30 days recurrence, though statistically non-significant.

Conclusion:

For treatment of SSTI with UMRSAB, consideration of oral antibiotics following source control and initial IV therapy can be an appropriate antimicrobial stewardship strategy. This study did not show worse outcomes in patients treated with sequential oral antibiotics compared to patients treated with IV antibiotics only. Further, prospective multicenter trials are needed to evaluate optimal treatment strategy.

Table 1:Univariate two-group comparisons

Group I: < 14 days	n= 33	30 days Recurrence	30 days Mortality	60 days Mortality
IV only	21	2 (9.5%)	0	0
IV + oral	12	0	0	0
p value		0.53	N/A	N/A
Group II: ≥ 14days	n= 82
IV only	63	5 (8%)	0	1 (1.5%)
IV + oral	19	1 (5%)	1 (5%)	1 (5%)
p value		1.00	0.232	0.412