Thursday, May 31, 2012

Antibiotics for MRSA abscesses? NO.


STUDY #1:
Schmitz et al. Randomized Controlled Trial of Trimethoprim-Sulfamethoxazole for Uncomplicated Skin Abscesses in Patients at Risk for Community-Associated Methicillin-Resistant Staphylococcus aureus Infection. Annals of Emergency Medicine, Vol 56, Sept 2010

Bactrim vs. placebo after incision and drainage.  

Multicenter, double-blind, RCT in 4 military ED's

outcome: treatment failure after 7 days or reduction of new lesion formation in 30 days

results:
                        Tx failure 7 days              New lesion within 30 days      
Placebo                     26%                                          28%
TMP/SMX                  17%                                           9%
Difference (95%CI)      9% (-2 to 21%)                         19% (4-34%)

As shown above, there was a significant difference of new lesions in 30 days.  only 45% were available at 30 days.  big confidence intervals.


STUDY #2
Duong et al. Randomized, Controlled Trial of Antibiotics in the Management of Community-Acquired Skin Abscesses in the Pediatric Patient. Annals of Emergency Medicine, Vol 55, May 2010

Bactrim vs. placebo after incision and drainage

double-bind RCT in pediatric patients

outcome: treatment failure within 10 days (need for second incision, IV antibiotics, continued erythema, warmth, fluctuance at 10 day follow up).

results:
              Failure to improve            10 day new lesions    90 day new lesions**
Placebo          5.3%                         26.4%                     28.8%
TMP/SMX       4.1%                         12.9%                     28.3%
** Note that only around 60% were effectively followed up at 90 days.

Conclusion: no difference in failure rates with or without antibiotics. 

Of note,  in treatment arm, only 46% of patients were compliant with antibiotics, taking at least half of the pills. 

Note that there are many other studies showing that antibiotic use does NOT eradicate MRSA.


BOTTOM LINE:
Immunocompetent patients with MRSA abscesses can be treated with I & D alone. Not enough data to support consistent antibiotic use. 

Consider addition of antibiotics in diabetics, immunocompromised, or systemically ill. 


Submitted by S. Morris.


Reference(s): study 1, study 2, picture

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