From the Research
Yes, you should culture a blister on the legs with a foul odor, even in the absence of purulence, fever, or chills. The foul odor suggests bacterial colonization or infection, which requires identification for proper treatment. To obtain a culture, clean the area with sterile saline (not antiseptics which could affect results), carefully open the blister with a sterile needle or scalpel, and collect fluid or tissue from the base using a sterile swab. While awaiting culture results (typically 48-72 hours), consider starting empiric antibiotic therapy such as cephalexin 500mg four times daily or doxycycline 100mg twice daily for 7-10 days, especially if there are signs of surrounding erythema or if the patient has risk factors like diabetes or immunosuppression, as suggested by studies such as 1 and 2. The culture helps identify specific pathogens and their antibiotic sensitivities, allowing for targeted therapy if empiric treatment fails. Foul-smelling wounds often indicate anaerobic bacteria or mixed infections that may not be obvious from clinical appearance alone, and early intervention can prevent progression to more serious infections like cellulitis or sepsis. It's also important to note that, according to 3, the role of CA-MRSA in nonpurulent cellulitis is less clear, but empirical coverage of CA-MRSA may not be necessary when treating nonpurulent cellulitis. However, the most recent and highest quality study, 1, found that clindamycin or trimethoprim-sulfamethoxazole in conjunction with incision and drainage improves short-term outcomes in patients who have a simple abscess, which supports the decision to culture and potentially treat the blister. Key points to consider include:
- The importance of proper wound cleaning and culture technique to avoid contamination and ensure accurate results
- The potential for anaerobic or mixed infections in foul-smelling wounds
- The need for empiric antibiotic therapy in certain cases, such as signs of surrounding erythema or patient risk factors
- The importance of targeted therapy based on culture results to minimize unnecessary antibiotic use and reduce the risk of resistance.