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Ultrasonographically guided needle aspiration -- a minimally invasive treatment for uncomplicated superficial skin abscesses -- has a failure rate of almost three in four, researchers reported.

In a randomized trial of 101 patients, an older method of treating abscesses -- incision and drainage -- had only one in five treatment failures, according to Romolo Gaspari, MD, PhD, of the University of Massachusetts Memorial Medical Center in Worcester, Mass., and colleagues.

Regardless of which treatment method was used, the presence of community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) reduced the success rate, Gaspari and colleagues reported online in Annals of Emergency Medicine.

Even in cases where CA-MRSA was involved, the failure rate of the needle aspiration procedure remained higher than that of incision and drainage, they reported.

While incision and drainage remains the treatment of choice for skin and soft tissue abscesses, some physicians have advocated needle aspiration as less invasive, causing less pain and scarring, and being more acceptable to patients, the researchers noted.

But the equivalence of the two procedures for uncomplicated superficial lesions has not been demonstrated, they noted.

To help clarify the issue, they conducted a nonblinded controlled trial, in which 54 emergency room patients at two academic centers were randomly assigned to incision and drainage and 47 to ultrasonographically guided needle aspiration.

The primary endpoint was treatment failure, during the procedure, two days later, or at seven days later. During the procedure, failure was defined as inability to drain the purulence -- later it was defined as residual abscess, continuing symptoms, or a need for a further intervention.

The initial hypothesis was that the two procedures would prove to have roughly identical results, Gaspari and colleagues reported, but instead the risk for needle aspiration proved "unacceptably high." Specifically:

• During the initial procedure, there were two failures in the incision group and 28 in the aspiration group, or 4% versus 60%.
• At day two, there were four failures in the incision group and three in the needle group.
• At day seven, there were four failures in the incision group and one failure in the needle group.
• Overall, the failure rate for incision and drainage was 20%, compared with 74% for needle aspiration. The difference between the groups was 54 percentage points.

S. aureus was isolated in 63% of the patients and 52% (or 33) had CA-MRSA -- with little difference between treatment groups.

Overall, the success of both methods was lower in patients with CA-MRSA than with other infections -- 8% versus 55% for needle aspiration, and 61% versus 89% for incision and drainage.

"We thought a less invasive method of treating abscesses would be preferable for both emergency physicians and patients," Gaspari said in a statement. "Even though it is more painful, we found instead that incision and drainage was required."

The study is one of two in the journal that suggest older methods might be more useful in dealing with MRSA.

The second study, led by Kalpana Gupta, MD, of the Boston Veterans Affairs Health Care System, and colleagues, examined the prevalence and predictors of S. aureus colonization.

The investigators performed active surveillance for methicillin-susceptible S aureus (MSSA) and MRSA colonization in 400 patients presenting at an urban emergency department, conducting culture testing on sites that included the anterior nares, oropharynx, palms, groin, perirectal area, wounds, and catheter insertion sites.

While the overall prevalence of MRSA in the study group was lower than that reported in other high-risk ambulatory care settings, the researchers found that that 80% of patients colonized with MRSA had the bacteria in a site other than the nose -- a key finding.

Only 45% of patients were colonized at an extra-nasal site, they added.

One implication is that -- since MRSA is spread by touch -- hand hygiene may be more important in controlling colonization than to focus on topical nasal antibiotics, Gupta and colleagues argued.

"It would be very costly to make testing of all emergency patients for MRSA standard practice, but very inexpensive to institute enhanced hand washing precautions," Gupta commented in a statement.