MRSA: The Small Print

A reader writes:

Interesting that you mentioned the MRSA article from Annals of Internal Medicine, but I'm surprised that you didn't note the limitations of this study. The Annals editors wrote in their summary

“The data were passively reported or retrospectively collected and are therefore subject to bias.”

They went on:

"Our study has limitations...

Our incidence estimates for San Francisco come from a passive surveillance system and may underestimate the incidence of true infection. We relied on retrospective chart review for identification of risk factors for multidrug-resistant USA300 infection in the 2 clinic populations; because data were not collected or documented systematically, our estimates of risk may be influenced by selection, referral, documentation, or other biases. Specific sexual behaviors were not assessed or documented in clinic charts; we therefore cannot comment on the association between multidrug-resistant USA300 infection and specific male–male sexual practices."

MRSA has been around a long time, and as a practicing Navy physician I have seen outbreaks in millitary populations for years.  A 2005 study by the Navy Environmental Health Center that did not make any headlines showed that community acquired MRSA was present in 3-5 % of Navy recruits.  There have been significant outbreaks in the SEAL training school in San Diego, as well as the Marine Recruit Training Depot, but this has not made the news.  MRSA has also been a problem for years in hospitals and nursing homes.  Now that someone has found a community outbreak in a gay population, it's "big" news ... bullshit.