Office laboratory diagnosis of skin and soft tissue infections

Some skin and soft tissue infections can be treated empirically without culturing. Some infectious sites should be cultured before initiating antimicrobial therapy. When there is a choice, permissive swab specimens are never as good as nonpermissive aspirate specimens. Swab specimens should be cultured semiquantitatively on agar media only in an attempt to distinguish normal flora contaminants from the infecting pathogen. Needle aspirate specimens can be obtained at most infectious sites invoking Sutton's law ("Go where the money is.") to identify the point of maximal involvement. Office laboratory identification in general should be limited to the identification of yeast forms on Gram stain and the initial separation of Group A streptococci from staphylococci. Other organisms should be sent to a referral laboratory for further identification and susceptibility testing.