Nocardia cyriacigeorgica--an established rather than an emerging pathogen.

In their recent report, Schlaberg et al. declare Nocardia cyriacigeorgica to be an “emerging pathogen” (3). However, no evidence is provided to support this claim. They refer to the review by Millar and Moore (2) for a definition of “an emerging pathogenic entity” but do not specify into which of the categories of emerging and reemerging pathogens distinguished by these authors they would place N. cyriacigeorgica. The only possibly applicable category would seem to be that of “an increase in reporting of novel pathogens as a result of improved identification and diagnosis such as those based on molecular techniques.” The key word here, however, is “novel,” and in a recent report also cited by Schlaberg et al., organisms previously described as members of Nocardia asteroides drug pattern VI were demonstrated by DNA-DNA hybridization to belong to the species N. cyriacigeorgica (1). In that publication, it was explicitly stated that N. cyriacigeorgica “is not a ‘new’ organism or an ‘emerging’ pathogen; rather, it is a newly named but longrecognized agent of human disease.” In the initial report describing six different “drug patterns” of N. asteroides (plus an additional “miscellaneous” group which included the N. asteroides type strain [ATCC 19247]) (4), N. asteroides drug pattern type VI was recognized as the most common of the clinical nocardial isolates studied. Therefore, N. cyriacigeorgica is not “novel” and we are not aware of any data suggesting that its incidence is increasing. Schlaberg et al. introduce additional confusion by referring to the “N. asteroides drug pattern VI type strain ATCC 14759.” This strain should be referred to as a “reference strain,” not a type strain. Type strains can only be designated for species named and described according to the accepted nomenclatural rules, and “N. asteroides drug pattern type VI” is not such a name. The type strain for the species to which the organism “N. asteroides drug pattern type VI” belongs is N. cyriacigeorgica DSM 44484. Our concerns may seem trivial to many. But the taxonomy of the genus Nocardia (and indeed of numerous other bacterial genera) is becoming increasingly complex as more and more species are delineated, often by dividing a previously recognized species into two or more species. Increasing diligence is thus required to assure that whatever clinically or otherwise useful information has been accumulated continues to be associated with the appropriate taxonomic entity.