LETTER
We read with great interest the recent publication of Tien and colleagues in which they describe the antimicrobial susceptibilities of a large number of Acinetobacter baumannii-Acinetobacter calcoaceticus strains isolated from a medical center in Taiwan (1). They suggested that antimicrobial susceptibility was negatively associated with virulent potential because more-susceptible strains were recovered from invasive infections (i.e., from sterile areas, such as the cerebrospinal fluid [CSF] or the bloodstream) than from noninvasive infections. The authors presented a rate of 7% of all-susceptibility strains from nonsterile areas, while this rate reached 35% for isolates from sterile areas. On the other hand, the percentage of all-resistant strains fell from 46% of isolates from nonsterile areas to 22% of isolates from sterile areas. This difference was shown to be statistically significant (P < 0.05).
Our question lies with the definition of “all-resistant” adopted by Tien and coworkers. As reported by those authors in the same report, the colistin resistance rate was 0%. How can they define their isolates as “all-resistant” if they did not find any strain resistant to colistin (colistin is included in the drugs evaluated in a footnote presented in their Table 1)?
Furthermore, having in mind the recently published consensus of resistance definitions (2), the strains categorized by Tien and colleagues as all-resistant should be categorized as extensively drug resistant (XDR). Finally, we believe that we have to pay attention to adopted definitions (in this case, perhaps a simple imprecision) used in the scientific literature in order to prevent future misunderstandings.
Footnotes
Ed. Note: The authors of the original article declined to respond.
REFERENCES
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