Multiple biotypes of Klebsiella pneumoniae in single clinical specimens

The occurence of multiple biotypes of Klebsiella pneumoniae within single specimens was determined in 59 clinical specimens. Biotyping was performed on five colonies of K. pneumoniae from each specimen, using the API 20E system (Analytab, Inc., New York) for identification of Enterobacteriaceae with strict adherence to the manufacturer's instructions. Multiple biotypes of K. pneumoniae were present in 31% (18) of the clinical specimens. Twenty-eight colonies representative of specimens with single and multiple biotypes were tested further for biotype reproducibility. Whereas genus and species identification was 100% reproducible, variation of one or more biochemical tests on serial transfers resulted in biotype reproducibility of only 64%. The greatest variation in biochemical tests occurred with urease (14%), indole production (10%) and citrate utilization (9%). Multiple biotypes in single specimens appear to be due to both inherent differences among the colonies in the specimen and variability in the system used to determine biochemical reactions. The presence of multiple biotypes limits the usefulness of biochemical typing for epidemiological surveilance of K. pneumoniae.