Figure 19-3 A, Rothia dentocariosa from broth. B, R. dentocariosa from solid media. (Courtesy Deanna Kiska, SUNY Upstate Medical University, Syracuse, NY.)
the body. Thus, only clinically relevant isolates should be identified fully. Indicators of clinical relevance include isolation from normally sterile sites or multiple blood culture bottles, isolation in pure culture or as the predominant organism from symptomatic patients who have not yielded any other known etiologic agent, and isolation from urine if present as a pure culture at greater than 10* cfu/mL or the predominant organism at greater than 105 cfu/mL. Coryneforms are more likely to be the cause of a urinary tract infection if the pH of the urine is alkaline or there are struvite crystals in the sediment.
The API Coryne strip (bioMerieux, Inc., St. Louis, Mo) and the RapID CB Plus (Remel, Inc., Lenexa, Kan) are commercial products available for rapid identification of this group of organisms; however, the databases may not be current with recent taxonomic changes. Therefore, misidentifications can occur if the code generated using these kits is the exclusive criteria used for identification.
Table 19-4 shows the key tests needed to separate the genera discussed in this chapter. In addition to the features shown, the Gram stain and colonial morphology should be carefully noted.
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