RECOGNITION OF A NOCARDIA-TRANSVALENSIS COMPLEX BY RESISTANCE TO AMINOGLYCOSIDES, INCLUDING AMIKACIN, AND PCR-RESTRICTION FRAGMENT LENGTH POLYMORPHISM ANALYSIS

Amikacin resistance, rare among nocardiae, was observed in 58 clinical isolates of nocardiae, All of these isolates hydrolyzed hypoxanthine, and 75 to 100% utilized citrate, D-galactose, and D-trehalose as sole carbon sources. Based on utilization of I-erythritol, D-glucitol, i-m yo-inositol, D-mannitol, and ribitol and susceptibility to amoxicillin -clavulanic acid, the 58 isolates were separable into four groups. One group was negative for I-erythritol and ribitol and included all the isolates belonging to Nocardia asteroides complex antibiogram type IV. The remaining three groups were positive for I-erythritol and ribitol and were grouped within Nocardia transvalensis. The group that includ ed the type strain was designated N. transvalensis sensu stricto, and the other two groups were designated new taxons 1 and 2, PCR-restricti on fragment length polymorphism (RFLP) analysis of a 439-bp segment of the 65-kDa heat shock protein gene with XhoI and HinfI produced ident ical patterns for 53 (91%) and 58 (100%) isolates, respectively, and d ifferentiated them from all other Nocardia taxa, NarI- and HaeIII-deri ved RFLP patterns clearly differentiated each of the four biochemicall y defined taxa, These four groups were also distinguishable by using t he chromogenic substrates in Dade MicroScan test panels, By high-perfo rmance liquid chromatography, these isolates exhibited the same unique mycolic acid-ester elution patterns that differed from those of all o ther clinically significant nocardiae. Gas-liquid chromatographic anal ysis of fatty acids also produced similar patterns for all isolates th at distinguished them from all other Nocardia taxa, but did not differ entiate the four taxa within the complex, We propose the designation N , transvalensis complex for these four groups of nocardiae, pending fu rther genetic evaluation.