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Roseomonas is a recently described genus of gram-negative coccobacilli formerly designated as "pink-coccoid" groups I through IV by the Centers for Disease Control and Prevention (Atlanta, Ga) because of the organism's characteristic pink colonies. Since 1991 we have isolated Roseomonas from eight patients; in seven from blood cultures and in one from a skin lesion. The seven blood isolates were from patients with clinically significant underlying diseases who had central venous catheters in place; the majority were associated with polymicrobial catheter infections. Additional characteristics of their infections are described. The eight isolates had originally been identified by us as CentersRoseomonas is a recently described genus of gram-negative coccobacilli 1 that had previously been designated as "pink-coccoid" groups I through IV 2 by the Special Bacteriology Reference Laboratory of the Centers for Disease Control and Prevention (CDC, Atlanta, Ga). On the basis of biochemical reactions and DNA relatedness of 42 pink coccoid isolates, Rihs et al 1 proposed that the genus Roseomonas should contain six new species: Roseomonas gilardii, Roseomonas cervicalis, Roseomonas fauriae, and unnamed genomospecies 4, 5, and 6. The strains they examined included 6 strains each of CDC-designated pink-coccoid groups I, II, III, and IV, along with a variety of other isolates. In this collection of 42 strains R gilardii turned out to be the most common isolate (23 of the 42). for Disease Control (CDC) pink-coccoid group III. These organisms were re-identified using the criteria of Rihs et al, and all isolates fit most closely with Roseomonas gilardii. Antibiotic profiles were fairly homogeneous showing susceptibility to many antibiotics, but uniform resistance to cefoxitin, ceftazidime, and piperacillin. Attempts to determine whether the isolates were the same strain by pulsed-field gel electrophoresis suggested that 3 of the isolates were similar. Random amplified polymorphic DNA analysis, however, demonstrated that each of the eight isolates was a unique strain.

Sequential stool cultures submitted for routine culture were screened for the presence of CDC group DF-3. Of 690 specimens, 11 (1.6%) yielded moderate to heavy growth of DF-3. Information on the 11 patients from whom these specimens were obtained showed that 4 had a history of prolonged diarrheal disease that resolved after specific therapy to eradicate DF-3, while for the other 7 patients no clear role could be established. Microbiological characterization of the stool isolates and 10 CDC strains of DF-3 suggested the presence of two subtypes within the group. Antibiotic susceptibility studies showed DF-3 to be relatively resistant to a wide variety of antibiotics.

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