an aerobic, gram-negative coccobacillus was isolated on bordet-gengou agar from a nasopharyngeal swab 48 hours after culture from a 6-month-old infant with suspected pertussis. the organism exhibited the following characteristics: macconkey agar: no growth urea: negative at 4 hours, positive at 24 hours oxidase: negative catalase: positive the most probable identification of this isolate is:
