Possible Postinfectious Immune Arthritis: Haemophilus influenzae Type b

Sir.—The report of septic arthritis by Granoff et al (Am J Dis Child132:488-490, 1978) interestingly reminds me of skeletal infections associated withHaemophilus influenzaetype b. The value of cultures in these cases is obvious. However, I am concerned about the 28-month-old boy (second case) in whom documentedH influenzaemeningitis was followed in ten days by suppurative arthritis of the left elbow. No organisms were seen or recovered although antigen was detected by countercurrent immunoelectrophoresis (CIE). I believe three points should be borne in mind about this case. First, there is the purported ampicillin susceptibility by agar disc diffusion method of this patient's isolate. Historically, this method of measuring susceptibility ofH influenzaehas lacked standardization. Thornsberry and Kirven¹have recommended an agar disc diffusion method that correlates with other susceptibility tests. It would be important for the authors to indicate the method used and/or zone