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February 1985

Ampicillin Resistance and Haemophilus influenzae Type b

Author Affiliations

Tulane University Medical Center Department of Pediatrics 1430 Tulane Ave New Orleans, LA 70112

Am J Dis Child. 1985;139(2):114. doi:10.1001/archpedi.1985.02140040012005

Sir.—Your commentary1 states that "Ampicillin resistance has been demonstrated in nontype b strains although at a much lower level than that observed by type b organisms." The reference to Long et al2 is provided to support that statement. I believe this is an incorrect statement and that the cited reference does not support it. The study of Long et al2 documents a 10.5% resistance rate for Haemophilus influenzae serotype b, 8.3% rate for nontype b, and 17.7% rate for nontypeable strains. I pooled the data for the last two groups and compared the proportion of ampicillin resistance to that observed among the type b isolates. By x2 analysis, the P value is.10. Thus, although the data given do not support a significant difference in rate of ampicillin resistance between type b and other strains, there is a trend toward a higher rate in the nontype