The isolate detected from this process was sent to the Streptococcus and Diphtheria Reference Unit
, Public Health England, Colindale, UK, and was confirmed to be a toxigenic C.
To determine the public health importance of the increase in cases, the Public Health Laboratory Service's (PHLS's) Streptococcus and Diphtheria Reference Unit and the PHLS Communicable Disease Surveillance Centre obtained more complete clinical information on nontoxigenic isolates referred in 1995 and 1996.
diphtheriae to the PHLS Streptococcus and Diphtheria Reference Unit for confirmation and toxin determination by both phenotypic (Elek and other immunoassays) and genotypic (polymerase chain reaction) methods (5,6).
Throat isolates of nontoxigenic Corynebacterium diphtheriae submitted to the Public Health Laboratory Service's Streptococcus and Diphtheria Reference Unit, from U.K.
Nontoxigenic Corynebacterium diphtheriae isolates from patients who traveled outside England and Wales in the previous 3 months, submitted to the Public Health Research Laboratory's Streptococcus and Diphtheria Reference Unit, 1995 Residence(a) Destination Ribotype Site London Australia A Throat London Sierra Leone A Throat Northwest Cyprus A Throat Northwest Holland A Throat Northwest Canary Islands A Throat Northwest Spain A Throat Wales Germany A Throat London France B Throat London Vietnam D Skin London Gambia E Throat London Canary Islands F Throat London Sudan H Skin Southeast Philippines J Skin London Ghana M Skin West Midlands Pakistan Q Blood London Morocco U Throat West Midlands Jamaica W Skin
diphtheriae isolates ascertained by the PHLS Streptococcus and Diphtheria Reference Unit during this period (Figure 1).