Numerical analysis of electrophoretic protein patterns of Group EF‐4 bacteria, predominantly from dog‐bite wounds of humans

Thirty‐seven strains of Group EF‐4 bacteria (from various countries) were characterized by one‐dimensional SDS‐PAGE of cellular proteins. They comprised 21 from dog‐bite wounds of humans, three from cat‐bite wounds of humans and five from human limb wounds which may have been inflicted by dogs or cats; there was also one each from a pet monkey, a tiger lung (fatal), a dog tonsil, a mouse, a cat liver, a wallaby mandible, a human vagina and one from a human limb wound which was apparently not inflicted by an animal. The protein patterns, which contained 45 to 50 discrete bands, were highly reproducible and were used as the basis for three numerical analyses. In the first, in which the principal protein bands (in the 34.8 to 41.3 kD range) were excluded, the 37 Group EF‐4 strains formed, at the 62% S level, two major clusters corresponding to strains producing a dihydrolase for arginine and those not doing so. In the second analysis, which included all the protein bands and which was performed only on the 22 arginine‐positive strains, two phenons formed (one of which could be further divided into two sub‐phenons) at the 56% S level. The third analysis, also based on all the protein bands, divided the 15 arginine‐negative strains into three clusters at the 56% S level. We conclude that high resolution PAGE combined with computerised analysis of protein patterns correlates exactly with the separation of Group EF‐4 into two biovars (also with the distinction of the biovars on the basis of G+C content). Reference strains of each of the PAGE types identified are available from the NCTC for inclusion in future studies.