Restriction fragment length polymorphism (RFLP) analysis of the amplified P1 gene was used
to type 153 strains of Mycoplasma pneumoniae isolated in France between 1977 and 1994, and
in Denmark between 1962 and 1994, and an additional group of 28 strains isolated from
Belgium and Germany between 1990 and 1993. Random amplified polymorphic DNA (RAPD)
analysis was tested on French, Belgian and German strains. Both methods separated the strains
into two groups corresponding to the two reference strains M129 (group I) and FH (group II),
and gave concordant results. When 75 selected strains of different geographical origin were
analysed by pulsed-field gel electrophoresis (PFGE), strains of group II fell into two closely
related subgroups, subgroup IIa corresponding to the reference strain FH, and subgroup IIb.
Most of the strains isolated in Denmark in the period 1962–86 belonged to group I. Almost all
strains isolated in France and Denmark between 1987 and 1988 were from group II, the two
subgroups being present. In 1991–3, almost all strains from France as well as Denmark,
Germany and Belgium belonged to group I.