M protein gene typing was used to analyse Streptococcus pyogenes
clinical isolates collected
between 1983 and 1995 in an area of central Italy from patients presenting
different types of
infections; the same isolates were also characterized by means of DNA fingerprinting.
M type 1 was the most common (50% of study strains), followed by M types
4, 12 and 6.
The proportion of M type 12 decreased with time, whereas M type 1 increased,
in agreement
with data obtained in many different areas. Most invasive strains belonged
to types M1 (30%)
and M12 (30%); on the other hand, the M1 type did frequently occur also
among non-invasive
isolates. DNA fingerprinting showed a correlation between M types and DNA
patterns. This report provides epidemiological information from a geographic
area not sampled
recently, and further shows the usefulness of the M genotyping technique,
which offers
potential advantages over conventional serological typing methods.