autotransduction allows the lysogen to survive and increase in
numbers even in the presence of counter selection, a trait that is
not possible when the phage is inactivated.
Lastly, to examine whether autotransduction occurs outside the
test tube, we infected Galleria mellonella wax moth larvae, a
commonly used virulence model for S. aureus with a 1:1 mix of
8325-SR and either 8325-4 SaPI or USA300. Just 1 hour post
infection, autotransduction was observed in the larvae infected
with the mix containing 8325-4 SaPI (Fig. 4a) but not after 6 h in
the mix containing USA300 (Fig. 4b) and not in the inoculum
used for injection. At 24 h post infection, autotransduction
approached frequencies comparable to those observed in
laboratory medium both in larvae infected with 8325-SR and
8325-4 SaPI or USA300. No transduction of 8325-4 SaPI or
USA300 was observed, implicating autotransduction in the
efficient spreading of antibiotic resistance genes in vivo.