Hi. I searched and didn't really come up with what I needed. Does anyone have a protocol for serial dilution (in LB broth) and quantitative culture (in LB-amp agar) of S. aureus? Thanks in advance for any help.

I do not know why you are growing S aureus in LB; LB is much better for E coli

and why are you culturing with ampicillin? is it carrying a plasmid?

when I want to quantify S aureus (we do this all the time for infection assays, gotta use consistent MOIs) I so a series of 10-1 dilutions and plate each one

every protocol is different, it depends on your starting culutre

what specifically are you trying to do?

I will be introducing a 1cc solution of staph grown in LB into a wound to cause infection. However, I need to quantify this solution so that I can know how many I am introducing. Later, I will use the same quantitative culture to compare relative levels of bacteria after treatment.

we used to use this method when we were doing animal work to induce subcutaneous wound infections in guinea pigs, with quantification of bacteria in the wound a couple days later

even if your system is different, maybe the quantification part will help you:

A B Kaiser and D S Kernodle
[i]Low-Inoculum Model of Clean Wound Infection[/i]

1999, Chapter 24, from the Handbook of Animal Models of Infection

it is tricky to get the MOI you want, good luck

Thanks a lot for the reference, that will certainly help.