[hiredhand]

Good points...

Not to elevate paranoia, but I know somebody who is qualified to suggest that Y. Pestis is "relatively easy" to engineer such that it's antibiotic resistant. This person suggested that perhaps Al Qaeda did this based on the supposition that if they're messing with plague, they "should" have had the necessary antibiotics to fight it if they had an "oopsie". Either they didn't have the antibiotics necessary to combat an exposure, or they designed it to be antibiotic resistant and then had the "oopsie".

[The_Reader_David]

Antibiotic resistance can be accomplished without engineering: just expose the bacteria to insufficient courses of antibiotics repeatedly (the reason we have antibiotic resistant strains of staph, TB, etc., but done intentionally).

In the case of plague it can be done in the rats until you have a strain that kills them in spite of antibiotics.

[Travis McGee]

At this point, even a natural outbreak can’t be ruled out.