Table 2. Rescue of OS cockroaches with antibiotics after lethal dose of F. tularensis LVS.

Groups of OS cockroaches (n=8-18) were infected with approximately 100 × LD₅₀ (between 1.3 × 10⁶ CFU and 3.4 × 10⁶ CFU) F. tularensis LVS using sharpened pipette tips. Then at 2, 48, and 96 hours post-infection, infected cockroaches were treated by intrahemocoel injection (i.h.) or peroral feeding (p.o.) of the antibiotics indicated. Statistical differences in survival endpoints were determined by log-rank (Mantel-Cox) analysis.

Antibiotic	Route	Dosea	Survival Rate	Log-rank Comparison
				to Vehicle Control	between Routes
Vehicle only	i.h.		0/18		n.s.
	p.o		0/10
Doxycydine	i.h.	32 μg	9/10	***	n.s.
	p.o	32 μg	10/10	***
Streptomycin	i.h.	32 μg	8/10	***	**
	p.o	32 μg	0/10	n.s.
Gentamicin	i.h.	32 μg	7/8	***	***
	p.o	32 μg	0/10	n.s.
Azithromycin	i.h.	100 μg	0/10	n.s.	n.s.
	p.o	100 μg	0/10	n.s.
Resazurin	i.h.	11 μg	0/10	n.s.	n.s.
	p.o	11 μg	0/10	n.s.
Additional control groups
Bacteria only	No manipulation		0/10	n.s.b
No Bacteria	No manipulation		10/10
	i.h. vehicle		18/18
	p.o. vehicle		6/6

Asterisks indicate significant differences compared to the corresponding vehicle control group or alternative route of delivery (**=p<0.01, ***=p<0.001).

^a=this dose was administered three times during the study.

^b=survival outcome in the no manipulation group was not statistically different than survival in either vehicle control group (i.h. or p.o.; p>0.05 for all comparisons).