Table 1. Description of bacteria.

Abbr.	Name	Description	Gram staining*
none	control	Mock infection	N/A
Rv	MTB H37Rv	A common laboratory strain of MTB	acid-fast
Rv+	heat-inactivated MTB H37Rv	Dead MTB H37Rv	acid-fast
GC	MTB GC1237	More virulent strain of MTB	acid-fast
BCG	bacillus Calmette-Guérin	Vaccine (attenuated M. bovis)	acid-fast
Smeg	Mycobacterium smegmatis	Non-pathogenic mycobacterium	acid-fast
Yers	Yersinia pseudotuberculosis	Facultative intracellular pathogen	Negative
Salm	Salmonella typhimurium	Facultative intracellular pathogen	Negative
Staph	Staphylococcus epidermidis	Extracellular pathogen	Positive

^*Mycobacteria are unable to be gram stained due to the low permeability of their cell walls. They are more closely related evolutionarily to gram-positive bacteria than gram-negative. However, their thick cells walls share features of gram-negative bacteria, e.g. a "pseudoperiplasm" similar to the gram-negative periplasm¹¹⁷.