ABSTRACT Gram-negative bacteria have an outer membrane (OM) impermeable to many toxic compounds that can be further strengthened during stress. In Enterobacteriaceae. the envelope contains enterobacterial common antigen (ECA). a carbohydrate-derived moiety conserved throughout Enterobacteriaceae. https://www.bekindtopets.com/limited-buy-TruCan-B-Oral-Bordatella-Vaccine-25-Single-Doses-top-mega/