Gram-negative bacteria strains

Gram negative Bacteria cells which lose the crystal violet during the decolorizing step and are then colored by the counterstain. Pseudomonas and Thiobacillus are examples of gram negative strains. 

Acquired resistance to bacitracin has been observed in laboratory strains of Staph, aureus, but resistance has been unstable and no resistant mutants have yet been isolated in vivo. Gram-negative bacteria are intrinsically resistant to bacitracin, which inhibits the transfer of pentapeptide units to petidoglycan. 

Leucocidins kill leucocytes and are produced by many strains of streptococci, most strains of Staphylococcus aureus and likewise most strains of pathogenic Gram-negative bacteria, isolated from sites of infection. 

A monobactam that is only active against gram-negative bacteria, including some strains of P. aeruginosa. Generally useful for nosocomial infections when aminoglycosides are to be avoided and in penicillin-sensitive patients. 

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