The spectrum of all sulfonamides is generally the same. Sulfonamides inhibit both grampositive and gram-negative bacteria, Nocardia, Actinomyces spp, and some protozoa sue as coccidia and Toxoplasma spp. More active sulfonamides may include several species o Streptococcus, Staphylococcus, Salmonella, Pasteurella, and even Escherichia coli in their spectra. Strains of Pseudomonas, Klebsiella, Proteus, Clostridium, and Leptospira spp are most often highly resistant, as are rickettsiae, mycoplasmas, and most Chlamydia.