Abstract: Bacterial infections, including Methicillin resistant Staphylococcus aureus (MRSA) infections are a major health problem that has created a pressing need for new antibiotics. Pyridazinone, rhodanine, and pyrazolethione compounds effective inhibit the enzymatic activity of sortase A (srtA) found in gram positive bacteria are disclosed. A structure activity relationship (SAR) analysis led to the identification of several pyridazinone and pyrazolethione analogs that inhibit SrtA with IC50 values in the sub-micromolar range. Compounds that inhibit the S. aureus SrtA sortase may function as potent anti-infective agents as this enzyme attaches virulence factors to the cell wall. Many of these molecules also inhibit the sortase enzyme from B. anthracis suggesting that they may be generalized sortase inhibitors. The novel compounds, compositions, uses, formulations, medicaments, articles of manufacture provide improved materials, uses, and treatments useful in combating infectious disorders.