CP-45,899, a Beta-Lactamase Inhibitor That Extends the Antibacterial Spectrum of Beta-Lactams: Initial Bacteriological Characterization

Abstract

CP-45,899 {3,3-dimethyl-7-oxo-4-thia-1-azabicyclo(3.2.0)heptane-2-carboxylic acid, 4,4-dioxide, [2S-(2a,5a)]} is an irreversible inhibitor of several bacterial penicillinases and cephalosporinases. In the presence of low concentrations of CP-45,899, ampicillin and other f,-lactams readily inhibit the growth of a variety of resistant bacteria that contain ,-lactamases. 899 In vitro susceptibility studies were performed in brain heart infusion broth as the basal medium. The broth was enriched with 5% (vol/vol) sheep blood for studies with Streptococcus pyogenes and 5% Fildes plus 2% IsoVitaleX for Haemophilus influenzae. Tests with Neisseria gonorrhoeae were performed on gonococcus agar base (BBL) supplemented with hemoglobin and IsoVitaleX. Studies with Bacteroides fragilis were carried out in prereduced brain heart infusion as described in the Anaerobe Laboratory Manual (3); incubation was in an 80% N2-10% C02-10% H2 gas mixture either in an anaerobic chamber or in GasPak jars equipped with gas-exchange capability.Methods. Minimal inhibitory concentrations (MICs) of antibiotics in combination with CP-45,899 were determined using a 7-by-7-concentration grid protocol in broth culture, as described by Sabath (8), with an inoculum of-i0 colony-forming units per ml.Testing for synergy against B. fragilis was performed by an agar dilution method similar to the broth dilution method.p8-Lactamase studies. The hydrolysis of ampicillin and penicillin G was determined by the microiodometric method of Novick (5). Cephaloridine hydrolysis was measured by following the decrease in ultraviolet absorbance at 255 nm (6). Conditions for both assays were identical: 0.5 M potassium phosphate, pH 6.5, and 37°C. Reactions were initiated by the addition of the cell-free ,B-lactamase, except in the case of preincubation experiments in which the inhibitor and enzyme were incubated together in the assay mixture for 10 min before initiation of the reaction by addition of substrate. With the cell-free extracts of Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa, the substrate was

Targeting Antibiotic Resistance

“…The first β‐lactamase inhibitor to be used was clavulanic acid ( 51 , discovered at Beecham Pharmaceuticals) in the mid‐1970s,166 followed over the next decade by sulbactam ( 52 )167 and tazobactam ( 53 ) 168. As seen in Figure 35, these β‐lactamase inhibitors all possess a β‐lactam core, but they have been shown to have only limited antibiotic activity.…”

Cefonicid: A stable .BETA.-lactamase inhibitor.

“…To our knowledge, this antibiotic is the first non-competitive inhibitor of a type I enzyme for which a Ki has been reported9). Neither clavulanic acid nor CP-45899, a penicillin sulfone, inhibit the class I 3-lactamases10, 11,12). Work is now underway to further delineate the structure-activity relationships in the cefonicid series.…”

Synthesis and .BETA.-lactamase inhibitory activity of 6-((1-heteroarylthioethyl-1,2,3-triazol4-yl)methylene)-penam sulfones.

“…1994 Scheme 2. followed by treatment with 0.1 n NaOH8).The resulting sodium salts were purified by reverse phase chromatography on Prepex 49~63 C18 and collected as homogeneous solids after freeze-drying. (Scheme 2) Results and Discussion…”