Antibiofilm Activity of GlmU Enzyme Inhibitors against Catheter-Associated Uropathogens

Abstract

The colonization of uropathogenic bacteria on urinary catheters resulting in biofilm formation frequently leads to the infection of surrounding tissue and often requires removal of the catheter. Infections associated with biofilms are difficult to treat since they may be more than 1,000 times more resistant to antibiotics than their planktonic counterparts. We have developed an antibiofilm composition comprising an N-acetyl-Dglucosamine-1-phosphate acetyltransferase (GlmU) inhibitor and protamine sulfate, a cationic polypeptide. The antibiofilm activity of GlmU inhibitors, such as iodoacetamide (IDA), N-ethyl maleimide (NEM), and NEM analogs, including N-phenyl maleimide, N,N-(1,2-phenylene)dimaleimide (oPDM), and N-(1-pyrenyl)maleimide (PyrM), was tested against that of catheter-associated uropathogens. Both IDA and NEM inhibited biofilm formation in Escherichia coli. All NEM analogs showed antibiofilm activity against clinical isolates of E. coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Staphylococcus epidermidis, and Enterococcus faecalis. The combination of oPDM with protamine sulfate (PS) enhanced its antibiofilm activity and reduced its effective concentration to as low as 12.5 M. In addition, we found that the in vitro inhibitory activity of oPDM-plus-PS-coated silicone catheters against P. aeruginosa and S. epidermidis colonization was superior to that of catheters coated with silver hydrogel. Confocal scanning laser microscopy further confirmed that the oPDMplus-PS-coated silicone catheters were almost free from bacterial colonization. Thus, a broad-spectrum antibiofilm composition comprising a GlmU inhibitor and protamine sulfate shows promise for use in antiinfective coatings for medical devices, including urinary catheters.Microorganisms can attach to and colonize any biomaterial surface, putting patients at risk for local and systemic infections. More than 900,000 episodes of catheter-associated urinary tract infections occur annually in acute-care hospitals in the United States, accounting for 40% of all nosocomial infections and involving between 10 and 30% of patients with indwelling urinary catheters (30). Catheter-associated urinary tract infection prolongs the hospital stay between an estimated 2.4 and 4.5 days, with resultant increased healthcare costs (15,16). Recent studies have shown that a wide range of persistent catheter-related infections may be related to the ability of bacteria to form biofilms (6, 28). Treatment of device-related infections with conventional antimicrobial agents frequently fails because microorganisms growing in biofilms are more tolerant or phenotypically resistant to antimicrobial agents than planktonic cells (24). The insensitivity of biofilm bacteria to antibiotics is a function of cell wall composition, surface structure, and phenotypic variation in enzymatic activity (8,14). It has also been suggested that the negatively charged exopolysaccharide is very effective in protecting bacterial cells from cationic antibiotics by restricting their permeation (2...

EfaR Is a Major Regulator of Enterococcus faecalis Manganese Transporters and Influences Processes Involved in Host Colonization and Infection

“…One candidate is glmU (repressed in the efaR mutant with a change of 3.2-fold; P ϭ 6.03 ϫ 10 Ϫ5 ). GlmU is involved in cell wall synthesis, and inhibitors of GlmU were found to nearly abolish biofilm formation by S. epidermidis (42).…”

Escherichia coli N-Acetylglucosamine-1-Phosphate-Uridyltransferase/Glucosamine-1-Phosphate-Acetyltransferase (GlmU) Inhibitory Activity of Terreic Acid Isolated from Aspergillus terreus

“…This finding co-relates well with already reported nonspecific GlmU inhibitors such as iodoacetamide, N-ethyl maleimide (NEM), and NEM analogues that have been reported to be effective against biofilm formation in Gram-negative and Gram-positive bacteria. 10 In addition to antimicrobial activity of terreic acid against Gramnegative pathogens, the microsomal stability studies predicted good stability of the compound. In literature, there are various reports describing potent E. coli GlmU inhibitors, but they do not exhibit simultaneous antimicrobial activity in Gram-negative wild-type strains.…”

“…Already reported inhibitors of the acetyltransferase domain of E. coli GlmU include 2-phenylbenzofurans 9 and nonspecific thiol reactive molecules such as iodoacetamide and N-substituted maleimides. 10 Multiple screening strategies also led to the discovery of novel E. coli GlmU inhibitors, including arylamines 11 and aryl sulfonamides. 6,12,13 Recently, an in silico screening strategy using ligand-guided and structure-guided techniques led to the identification of two promising sulfonamide inhibitors.…”

Complicated Catheter-Associated Urinary Tract Infections Due toEscherichia coliandProteus mirabilis

“…Therefore, inhibitors of GlmU in conjunction with protamine sulfate show promise for use in anti-infective coatings for urinary catheters (44). These compounds have antibiofilm activity against clinical isolates such as E. coli, P. aeruginosa, K. pneumoniae, S. epidermidis, and E. faecalis, and N,NЈ-(1,2-phenylene)dimaleimide-plus-protamine sulfate-coated silicone catheters have a reduced bacterial colonization rate for P. aeruginosa and S. epidermidis than catheters coated with silver hydrogel in vitro (44).…”