The accessibility of cross-reactive anti-lipopolysaccharide-core monoclonal antibodies to Escherichia coli grown in sub-MICs of temocillin and other antibiotics.

Two broadly cross-reactive anti-lipopolysaccharide core monoclonal antibodies WN1 222.5 and SZ27/150.3 were used in an ELISA system to detect the accessibility of core epitopes in Escherichia coli (four clinical isolates and NCTC 10418) grown to early stationary phase in the absence and presence of a half, a quarter and an eighth the MIC of temocillin, ampicillin, chloramphenicol, gentamicin and ciprofloxacin. The bacteria were coated on to ELISA microtitre plates. By comparing ELISA-titre ratios, temocillin induced a significantly large increase in binding of WN1 222.5 to all strains except NCTC 10418. Ampicillin and chloramphenicol induced a small increase in the binding of WN1 222.5 in some instances. Ciprofloxacin and gentamicin caused no increase in binding. Lipopolysaccharide SZ27/150.3 was only tested against temocillin-grown bacteria, but binding was not increased significantly compared with WN1 222.5. The results obtained demonstrate the potential use of temocillin to improve the clinical efficacy of immunotherapeutic monoclonal antibodies in Gram-negative sepsis.