Recent outbreaks of disease caused by Escherichia coli O157:H7 have focused much attention on this newly emerged pathogen. Identification of the H7 flagellar antigen is critical for the confirmation of E. coli O157:H7; however, clinical isolates are frequently nonmotile and do not produce detectable H antigen. To further characterize nonmotile isolates (designated NM), we developed a PCR-restriction fragment length polymorphism (PCR-RFLP) test to identify and characterize the gene encoding the H antigen (fliC) in E. coli. The entire coding sequence of fliC was amplified by PCR, the amplicon was restricted with RsaI, and the restriction fragment pattern was examined after gel electrophoresis. Two hundred eighty E. coli isolates representing serotypes O157:H7 and O157:NM, flagellar antigen H7 groups associated with other O serogroups, and all other flagellar antigen groups were analyzed. A single restriction pattern (pattern A) was identified for O157:H7 isolates, O157:NM isolates that produced Shiga toxin (formerly Shiga-like toxin or verotoxin), and 16 of 18 O55:H7 isolates. Flagellar antigen group H7 isolates of non-O157 serotypes had one of three banding patterns distinct from pattern A. A wide variety of patterns were found among isolates of the other 52 flagellar antigen groups; however, none was identical to the O157:H7 pattern. Thirteen of 15 nonmotile strains that did not produce the A pattern had patterns that matched those of other known H groups. The PCR-RFLP in conjunction with O serogroup determination will be useful in identifying E. coli O157:H7 and related strains that do not express immunoreactive H antigen and could be expanded to include other clinically important E. coli strains.

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The ex vivo infection models presented here should be helpful in the screening of novel antimicrobials and constitute a prerequisite for future clinical studies.

A non‐toxic hydrolytically fast‐degradable antibacterial hydrogel is herein presented to preemptively treat surgical site infections during the first crucial 24 h period without relying on conventional antibiotics. The approach capitalizes on a two‐component system that form antibacterial hydrogels within 1 min and consist of i) an amine functional linear‐dendritic hybrid based on linear poly(ethylene glycol) and dendritic 2,2‐bis(hydroxymethyl)propionic acid, and ii) a di‐N‐hydroxysuccinimide functional poly(ethylene glycol) cross‐linker. Broad spectrum antibacterial effect is achieved by multivalent representation of catatonically charged β‐alanine on the dendritic periphery of the linear dendritic component. The hydrogels can be applied readily in an in vivo setting using a two‐component syringe delivery system and the mechanical properties can accurately be tuned in the range equivalent to fat tissue and cartilage (G′ = 0.5–8 kPa). The antibacterial effect is demonstrated both in vitro toward a range of relevant bacterial strains and in an in vivo mouse model of surgical site infection.

Restriction fragment length polymorphism analysis of a PCR-amplified DNA fragment of the gene coding for 16S rRNA was performed on 148 previously characterized strains of Campylobacter, Helicobacter, Arcobacter, and Wolinella succinogenes and 13 Campylobacter-like isolates. These strains included clinical, animal, and environmental isolates. PCR amplification generated a 283-bp fragment from all species. The amplicon from each strain was digested with six restriction endonucleases (AccI, AvaI, DdeI, HaeIII, HpaII, XhoI). DdeI was useful for the initial grouping of the strains. Additional discrimination within the different DdeI groups was obtained with AccI, HaeIII, HpaII, and XhoI digestions. The PCR-restriction fragment length polymorphism analysis allowed for the discrimination of members of the genus Campylobacter from members of closely related genera and discrimination between Campylobacter species. The proposed method is simple and rapid and can be useful for the routine identification of Campylobacter-like organisms in clinical or epidemiologic studies.