Little has been reported on the serological relationship of halophilic bdellovibrios (Bd). Immunodiffusion analysis performed with rabbit or mouse Bd antisera developed against eight halophilic Bd isolates and one terrestrial Bd isolate, when reacted with soluble antigen preparations of 45 isolates of halophilic Bd, allowed separation into seven serogroups, which were distinct from the terrestrial isolate. Soluble antigen preparations of prey bacteria, Vibrio parahaemolyticus P-5 (P-5) and Escherichia coli ML 35 (ML 35), exhibited no reactivity with the antisera by immunodiffusion. Immunoelectrophoresis revealed the presence of three distinct antigens in homologous reactions and one shared antigen in heterologous Bd reactions. Shared antigens were noted between halophilic and terrestrial Bd, in addition to between halophilic Bd strains, indicating the possible existence of an antigen(s) which may be shared among all Bd. Again, no shared antigen was noted when P-5 or ML 35 was allowed by immunoelectrophoresis to react with the antisera. Prey susceptibility testing of the seven distinct groups of halophilic Bd, using 20 test prey, produced essentially identical spectra for each group, indicating that this was not a useful technique in delineating the Bd. While immunoelectrophoresis was able to demonstrate an antigen common to all Bd tested, immunodiffusion was able to delineate strains on the basis of a "serogroup specific" antigen. This suggests that immunological tools may serve as important means to study the taxonomy of halophilic Bd, as well as in the formation of a clearer taxonomic picture of the genus Bdellovibrio.

The genetic diversity between major meticillin-resistant Staphylococcus aureus (MRSA) lineages was probed using fluorescent amplified fragment length polymorphism (FAFLP) as a random genome sampling tool. Genomic DNA was digested with endonucleases BglII and Csp6I and a subset of the restricted fragments were amplified using the primer pair BglII+A and Csp6I+0. Sixty-seven FAFLP profiles consisting of 46-68 amplified fragments ranging in size from 50 to 600 bp were exhibited amongst the 71 isolates analysed. Cluster analysis of FAFLP data revealed concordance with spa typing and MLST clonal complexes (CC), with isolates of each CC grouping in the same FAFLP cluster. Furthermore, FAFLP could differentiate subtypes within the homogeneous CC22 isolates and also between MLST sequence types 8 and 239. The discriminatory power of FAFLP was 0.998 compared to values of 0.975 and 0.909 for spa typing and MLST, respectively. Thus, FAFLP analysis proved to be a rapid, reproducible and highresolution tool that displayed the microheterogeneity within MRSA lineages. Using FAFLP data, lineage-specific fragments were identified and sequenced; these encoded toxins, antibiotic resistance determinants and bacteriophage resistance factors. Lineage-specific sequence variations were observed, which may provide insights into the evolution and fitness of successful lineages. This will also aid in the development of rapid and high-throughput diagnostic PCRbased assays for the identification of MRSA lineages in resource-poor settings.

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