A comparison of flagellar typing and phage typing as means of subdividing the O groups of Pseudomonas aeruginosa.

Strains of Pseudomonas aeruginosa from hospitals were typed by O and H serology and bacteriophage typing. The H sera were prepared against purified flagella of six type strains. The most common O serogroups were O6, O11, O16 and O10, and together these groups represented more than half of the total number of strains. O subgrouping proved useful for the further division of groups O2 and O6. Percentage H typability was high, and many H patterns were found. Comparison of H typing and phage typing as a means of making subdivisions within O groups showed that, although the general discriminatory power of the two methods was similar, H typing performed better than phage-typing in the more common O serogroups.