Klebsiella marker systems

Klebsiella marker systems include determination of susceptibility patterns, serotype, bacteriocin susceptibility, bacteriophage susceptibility, biotype, and plasmid content, size and endonuclease fragment size. Susceptibility patterns are useful only if unusual patterns (ie, aminoglycoside resistance) occur. Serotypes are stable, reproducible markers. Over 90% of isolates can be serotyped and epidemiologically unrelated strains are widely distributed among the 72 standard types. Antisera are not available commercially except to types 1 to 6 and serotyping is expensive and time-consuming. Bacteriocin susceptibility typing is easier and cheaper but reproducibility is sometimes poor. Depending on the producer strains used, between 67% and 96% of strains are typable. As a single typing method, bacteriophage typing is not very sensitive. Only 70% of strains are typable and 20% are of a single type. There are two major problems with most biotyping systems: poor reproducibility and poor sensitivity. A high percent of strains is the same type. Plasmid analysis is technically the most complicated but is important if strains are aminoglycoside resistant. No one method is ideal, and characterization of isolates from an outbreak is best done by using several different marker systems.