Application of a PCR-Based Technique for Detecting and Discriminating Between Mycoplasma species form California Sea Lions (zalophus californianus)
Brian M. Aldridge1; Brett Smith1; Jeffrey L.
Stott1; Frances Gulland2; Judy Lawrence2; Marry
Bacterial infections are an important cause of morbidity and mortality in
marine mammals. The accurate identification of a suspected bacterial pathogen relies on culture
followed by time-consuming and subjective phenotypic tests. In human medicine molecular
diagnosis is playing an increasingly important role in the rapid detection and identification of
pathogenic organisms in clinical samples. The genetic variation of ribosomal genes, which are
universally present in bacteria, offers an alternative to culturing for the detection and
identification of these organisms. The 16S ribosomal gene is an excellent candidate for
molecular bacterial detection since it contains conserved sequence regions ideal for primer
targeting as well as regions of variability useful for species identification. We have recently
adapted a novel molecular biology technique to differentiate 16S rRNA gene sequences from
different mycoplasma strains isolated from California sea lions (Zalophus californianus).
This technique involves polymerase chain reaction (PCR), denaturing gradient gel electrophoresis
(DGGE) and automated DNA sequencing.
This technique has potential as a sensitive, rapid, and reliable alternative
to routine culture-based methods for detecting and distinguishing a wide range of bacteria.
Empirical antibiotic selection has become increasingly complicated and expensive, particularly
since heavy use may contribute to the acquisition of resistance in some bacteria. It is
important therefore to continue to improve our ability to accurately, cost-effectively, and
rapidly diagnose infectious diseases in marine mammals in captivity or rehabilitation, so that
specific, appropriate, and effective antimicrobial therapy can be initiated promptly.