Advanced Techniques in Diagnostic Microbiology

460 S. R. Frye and M. Healy
molecular typing methods may provide additional tools to help discern the answers
to the above questions.
Probiotics
Advances in patient treatment also demand advances in molecular typing techniques.
Probiotic agents are increasingly used in clinical practice for the treatment
and prevention of a variety of infectious and inflammatory conditions. Rep-PCR
and other strain-typing methods can be used to identify and discriminate probiotic
organisms such as bifidobacterial isolates (Masco et al., 2003; Vitali et al.,
2003) and the closely related Saccharomyces cerevisiae and S. boulardii (Fietto
et al., 2004). Probiotics are generally safe and infections associated with probiotic
strains of lactobacilli are extremely rare, but complications of probiotic use can
occur. Bacteremia occured in a child after ingestion of a Lactobacillus rhamnosus
GG probiotic tablet. Strain typing with PFGE showed identity between the tablet
and bloodstream isolates (De Groote et al., 2005). Additionally, two patients received
probiotic lactobacilli and subsequently developed bacteremia and sepsis attributable
to Lactobacillus species. Rep-PCR DNA fingerprinting analysis showed
that the Lactobacillus strain isolated from blood samples was indistinguishable
from the probiotic strain ingested by the patients. This report (Land et al., 2005)
should serve as a reminder that these agents can cause invasive disease in certain
populations and that advances in medical treatment are often accompanied by new
requests for the laboratory.
Potential Future Applications
Additional studies demonstrate the use of the DiversiLab System for identification
of bacteria and fungi (Cangelosi et al., 2004; Healy et al., 2004; Kontoyiannis
et al., 2005; Pounder et al., 2005). The DiversiLab System represents an effective
platform for microbial genotyping in microbiology laboratories. Traditionally, the
rep-PCR methodology has been used for subspecies and strain discrimination.
With the advances in bioinformatics technology, the rep-PCR methodology could
be used for niche identification where rapid methods may not be useful (Healy et al.,
2004, 2005; Kontoyiannis et al., 2005). Identifications are based on positive DNA
fingerprint matches to a similar fingerprint from a well-characterized collection
stored in the database. Therefore, future applications include the capability for
additional identification assays with compilation of new databases and expansion
of the current databases.
The DiversiLab System has potential to be the standardized platform for routine
bacterial and fungal genotyping in the clinical microbiology laboratory. The DiversiLab
System offers efficiency, excellent discriminatory power, and reproducibility
in order to allow for database building, intersite comparisons, and expedited report
generation. The small footprint of the automated system conserves work space, and
the Web-based interface enables remote access and data portability for assessment