Analysis of polymicrobial infections in patients

Edited by the Laboratorytalk editorial team Mar 28, 2006

Simultaneous analysis of DNA from multiple bacterial species present in a single specimen observed in transplant patients offers opportunity to address new markets

Transgenomic has announced that an application of its Wave System will be highlighted in a presentation at the American Society of Microbiology Conference on Polymicrobial Diseases, to be held 19-23 October in Lake Tahoe, Nevada.

This conference deals with the potential causes of infectious diseases that involve multiple microbial pathogens.

The Wave application to be highlighted represents a novel approach to the molecular analysis of bacterial species diversity in urinary tract specimens obtained from immunosuppressed kidney transplant patients.

While the Wave System is often used to detect genetic variations relative to a normal (or reference) copy of a gene of interest, this new application capitalizes on its ability to separate several similarly- or identically-sized DNA fragments that differ among bacterial species in their exact DNA sequence.

This produces an output on the Wave System consisting of distinct peak profiles, which facilitates identification of the various individual species in the specimen from which the DNA was obtained.

Importantly, individual DNA fragments can be isolated following separation on the Wave System, enabling the DNA sequence analysis of specific fragments derived from each species in a mixture.

Trinad Chakraborty, director, Institute of Medical Microbiology, Hospital of the Justus-Liebig University Giessen in Giessen, Germany, and his colleague Eugen Domann, commented on the significance of their group's use of the Wave System.

"Because of treatment with immunosuppressive drugs, kidney transplant patients suffer not only from infection by common pathogens, but are also prone to opportunistic infections with unusual pathogens".

"Although culture-based and biochemical microbial identification strategies are useful for many of the common causative agents in urinary tract infections, fastidious, non-cultivatable or unusual organisms may escape detection by these methods".

Dr Chakraborty continued: "Using the Wave, we were able to provide evidence of infection in culture-negative specimens, distinguish between closely related bacterial species, and to identify as many as five different species in the same sample".

"The throughput capacity of the current instrumentation is sufficient to take this technology into the realm of clinical and translational microbiological research, as well as other applications".

Collin D'Silva, Transgenomic's CEO, pointed out that use of the Wave System in this setting provides an example of its potential to offer unique solutions of a broad range of challenging analytical problems, resulting in access to new market opportunities".

"The excellent work of Dr Chakraborty's group represents a novel application of our technology that has far-reaching implications".

"There has been considerable progress in molecular approaches to the identification of bacterial species".

"However, existing strategies for the analysis of mixed microbial infections typically require labour-intensive and time-consuming manual techniques that do not readily allow for isolation and collection of individual DNA fragments for subsequent DNA sequencing".

D'Silva continued: "We believe that in addition to the specific application to be described at this conference, the Wave System will also prove valuable in the analysis of other polymicrobial infections involving viral, fungal and parasitic pathogens, as well as in the evaluation of complex environmental microbial communities.".