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Application and validation of PFGE for serovar identification of Leptospira clinical isolates
Renee L Galloway1, Paul N Levett
1Bacterial Zoonoses Branch, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America. zul0@CDC.GOV
Abstract:
Serovar identification of clinical isolates of Leptospira is generally not performed on a routine basis, yet the identity of an infecting serovar is valuable from both epidemiologic and public health standpoints. Only a small number of reference laboratories worldwide have the capability to perform the cross agglutinin absorption test (CAAT), the reference method for serovar identification. Pulsed-field gel electrophoresis (PFGE) is an alternative method to CAAT that facilitates rapid identification of leptospires to the serovar level. We employed PFGE to evaluate 175 isolates obtained from humans and animals submitted to the Centers for Disease Control and Prevention (CDC) between 1993 and 2007. PFGE patterns for each isolate were generated using the NotI restriction enzyme and compared to a reference database consisting of more than 200 reference strains. Of the 175 clinical isolates evaluated, 136 (78%) were identified to the serovar level by the database, and an additional 27 isolates (15%) have been identified as probable new serovars. The remaining isolates yet to be identified are either not represented in the database or require further study to determine whether or not they also represent new serovars. PFGE proved to be a useful tool for serovar identification of clinical isolates of known serovars from different geographic regions and a variety of different hosts and for recognizing potential new serovars.
Insights
Pulsed-field gel electrophoresis (PFGE) offers a rapid method for identifying Leptospira serovars from clinical samples. This technique successfully identified known serovars and potential new ones in 175 isolates, aiding public health efforts.
Area of Science:
- Microbiology
- Molecular Biology
- Epidemiology
Background:
- Serovar identification of Leptospira is crucial for epidemiology and public health but is not routinely performed.
- The reference method, cross agglutinin absorption test (CAAT), is only available in a few global laboratories.
- Pulsed-field gel electrophoresis (PFGE) provides an alternative, rapid method for serovar identification.
Purpose of the Study:
- To evaluate the utility of PFGE for serovar identification of clinical Leptospira isolates.
- To identify known and potentially novel Leptospira serovars from human and animal samples.
- To assess PFGE's effectiveness compared to traditional methods.
Main Methods:
- PFGE was employed to analyze 175 clinical isolates of Leptospira obtained between 1993 and 2007.
- The NotI restriction enzyme was used to generate PFGE patterns.
- Patterns were compared against a reference database of over 200 strains.
Main Results:
- PFGE successfully identified the serovar for 136 (78%) of the 175 clinical isolates.
- An additional 27 isolates (15%) were identified as probable new serovars.
- The method proved effective for diverse isolates from various hosts and geographic regions.
Conclusions:
- PFGE is a valuable tool for routine serovar identification of clinical Leptospira isolates.
- The technique aids in recognizing both known and potentially novel serovars.
- PFGE enhances epidemiological surveillance and public health response for leptospirosis.
