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Evaluation of three molecular typing techniques for nonfermentative Gram-negative bacilli
Suzane Silbert1, Michael A Pfaller, Richard J Hollis
1Laboratório Especial de Microbiologia Clínica, Disciplina de Doenças Infecciosas e Parasitárias, Universidade Federal de São Paulo, São Paulo, Brasil.
Infection Control and Hospital Epidemiology
|November 3, 2004
Summary
Automated ribotyping and ERIC-PCR offer faster results for typing nonfermentative gram-negative bacilli compared to PFGE. While PFGE has the highest discriminatory power, the other methods provide comparable results more efficiently.
Area of Science:
- Medical microbiology
- Molecular biology
- Infectious diseases
Background:
- Nonfermentative gram-negative bacilli are significant opportunistic pathogens.
- Accurate bacterial typing is crucial for infection control and outbreak investigations.
- Limited data exists on the comparative performance of DNA typing techniques for these bacteria in Latin America.
Purpose of the Study:
- To evaluate and compare automated ribotyping, PFGE, and ERIC-PCR for typing nonfermentative gram-negative bacilli.
- To assess the discriminatory power, reproducibility, turnaround time, cost, and ease of interpretation of each method.
Main Methods:
- One hundred twenty-six nonfermentative gram-negative bacilli (Pseudomonas aeruginosa, Acinetobacter baumannii, Stenotrophomonas maltophilia) were collected from Latin American hospitals.
- Bacterial isolates were typed using automated ribotyping, PFGE, and ERIC-PCR.
- Hunter's generalized formula was used to calculate the discriminatory power of each technique.
Main Results:
- All techniques demonstrated 100% reproducibility.
- Automated ribotyping and ERIC-PCR yielded results faster than PFGE.
- PFGE exhibited the highest discriminatory power for Acinetobacter baumannii (0.94), while all methods performed excellently for Pseudomonas aeruginosa (0.98).
- For Stenotrophomonas maltophilia, PFGE and ERIC-PCR showed higher discriminatory power (0.90) than automated ribotyping (0.82).
Conclusions:
- PFGE is the most powerful discriminatory technique for typing nonfermentative gram-negative bacilli.
- Automated ribotyping and ERIC-PCR are viable alternatives, offering faster results with comparable discriminatory power and lower costs.
- These findings support the selection of appropriate DNA typing methods based on specific needs for speed, cost, and discriminatory power.