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Epidemiological typing of Stenotrophomonas maltophilia
1Laboratoire de Bactériologie-Virologie-Hygiène, Centre Hospitalier, Universitaire Rangueil, Toulouse, France.
Abstract:
Stenotrophomonas maltophilia is increasingly recognized as a cause of hospital-acquired infection and respiratory tract colonization in cystic fibrosis patients. A number of methods have been described for the typing of strains in epidemiological studies. Pulsed-field gel electrophoresis (PFGE) of total chromosomal DNA cleaved by low-frequency restriction site endonucleases (XbaI, SpeI) is highly discriminatory and defines populations at the strain level. Other molecular methods such as ribotyping with restriction endonucleases (BamHI, ClaI, BelI, EcoRI) can be used to subdivide the species but with reduced discrimination compared with PFGE. Polymerase chain reaction (PCR) fingerprinting techniques utilizing random primers or those directed against repeat motifs (ERIC, REP) are rapid and offer high discrimination for the study of outbreaks. A consistent finding from a number of incidents is the high diversity of strain types of S. maltophilia identified and the low incidence of cross-infection between patients.
Insights
Stenotrophomonas maltophilia infections are common in hospitals and cystic fibrosis patients. Molecular typing methods reveal high strain diversity and infrequent patient-to-patient spread of this opportunistic pathogen.
Area of Science:
- Clinical Microbiology
- Infectious Diseases
- Molecular Epidemiology
Background:
- Stenotrophomonas maltophilia is an emerging opportunistic pathogen causing hospital-acquired infections.
- Respiratory tract colonization by S. maltophilia is a significant concern in cystic fibrosis (CF) patients.
- Accurate strain typing is crucial for understanding transmission dynamics and infection control.
Purpose of the Study:
- To review and compare molecular typing methods for S. maltophilia.
- To assess the discriminatory power of different techniques in epidemiological studies.
- To characterize the strain diversity and transmission patterns of S. maltophilia.
Main Methods:
- Pulsed-field gel electrophoresis (PFGE) of chromosomal DNA digested with XbaI and SpeI.
- Ribotyping using restriction endonucleases BamHI, ClaI, BelI, and EcoRI.
- Polymerase chain reaction (PCR) fingerprinting with random primers and repetitive elements (ERIC, REP).
Main Results:
- PFGE offers high discriminatory power for defining S. maltophilia strain populations.
- Ribotyping provides species subdivision with lower discrimination than PFGE.
- PCR fingerprinting methods are rapid and highly discriminatory for outbreak investigations.
- Consistent findings across studies indicate significant S. maltophilia strain diversity.
- Cross-infection between patients due to S. maltophilia appears to be infrequent.
Conclusions:
- Multiple molecular typing methods are available for S. maltophilia, each with varying discriminatory capabilities.
- PFGE is the gold standard for high-resolution strain typing.
- The high genetic diversity and low cross-infection rates suggest endogenous or environmental sources are more common than patient-to-patient transmission.