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Characterization of noncapsulate Haemophilus influenzae by whole-cell polypeptide profiles, restriction endonuclease
1Department of Medical Microbiology, University of Aberdeen Medical School, United Kingdom.
Abstract:
Thirty-four clinical isolates of noncapsulate Haemophilus influenzae representing isolates with either related or dissimilar patterns of whole-cell polypeptide profiles on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) were further characterized by restriction enzyme analysis (REA) and rRNA gene restriction patterns. Total cellular DNA was extracted by a rapid, microcentrifuge-scale method and digested with BamHI, which gave a pattern of about 18 discrete bands. This confirmed the five closely related groupings suggested by SDS-PAGE. Isolates dissimilar by SDS-PAGE were also distinguishable by REA. However, there was no correlation between the degrees of similarity estimated from whole-cell polypeptide profiles and those obtained from REA for the dissimilar isolates. Therefore, inferences of genetic relatedness made on the basis of these data should be interpreted with caution. rRNA gene restriction patterns also confirmed the groupings suggested by the other two techniques. We conclude that the three methods were highly discriminatory and that whole-cell polypeptide patterns or REA with BamHI would be appropriate techniques for epidemiological studies of noncapsulate H. influenzae.
Insights
Whole-cell polypeptide profiles and restriction enzyme analysis (REA) effectively identified groupings in noncapsulate Haemophilus influenzae. These molecular typing methods are suitable for epidemiological studies of this bacterium.
Area of Science:
- Microbiology
- Molecular Biology
- Epidemiology
Background:
- Non-encapsulated Haemophilus influenzae (non-encapsulated H. influenzae) is an important human pathogen.
- Accurate typing methods are crucial for tracking the spread and understanding the epidemiology of non-encapsulated H. influenzae.
Purpose of the Study:
- To evaluate the discriminatory power of whole-cell polypeptide profiling, restriction enzyme analysis (REA), and rRNA gene restriction patterns for typing non-encapsulated H. influenzae.
- To assess the correlation between these molecular techniques in determining genetic relatedness.
Main Methods:
- Thirty-four clinical isolates of non-encapsulated H. influenzae were analyzed.
- Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) was used for whole-cell polypeptide profiling.
- Restriction enzyme analysis (REA) with BamHI and rRNA gene restriction patterns were employed for DNA-based typing.
Main Results:
- SDS-PAGE revealed five related groupings among the isolates.
- REA with BamHI confirmed these groupings and distinguished between dissimilar isolates.
- No correlation was found between SDS-PAGE and REA similarity for dissimilar isolates, suggesting caution in interpreting genetic relatedness.
- rRNA gene restriction patterns corroborated the groupings identified by SDS-PAGE and REA.
Conclusions:
- Whole-cell polypeptide profiling, REA with BamHI, and rRNA gene restriction patterns are highly discriminatory techniques for non-encapsulated H. influenzae.
- SDS-PAGE or REA with BamHI are suitable for epidemiological investigations of non-encapsulated H. influenzae.