Identification and serotyping of atypical Legionella pneumophila strains isolated from human and environmental sources.
OBJECTIVE
To validate identification methods for Legionella pneumophila strains that cannot be serotyped into the known serogroups and to characterize their antigenic diversity.


RESULTS
Fifty L. pneumophila strains that could not be serogrouped, but which had been confirmed as L. pneumophila by mip gene sequencing, were further identified phenotypically. We used (i) MONOFLUO anti-Legionella Staining Reagent (Bio-Rad) (50/50), (ii) an in-house prepared immunoblot assay for the detection of L. pneumophila- specific Mip protein epitope (50/50), (iii) fatty acid analysis using the Microbial Identifications System (MIDI) (47/50) and (iv) Oxoid agglutination tests (44/50). The serological diversity was further characterized by testing with five serogroup-cross-reactive monoclonal antibodies, resulting in nine phenons.


CONCLUSIONS
The division of L. pneumophila into 15 serogroups does not reflect the serogroup heterogeneity. Results of these tests indicate that there are more serogroups.


CONCLUSIONS
MONOFLUO anti-Legionella Staining Reagent is the only commercially available tool for identifying atypical strains of L. pneumophila. If necessary for epidemiological purposes, the antigenic heterogeneity of these strains can be analysed by monoclonal antibodies.
Helbig
J H
JH
Medizinische Fakultät TU Dresden, Institut Medizinische Mikrobiologie und Hygiene, Dresden, Germany. j.helbig@mailbox.tu-dresden.de
Benson
R F
RF
Pelaz
C
C
Jacobs
E
E
Lück
P C
PC
D000940:Antigenic Variation / Q000276:immunology; D000942:Antigens, Bacterial / Q000276:immunology; D001426:Bacterial Proteins / Q000235:genetics; D001483:Base Sequence; D044822:Biodiversity; D003429:Cross Reactions / Q000276:immunology; D004269:DNA, Bacterial / Q000235:genetics; D004783:Environmental Microbiology; D000939:Epitopes / Q000276:immunology; D005227:Fatty Acids / Q000032:analysis; D005798:Genes, Bacterial / Q000235:genetics; D006801:Humans; D016952:Legionella pneumophila / Q000145:classification / Q000276:immunology / Q000302:isolation & purification*; D007877:Legionnaires' Disease / Q000382:microbiology*; D008070:Lipopolysaccharides / Q000276:immunology; D019696:Peptidylprolyl Isomerase / Q000235:genetics; D010641:Phenotype; D012703:Serotyping / Q000379:methods*; D013045:Species Specificity
D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D004269:DNA, Bacterial; D000939:Epitopes; D005227:Fatty Acids; D008070:Lipopolysaccharides; C512922:Mip protein, Legionella pneumophila; D019696:Peptidylprolyl Isomerase