Molecular epidemiology of Legionella species by restriction endonuclease and alloenzyme analysis

Abstract

As part of an ongoing investigation into nosocomial Legionella infections at Stanford University Medical Center (SUMC), we applied the technique of restriction endonuclease analysis (REA) to determine strain differences among three species, including Legionella pneumophila, Legionella dumoffii, and Legionella micdadei. A total of 26 human and environmental water isolates from SUMC were selected for REA and compared with control strains that were not epidemiologically linked to SUMC. REA results were compared with results of alloenzyme typing, typing by monoclonal antibodies, and plasmid fingerprinting in all but L. micdadei strains. REA and alloenzyme typing showed that SUMC patient isolates were derived from distinct strains of three species. L. pneumophila strains from SUMC patients were genotypically identical to those isolated from potable water. REA was especially useful in proving that SUMC L. dumoffii patient isolates were derived from a single strain and that patients may have been exposed to a common source(s). REA typing correlated well with alloenzyme typing. These methods complement serologic typing of L. pneumophila and provide discriminating capability between strains of other Legionella species such as L. dumoffii, for which serologic types have not been identified. In addition, REA typing is somewhat easier to perform than alloenzyme typing and can be done in clinical laboratories.

Epidemiology of Staphylococcus aureus during space flight

“…The development of pulsed-field gel electrophoresis for the separation of larger DNA fragments has provided an improved means for examination of the total genomic DNA of bacterial isolates [23,28,29]. Methods have since been developed for the examination of both gram-positive [30-331 and gram-negative [24,25,34,35] bacteria.…”

Molecular epidemiology of Legionella pneumophilia serogroup 1 by ribotyping with a non-radioactive probe and PCR fingerprinting

“…Serotyping of L. pneumophila strains by specific antibodies is widely used, but is of limited value since most L. pneumophila infections are induced by serogroup 1. Other epidemiological markers used in the investigation of legionellosis are monoclonal antibody-subtyping of serogroup 1, alloenzymes, outer membrane proteins, and plasmid analysis [4][5][6]. Study of DNA digests with restriction endonucleases and standard or pulse electrophoresis was proposed [4,7].…”

“…Other epidemiological markers used in the investigation of legionellosis are monoclonal antibody-subtyping of serogroup 1, alloenzymes, outer membrane proteins, and plasmid analysis [4][5][6]. Study of DNA digests with restriction endonucleases and standard or pulse electrophoresis was proposed [4,7]. Restriction fragments of L. pneumophila DNA were used as probes for molecular typing of nosocomial iso-SSDI 0928-8244(94)00011-H 24 lates from the same serogroup (serogroup 3) which had no plasmids [3].…”

“…2. PCR fingerprinting of L. pneumophila serogroup 1 strains by using an arbitrary primer.Lanes 1,2,3,4,5,9,12, 13, 14, 15, 16, 17: unrelated strains. Lanes 6, 7, 8 and 10: related strains.…”

Assessment of fluorescent amplified fragment length polymorphism analysis for epidemiological genotyping of Legionella pneumophila serogroup 1

“…The present study compared the results obtained with a double-enzyme fAFLP protocol performed on three different platforms (one gel-and two capillary-based) in different laboratories, using a well-characterised set of 50 strains of L. pneumophila sg 1. The aims of the study were: (1) to assess the reproducibility (R) and epidemiological concordance (E) of the fAFLP protocol on each platform; and (2) to assess the suitability of fAFLP for fingerprinting, or typing, of L. pneumophila sg 1. To facilitate these assessments, results were compared with those obtained from a previous study using the standardised nonfluorescent method [9].…”