Legionella Jordanis

''Legionella jordanis'' is a Gram-negative bacterium from the genus ''Legionella'' which was isolated from the Jordan River in Bloomington, Indiana and from the sewage in DeKalb County, Georgia. ''L. jordanis'' is a rare human pathogen and can cause respiratory tract infections.

History

''Legionella jordanis'' strain BL-540 was first isolated from water samples taken at the Jordan River in Bloomington, Indiana by Cherry et al. in 1978. Another strain characterized as ABB-9 was discovered in 1980 from sewage collected in DeKalb County, Georgia. The specific epithet ''jordanis'' was derived from the name of the river in which was discovered. The two strains were both Gram-stained. The Sudan black B fat stain for lipids and the Wirtz-Conklin method were used to demonstrate spore formation. Acid-fast staining was used, as well. The cultures were streaked onto trypticase soy agar (TSA) and charcoal yeast extract (CYE) agar slants, and were left to incubate around 36 °C in candle extinction jars that remove oxygen from the jar by burning a candle with the lid tightly sealed. The cultures failed to grow on the TSA plates, but did show growth on CYE slants which Cherry et al. expected. They were removed at 24- and 48-hour periods and tested for oxidase and catalase production.

Characterization

The order Legionellales comprises two families, Legionellaceae'' and ''Coxiellaceae. The family Legionellaceae includes the genera ''Legionella'' and relatives ''Fluoribacter'' and ''Sarcobium''. The colonies that appeared around the third day in the CYE slants were grey and raised with a “ground-glass appearance". It was positive for both oxidase and catalase production. Strains of ''L. jordanis'' are thin, motile Gram-negative rods that range in size from 0.3 to 0.9 μm wide by 2 to 20 μm long. In addition, it is not encapsulated or non-spore-forming. After being stained with Sudan B, many of the cells did not have fat deposits. Gas-liquid chromatography-mass spectrometry show that all known species of ''Legionella'' contain large amounts of branched-chain fatty acids. DNA that was unlabeled from BL-540 was tested against labeled DNAs from the six recognized ''Legionella'' species. When reactions were performed at an incubation temperature of 60 °C, relatedness of BL-540 to the other DNAs were between 4 and 20%. When reactions were performed at a higher incubation temperature of 75 °C, the relatedness ranged from 0 to 10%. The results indicated that ''L. jordanis'' was a new species. The two strains, BL-540 and ABB-9, were almost identical when DNA relatedness reactions were performed at both 60 and 75 °C.

Pathogenesis

''L. jordanis'' is an opportunistic pathogen. It has been shown to cause lower respiratory tract infections in humans and is responsible for causing a type of pneumonia commonly referred to as Legionnaires' disease. Lung infection with ''L. jordanis'' is sometimes misdiagnosed as an ''Aspergillus'' mold infection. This mold also causes a fatal type of pneumonia which ''L. jordanis'' is able to mimic. Using human sera, indirect fluorescent antibody tests strongly indicated that unrecognized human infections with ''L. jordanis'' may be occurring. A study of patients from Memorial Sloan-Kettering Cancer Center in New York, NY revealed a possible risk of nosocomial infections from shower heads found to contain ''L. jordanis''. After this finding, monthly shower head disinfection procedures were instituted, but about 19% of shower heads remained positive for ''Legionella''. Infections of individuals who are not immunocompromised are also possible.

Metabolism and genomics

Newton, et al. cultured ''L. jordanis'' and various other species of ''Legionella'' in BCYE or ACES broth. DNA extraction and PCR amplification were done under standard conditions. However, due to low GC-content and the mismatching of base pairs, the temperature used during subtractive hybridization was adjusted to 35 °C. Small amounts of biosynthetic enzymes L-cysteine synthase and acetyltransferase were detected in ''L. jordanis'' and ''L. pneumophila''; 19 open reading frames (ORFs) were found in ''L. jordanis'', with a range of punitive functions making up around 47.5% of the 41 sequences represented by 40 ORFs. ''L. jordanis'' was found to contain the gene loci ''sidH'', ''sidE'', ''sidB'', and ''sidG'' which express a Dot/Icm effector protein. This effector protein is essential for ''L. pneumophila'' to infiltrate host cells, so it is thought to be used as a virulence factor in ''L. jordanis'', also. Both strains of ''L. jordanis'' tested positive for proteolysis and hemolysis. They did not test positive for cytotoxicity. Several species of ''Legionella'' “produced different proteolytic cleavage patterns on synthetic peptide substrates.” This suggests some genetic differences exist between the proteases produced by the different species of ''Legionella'', despite them having some similarities. ''L. jordanis'' also appears to contain complex chains of lipopolysaccharides. ''Legionella'' species use amino acids as both carbon and energy sources.

Ecology

The first two isolates of ''L. jordanis'' were from the waters of the Jordan River in Indiana. The strain was designated as BL-540. This area of the river was near an outbreak of Legionnaires' disease, which is caused by ''L. pneumonphila''. Another isolate was found in sewage located in DeKalb County, Georgia. This strain was designated as ABB-9. ''Legionella'' species are aquatic organisms and typically inhabit freshwater environments with humans being accidental hosts. Most isolates of ''Legionella'' have been from air-conditioning cooling towers and potable-water distribution systems, but they can also be found in other thermally polluted water sources such as air conditioners, spa equipment, fountains, humidifiers, or showers. They can also be collected on the surfaces of lakes, mud, and streams. They can grow in temperatures ranging from 5 to 63 °C; optimal growth occurs between 25 and 40 °C.

See also

* Bacterial pneumonia

References

External links

Type strain of ''Legionella jordanis'' at Bac''Dive'' - the Bacterial Diversity Metadatabase

{{Taxonbar, from=Q15395914

Legionellales
Bacteria described in 1982