Study On The Distribution And Genetical Typing Of Legionella In Environmental Water Of Guangzhou City By AFLP Markers

Legionellae are facultative intracellular Gram-negative bacteria that are ubiquitous inhabitants of natural and man-made water systems. From this environment, Legionellae can be transmitted to humans by inhaled infectious droplets. On the other ways, human also may be infected by directly drinking or contacting the infectious water for the injured skin or mucosa. More than 50 species and 70 sero-groups have been identified in the familly of Legionellace, however, some new species are still being detected in the envrionmental water. Most diagnostic tests are directed at the species that causes most of the reported human cases of legionellosis, L. pneumophila serogroup 1. For this reason, information on the incidence of human respiratory disease attributable to other species and serogroups of legionellae is lacking. Approximately one-half of the 50 species of legionellae have been associated with human disease. Since all legionellae are presumed to be capable of intracellular growth in some host cell, it is likely that most legionellae can cause human disease under the appropriate conditions. For some reasons, Legionnaire disease are classified as infectious diseases in some western countries. For lacking the corresponding vaccine, there is a critical need for surveillance for travel-related legionellosis in the envrionmental water.44 water samples, collecting for the lakes of 8 parks in Guangzhou city during the August to October in 2006, were pre-treated and cultivated according to the Procedure for the recovery of Legionella from the environment published by the Center for Disease Control and Prevention of USA in 2005, and the charichacterists of this microorganise were also well considered. The strains of presumptive Legionella were analyized by latex agglutination test, biochemical characterization, composition of cellular fatty acids and amplified fragment length polymorphism, and the further genetic subtyping were completed according to the Standard European Working Group on Legionella Infections Amplified Fragment Length Polymorphism Protocal(version 1.2) by TIAN GEN 2×PCR Mix Master. The results showed that Legionella were found in all parks and the cultured positive rate was 61.36% of 44 samples. 31 different stains were detected, including 20 strains of L. pneumophila, 1 strain of L. oakridgensis,1 strain of L. sainthelensi, 4 strains of L. longbeachae and 5 strains of L. feeleii.41 strains of L. pneumophila were anaylized by an amplified fragment length polymorphism protocol. 31 genetic subtypes were obtained, which 10 types were nearly identical to the EWGLI AFLP types at the same analytical zone. The shortcoming is that the technique of AFLP needed to be strictly controled the laboratory condition of procedure. However, AFLP is still a useful DNA finger print technique with a strong power of discrimination and it can provide valueable epidemiological data for Legionella'disease.