What are the known methods that confirm a certain bacterial strain is pathogenic or not?
Most of the enterogastric and glandular bacteria are hemolytic in nature, for example Helicobacter pylori are a type of bacteria that may infect around two-thirds of the people in the world. They grow enormously, burst open the RBSc and causes blood perfusion, yes, haemolysis test on blood agar plates can be considered as a pathogenecity test for bacteria.
yes...for S. aureus, Bacillus cereus, E. coli and P. aeruginosa, hemolysin is deficinitely a main virulence factor...also for El Tor V. cholerae and Aeromonas spp.
Haemolysis test indeed test for virulence which could be performed very easy and meaningful results could be obtained. If you need to look for specific virulence factors go for gene based detection using PCR. While beta haemolysis results in complete haemolysis and could be seen as clearing zone around the colony in a blood agar plate, gamma haemolysis result in partial haemolysis and could not be identified as easily as beta haemolysis.
I agree with Traci's answer. Also You have to keep in mind that not all pathogenic bacteria are haemolytic, see for example the different pathogenic E. coli.
Haemolysis may be an indicator for virulence, but there could be non- haemolytic strains of a pathogenic organism (ie. inability to produce haemolysis does not necessarily make an organism to be non-pathogenic). Also, some pathogenic organisms may even lose and regain hemolytic ability (We once encountered Aeromonas species that showed this behaviour). I would, therefore, agree with Mohamed that detection of gene for virulence factor is more definitive way to test for virulence.
I agree with Traci,s answer ,some bacteria hemolysis blood on blood agar but their consider non pathogenic.
Considerando-se que é de conhecimento geral que nem todas as bactérias são hemolíticas e existem métodos complementares para a comprovação, concordo plenamente com o comunicado de Traci L Testerman que citou métodos complementares relevantes de uso rotineiro. Abraços. Robson Maia
I agree with tracy..the ability to lyse red blood cells is important for virulence in several bacterial species but not all..
I think there is a role of RBC's zeta potential in vivo pathogenecity mechinism including haemolysis which leading to damaging of erythrocytes.
Ability to lyse RBCs (Haemolysis) may have a role in pathogenic potential of an organism especially in invasion and multiplication of the organisms since the lysed RBCs provide nutrients for the organism. However, haemolysis on plate does not necessarily have to be a proof of pathogenicity. Many microorganisms found to be pathogenic have not achieved that by their haemolytic ability. For example, Clostridium tetani is haemolytic, but the pathogenicity is derived majorly from the action of the tetanospasmin toxin produced. Strept pneumo is alpha haemolytic, yet not a common blood pathogen. To say that the ability of an organism to cause haemolysis on plate means it is pathogenic is not be true.
Depends on the microorganism. Check virulence factors: if hemolysins are included this may be an indication. However bacteria may have various mechanisms for hemolysis, some are virulence factors, some are not, By the hemolysis test alone you don't know which is acting.
I think it depends on the organism. For instance, if you are culturing Listeria monocytogenes on blood agar, the presence of haemolysis indicates that the organism is virulent.
It depends on the organism. You need to check the virulence factors.
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