Microorganisms tend to be host specific, to varying degrees. Some found in or on humans have no harmful effect on poultry. Others may not harm poultry, but cause serious problems in people. Others may be specific for dogs or cattle or turtles or whatever. So the isolation of organisms on poultry does not necessarily mean that there is any danger to consumers.
Some organisms do affect more than one species.
When these mechanisms are working, massive doses of a disease- causing microorganism must be ingested before the defense system is overwhelmed and disease actually results. Depending on the individual organism, we have seen estimates for the numbers of organisms required to cause a health problem ranging from thousands to millions. They don't give that information. We have no way to confirm or disprove this number. In a recent study from the University of Arkansas, groups of 12 whole broilers of three different brands were purchased in a local grocery store and checked for Salmonella.