Which bacteria is worst humans or dogs?

It's not accurate to label bacteria as "worst" for humans or dogs, as different bacteria can cause varying degrees of harm depending on the host and the environment. Some bacteria are harmful to humans but may be harmless to dogs, and vice versa. The impact of bacteria largely depends on the individual's immune system, health status, and specific bacterial strain involved. Ultimately, both humans and dogs can be affected by pathogenic bacteria, making it essential to maintain good hygiene and preventive care for both species.