Bloats are the strongest of the early wave enemies that you will encounter. Their primary means of attacking is spewing damaging bile at anyone within a few feet of them, making hit-and-run tactics ineffective, and they can explode in a shower of the stuff when killed. Fortunately, the explosion can damage specimens in range as well.
The easiest way to kill a Bloat is with a head shot from a distance. Even if this does not kill the Bloat outright, it will leave him incapable of spewing bile and force him to rely on his much weaker melee attack. Even better, a headless Bloat will usually bleed out before reaching the players if decapitated from a sufficient distance, allowing players to save ammo.
Avoid melee attacks, as the Bloat explodes when killed and will damage nearby players. If possible, lure the Bloat into a group with other enemies and then cause it to explode. Both Gorefasts and Fleshpounds are known to attack bloats that damage them.