173 does like to spawn a lot in the latest updates, and when he does the thing you mentioned, spawning on you when you go through a door, i usually turn my sight to the room i just came from then walk backwards through the door.
He never seems to spawn when i do that.
Minor question, the room you came from, was it like this?

He spawns in that room? Ouch.
If you get the chance to run back to the start room where he killed the class d guys and the guard, try luring him into his containment chamber and then run out of it when gets into it.
Run back into the hallway and close the door.
You should have enough time to collect the items and exit through the other door.
But if he gets back into the hallway , you could try lure him again, then run through the hall while still looking at where 173 is.

I hope this helps you get past him, hes a sneaky one.

Does he trap you when blinking?
If that happens i don't really know what to do at that point.
If he is following you, don't break your line of sight, even if you turn corners.

Helped you the best i can, sorry if it wasn't enough.