Aerangis distincta rot

[estación seca]

If it's bacterial rot, the bacteria aren't present beyond the margin of the brown mark. But they are all over the brown partm, and anything that touches the brown part can get contaminated, ready to transmit the bacteria to something else. So, you need to treat it as infectious.

Scrub your hands with soap and water. Cut off the leaf below the brown mark and put it straight into the trash. Sterilize your blade afterward by heating in the oven or exposing to alcohol for 20 minutes. Scrub your hands again. Treat the plant if you wish, but with good cultivation the bacteria should not attack.