The germ is very small and can float distances thru the air. That’s why active cases are isolated in negative pressure rooms. A surgical mask won’t protect you. I’m not an expert but I would think everyone on the plane was exposed.
scenario at hand
Pt with extreme-drug-resistant TB - in his lungs, trachea, mouth, nose, on his fingers, etc etc....long airline trip - talking, breathing, clearing throat, coughing (hopefully covering his mouth with hands - up to restroom, with organism on hands/fingers, uses latch on door - whoops! tourist B comes along, maybe chit-chats with him at close quarters near door to restroom.....then uses both inner and outer doorlatches after the patient.....returns to his seat (maybe 15 rows from the patients seat), deposits it onto the armrest he/she shares with person in next seat.....
CDC and politicals are downplaying this.....they will tell you that it is “inhaled”....true enough....but far from the whole truth.....this guy should have been quarantined when they found him in Italy.....his trail of possible and even likely exposure will ultimately be of interest to people in 4 countries besides the US and those on the same airliners. Granted, the contagion of this case is no greater or less than any other TB or respiratory disease.....but they call this strain “Extremely Drug Resistant TB” for a very good reason.....its resistance to TB drugs.....dramatically increases its morbidity and mortality.