I am retired, but the only times we saw this infection was after colonoscopies. Improper washing and autoclave were the main culprits. A very difficult to treat infection, I recall that some patients who had died.
This is absurd science at its best. Corrections for "weight, smoking, alcohol use, and history of lung diseases" are enormous. Small changes in the corrections for these larger effects (confounders) will lead to much greater than the 14% greater risk in lung cancer found in this study. Epidemiologists need to perform sensitivity analysis on the parameters used in their corrections.