The commenter did not expound on any specific evidence that would suggest a bacterial lung infection. 2 weeks of malaise and non specific upper respiratory symptoms is not strong evidence of a bacterial pneumonia, sorry.

For external infections, observation by visible inspection is still evidence, a sign, not a symptom. So, not sure what your point is. Erysipelas is invariably diagnosed by signs, not symptoms. Very rarely are bacterial infections diagnosed by symptoms alone.