What is ‘polymicrobial respiratory tract infection’ that Pope Francis is suffering from?

Pope Francis’ hospitalisation continues as he is being treated with a ‘complex clinical’ condition, says the Vatican. He has been diagnosed with a ‘polymicrobial infection’ of his respiratory tract. What is this illness?

What is ‘polymicrobial respiratory tract infection’ that Pope Francis is suffering from?
Pope Francis’ hospitalisation continues as he is being treated with a ‘complex clinical’ condition, says the Vatican. He has been diagnosed with a ‘polymicrobial infection’ of his respiratory tract. What is this illness?