Pope Francis’ respiratory infection is presenting a “complex clinical picture” that will require further hospitalization, the Vatican said Monday, as concerns grew about the increasingly frail health of the 88-year-old pontiff.

The Vatican says Pope Francis’ respiratory tract infection is presenting a “complex clinical picture” that will require further hospitalization

Francis was serene after arriving at Rome’s Gemelli hospital after presiding over his morning audiences, Vatican spokesperson Matteo Bruni said.

Vatican spokesman Matteo Bruni said the results of tests conducted in recent days and Monday indicate the pope is suffering from a “polymicrobial respiratory tract infection” that has necessitated a further change in his drug therapy.

The Vatican says Pope Francis’ respiratory tract infection is presenting a “complex clinical picture” that will require further hospitalization.

The Vatican says Pope Francis’ respiratory tract infection is presenting a “complex clinical picture” that will require further hospitalization.

The Vatican says Pope Francis' respiratory tract infection is presenting a "complex clinical picture" that will require further hospitalization.

Pope Francis’ respiratory tract infection is presenting a “complex clinical picture” that will require further hospitalization, the Vatican said Monday as concerns grew about the increasingly

Pope Francis' respiratory infection is presenting a "complex clinical picture" that will require further hospitalization, the Vatican said Monday, as concerns grew about the increasingly frail health of the 88-year-old pontiff.

The Argentine pope, a known workaholic who keeps up a grueling pace despite his many ailments, was admitted to Rome’s Gemelli hospital on Friday after a weeklong bout of bronchitis worsened. It was his fourth hospitalization since his 2013 election and raised questions about his increasingly precarious health.

What is a polymicrobial respiratory tract infection? Essentially, it means there’s a mix of bacteria, viruses, fungi, or parasites growing in someone’s lungs. "Often times, pe