The Pope's 'polymicrobial respiratory tract infection' explained

Vatican authorities say that Pope Francis has a complex infection in his respiratory system and will require more targeted drug treatment. Officials said the 88-year-old Pope is suffering from a "polymicrobial respiratory tract infection," but gave no further details Monday on the severity of his illness or what would change in his treatment.

Here's a look at the Pope's latest diagnosis and what his treatment could involve.

Essentially, it means there's a mix of bacteria, viruses, fungi or parasites growing in someone's lungs.

"Oftentimes, people will get a bronchitis or an airway infection and that can often start a cascade of multiple problems, including infections in the lungs," said Dr. Maor Sauler, who specializes in adult pulmonary and critical care medicine at Yale University's School of Medicine. He said such issues were common in older people whose immune systems might be weaker or had complex health issues.

"It likely means he has more than one organism in his lungs," Sauler said, explaining that the Pope's doctors might have to adjust his treatment to make sure the antibiotics attack all the various organisms.

For someone with the Pope's medical history — he lost part of his right lung decades ago and has previously had pneumonia — it's worrying that he's been hospitalized.

Dr. Nick Hopkinson, medical director of Asthma + Lung UK, said most healthy people would likely recover quickly from bronchitis.

But in people whose lungs are already damaged, "bacteria can come and colonize the airways and you start to see infections which makes it more difficult to treat." In people with lungs that have been previously compromised, they might need help breathing, including oxygen support or chest physiotherapy to help them clear fluids building up in their lungs.

Still, Hopkinson said that getting the Pope on the right medications should help.

"If they've identified particular things to treat, they can treat those and he'll start to recover."

That depends. Antibiotic treatments typically take from a few days up to about two weeks. Hopkinson said the Pope might be given various medicines, including ones that people typically take for asthma or conditions like chronic obstructive pulmonary disease, in addition to getting physiotherapy to help keep his chest as clear as possible.

"Some infections require prolonged treatment because they're just harder to clear from the system," Hopkinson said. "It sounds like they've identified the bugs that are responsible and they'll be able to treat those — but we'll just have to wait and see."

Dr. Peter Openshaw, a lung expert at Imperial College London, said the presence of multiple organisms wasn't unusual in people with complex medical histories but could be hard to manage.

Pneumonia is a likely worry.