Polymicrobial infection: What's the 'complex clinical situation' that has affected Pope Francis' health?

Since Friday, Pope Francis has been hospitalised following a respiratory infection, and the Vatican has cancelled his upcoming events and public appearances. The 88-year-old, who had a part of his right lung removed in the past and has suffered quite a few bouts of pneumonia, is currently stable and is advised to rest and take a break from his pastoral responsibilities. The Vatican said that he is currently treated for a 'complex clinical situation' due to a 'polymicrobial infection' in his respiratory tract. It is a condition caused by two or more microorganisms, like fungi, parasites, bacteria or viruses, simultaneously.
According to the National Institutes of Health, they have been recognised with increasing frequency in recent years, and apparently, it's difficult to treat them or even diagnose them. It is often found in older people with weak immune systems and those who have suffered recent surgeries or injuries. Natural germs on the skin, gut, mouth, and other parts of the human body also cause it. 

How to stay safe from the infection
1) Regular practice of good hygiene is of utmost importance. Any wounds or injuries should be cleaned and covered to prevent germs from festering. Also, check whether the dressing, surgeries and similar procedures on your body are done in sterile environments. 
2) If you still notice any infections, get prompt treatments before they worsen.
3) Ensure your immune system is healthy through a proper diet, stress management and exercise.
4) Avoid sharing sanitary items like tissues, napkins and towels with others. 
5) Avoid touching healing blemishes or wounds with your hand or other items.