What are the signs of a bacterial infection? Experts explain.

Madonna's longtime manager Guy Oseary announced Thursday on Instagram that the Queen of Pop was quietly hospitalized on Saturday after developing a serious bacterial infection. That led to a "several day stay in the ICU."

Oseary said that while the 64-year-old's health is "improving," she's "still under medical care." Her Celebration Tour, which is scheduled to start on July 16, is being postponed as a result. A source later told People that Madonna is now back home and feeling better.

Details on Madonna's infection are scarce, but her hospitalization raises a lot of questions about bacterial infections in general. So what are the most common bacterial infections and what are their symptoms? Doctors break it down.

What are the most common bacterial infections?

“Bacterial infection” is a broad term, and experts say there are a lot of illnesses that fit into this category. Still, Dr. Thomas Russo, chief of infectious diseases at the Jacobs School of Medicine and Biomedical Sciences at the University at Buffalo in Buffalo, N.Y., tells Yahoo Life that some are more common than others. Those include the following:

• Soft-tissue infections, including cellulitis, are often caused by the bacteria staphylococcus (aka “staph”) or streptococcus (“strep”). “These can be caused by a break in someone’s skin, which may be apparent or not apparent,” Russo says.

• Urinary tract infections. UTIs are usually caused by Escherichia coli (E. coli) and can include bladder and kidney infections, he says.

• Pneumonia. The lung infection causes the air sacs in the lungs to fill with fluid or pus and can be life-threatening, Russo says. It’s often caused by Streptococcus pneumoniae or Legionella.

While less common, serious bacterial infections can also include meningitis (an inflammation of the protective membranes covering the brain and spinal cord known as the meninges), a heart valve infection or a bloodstream infection, Dr. Amesh A. Adalja, a senior scholar at the Johns Hopkins Center for Health Security, tells Yahoo Life. These can be serious and life-threatening, Russo says.

How can you tell a bacterial infection from a viral infection?

That’s tricky. “It’s not possible to easily distinguish a viral from a bacterial infection without testing,” Adalja says. Meaning, you'll need to see a doctor to know for sure if your infection is caused by bacteria.

However, Russo says there are some clues that you could be dealing with a bacterial infection over a viral infection. “Most common viral infections cause respiratory tract infections,” he says. “Viruses less commonly cause pneumonia, with the exception of the flu and COVID.”

With a lung infection, you’re more likely to cough up green, yellow or bloody mucus, if it's caused by a bacterial infection, Russo says.

More than 85% of urinary tract infections are caused by bacteria from the intestine or vagina, making bacteria a very common cause of UTIs, Dr. Richard Watkins, a professor of internal medicine at Northeast Ohio Medical University, tells Yahoo Life. So, if you have a UTI, it's most likely due to bacteria.

In general, “bacterial infections cause symptoms that cause people to seek medical attention,” Adalja says. “For example, people with bacterial pneumonia can become short of breath and visit the emergency department, or someone with a bacterial urinary tract infection may have burning with urination and visit the emergency department,” he says.

What are the signs that you should seek medical care for a bacterial infection?

Every bacterial infection is slightly different. As a whole, it’s a good idea to seek medical attention for any infection that causes a fever of 100.4°F or higher, a fever with a headache or a fever with shaking chills, Watkins says. Russo says that more common bacterial infections may have the following symptoms:

• Soft-tissue infection: An area of skin that’s painful to the touch, warm and red

• Urinary tract infection: Pain during urination, frequent urination, cloudy or smelly urine and flank pain

• Pneumonia. Cough with phlegm, fever and headache

“General symptoms with a bacterial infection are fever, malaise, headache and, occasionally, muscle aches,” Russo says.

How are bacterial infections treated?

Once someone is diagnosed with a bacterial infection, that person is usually put on antibiotics, Watkins says. “Generally, when someone is admitted to the hospital for a bacterial infection, they are treated with intravenous antibiotics, then transitioned to oral ones when they are better,” he says. “Doctors treat less severe infections with oral antibiotics in outpatient settings.”

But some bacteria are resistant to antibiotics, which can make treatment more complicated — doctors may need to try different classes of antibiotics or switch to a different form of antibiotic. “Sometimes bacteria can be resistant to oral antibiotics and IV ones are the only option,” Watkins says.

If someone has a serious bacterial infection of the skin or abdomen, that person may need surgery in some cases, Adalja says.

“If you’re not feeling well and you’re uncertain of what you have, it’s best to reach out to a health care provider as soon as possible,” Russo says. “Bacterial infections can progress and lead to more serious complications, even if you’re young and healthy. It’s best to err on the side of caution.”

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