HOUSTON -- Little is known about the condition Former President George H.W. Bush is currently in, but what we know for sure is it can be serious.

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Doctors say anytime bacteria enters the bloodstream, it is called sepsis, which can be life-threatening. But the good news is the former president is responding to treatments.

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“He has a source of an infection, usually in elderly patients, the two most common sources are the lungs or the urinary tract infection. So either pneumonia or coming from the urine," said Dr. Laila Woc-Colburn, Baylor College of Medicine Associate Professor of Infectious Diseases.

Dr. Woc-Colburn says common symptoms that occur along with sepsis include fatigue, fever, unresponsiveness and low blood pressure.

She says treatment for that begins immediately at the hospital.

“If you have low blood pressure, we start them with IV fluids, and then we give them what we call broad spectrum antibiotics. Meaning that it covers all basis, it covers the staph, the strep and e. Coli," Dr. Woc-Colburn said.

Through further tests, doctors find the source.

“The blood cultures are going to determine what type of bacteria they have," Dr. Woc-Colburn said.

Once they know, doctors can then tailor the treatment plan to the patient.

But she says without knowing the type of bacteria, it’s hard to know exactly where the infection came from.

“We do have some bacteria that have resistance to antibiotics that are harder to treat," Dr. Woc-Colburn said.

Dr. Woc-Colburn says it is good to hear that the 41st president is responding to treatments, but she says the first 24 to 48 hours are critical.