What is a blood infection?

HOUSTON – As former President George H.W. Bush recovers from a blood infection at Methodist Hospital, KPRC2 is learning more about the infection and what type of treatment he likely is receiving.

Here's what you need to know.

Are blood infections common?

Yes, according to Dr. Laila Woc-Colburn, associate professor of internal medicine at Baylor College of Medicine.

"We often see this in our elderly population," Woc-Colburn said.

Woc-Colburn specializes in infectious diseases, but she is not Bush's personal doctor.

What is a blood infection?

Woc-Colburn said blood is infected when bacteria make their way into the bloodstream.

"When you have a bloodstream infection, it means that we've been able to detect bacteria -- either by a culture or by a method we call molecular testing," Woc-Colburn said.

From where do the bacteria come?

Bacteria should not be in blood and when they are, there's a problem.

According to Woc-Colburn, elderly patients -- like Bush -- usually see bacteria enter the blood from either a form of pneumonia or a urinary tract infection.

The infection is treated with antibiotics, once doctors determine the type of bacteria in question.

"Knowing what it is, it helps us in the medical field treat it more aggressively and actually target it," Woc-Colburn said.

Is age a factor in the rate at which a patient being treated for a blood infection can recover?

Yes. Previous illness and current health status are factors, too.

"Because their immune system is not as robust, and they might be debilitated for other reasons, we try to treat them aggressively before it gets out of hand," Woc-Colburn said.

Woc-Colburn told KPRC2 once the bacteria strain in question is identified and antibiotics are prescribed, the recovery process can begin.