CNN  — 

Former President Bill Clinton was admitted to the University of California Irvine Medical Center’s intensive care unit for a urinary tract infection that spread to his bloodstream, his doctors told CNN on Thursday.

“He was admitted to the ICU for close monitoring and administered IV antibiotics and fluids. He remains at the hospital for continuous monitoring,” according to a joint statement Thursday evening from Dr. Alpesh Amin, chair of medicine at UC Irvine Medical Center, and Dr. Lisa Bardack, Clinton’s personal primary physician. They said that Clinton was in the ICU for privacy and safety, not because he needs intensive care.

Clinton has been in good spirits, talking to family and staff, and has been up and walking, according to both his doctors and his staff. The 42nd President is annoyed that he has to be in the hospital but is chatting and joking, a spokesperson, Angel Urena, said. He has two books with him, including Colson Whitehead’s “Harlem Shuffle,” and Hillary Clinton visited with him Friday.

President Joe Biden also spoke with the former President in a phone call on Friday.

Hillary Clinton leaves after it was announced that former President Bill Clinton was admitted to the University of California Irvine Medical Center in Orange, California, on October 14, 2021.

Clinton’s doctors had said “after two days of treatment, his white blood cell count is trending down and he is responding to antibiotics well,” adding that they “hope to have him go home soon.”

Urena said in a statement that as of Friday, “all health indicators are trending in the right direction, including his white blood count which has decreased significantly,” and the former President would remain in the hospital overnight to receive further IV antibiotics.

According to a source familiar with the situation, the kind of antibiotic needed to treat Clinton’s type of infection has to be administered via IV and not orally, which is why he’s remaining in the hospital.

Clinton, who was in California for a private event for his foundation, had been feeling fatigued on Tuesday and was admitted to the hospital after testing, according to his office. Hillary Clinton went to the event on Thursday evening to “represent both of them” and then went to the hospital to be with the former President, a Clinton spokesman told CNN.

The former President’s doctors said urologic infections are very common in older people, and they are easily treated, although they can quickly spread to the bloodstream. His vital measurements are all stable, the doctors said.

Clinton, 75, had quadruple bypass heart surgery in 2004 and had two stents inserted to open one artery in 2010. But his doctors stressed his hospitalization is not heart- or Covid-19-related.

Urena said Thursday that the former President was “on the mend” and “in good spirits.”

“On Tuesday evening, President Clinton was admitted to UCI Medical Center to receive treatment for a non-Covid-related infection. He is on the mend, in good spirits, and is incredibly thankful to the doctors, nurses, and staff providing him with excellent care,” Urena said.

This story has been updated with additional reporting Friday.

CNN’s Sara Sidner and Dan Merica contributed to this report.