The former US president Bill Clinton’s health is improving but he will remain in a California hospital for at least another night to receive antibiotics intravenously for a urological infection that spread to his bloodstream, his spokesperson said on Friday.

The 75-year-old Clinton, who served as president from 1993 to 2001, entered the University of California, Irvine, medical center on Tuesday evening after suffering from fatigue. He spoke with Joe Biden on Friday.

Clinton’s spokesperson Angel Ureña said that Clinton’s white blood count has decreased, indicating his health is improving.

“All health indicators are trending in the right direction, including his white blood count which was decreased significantly,” Ureña said on Twitter. “In order to receive further IV antibiotics, he will remain in the hospital overnight.”

Since his admission to the intensive care unit at the hospital, Clinton has received fluids along with antibiotics, his doctors said.

His wife, a former secretary of state and 2016 Democratic presidential nominee Hillary Clinton, was at the hospital on Thursday and Friday, and the two read books and talked about politics, Ureña told Reuters.

It remained unclear when Clinton would be released.

Biden said Clinton would likely go home soon, though it was not clear whether he would be released on Saturday or later.

“He is getting out shortly. … Whether that’s tomorrow or the next day, I don’t know,” Biden told reporters in Connecticut. “He’s doing fine. He really is.”

On Thursday, Ureña said Clinton was “up and about, joking and charming the hospital staff”.

Clinton has dealt with heart problems in the past, including a 2004 quadruple bypass surgery and a 2010 procedure to open a blocked artery.

The Democrat served two terms in the White House, overseeing strong economic growth while engaging in bruising political battles with congressional Republicans.