Sepsis, characterized by a whole-body inflammatory state caused by infection, can progress to blood circulatory dysfunction and eventually death. It is considered especially dangerous for the elderly or patients in critical condition and can lead to septic shock, which has a fatality rate of more than 60 percent.
The development, announced by Dr. Joko Raharjo at the Pertamina Hospital in the Indonesian capital, signaled another grave turn for Suharto, who has already suffered multiple organ failure.
Doctors responded by maximizing intensive care and administering intravenous anti-infection drugs, said another doctor, Marjo Subiandono.
Suharto was rushed to a hospital suffering from anemia and a dangerously low heart rate Jan. 4.
After initially responding well to a blood transfusion and dialysis, his health sharply deteriorated. Aides said privately he appeared several times to be on the verge of death.
The retired five-star general's lungs and kidneys were barely functioning Monday, though his heart had shown signs of improvement and he responded to family members and regional leaders who visited him at his bedside.
One of Suharto's lungs was infected with mild pneumonia, and physicians were trying to make sure it did not spread to his other lung, said Hadiarto Mangunnegoro, a pulmonologist.
Suharto, whose 32-year regime was widely regarded as one of the 20th century's most brutal and corrupt, was ousted a decade ago amid student protests and nationwide riots, opening the way for democracy in this predominantly Muslim nation of 235 million people.
He withdrew from public life, venturing from his mansion on a leafy lane in Jakarta only to attend family functions or for medical emergencies.
A series of strokes in recent years left Suharto with permanent brain damage and impaired speech - and kept him from facing trial.
He has been accused of overseeing the killings of more than a half million leftist opponents soon after seizing power in a 1965 coup. Hundreds of thousands more were killed or imprisoned in the decades that followed - crimes for which no one has ever been punished.
Transparency International has said Suharto and his family amassed billions of dollars in state funds, an allegation he has denied.
On Monday, Malaysia's former prime minister, Mahathir Mohamad, visited Suharto, a longtime friend. Former Singapore Prime Minister Lee Kwan Yew dropped a day earlier.
"(I am) very sad, because when I last met him he could still think clearly," Mahathir told MetroTV after praying at Suharto's bedside and whispering in his ear. "It never crossed my mind that in one year's time his condition would deteriorate so much."