Editor's note: This popular story from the Daily Briefing's archives was republished on May 24, 2023.

Doctors initially believed a 22-year-old woman's "painful attacks" were caused by an autoimmune disorder, until an infectious disease doctor found the source of the attacks—a bacterium "just rare enough" to go undiagnosed for more than a year.

Expedite patient diagnosis

'A series of painful attacks'

For over a year, the 22-year-old woman "had been repeatedly ill" with "a series of painful attacks," Sanders writes. Initially, doctors attributed the woman's symptoms to a flare-up of pemphigus—an autoimmune disease she had been diagnosed with five years earlier. However, testing quickly ruled out her autoimmune disease as a potential cause of the more recent health issues.

The woman had been on and off antibiotics for an infection that had appeared a month earlier on her stomach. When she first noticed the infection, she went to see her primary care physician, Robert Figura.

After evaluating the "patch of pink about the size of a golf ball" on the woman's left hip, Figura ordered a CT scan, which revealed an infection in the woman's pelvis and abdominal wall.

For the next two weeks, she took two antibiotics, and the infection seemingly cleared—the redness, swelling, and pain eventually went away.

Unfortunately, the bulge soon reappeared and kept growing. When it grew to the size of a tennis ball, Figura told the patient she needed to go to the ED.

Diagnosis

When the woman arrived at Northshore University Hospital, she had a fever of almost 103 degrees, with what appeared to be " a pretty straightforward skin infection," Sanders writes.

However, a quick review of her records unearthed a more complex story. The woman had recently received treatment for several subsequent infections. "She had just been treated for an infection. One month earlier she was treated for an infection around her fallopian tubes that extended into her abdominal wall. Now she appeared to have another infection," Sanders writes.

However, the woman was told that the infection was just a cellulitis—an infection in her skin—and was treated with intravenous antibiotics and finally sent home with two other antibiotics.

According to Sanders, the woman "was discouraged and depressed," over worries that the infection and attacks would return. 

Then, a relative recommended she visit Brett Williams, an infectious disease doctor at Rush University Medical Center.

When Williams was reviewing the patient's records, two things stood out to him. "First, she got better when on antibiotics, but when they were stopped, the infection seemed to come right back," Sanders writes. "It wasn't just that she felt worse. Within weeks or even days of ending her course of antibiotics, she developed fevers and other objective evidence of a new or worsening infection. That was unusual."

Second, he noticed that it looked like her issues started after she got an IUD—suggesting a possible case of pelvic inflammatory disease (PID). Ultimately, Williams was able to eliminate PID as a possibility.

He identified an "unusual bug that could account for both of these oddities"—a bacterium called actinomyces. Typically, the organism can be found in the mouth, colon, and sometimes the vagina. It has also been associated with PID in patients who have IUDs. "It's an aggressive bug and can spread throughout the body," Sanders notes. "If not thoroughly wiped out, it can come back again and again."

Treating 'a bug that's just rare enough' to go undiagnosed for more than a year

During his visit with the patient, Williams explained that it takes much longer to treat actinomyces than most bacteria. "For an extensive infection like this, one that had spread from her uterus through her pelvic wall into her thigh, she would need at least six months of antibiotics," Sanders writes.

The woman took doxycycline for a year and stopped the medication last fall. So far, the infection has not returned, and Williams said he hopes it won't. The patient is "thrilled" to have returned to her usual workout and volleyball routines.

Sanders asked Williams why the woman's diagnosis was so easy for him to make after it stumped so many others. "It's a bug that's just rare enough so that internists won't see it but common enough so that infectious-disease docs like me will run across it pretty regularly," he said. "And that makes all the difference." (Sanders, New York Times Magazine, 4/30)