Bacterial Infections: Hard to Detect Among AN Patients

Fever and immune responses help patients recover from infectious disease. Recovery seems to be aided by an array of innate and adaptive immune responses and the suppression of viral and bacterial growth by body temperatures above the optimal temperature range of the infectious organism. However, bacterial infections may be overlooked in patients with anorexia nervosa because of the lack of a common marker-fever.

A team of Australian and Canadian researchers examined the charts of 311 consecutive hospital admissions of AN patients and compared these to patients with bacterial infections in the hospital (Int J Eat Disord 2005;37:261).

Lack of fever among the AN patients was one reason the bacterial infections were not diagnosed sooner. Because it took longer to detect the infections, the complications from bacterial infection were greater among the AN patients than among those patients without AN who were hospitalized with bacterial infections.

Dr. Rhonda F. Brown and colleagues reviewed the medical records of 311 consecutive AN patients admitted to Royal Prince Alfred Hospital, Sydney, Australia, from January 1, 1992 to December 31, 2002. Detailed temperature data were collected for all cases of infection, from the onset of the bacterial infection until discharge from the hospital. Each case was matched to a general medical admission patient who had a bacterial infection; the two groups were matched by age, gender, site of infection, and when specified, the infective organism.

Most AN patients had serious infections

Twenty-three AN patients had documented bacterial infections. Of these 23 cases, 16 presented with serious infections: 5 with pneumonia, 5 with urinary tract infections, 3 with cellulitis, 2 with foot infections, and 1 with inflamed tonsils. All but 5 patients had body temperatures lower than 98.6° F, and some had temperatures as low as 95.5°F.

None of the patients died during hospitalization, but the course of infection was complex in some. For example, 2 patients had two infections at admission—1 had both pneumonia and a urinary tract infection, and 1 had pneumonia followed by an infected central line. There was also a high rate of comorbid disease. AN patients with infections often were dehydrated and had a range of metabolic disorders, including hypokalemia, hyponatremia, and hypoglycemia. Other common diagnoses were osteopenia/osteoporosis, anemia or depression. Low serum calcium, iron, magnesium, phosphate or zinc levels were also reported.

To complicate matters even more, some patients presented with occult disease or symptoms that were difficult to diagnose on admission. For example, 2 patients were admitted with unexplained weight loss, delirium, and weakness and 1 with unexplained edema, rapid weight increase and hypoproteinemia.

AN patients who did have a fever had more serious bacterial infections, although most patients with serious bacterial infections did not have fever.

Approximately one-third of the patients were unconscious or collapsed on admission. Patients who were admitted with bacterial infections had serious disease. They were more likely to develop complications such as renal failure, and to be readmitted for treatment of infection than non-anorectic control patients with infections, and AN patients had longer hospital stays marked by more serious complications.

A need for special attention and testing

Currently there are no recommendations for special prophylaxis, monitoring, early treatment, or special treatment of bacterial infections in AN patients. The authors recommend that clinicians be alert to the possibility of hidden bacterial infections among AN patients and that an early complete blood count and bacterial cultures be taken be taken when infection is suspected.