BOSTON – Because asymptomatic Clostridium difficile colonization is so common among infants, routine testing in cases of diarrhea isn’t warranted, according to Dr. L. Clifford McDonald.
Up to 70% of newborns may be colonized with C. difficile, but that percentage drops rapidly over the first 2 years of life as babies develop a healthy intestinal microbiome.
"In children younger than 2 years, consider other diagnoses first, especially if there hasn’t been any exposure to antibiotics," said Dr. McDonald, senior adviser for science and integrity in the division of health care quality promotion at the Centers for Disease Control and Prevention. "Colonization in this age group doesn’t carry as much weight as it does in other age groups."
The clinical picture begins to change after age 2 when the intestinal flora is well established. "Certainly over 2 years old, C. difficile is not part of the normal microbiota. In this case, you should test and treat as you would in an adult," Dr. McDonald said at the annual meeting of the American Academy of Pediatrics.
Hospital discharge data show about 500,000 health care–acquired C. difficile infections occur each year. This results in about 20,000 excess deaths annually – mostly in older people – and several billion dollars in excess health care costs. Most of the patients are older than 65, but the number of infections is rising in younger people as well.
Antibiotic exposure plays a large part in the changing frequency and toxicity of the infections, Dr. McDonald said. "The bacteria first developed a resistance to fluoroquinolones, and now we are seeing clindamycin-resistant strains," he noted.
One study has examined C. difficile infection outcomes in a national database of children’s hospital discharge records. Children with the infections were 20% more likely to die, 36% more likely to have a colectomy, and four times more likely to have an increased length of stay. They were 11 times more likely to have inflammatory bowel disease and significantly more likely to be on immunosupressant or antibiotic regimens (Arch. Ped. Adolesc. Med. 2011;165:451-7).
"So although these infections are not as common in children as they are in older individuals, you can see there are still some very serious sequelae," he said.
Researchers have identified some risk factors for toxigenic C. difficile strains in young children and infants, including formula feeding and cesarean section. Diseases that require immunosuppression and antibiotics also predispose to the infection, probably because they perturb the normal gut flora. Most transmission occurs in a day care or health care setting, including the hospital.
"We are also seeing new data that infants colonized with C. difficile in the first year of life seem to have higher rates of allergy at up to 5 years old," Dr. McDonald said. "The presence of C. difficile is probably a marker of a perturbation of the child’s intestinal flora and delayed establishment of the normal microbiome," which predisposes to atopy.
Until recently, the treatments of choice have been metronidazole and vancomycin. Although effective for quelling the infection, both have a recurrence rate of 20%-30%. Most recurrences occur soon after treatment, while the microbiota are still off balance, Dr. McDonald said.
A new drug, fidaxomicin, may offer a better solution. Approved by the Food and Drug Administration last May, the drug is not systemically absorbed – a benefit in C. difficile infections. Patients treated with fidaxomicin appear to have a lower recurrence rate – 15% vs. 25% with vancomycin in a phase III trial published earlier this year (N. Engl. J. Med. 2011;364:422-31).
However, Dr. McDonald noted, the drug was not studied in young children.
Dr. McDonald said he had no relevant financial disclosures.