In November 2016, hospital A told the North Carolina Division of Public Health that routine annual tuberculosis screening of its neonatal intensive care unit (NICU) staff had found six people with newly positive tuberculin skin tests (TSTs). All six had cared for an infant diagnosed after death with congenital tuberculosis. The state worked with county health departments and the hospital to investigate.
The infant and the mother
The baby was born at hospital A in July 2016 at 25 weeks of gestation to a mother originally from a country with high tuberculosis prevalence. After delivery the mother developed respiratory distress needing intubation; a bronchoalveolar lavage specimen tested negative for acid-fast bacilli. The infant, admitted to the NICU with fever and respiratory failure and supported by high-frequency oscillatory ventilation, died after 17 days.
A month after the birth, Mycobacterium tuberculosis grew from a culture of the mother's lavage specimen. An investigation around her found no positive skin tests among staff. Then acid-fast bacilli were found in the stored placenta, and records from fertility treatment 2 years earlier at a hospital in another state showed granulomatous salpingitis consistent with genitourinary tuberculosis — history the delivery and NICU staff had not known. No investigation had been done around the infant.
The contact investigation
Contacts were anyone who treated the infant or spent time in the open NICU with it.
| Group | Result |
|---|---|
| Health care staff | 132 of 135 (98%) evaluated; 7 (5%), including the original six, newly positive (skin test induration 10–20 mm). All had performed at least one aerosol-generating procedure, such as intubation or open suctioning, on the infant; none had been exposed to the mother or had other known exposure |
| NICU volunteers | All 29 notified; 15 (52%) screened, all negative |
| NICU visitors | 23 tested; 1 (4%) positive by interferon-gamma release assay (IGRA) — someone with no other risk factors who had spent hours a day over 11 days beside a neighboring infant |
| Other NICU infants | 26 present; families of 25 (96%) notified, 1 not found; 22 (85%) assessed — none had a positive test or active disease. 18 (82%) began preemptive treatment for latent TB and 4 (18%) were monitored without treatment |
For exposed infants, the state recommended a TST and IGRA, a clinical exam with chest x-ray, 9 months of preventive isoniazid, and monitoring to age 2. Treatment was recommended even without a positive test because infants' tests can be falsely negative and infants are at higher risk of active disease. All infected adults received treatment for latent TB through local health departments.
Why it spread
Congenital tuberculosis is rare, but spread from infected infants to health workers has been documented; spread to visitors or other patients had previously been reported only through contaminated medical equipment. Here, likely factors were the high bacterial load of congenital infection, repeated aerosol-generating procedures, and high-frequency oscillatory ventilation with an unfiltered exhaust.
Lessons
- Tuberculosis has been linked to infertility, especially in high-prevalence countries. Finding and treating latent and active TB in pregnant women and those trying to conceive can protect their babies.
- Infants born to mothers with TB risk factors who have a compatible illness should be thoroughly evaluated for tuberculosis.
- Even when TB isn't suspected, routine measures such as closed suctioning and filtered ventilator exhaust may reduce exposure.
- When exposure happens, following contact investigation guidelines quickly identifies everyone at risk — including visitors who shared the air with an infected infant for long periods or during aerosol-generating procedures.
Sources
Based on Rinsky JL, Farmer D, Dixon J, et al., "Notes from the Field: Contact Investigation for an Infant with Congenital Tuberculosis Infection — North Carolina, 2016," MMWR Vol. 67, No. 23, CDC; a work of the United States government in the public domain.
Licence: CC0 1.0 (public domain) · Adapted from www.cdc.gov
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