Reports on HIV/AIDS: 1990

OCTOBER 12, 1990, MMWR, Vol. 39, No. 40, pp. 718-722
rooms if they wore masks; however, patients sometimes removed masks for short
periods while out of their rooms. Aerosolized pentamidine treatments and diagnostic
sputum inductions were performed at the bedside. All 24 rooms on the HIV ward were
used for AFB isolation. Testing of 23 of these rooms with smoke tubes indicated that
six had positive pressure relative to the hallway.
Patients with TB (including some subsequently reported to have MDR-TB) received
follow-up care, including aerosolized pentamidine administration and sputum inductions, at the HIV clinic. Based on tests using smoke tubes, the pentamidine rooms had
positive pressure relative to the central treatment area, which, in turn, had positive
pressure relative to the adjacent waiting area. The engineering diagrams indicated
that air from the sputum induction room was recirculated into other areas of the HIV
clinic.
Primary isolation and identification of M. tuberculosis was performed at the
hospital's mycobacteriology laboratory. Isolates were then sent to the state mycobacteriology laboratory for drug-susceptibility testing. Because of the time required
for completion and verification of susceptibility testing, results were not available to
clinicians for at least 8 weeks after specimen collection.
Reported by: R Uttamchandani, MD, R Reyes, MD, S Dittes, MD, T Cleary, PhD, A Pitchenik, MD,
M Fischl, MD, Univ of Miami; J Otten, A Breeden, C Hilsenbeck, PhD, Jackson Memorial
Hospital; J Burr, MD, Dade County Public Health Unit; J Simmons, MD, District 11, W Bigler,
PhD, H Valdez, R Cacciatore, J Witte, MD, RA Calder, MD, State Epidemiologist, Florida Dept of
Health and Rehabilitative Svcs. Hospital Infections Program, Center for Infectious Diseases; Div
of Tuberculosis Control, Center for Prevention Svcs, CDC.
Editorial Note: Although airborne transmission of M. tuberculosis in health-care
settings has been described (1-4), this appears to be the first documentation of
nosocomial transmission of drug-resistant TB. The clinical and epidemiologic findings in this investigation suggest that most MDR-TB cases were newly acquired
tuberculous infection rather than reactivation of latent infection. In addition, the
findings indicate transmission of infection to household contacts and, possibly, to
HCWs.
Factors that may have contributed to this outbreak included 1) delays in adequate
treatment of MDR-TB because of the length of time required to perform and verify
drug-susceptibility tests; 2) prolonged periods of infectiousness in patients whose
cure was delayed by MDR-TB; 3) inadequate duration of, and occasional lapses in,
AFB isolation precautions on the HIV ward; 4) delays in recognition of TB in some
patients (5); 5) presence of MDR-TB patients in the HIV clinic while still infectious
because of delayed recognition of drug resistance; and 6) improperly balanced
ventilation in the HIV ward and clinic.
To reduce the risk for nosocomial TB transmission, patients with suspected or
confirmed TB should be placed in AFB isolation and started on effective anti-TB
therapy. While hospitalized, they should remain in AFB isolation until clinically
improved with substantial reduction in cough and until the number of organisms on
sequential sputum AFB smears is decreasing (6,7; CDC, unpublished datat). Determination of infectiousness should be based on assessment of both clinical and
bacteriologic response to therapy (6,7; CDC, unpublished data). Patients who are
likely to be infected with drug-resistant organisms should remain in AFB isolation
until AFB smears are negative (6; CDC, unpublished data). Patients with infectious TB
tUpdated guidelines for preventing transmission of TB in health-care settings where persons
with HIV infections receive care are in preparation as an MMWR Recommendations and
Reports.

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