CDC History of Tuberculosis Control - Medical and Public Health ...

contacts tested, 56 had a positive TST (10 mm
induration), including 3 of 4 household
members, 16 of his 24 classroom contacts, 10
of 32 school-bus riders, and 9 of 61 day-care
contacts. A total of 118 persons received
preventive therapy. The 9-year-old patient’s
twin brother had TB, but was deemed not
infectious on the basis of a negative sputum
smear. This investigation showed that children
with TB, especially cavitary or laryngeal TB,
should be considered infectious, and that
screening of their contacts may be required.
Spread of Strain W, a highly drug-resistant
strain of Mycobacterium tuberculosis, across
the United States (Agerton, Valway,
Blinkhorn, et al. Clin Infect Dis 1999;
29:85-92).
Strain W, a highly drug-resistant strain of
Mycobacterium tuberculosis, was responsible for
large nosocomial outbreaks in New York in
the early 1990s. This article is a review of data
from epidemiologic investigations, national
TB surveillance, regional DNA fingerprinting
laboratories, and the CDC Mycobacteriology
Laboratory to identify potential cases of TB
due to Strain W. From January 1992
through February 1997, 23 cases were
identified in nine states and Puerto Rico; 4
of the 23 cases transmitted disease to 10
other people. Eighty-six contacts of the 23
cases were presumed to be infected with
Strain W. The authors conclude that Strain
W TB cases will occur throughout the
United States as persons infected in New
York move elsewhere. CDC asked health
departments to notify CDC of cases of TB
that were resistant to isoniazid, rifampin,
streptomycin, and kanamycin. The references
for this article include citations for earlier
investigation results that have been published,
including this next one.
Transmission of a highly drug-resistant
strain (Strain W1) of Mycobacterium
tuberculosis: Community outbreak and
nosocomial transmission via a contaminated
bronchoscope (Agerton, Valway, Gore, et
Notable Events in TB Control
63
al. JAMA 1997;278:1073-1077).
In 1995, eight patients with MDR TB were
identified in South Carolina; all were resistant
to seven drugs and had matching DNA
fingerprints (Strain W1). Community links
were identified for five patients (patients 1-5),
but no links were identified for the other three
patients (patients 6-8) except being hospitalized
at the same hospital as one community
patient. Patients 5 and 8 both died of MDR
TB less than one month after diagnosis.
Patients 6 and 7 each had one positive culture
for MDR TB; specimens were collected during
bronchoscopy. Patient 6 had a skin test
conversion after bronchoscopy. Neither
patient 6 nor patient 7 had a clinical course
consistent with MDR TB, neither was treated
for MDR TB, and both are alive and well.
There was no evidence of laboratory
contamination of specimens, transmission on
wards, or contact among patients. All four
received bronchoscopy in the same month.
Observations revealed that bronchoscope
cleaning and disinfection was inadequate and
led to subsequent false-positive cultures in
patients 6 and 7, transmission of infection to
patient 6 and active
MDR TB to patient 8.
An outbreak involving
extensive transmission
of a virulent strain of
Mycobacterium
tuberculosis (Valway,
Sanchez, Shinnick, et
al. N Engl J Med
1998;338:633-639).
From 1994 to 1996 there was a large outbreak
of TB in a small, rural community with a
population at low risk for TB. Twenty-one
patients with TB were identified; the DNA
fingerprints of the 13 isolates available for
testing were identical. To determine the extent
of transmission, we investigated both the close
and casual contacts of the patients. Using a
mouse model, we also studied the virulence of
the strain of Mycobacterium tuberculosis that
caused the outbreak. The index patient, the