In contrast to the widely-held conc

In contrast to the widely-held concept that infection with Mtb
is life-long, Dr. Nardell noted multiple examples of transient Mtb
infection in humans, as reflected by tuberculin skin test (TST) or
interferon-gamma release assay (IGRA) reversions [1] as well as
reversions seen in the natural transmission human-to-guinea pig
model [2]. Laboratory exposure to aerosol delivery of 20–50 colony
forming units (CFU) of Mtb in the highly susceptible guinea pig
model resulted in uniform infection and death that varied by the
virulence of the strain [3]. A natural infection model in guinea
pigs, however, resulted in a spectrum of outcomes including apparent
latency, reversions and reinfection [4]. This natural infection
model was established in the Airborne Infections Research Facility
(AIR) in South Africa, a six-bed, multidrug-resistant tuberculosis
inpatient hospital ward in which 362 guinea pigs were continuously
exposed to patient exhaust air over a period of four months.
Mtb infection was assessed with monthly serial TSTs, where the
cutoff point for a positive TST was greater than or equal to six
millimeters (mm) followed by evaluation of histological disease
progression at necropsy. After four months, 91 (25%) of the animals
had no evidence of infection, with 271 (75%) infected. Reversion
from a positive to negative TST was seen in 53 (15%) of
the animals, and was only seen in animals with a TST reaction
of less than 14 mm. None of those animals progressed to active
disease. Thirty-three (62%) of the 53 reverted animals became reinfected
by the end of the study due to ongoing exposure. Fifty-four
(15%) of all infected guinea pigs subsequently developed active TB
disease.

ผลลัพธ์ (ไทย) 1:

In contrast to the widely-held concept that infection with Mtbis life-long, Dr. Nardell noted multiple examples of transient Mtbinfection in humans, as reflected by tuberculin skin test (TST) orinterferon-gamma release assay (IGRA) reversions [1] as well asreversions seen in the natural transmission human-to-guinea pigmodel [2]. Laboratory exposure to aerosol delivery of 20–50 colonyforming units (CFU) of Mtb in the highly susceptible guinea pigmodel resulted in uniform infection and death that varied by thevirulence of the strain [3]. A natural infection model in guineapigs, however, resulted in a spectrum of outcomes including apparentlatency, reversions and reinfection [4]. This natural infectionmodel was established in the Airborne Infections Research Facility(AIR) in South Africa, a six-bed, multidrug-resistant tuberculosisinpatient hospital ward in which 362 guinea pigs were continuouslyexposed to patient exhaust air over a period of four months.Mtb infection was assessed with monthly serial TSTs, where thecutoff point for a positive TST was greater than or equal to sixmillimeters (mm) followed by evaluation of histological diseaseprogression at necropsy. After four months, 91 (25%) of the animalshad no evidence of infection, with 271 (75%) infected. Reversionfrom a positive to negative TST was seen in 53 (15%) ofthe animals, and was only seen in animals with a TST reactionน้อยกว่า 14 มม. สัตว์เหล่านั้นไม่มีหน้าไปเพียงใดการใช้งานโรค สามสิบสาม (62%) ของสัตว์เปลี่ยนกลับ 53 มักกลายเป็นโดยจุดสิ้นสุดของการศึกษาเนื่องจากความเสี่ยงอย่างต่อเนื่อง ห้าสิบสี่(15%) ทั้งหมดติดเชื้อ TB ใช้หนูตะเภามาพัฒนาโรค