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Transcript
Resident Version
Management of Hospitalized Patients with Suspected
Pulmonary Mycobacterium Tuberculosis
Created by Dr. Peggy Beeley
Objectives:
1. Recognize patients who fit criteria for possible Pulmonary Tuberculosis.
2. Understand the basic immunology of initial TB infection and reason for various
clinical presentations.
3. Understand the epidemiology of transmission and the importance of respiratory
isolation and personal protective gear.
4. Know the diagnostic testing required for confirmation of a Pulmonary
Tuberculosis diagnosis.
References:
1. American Thoracic Society/Centers for Disease Control and
Prevention/Infectious Disease Society of America: Controlling Tuberculosis in the
United States
2. Am J Respir Crit Care Med Vol 172, pp 1169-127, 2005
3. MMWR: Guidelines for Preventing the transmission of Mycobacterium
tuberculosis in Health-Care Settings, 2005
4. Mandell’s Principles and Practice of Infectious Diseases, Sixth edition
Disclaimer: This exercise primarily focuses on prevention of transmission of Pulmonary
MTB in the hospital setting and management during evaluation of a patient suspected of
having this disease. References to MTB treatment will be limited as the complex subject
requires much more time than allotted. All patients strongly suspected of having TB
should be referred to an Infectious Diseases Specialist and Pulmonary Medicine
Specialist with experience and knowledge of the diagnostic criteria and treatment
considerations for each individual case. Placing your patient in respiratory isolation and
ordering AFB smears and culture is an automatic Hospital Epidemiology consultation.
The epidemiology staff members follow the patient until exclusion criteria are met or
until the patient is discharged.
1
Discussion Outline:
Facts about TB and Transmission:
1. Epidemiology: In the years 1985-1992 the United States saw a resurgence of
Pulmonary MTB.
a. Prior to 1985 TB cases in the US had fallen in numbers each year.
b. After 1985 cases began to rise dramatically with peak of 10.5 per 100,000
population, then decline in 1992 to 5.2 per 100,000 population, the lowest in
recorded history.
c. The causes of increased number of cases in the late 1980s included in part: HIV
disease, international travel, rise in homelessness and relaxation of TB control
measures in hospitals and institutions.
2. Recognition of potential cases rests primarily upon astute clinical observation by
providers of infected persons seeking medical care.
a. Cardinal features to identify patients early during triage include:
 Constitutional Symptoms
 Hemoptysis
 Chronic cough
 Weight loss of >10 lbs
b. These features have high sensitivity but low specificity in recognizing Pulmonary
TB cases.
c. Masking patient with two or more of these symptoms on arrival to the hospital,
before chest x-ray or other diagnostic procedures, is important to reduce exposure
to other patients and HCWs.
3. High Risk groups include: HIV positive individuals, immigrants from high risk
regions, persons with known exposure, institutionalized patients, the homeless and
persons with abnormal immune systems, i.e. immunotherapy in Rheumatoid arthritis,
Corticosteroid treatment and ESRD.
4. Understanding MTB infection and the various presentations:
a. The initial focus is usually sub-pleural in the mid-lung zones (middle lobe, upper
lower lobe or lower upper lobe) where greater airflow favors delivery of the
bacteria. Generally there is a single focus but several foci may occur in one fourth
of cases.
b. Infection occurs primarily by inhalation of infectious airborne droplet nuclei.
c. Immunity:
 Although lung macrophages ingest the bacterium, during early infection the
growth is uninhibited by macrophages alone.
 Blood borne lymphocytes are attracted to the site and eventually lead to
antigen sensitivity and ultimate sequestration and granuloma formation with
lymphocytes, macrophages, Langhans giant cells, and fibroblasts being key
players. T cell activation orchestrates these cells and is critical in containment.
2


Lymphatic/hematologic spread occurs prior to development of adequate tissue
hypersensitivity to contain the growth of the bacilli.
1. Favored sites of deposition include the apices of the lungs, lymph
nodes, kidneys, vertebral bodies, and close to the meninges.
2. Thus, post-primary (or reactivation) MTB is more commonly seen in
these sites.
Persons with normal immune systems develop hypersensitivy more easily and
thus, generally are able to sequester bacterial spread earlier in infection.
1. Although sequestered within granulomas, bacilli remain viable and can
escape at any time, thus leading to replication and active infection.
2. Treating asymptomatic persons with a positive skin test prevents reemergence of MTB at a later time.
d. Primary Pulmonary Tuberculosis may lead to:
 A sub-acute pneumonia or slowly progressive pneumonia with cavitary
development or be asymptomatic leading to Latent TB infection (LTBI).
 Persons with abnormal immune systems may have unusual presentations of
primary MTB.
e. Post Primary Pulmonary TB may occur months to years after primary infection.
 3-4% of infected persons develop active TB within the first year, 15% lifetime
risk.
 Post Primary Pulmonary infection usually presents as asymmetrical
pulmonary involvement.
 Caseation, cavity formation and fibrosis are common.
 Classically this presents as posterior apical disease due to poor lymphatic flow
and, perhaps, the relative hyperoxic environment and aerobic nature of MTB.
 Cavitary disease leads to unimpeded bacteria replication and is considered
more contagious than non-cavity disease due to drainage of the cavity into the
bronchi that is easily aerosolized by cough.
f. Initial Evaluation:
 Chest x-ray
 Sputums for AFB (stain and culture)
1. Early morning sputums from overnight pooling of bronchial secretions
are best.
2. CDC now gives alternative recommendations of 3 sputums in 48 hours
with inclusion at least one early am sputum. This is felt to have
significant yield without the extra-cost of Respiratory Isolation days.
3. Nucleic Acid Amplification on sputum is also a way to diagnose MTB
early but does not replace the need for sputum culture where the
isolate can be tested for resistance patterns.
 Placement of TST on the patient with documented reading at 48 hours.
 Pulmonary Medicine and Infectious Disease Consultation if there is a high
suspicion of pulmonary TB.
 Chest CT scan may provide additional information suggestive of the diagnosis.
3

Bronchoscopy should be considered if sputums are of poor quality or if the
urgency of making a diagnosis demands it.
5. TB Control within the Hospitalized Setting
 Patients with upper lobe pulmonary processes should be considered potentially
infected with TB until TB is excluded.
 HIV positive patients with respiratory symptoms and/or abnormal chest x-rays
should always be placed in Respiratory isolation until TB is excluded.
 Aerosolized droplet nuclei particles are the primary mode of transmission.
1. These particles remain airborne long after infected persons leave an
area.
2. A cough or 5 minutes of talking or singing can produce 3000 – 5000
infectious particles. Sneezing can aerosolize many more particles.
3. Laryngeal TB is the most infectious form of MTB.
4. Fomite transmission is rare but can occur in some setting i.e. poorly
sterilized endoscopes.
 Isolation techniques include:
1. Negative Pressure Respiratory Isolation Rooms are one of the most
important preventions of transmission in health care settings.
2. High efficiency particulate air filtration (HEPA) to cleanse air of
infectious droplets and reduce circulation to persons in close proximity
on a temporary basis (equipment used in temporary holding areas, i.e.
ER).
3. N-95 masks with appropriate fit testing, soon to be a yearly ritual by
all HCWs.
4. Training patients on appropriate respiratory hygiene, including cough
etiquette procedures, is an important prevention of transmission.
5. Masking patients who are being transported within a health care
facility (usually with a surgical mask).
6. Infection does not generally occur outdoors, although patients would
be advised to remain at a distance from others even in this setting.
(FYI for your insistent smokers who threaten leaving AMA without a
permitted smoke break)
7. Patients remain potentially infectious until on treatment for several
days to weeks (exact amount of time depends on organism load and
other factors).
a. Sputum smears for AFB collected after initiation of therapy
may continue to be positive for up to three weeks but not grow
in culture.
b. The safest approach is probably to continue isolation until
discharge.
c. If discharge is delayed, request Pulmonary or Infectious
Diseases Consultant input before stopping respiratory isolation.
4
6. Tuberculin Skin Testing or TST, formerly known as PPD
a. TST is very important in the reduction of transmission of MTB by detecting early
infection in persons known to be exposed or at high risk of exposure.
b. Tuberculin positivity occurs 3-8 weeks after infection and indicates the
development of cellular immunity and tissue hypersensitivity
c. TST is recommended yearly for HCW and other high risk groups
1. If TST was done more than 1 year ago in newly hired HCWs, boosting
with a second TST is recommended to exclude remote infection in which
cellular immunity hypersensitivity to MTB has waned. This is generally
repeated within one to two weeks of initial TST.
2. When MTB exposure occurs in the Health Care setting, TST should be
obtained immediately upon notification of the exposure and repeated in 812 weeks.
3. HCWs with LTBI discovered through TST and without pulmonary
symptoms or an abnormal chest x-ray are safe to return to work but are
strongly encouraged to undergo LTBI treatment.
d. TST evaluation depends on the risk of the population being tested. Examples of
this include:
1. High risk: ≥5mm of induration (Example AIDS patients)
2. Medium risk: ≥ 10 mm of induration (Example: HCW with exposure risk)
3. Low risk: ≥15 mm of induration (General US population)
4. See CDC guidelines or Sanford’s for more detail.
e. False positives represent non-tuberculous mycobacterial infection:
1. This includes BCG or bacillus Calmetteused in high prevalence countries).
2. Unless BCG was given very recently, TST of > 10mm is highly suggestive
of MTB infection.
f. False negatives TST
1. Occurs in at least 20% of persons with active TB.
2. Other causes include: general illness, malnutrition, sarcoidosis,
intercurrent infections, reticuloendothelial disease, corticosteroid therapy
and immunocompromised individuals (i.e. AIDS)
3. Remote MTB infections with loss of Tuberculin Reactivity
g. Prior BCG vaccination and prior positive TST is not a contraindication to TST in
evaluating for active TB disease.
5
Review Questions:
1. 32 year old gay male from San Francisco presents to our ER soon after moving to
Albuquerque. In recent weeks he has developed night sweats, weight loss and
complains that his smokers cough has seemed more productive and more frequent
than usual. He was healthy until recently and has no past medical history except
Childhood Asthma. He has not been to a doctor in years. He admits to having anal
receptive sex with many male partners, mostly at SF bathhouses. Although he is
usually careful to have partners use condoms, he admits that he sometimes has
unprotected sex in “moments of passion”. He has never been tested for HIV due to
the fear of finding out he might be infected. As the admitting Resident you are called
to evaluate him for admission after a chest x-ray reveals left lower lobe pneumonia.
Which of the following is true?
A. Respiratory isolation is not necessary since Pulmonary TB does not present as lower
lobe disease
B. A sputum specimen for acid fast smear and culture and blood cultures should be
obtained as soon as possible. Community acquired Pneumonia treatment should be
started while waiting for test results.
C. A negative TST excludes the diagnosis of pulmonary TB allowing Respiratory
isolation to be discontinued.
D. Three negative smears of sputum for AFB excludes the diagnosis of pulmonary TB in
this patient.
E. HIV testing should be done and Community acquired pneumonia treatment and antiTB medications should be started immediately until the diagnosis of Pulmonary TB is
excluded.
6
2. The hospital epidemiologist calls you and tells you that a patient you cared for 2
weeks ago has confirmed MTB from sputum culture.
You immediately review her medical record and begin to recall the details of the case.
Ms. N is an 80 year old Vietnamese female who has recently come to the United States to
visit her daughter for a month. Her daughter brought her to the hospital on the second day
of her visit because Ms. N had dramatically lost weight since her daughter last saw her.
The daughter also noticed a persistent cough. Upon reviewing the chart and seeing the
patient you have a strong suspicion of TB. The ER Attending had the same suspicion and
immediately had placed her in respiratory isolation (private room with HEPA filtration).
Her chest X-Ray revealed a right middle lobe infiltrate but no cavitations. She was
dehydrated with mild tachycardia and a small supplemental oxygen requirement. She was
placed on CAP therapy (Levofloxacin and Cefotaxime) and 3 early morning sputum
smears/cultures for acid fast bacilli and blood cultures were obtained. A TST was placed
and was negative at 48 hours. By hospital day 4 the acid fast smears were reported out as
negative and blood cultures remained negative. Isolation was discontinued. She appeared
to be clinically improving with less cough and her vitals had returned to normal. Chest XRay showed minimal or no improvement but was attributed to delay of radiographic
improvement which is often seen in CAP. The patient reported feeling better and
requested discharge under her daughters care. She was treated with outpatient
Levofloxacin and had a scheduled follow-up in MFU.
You, as a UNM employee, had a required TST placed 10 months ago that was negative.
Which of the following is true?
A. You immediately get a TST and Chest X-Ray. If both are normal, no follow-up is
required.
B. You wait and have TST placed in 3 months
C. You immediately have TST placed, start Isoniazid/pyridoxine therapy and request
counseling for occupationally acquired PTSD
D. None of the above
Case discussion:
Why would the patient seem to be improving?
7
Post Module Evaluation
Please place completed evaluation in an interdepartmental mail envelope and address to
Dr. Wendy Gerstein, Department of Medicine, VAMC (111).
1) Topic of module:__________________________
2) On a scale of 1-5, how effective was this module for learning this topic? _________
(1= not effective at all, 5 = extremely effective)
3) Were there any obvious errors, confusing data, or omissions? Please list/comment
below:
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
4) Was the attending involved in the teaching of this module? Yes/no (please circle).
5) Please provide any further comments/feedback about this module, or the inpatient
curriculum in general:
6) Please circle one:
Attending
Resident (R2/R3)
Intern
Medical student
8