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Case presentation
Tania Jain
Chief medical resident
Detroit Receiving Hospital
Idea of an M and M conference
• Learn (that’s why we are in a training program ;)
• Improve the system (we owe it to the hospital !)
Idea of an M and M conference
• Learn (that’s why we are in a training program ;)
• Improve the system (we owe it to the hospital !)
• Have fun
At admission
• 68 yo man with h/o CAD (s/p MI and PCI in 2006)
• 2 weeks of generalized abdominal pain, constipation (8 days) and weight loss (15-20 lbs)
• ROS – cough
Other histories….
• PMHx: CAD (patient reports he doesn't take any medications, currently)
• PSHx: Cardiac stent 2006• Family Hx: Mother - MI, Father - TB• Social Hx: 1PPD x 20 years (quit 2006); 1
fifth/day (quit 2006); remote IV heroin (60's and 70's)
• Allergies: NKDA
Physical exam
• HR 117
• Vital signs including RR and O2 Sat. were normal range (12-18/ 96-100%)
• Respiratory: Positive egophony on left lung.
• Gastrointestinal: Diffusely tender to palpation without rebound/ guarding, no masses
ER work-up
• Abdominal XR =
No obstruction/ air fluid level
Atelectasis with central bronchial obstruction
More about the cough ?
• Cough productive of thick, white phlegm.
• Dyspnea at rest as well as fatigue, generalized weakness and inability to walk
• No fever, night sweats, hemoptysis
• Only exposure in distant past (father; died many years ago)
CT Chest
• Multiple cavitary lesions• Largest left lung apex 3.8 x 4.7 cm
with nodular thickened wall• Smaller cavitary lesions in L lung
base• R lung: smaller areas of ground-glass
opacities with areas of tree in bud appearance.
Other labs
• K 2.9
• Liver enzymes 38/ 63/ 70
• Blood cultures sent (negative)
• AFB smear x3 ordered
• TB QuantiFERON® ordered
• HIV ordered
• TB isolation precautions
Day 2
• With Pulmonary consulted, plan is to pursue a bronchoscopy if AFB x3 negative (concern infections vs malignancy)
By Day 5
• 3 x AFB sputum smear reported negative
* producing very little sputum
* one sample was induced sputum by RT
* One morning sample
Oh BTW….
• The morning of day 5 (which is the day patient scheduled for bronchoscopy), TB QuantiFERON® reported positive
What do you do now ?
? Discontinue isolation? Bronchoscopy? Nucleic acid amplification? Treat active TB? Treat latent TB
What actually happened ?
• AFB isolation discontinued
• Patient underwent bronchoscopy
A few hours post-bronchoscopy…
• Tachypneic with RR 30s• Tachycardic to HR 150s• Hypoxic w/ SPO2 92 on 4L NC• Accessory muscle use. Crackles, most prominent
over left upper lung field. Decreased breath sounds, more prominent on left side
• ABG 7.5 / 22 / 65 / 20 / 93, lact 3.4• Transferred to MICU for new sepsis secondary to
HCAP ; Rx vancomycin and cefepime
Day 6 & 7
• BAL smear : 4+ AFB
• AFB isolation re-initiated
• Started on RIPE
• Blood and respiratory fungal cultures negative
Back on floors
• Repeat 3 AFP sputum - negative• BAL sent for susceptibility testing• Continued RIPE and AFB isolation• Discharged after 2 weeks inpatient
RIPE; Detroit/ Michigan dept of health informed; TB clinic follow up
• Day 30, sputum cultures (from day 2, 3) are reported positive for Mycobacterium tuberculosis
Aim
• To understand the following about TB diagnosis and prevention :
? CDC guidelines to prevent transmission? Testing for TB diagnosis ? Role of bronchoscopy? When in doubt
Typical TB patient
• Cough >= 3 weeks/ weight loss/ fever/ night sweats
• Chest xray
• Sputum Smear
• Sputum culture
• Sputum drug susceptibities
Our patient decision tree in retrospect !
“Latent” and Active TB
• Infected but not symptomatic
• Not infectious
• skin test or blood test result indicating TB infection
• normal chest x-ray and a negative sputum test
• Needs treatment for latent TB
• Skin/ blood test positive• Abnormal chest XR or
positive sputum• Symptoms
• Treatment for TB disease
Preventing transmission
• Who to isolate ?
“Anyone suspected to have TB disease OR has known TB disease and has not had enough treatment”
How to identify “infectious” patient ?
• Cough > 3 weeks• Cavitation on chest xray• Positive AFB sputum smear• Lung/ laryngeal involvement• Failure to cover mouth/ nose• Cough-inducing/ aerosol generating prcedures
* Extrapulmonary TB is not infectious unless open abscess or lesion
When to discontinue isolation in a TB “suspect”
• Likelihood of TB
AND
Another possible diagnosis
OR
AFB smears negative x 3
Excerpts from CDC :
• Hospitalized patients for whom suspicion of TB remains after 3 negative AFB sputum smear should not be released from airborne precautions until they are on standard multidrug antituberculosis treatment and are clinically improving.
Fun fact
• In one study, 17% of transmission occurred from person with negative AFB smear results.
Behr MA etal. Transmission of mycobacterium tuberculosis from patients smear-negative for acid-fast bacilli. Lancet 1999;353:444-9
When to discontinue isolation in a TB
“disease”
• Effective therapy for 2 weeks
• Clinical improvement
• AFB smears negative x 3
How about discharge home ?
• Specific plan for follow up
• Standard multidrug TB Rx and DOT
• No infants/ children < 4 yrs or immunosuppressed
• Immunocompetent members have been exposed
Diagnostic procedures for TB
QuantiFERON® TB Gold
• Cell mediated immune response
• IFN gamma
• ELISA based
• Positive in both latent and active disease
Tuberculin skin test
• PPD, 48-72 hrs• Beyond 72 hours ?
*repeat
*If ≥15 mm up to 7 days +
Measure the induration; not redness
OK to do in HIV, BCG exposure,
pregnancy
>5 mmhighest risk, HIV, known exposure
>10 mm
other risk factors
>15 mm
no known risk factors
Interpreting the TST
Size of induration:
Chest radiography
• Active disease: upper lobe infiltration/ cavity/ effusion
• Healed: nodules, fibrotic scars, calcified granulomas or basal pleural effusion
• Normal in latent TB
• HIV: infiltrate in any lung zone, mediastinal or hilar LAD, normal
Sputum samples
• 3 samples, 8 – 24 hours apart, atleast 1 morning
• Type:
Spontaneous expectoration
Induced sputum
Gastric aspirate (esp children)
Bronchoscopy sample
• Stained smear - Auramine rhodamine/ Ziehl-Neelsen or Kinyoun stained smear under flourescence microscopy
• Culture – definitive identification, drug susceptibilities
Nucleic acid amplification
•70% sensitivity in smear negative
•Utilize a lot of amount of specimen, which could be used for culture/ drug susceptibilities
•Should not replace culture and drug-
susceptibility testing in suspected TB.
Role of bronchoscopy
• Those with negative induced-sputum results still suspected with TB are then referred for bronchoscopy
• 30 suspected cases:
Induced sputum smear/culture 60 days
BAL culture + 3/30 (10%)
BAL smear + none
BAL NAA + none
Lower yield
• Operator expertise
• Lidocaine – antibacterial and antifungal properties
Diagnostic utility
• Drug susceptibilities
• Identification of alternative diagnosis: granulomatous/ malignancy
101 Smear negative patients
• BAL culture:
Sensitivity 73%
NPV 91%
• Induced sputum:Sensitivity 87%NPV 96%
Low costWell tolerated
Excerpt from
* If possible, bronchoscopy should be avoided in patients with a clinical syndrome consistent with pulmonary or laryngeal TB disease because bronchoscopy substantially increases risk for transmission either through an airborne route or a contaminated broncoscope, including in persons with negative AFB sputum smear results.
• If the underlying cause of radiographic abnormality remains unknown, additional evaluation with bronchoscopy might be indicated; however, in case where TB disease remains a diagnostic possibility, initiation of a standard TB regimen for a period before bronchoscopy might reduce the risk for transmission.
Excerpt from
• If bronchoscopy is performed, because it is a cough-inducing procedure, additional sputum samples for AFB smear and culture should be collected after the procedure to increase the diagnostic yield.
Excerpt from
HIV Testing Who to test for HIV ?
Every patient with latent or active TB
Why ?
Progression from latent to active TB.
Rapid progression/ fatal.
Rapid expansion of outbreaks.
What test ?
Rapid HIV/ Standard labs assays
Hot off the press from MMWR..
DMC does not have this test available !
• Automated nucleic acid amplification test that can simultaneously identify M. tuberculosis and rifampin resistance within 2 hours.
• 98 percent of patients with smear-positive tuberculosis and 72 percent of patients with smear-negative/culture-positive tuberculosis
This recent newsletter says…• To aid in decision of whether continued airborne isolation
is warranted for pts with suspected pulmonary TB.
• Per the data presented at Conference on Retroviruses and Opportunistic Infections in Seattle in Feb 2015, negative Xpert MTB/RIF assay results form either one or two sputum samples are highly predictive of results of two or three negative AFB sputum smears.
• Single negative Xpert assay NPV 99.7% (99.6% in USA and 100% outside)
• Two serial negative NPV 100%
Take home !
• High suspicion
• “Intraweb” / DMC resources
• Take you own history
• It’s ok to seek help when in doubt
Acknowledgments
Dr D. KissnerDr R. RoxasDr S. Dhar
CDC
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