Tuberculosis Flashcards
What is Tuberculosis?
An aerobic, non spore forming AFB. It is non motile and slow growing.
What is the reservoir of TB?
Humans although rarely, elephants can contract the infection
What are the barriers to acquiring an infection with TB?
Public Health Structure
Air Exchange
Alveolar Macrophages
CD4 and CD 8 Lymphocytes
How is a TB infection acquired?
Aerosolized droplets from coughing and sneezing.
What is the pathophysiology of TB infection?
AFB inhaled. Upon arrival in alveolus, they enter the alveolar macrophage and is encased in phagosome. The phagosomes fuse with lysosomes which digest them. CD4 and CD8 lymphocytes attack the AFB. The AFB is surrounded by a granuloma- the Ghon Complex.
What organ systems are affected by TB?
Pulmonary
Lymph Nodes
Pleura
CNS
What findings are associated with TB?
Non Specific X Ray findings at 10 days
Granuloma at 4 weeks
Positive skin test at 5 weeks
Visible chest x ray changes at 6 weeks
What are the two types of TB?
Latent (LTBI) Isocitrate Lyase\
Active
What are the first line drugs to treat TB?
INH, Rifampin, Pyrazinamide, Ethambutol, Rifabutin, Rifapentine
What are the second line drugs?
Streptomycin, Cycloserine, PAS, Amikacin/Kanamycin, Capreomycin, Levofloxicin, Moxifloxicin,Gatifloxicin
What are mechanisms of action of the first line drugs?
INH- disrupts cell membrane by interfering with Mycotic Acid Synthesis
Rifampin acts on Bacterial RNA Polymerasealtering Protein
Pyrazinamide- requires intra-bacterial activation in an acidic environment. It alter membrane efflux.. Works on M TB only
Ethambutol- Disrupts cell wall. does not require activation.
What is MDR TB?
TB resistant to INH and Rifampin. Seen especially in India, China and Russia.
What is XDR TB?
TB resistant to INH, Rifampin, Flouroquinolones and Aminoglycosides.
What is DOTS therapy?
Directly
Observed
Treatment
Short Course
What are some facts about Scrofula?
Painless
Usually in HIV pts.
Skin test + 77-100% 0f the time
6 month treatment
What are some facts about Pleural TB?
Sputum helps less than 40% of the time
Aspirate is usually serosanguineous with elevated Lactate levels and low Glucose levels
What are new some new tests for TB?
Adenosine Deaminase (ADA) and ADA Iso2- hig PPV where incidence is high QuantIferon- 89% sensitive and 92% specific, not influenced by BCG
What are some facts about Bone and Joint TB?
Painful Takes about 2 years to diagnose Usually involves two vertebrae and disc space in between Cord Compression 25-75%of the time Abscess formation and sinus tracts Dx with MRI esp in early disease Treat for 6 to 9 months
Facts about GU TB?
Silly putty kidney
acts like Pyelonephritis
Causes infertility in women
6 month treatment
Facts about Pericardial TB?
Most common cause of Pericarditis in Africa and Asia
Effusion is Exudative
6 month treatment
Facts about GI TB?
Involves Ileocecal area
Facts about Miliary TB?
Dx by CXR Presents like the Flu More often in immunocompromised 6 month treatment Look alike is Lymphoid Interstitial Pneumonitis, seen in EB virus, associated with enlarged Parotids and Lymphadenopathy and clubbing
Facts about CNS TB?
Kids
presents like meningoencephalitis or non specific sx.
Blocks CSF flow in subarachnoid space
Tuberculomas in Brain
reduced serum Sodium
non specific CSF with high lymphocytes and protein but low glucose
Treated with INH/Cycloserine/Ethionamide/PAS and
FQ
Treat for 9 to 12 months, just like MDR TB
3 stages:
1. Fever, Listless, Irritable
2.Confusion, Focal CNS defects, papilledema
3. Coma, paralysis
Otitis Media with 7th nerve palsy, think TB
When to use steroids?
TB Meningitis, elevated ICP, Pericardial Effusion, Pleural Effusion with respiratory distress and mediastinal shift, enlarged mediastinum , Miliary TB with Capillary block
What is the value of BCG?
Reduces CSF disease by 75%+
Effect lasts for 10 years
Kids who receive it get milder disease
Most effective in the first year of life
What is the role of surgery in TB?
Pericardial WIndow
Drainage of PLeural fluid
CSF SHunt
Spinal Decompression
How does pediatric TB differ from Adult disease?
Smears are less frequently +
Sputum is less frequently produced
Skin tests are less often positive
Reduced transmission to others
How is a presumptive dx of TB in Children made?
+ PPD
Abnormal CXR or physical finding
Recent exposure ( Grandparents with TB will infect 10 to 15 people per year)
Children under 5 yrs who are well and with hx of exposure will be treated for 6 months, children over 5 will be observed
What are X Ray findings associated with TB?
Hyperinflated segment Atelectasis Consolidation Pleural Effusions or Empyema Rarely a focal mass or cavitation Miliary- looks like a snowstorm
Who should be isolated?
Those with: Cavitations Renal TB Draining SInuses Those producing sputum Treat for 3 months
What do you do if RUQ pain develops while on TB meds?
Stop all meds,
Start IN Amikacin and oral Ethambutol
When LFTs return to normal for 2 weeks, restart INH
INH, PZA and Rifampin all cause hepatitis
Def of Hepatitis: AST > 3x nl with sx or 5x nl without sx
What are new tests for Dx of M TB?
NAAT- Nucleic Acid Amplification Test- same day results, 40-77% sensitive, intermediate between smears and cultures
If culture is positive, nucleic acid probe will give results in 2 hrs with sens/spec of 100%. It requires 10to5th orgs.
Molecular Beacon Testing (MB)-IDs TB and screens for UNH and Rifampin resistance using real time PCR
Line Probe Manual Amplification
What are the approaches to treatment of TB?
Start all 4 drugs together
Start 1 and then consecutively add the other 3 (Ramp Up Approach)- use with elders, those with active liver disease, patients on second line drugs, those with prior drug problems
Monitor monthly
What are some generalizations about TB therapy?
All TB drugs can cause a rash
Petechial rash due to rifampin, do not start again
Urticaria- stop drugs until rash is gone then resume, starting with Rifampin then INH
Peripheral neuropathy due to INH
Nausea and Vomiting- take with a light snack, then use antiemetic 60 minutes before dose then hold drugs and re-introduce
Joint pain due to PZA- Bengay/NSAIDS
Dizziness- increase dose of B6
Persistent+ sputum, treat for 12 mos
If drugs are interrupted for less than 14 days, continue with same treatment course
If drugs are interrupted for more than 14 days, restart as if beginning regimen all over again
Fasting for Ramadan- shift from DOT to Supervised
MDR TB treated for 18 to 24 mos, with PICC line used 5 days /week for 1st 2 months, then 3 days/ week for following months
What is the paradoxical reaction?
Increased size of lymph nodes due to antigen release
usually occurs after 6 to 7 weeks of therapy
Lasts about 2 months
Use steroids
Drain fluid collections
continue therapy
What do you do if the patient has MDR TB?
Treat for 18 to 24 mos. with bid DOT
Use PICC line
Keep the patient isolated until the cultures are negative
What sx occur with Ethionamide and PAS? What labs need to be monitored?
N,V, metallic taste, hepatotoxicity, peripheral neuropathy
Check TSH monthly
What are side effects of Cycloserine?
Depression, Psychosis, seizures
Aminioglycoside side effects?
Ototoxicity-check audiogram and vestibule monthly
Nephrotoxicity- check BUN and Creatinine monthly
What is Iris Syndrome?
Seen in HIV patients receiving treatment-Inflammation occurs with Reconstitution of Immune System
What are some unusual clinical manifestations of TB?
Empyema Necessitans due to UL infiltrates
Acneiform Lesions due to Cutaneous Mycobacteriosis
TB Verrucosus Cutis
Scrofuladerma- I and D in a non dependent location
