Flashcards in Treatment of TB Deck (58)
1st line drugs for TB
Pyridoxine can be added adjectively to TB treatments. Why?
TO prevent drug-induced neuropathy
What are the majors organs affected by TB?
-nodes, pleura, bones, and joints
How is TB spread?
inhalation of infectious droplet nuclei aerosolized by pulmonary TB
What is MDR TB?
resistant to isoniazid and rifampin.
What is XDR TB?
resistant to isoniazid and rifampin plus a fluoroquinolone and one of the three second line drugs
Describe the mycobacterial cell wall
The mycobacterial cell wall consists of an inner layer and an
outer layer that surround the plasma membrane
How is the inner layer of the mycobacterial wall constructed?
The inner compartment consists of peptidoglycan (PG), arabinogalactan (AG), and mycolic acids (MA) covalently linked
together to form a complex known as the MA-AG-PG complex that extends from the
plasma membrane outward in layers, starting with PG and ending with MAs
complex is insoluble and referred to as the essential core of the mycobacterial cell
While multidrug resistance has recently grabbed headlines, mycobacteria are
inherently resistant to numerous antibiotics. Why?
Mycobacteria have unusually impermeable cell walls that are thought to be advantageous in stressful conditions of osmotic shock or desiccation as well as
contributing to their considerable resistance to many drugs.
T or F. Lipophilic drugs, such as fluoroquinolones or rifamycins, pass more easily through the lipid-rich cell wall and
thus are more active.
What is another reason for resistance to antibiotics in Mycoplasma TB?
TB forms caseous granulomas, which is composed of macrophages (where the TB resides), neutrophils, and a cuff of lymphocytes
Poor penetrative ability of the drugs into the granuloma, coupled with the hypoxic centre and fibrotic ring can all impact drug
Other possible resistance mechanisms to drugs?
efflux pumps, antibiotic-modifying or -degrading enzymes such as β-lactamase, target-modifying
enzymes, and decoys that mimic the drug target.
What is the most common cause of TB treatment failure?
poor adherence (leads to resistance!)
T or F. TB infection can be latent or active
Are those with latent infection likely to spread TB?
No, with a latent infection, the patient is
initially asymptomatic (this may progress, as shown) and is not a public health risk.
How could you ID a latent TB infection?
chest X-ray would appear normal, however, a TB skin test would yield a positive
T or F. The majority of patients who become infected do not go on to experience
T; their immune systems can intervene. However, the risk of active disease
development is clearly greater in immunocompromised patients.
What are the symptoms of active TB?
-cough (progressing to productive), chest pain, SOB
-flu like symptoms, fever
-weight loss, fatigue
Before beginning immuosuppressants like TNF-alpha inhibitors, a TB test should be performed to avoid allowing latent TB to become active. What should be done if the assay shows a positive result?
Anti-tubercular drug treatment should
be initiated. What is not resolved is whether or not this prolonged treatment regimen needs to be completed before the immunosuppressive drugs can be initiated.
Rules for reading a TB test
-measure rxn within 48-72hrs
-measure induration, not erythema
-record rxn in millimeters, NOT positive/negative
What is the preferred drug regimen for HIV patients, children 2-11 yoa, pregnant women with pyridoxine/vitamin B6 supplementation with LATENT TB?
Isoniazid 1x daily for 9 months
What is the preferred drug regimen for persons over 12 yoa with LATENT TB?
Isoniazid + Rifapentine 1x weekly for 3 months
When is Isoniazid + Rifapentine 1x weekly for 12 weeks contraindicated?
-Under 2 yoa
-With concurrent anti-retrovirals
-Women expecting to be pregnant
How to manage patients that miss treatment?
Extend or re-start treatment and use DOT
What is the preferred drug regimen for ACTIVE TB initial phase?
Daily INH, RIF, PZA, and EMB for 56 doses
What is the preferred drug regimen for ACTIVE TB continuation phase?
Daily INH and RIF for 126 doses (18 weeks) or twice-weekly INH and RIF for 36 doses (18 weeks)
What is the purpose of the initiation phase of TB treatment?
Kill most of the bacilli (but some can survive longer)
T or F. The initial phase of TB treatment determines the ultimate effectiveness of the regimen
What is the purpose of the continuation phase of TB treatment?
finishes killing TB