TB Flashcards
Refers to bacterial resistance in patients with some record of previous treatment
Acquired resistance
Infection associated with tuberculin hypersensitivity as show by a positive tuberculin skin test with no striking clinical or roentgenographic manifestations
Asymptomatic or latest tuberculosis infection (LTBI)
attenuated vaccine strain of M. bovis used to immunize against tuberculosis
Bacillus Calmette-Guerin
TB, usually pulmonary, excreting bacilli resistant to one or more antituberculosis drugs
Drug-resistant TB (DR-TB)
A person who has had a recent contact with another person with suspected or confirmed contagious pulmonary tuberculosis disease and who has a negative tuberculin (or IGRA) reaction, normal PE findings, and chest x-ray findings that are not compatible with TB
Exposed person
A subset of MDR-TB with a strain of M. tuberculosis complex that is resistant to isoniazid and rifampicin, any quinolone, and at least one of three second-line injectable drugs: kanamycin, capreomycin or amikacin
Extensively drug-resistant TB (XDR-TB)
Time interval from exposure to the mycobacterium to the development of delayed type hypersensitivity reaction as manifested by a positive TST (or IGRA)
Incubation period
Mycobacterium tuberculosis complex infection in a person who has a positive TST (or IGRA) result, with no clinical manifestations of disease and chest radiograph findings that are normal
Latent tuberculosis infection
Resistance to at least isoniazid and rifampicin
Multidrug-resistance (MTB)
Resistance to more than one antituberculosis drug, other than isoniazid and rifampicin
Poly-resistance
Composed of primary focus, lymphangitis, localized pleural effusion and regional lymphadenitis, demonstrable by radiographic study
Primary complex
Bacterial resistance present in patients who have received prior treatment with antituberculosis drugs
Secondary resistance
bacterial resistance present in patients who have not received prior treatment with antituberculosis drugs
Primary resistance
Aseptic reactive polyarthritis in TB
Poncet disease
Most common ocular manifestation of TB
choroiditis
Criteria for congenital TB
Any infant with a TB lesion and one more ore of the ff:
- Present within the first week of life
- A primary hepatic complex or caseating hepatic granuloma
- TB infection of the placenta or endometrial TB in the mother; or exclusion of the possibility of postnatal transmission by excluding TB in other contacts
A patient who has never had treatment for TB or who has taken anti-TB drugs for less than one month
New case
A patient who has been previously treated with anti-TB drugs for at least one month in the past
Retreatment case
Resistance to one first line anti-TB drug only
Monoresistant TB
Criteria for diagnosis of active TB infection
3 more of of the ff:
- Exposure to an adult/adolescent with active TB disease (epidemiologic)
- Signs and symptoms suggestive of TB (clinical)
- Positive tuberculin skin test (immunologic)
- Abnormal chest radiograph suggestive of TB (radiologic)
- Laboratory findings suggestive of TB (histological, cytological, biochemical, immunological and/or molecular) (Laboratory)
Presumptive TB for patients 15 years old and above
Cough at least 2 weeks duration with or without the ff:
- significant and unintentional weight loss
- fever
- hemoptysis
- chest/back pains not musculoskeletal
- easy fatigability or malaise
- night sweats
- shortness of breath or DOB
OR unexplained cough of any duration in:
- a close contact of a known active TB case
- high-risk clinical groups and high risk populations
Presumptive TB in patients below 15 years old
At least 3 of the ff:
- coughing/wheezing of 2 weeks or more, especially if unexplained
- unexplained fever of 2 weeks or more after common causes have been excluded
- weight loss/failure to gain weight/loss of appetite
- failure to respond to 2 weeks of appropriate antibiotic therapy for lower respiratory tract infection
- failure to regain previous state of health 2 weeks after viral infection or exanthema
- fatigue, reduced playfulness or lethargy
Or any 1 of the above in a child who is a close contact of a known active TB case
A negative TST obtained less than __ after exposure is unreliable for excluding TB infection
8 weeks
A repeat TST is done at __ after a negative TST in a TB symptomatic child or in children four years and below
3 months
Standard test dose of TST
5 TU
Site of TST
2 inches below the elbow joint in the volar aspect of the forearm
A pale wheal of __ in diameter should be evident after injection; otherwise repeat test on an area at least __ away from the original site
6-10 mm diameter
2 inches from the original site
Positive TST reactions can be measured accurately up to __, while negative TST reactions can be read accurately up to __
Positive TST - 7 days
Negative TST - 72 hours
Post BCG tuberculin reactions develop __ after vaccination and wanes after __
Develop 6-12 weeks after vaccination
Wanes after 5 years
TST should be postponed for __ from a live-vaccine administration, or at the same time with a live-vaccine on different sites
4-6 weeks
TST should be delayed for __ after a bout of measles, mumps, chickenpox or whooping cough
2 months
Storage temperature of tuberculin
2-8 degrees
TST positive cut-off size
10 mm or more
or 5 mm or more in the ff:
1. severely malnourished children
2. immunocompromised
TST positive cut-off size as defined by The American Thoracic Society
≥5 mm with high risk:
1. HIV-infected
2. Close contact with an infectious TB source
3. CXR consisted with TB
4. Organ transplant recipients
5. Immunosuppressed (taking equivalent of >15 mg/d of prednisone for 1 month or those taking TNF-a antagonists)
≥10 mm for populations with high risk of having TB infection and disease and for persons living in areas where TB is highly prevalent
≥ 15 mm for populations with no risk factors
TST is preferred over IGRA for children less than __
5 yr
Radiologic hallmark of reactivation TB
cavitation
Pulmonary lesions in TB exceeding __ should be resected
3 cm
Preferred imaging modality in TB spondylitis
MRI
Triad of juxtaarticular osteoporosis, peripherally located osseous erosions, gradual narrowing of interosseous space
Phemister triad, TB arthritis
Thickening of the ileocecal valve lips or wide gaping of the valve with narrowing of the terminal ileum
Fleischner sign, GI TB
The primary sign of tuberculous pericarditis is pericardial thickening of __ as seen on CT
more than 3 mm
Minimum desired sputum volume
3 mL
A patient previously treated for TB who has been declared cured, or completed treatment in their most recent treatment episode, and is presently diagnosed with bacteriologically-confirmed or clinically-confirmed TB
replapse
A patient who has been previously treated for TB and whose treatment failed at the end of their most recent course. Includes:
- sputum smear or culture positive at 5 months or later during treatment
- clinically diagnosed patient for whom sputum examination cannot be done and who does not show clinical improvement anytime during treatment
Treatment after failure
A patient who was previously treated for TB but was lost to follow-up ≥ 2 months in their most recent course of treatment and is currently diagnosed with either bacteriologically-confirmed or clinically-diagnosed TB
Treatment after lost to follow up
Patients who have been previously treated for TB but whose outcomes after their most recent course of treatment are unknown o rundocumented
Previous treatment, outcome unknown
Stains used for AFB smear microscopy
Ziehl-Neelsen
or Kinyoun carbol fuschin stains
Solid culture media used in TB
Loewnstein-Jensen
Ogawa
Middlebrook
In solid culture, isolation of MTB organisms require __ and another __ for susceptibility testing
4-6 weeks to isolate
another 2-4 weeks for susceptibility studies
In TB, liquid culture systems provide results in __, up to __ for negative result
4-14 days
42 days for negative result
Isoniazid preventive therapy is recommended for:
- all HIV-positive individuals
- Children less than 5 yr who are household contacts of a bacteriologically-confiremd TB case, regardless of TST result
- Children less than 5 yr who are household contacts of a clinically diagnosed TB case if TST is positive
Isoniazid dose and duration of treatment for preventive therapy
10 mkday OD x 6 months
In TB treatment, what is Cat I? Treatment regimen?
PTB, new;
Extrapulmonary TB, new, except CNS/bones or joints
2HRZE/4HR
In TB treatment, what is Cat Ia? Treatment regimen?
Extrapulmonary TB, new, CNS/bones or joints
2HRZE/10HR
In TB treatment, what is Cat II? Treatment regimen?
Pulmonary or extrapulmonary TB, previously treated drug-susceptible TB
- relapse
- treatment after failure
- treatment after lost to follow-up
- previous treatment unknown outcome
2HRZES/1HRZE/5HRE
In TB treatment, what is Cat IIa? Treatment regimen?
Extrapulmonary, previously treated drug-susceptible TB, CNS/bones or joints
2HRZES/1HRZE/9HRE
Corticosteroids are used in which forms of TB?
Meningitis, pericarditis, endobronchial, miliary
*pleural effusion, not routinely recommended
Dose of prednisone given in TB
2-4 mkday (max 60 mg/day) for 4-6 weeks (11 weeks for pericarditis)
Treatment completed as recommended by the national policy without evidence of failure and three or more consecutive cultures taken at least 30 days apart are negative after the intensive phase
Cured
Treatment completed as recommended by the national policy without evidence of failure but no record that three or more consecutive cultures taken at least 30 days apart are negative after the intensive phase
Treatment completed
Drugs in MDR-TB
At least 4, but 5 if possible and should include:
- any of the first line drugs to which the strain is susceptible
- injectable drug (given for 8 months)
- quinolone
Full treatment course can last for 20-24 months
Management of XDR-TB
- use any Group 1 that may be effective
- use an injectable for at least 12 months or the whole treatment
- later generation fluoroquinolone such as moxifloxacin
- use all Group 4 agents that have not been used extensively in a previous regimen
- use 2 or more agents from Group 5
- consider high-dose isoniazid if low-level resistance is documented
- consider adjuvant surgery if there is localized disease
- ensure strong infection control measures
- treat HV
- provide comprehensive monitoring and full adherence support
Group 1 drugs
First-line oral agents
isoniazid, rifampin, ethambutol, pyrazinamide
Group 2 drugs
Injectable agents
kanamycin, amikacin, capreomycin, streptomycin
Group 3 drugs
Fluoroquinolones
moxifloxacin, levofloxacin, ofloxacin
Group 4 drugs
Oral bacteriostatic second-line agents
Ethionamide, prothionamide, cycloserine, terizidone, p-aminosalicylic acid (PAS)
Group 5 drugs
Agents with unclear efficacy
Clofazimine, linezolid, amoxicillin-clavulanic acid, thioacetazone, imipenem/cilastatin, clarithromycin, high-dose isoniazid (16-20 mkday)
Mangement of pregnant mothers with latent TB infection
IPT x 9 months, at least 6 months with pyridoxine supplementation
Women who become pregnant while on treatment for TB should continue therapy, except for which drugs?
streptomycin
fluoroquinolones
Schedule of ALT monitoring for TB with liver disease
2x a week for the first 2 weeks, then weekly until the end of the second month, and monthly until the end of treatment
Treatment of TB in children with liver disease
2HRE/7HR or 2HRE+fluoroquinolone or aminoglycoside/4HR In decompensated liver cirrhosis: ES+fluoroquinolone x 18-24 months
Hepatotoxicity may occur anytime during treatment but usually manifest in the first __of therapy
2-4 weeks
Drug induced liver injury is defined as AST level __ in the presence of symptoms or __ in the absence of any symptoms
3 or more times than the upper limit of normal if symptomatic
5 times more than the upper limit if asymptomatic
Dose adjustment of ethambutol and pyrazinamide in TB with renal impairment
three times a week
Antituberculosis drugs that are significantly dependent on renal clearance
ethambutol levofloxacin cycloserine kanamycin amikacin capreomycin streptomycin
Which of the first line drugs is efficiently removed by hemodialysis? Which is not removed by hemodialysis?
Efficiently removed: pyrazinamide
Not removed: rifampicin
Schedule of TST for children with HIV
annual
Primary prophylaxis for TB in children with HIV (asymptomatic, no contact with TB case)
For children living with HIV who are more than 12 mo:
6 months of IPT at 10 mkday, range 7-15 mkday, max dose 300)
T/F: BCG vaccine should not be given to children with HIV because of risk of disseminated BCG disease
T
T/F: All children living with HIV who have successfully completed treatment for TB disease should receive isoniazid for an additional 6 months
T
Indications of isoniazid prophylaxis for solid organ transplant recipients
- Tuberculin reactivity ≥5 mm before transplantation
- Patients with the ff characteristics regardless of reactivity
- radiographic evidence of old TB and no prior prophylaxis
- history of inadequately treated TB
- close contact with an infectious patient
- recipient of an allograft from a donor with a history of untreated TB or tuberculin reactivity without adequate prophylaxis - Newly infected persons (recent conversion of tuberculin test to positive)
Reintroduced first in rechallenge after skin reaction
Isoniazid
Then rifampicin after 3 days
Which drug is introduced first or rechallenge after hepatitis?
Rifampicin
Then isoniazid if no increase in ALT after 1 week
Which of the first line anti tb drugs is most likely to cause arthralgias
Pyrazinamide
BCG Dose
- 05 mL for newborns to 1 mo
0. 1 mL thereafter
Time course from vaccination to scar formation with BCG
12 weeks
First line anti-TB drug most likely to cause influenza syndrome
Rifampin (esp in intermittent regimens)
Timing of starting TB treatment in people living with HIV
TB treatment started first, followed by ART within 8 weeks, within 2 weeks for CD4 count below 50
Temporary clinical deterioration that may occur within 3 months of starting ART and most commonly within the first month
Immune reaction inflammatory syndrome (IRIS)
TB prophylaxis for patients receiving anti-TNFa therapy
6H
Or 3RH
Dose of pyridoxine
10 mg per 100 mg isoniazid OD
