tb and infective endocarditit

Infective endocarditis

Types: 1. acute bacterial endoc
2. subacute Bacterial endocarditis (SBE)
3. non bacterial endocarditis: ex. viral, fungi.
Etiology:
- strep. viridians (α-hemolytic strep) &staph. aureus are the leading cause.
Rx: 1. Antibiotics should be immediately
Strep species: penicillin G 250,000 u/kg/24 hour ÷6 not to exceed 20 million U/24 hour for 4 weeks +gentamicin ÷3 not to exceed 240 mg/24 hour for 2 weeks.
If the patient is allergic to penicillin give: vancomycin 40-60 mg/kg/day ÷3 not to exceed 2 g/day for 6 weeks + gentamicin
Staph species: nafcillin 200 mg/kg/day ÷4 not to exceed 12 g/day for 6 weeks. if methicillin resistant or penicillin allergy give vancomycin + optional TM/SMX 12 mg/kg/day ÷3 max 1g/day for 6 weeks.
Hemophilus spacies: ampicillin + optional gentamicin for 4 weeks.
Fungal: amphotericin B & 5-fluorocytosine
In non-staph disease, bactremia us. resolves in 24-48 hour whereas fever resolves in 5-6 days with appropriate Antibiotic Rx. Staph take longer.
2. digitalis, salt restriction & diuretic therapy should be used for heart failure
3. may need surgical intervention
Prevention: 1. Antimicrobial prophylaxis before various procedures including dental cleaning in susceptible pt.
2. Continuing education regarding prophylaxis.
3. General dental care & oral hygiene.
4. Vigorous Rx of sepsis & local infection.
5. Careful asepsis during heart surgery & catheterization.


Tuberculosis
- Bacterial characteristics:
There are three populations of the M. tuberculosis organism:
actively growing extracellular bacilli in pulmonary cavities: in this population the drug resistance develops most rapidly.
slow growing bacilli which are inside macrophages: many drugs are not active because the intracellular environment is acidic.
slower growing bacilli in area of poor blood supply.

- Rifampicin is the only drug that is bactericidal against all three populations.

- Isoniazid (INH), streptomycin (SM) and the other aminoglycosides are bactericidal against extracellular bacilli. Isoniazid is also bactericidal against intracellular organisms.
- Pyrazinamide (PAZ) is bactericidal only against intracellular organisms and works well in an acidic pH.
- All other first line anti TB drugs are bacteriostatic.
Of the alternative drugs, which can be used in the treatment of drug-resistant TB, the quinolones have the highest bactericidal activity.
- Mantoux test: is the intradermal injection of 5 I.U (0.1 ml) of purified protein derivative. Then read the reaction 48-72 hours after injection.

Rx of TB: drug regimens are:

Duration
Drugs
Disease
6 months
Rifampicin+ Isoniazide
Active pulmonary T.B or disseminated or military T.B
1st 2 m
+ Pyrazinamide


1st 2 m
If resistance also add Ethamb or SM

9-12 m

4 drugs regimen
Pulmonary TB+joint + bone
6-9 m
4 drug regimen + steroid
TB meningitis or pericardial
9-12 m
INH + Rifampicin
TB + HIV
1st 2 m
+ PZA

9 m
(Rifampicin or PZA) + Ethambutol
INH resistance
12-18 m
PAZ + Ethambutol
INH & Rifadin resistance
6-9 m
or PAZ + Flouroquinolon


Patients taking regimens containing rifampicin and isoniazid should be
non-infectious within 2 weeks.
Side Effects
Dose
Drug
- peripheral neuritis competitive inhibition of vitamin B6 utilization numbness, tingling in hands or feet
- hepatotox transient increase serum transaminase
- pellagra
- hemolytic anemia in pt with G6PD deficiency
- increase phenytoin level by blocking its metabolism toxicity
10 mg/kg/day once
oral or i.m
maximum 300 mg
before breakfast
INH
- orange discoloration of urine & tears
- hepatotoxicity, malabsorption
- thrombocytopenia
- influenza-like syndrome
- interact with: quinidine, cyclosporine, warfarin, protease inhibitors, steroids
10 mg/kg/day
oral or i.v
maximum 600 mg
before breakfast
Rifampicin
- Arthralgia
- arthritis
- gout (hyperurecemia)
35 mg/kg/day
once oral
Maximum 2 g
Pyrazinamide


- penetrates inflamed meninges well but not cross un inflamed meninges
- damage the vestibular & auditory portions of 8th cranial nerve so contraindicated in pregnant female (hearing loss)
15 mg/kg/day
i.m or i.v
Maximum 1 g
Streptomycin
- optic neuritis
- red-green color blindness
15 mg/kg/day
once or twice orally
maximum 2.5 g
Ethambutol
- hepatitis
- avoid in pregnancy
15 mg/kg/day for 2 or 3 doses
Maximum 1 g
Ethionamide
Or prothianamide

other drugs:

- Kanamycin & amikacin in SM resistant cases
Ciprofloxacin (S.E: distruction of the growing cartilage so it is C.I in child) & ofloxacin (which are quinolones)
- indicated for steroids (prednisolon 2 mg/kg/day 4-6 weeks):
1. military TB
2. endobronchial TB which respiratory distress, localized emphysema segmental pulmonary lesions
3. TB meningitis
4. pericardial effusion
5. pleural effusion
- indications of B6 in TB: Pregnancy
Breast feeding
HIV
Malnutrition
- TB laryngitis Rx for 2 yr.
- In pregnancy, standard therapy should be given, although streptomycin should not be used as it may be ototoxic to the fetus. It is considered safe for mothers to breast feed while taking anti-tuberculous treatment.
- Women using the oral contraceptive pill should be advised to use other non-hormonal methods of contraception for the duration of rifampicin treatment and for 8 weeks afterwards.
- Ethambutol undergoes extensive renal elimination and therefore dose
reduction is needed in renal disease.
- Streptomycin must be used with considerable caution to prevent toxicity and is best avoided in renal failure.
- Monitoring of liver enzymes is recommended in patients with liver failure or in alcoholics because rifampicin, isoniazid and pyrazinamide are all potentially hepatotoxic. However, increases in transaminases at the start of anti-tuberculous treatment occur frequently. These are usually transient and not a reason for stopping treatment unless frank jaundice or hepatitis develops, in which case all drugs should be stopped. It is usually possible to restart treatment when transaminases returned to pre-treatment levels.
- Isoniazid is the most usual agent to which resistance is seen.
- Rifampicin interacts with many medications, including methadone, protease inhibitors and nonnucleoside reverse transcriptase inhibitors used to treat HIV infection, macrolide antibiotics, warfarin and hormonal contraceptives.
It will colour the urine orange-red within approximately 4 h of a dose.
- Ethambutol ocular toxicity (optic neuritis) is the most important side effect of ethambutol.
Patients should be tested for both visual acuity and red green colour discrimination before treatment.
- Chemoprophylaxis is usually with isoniazid alone for 6 months or rifampicin and isoniazid for 3 months.
- BCG vaccine contains a live, attenuated strain derived from M. bovis. It does not protect against infection, but it prevents the more serious forms of disease such as miliary TB and meningeal TB.


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صلاح مهدي فرحان
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