Pulm Flashcards
Acute respiratory distress syndrome (ARDS)
Acute, diffuse inflammatory form of lung injury and respiratory failure due to many causes.
Risk factors for ARDS
Gram-negative sepsis most common cause
Other causes of ARDS
Trauma, severe pancreatitis, aspiration pneumonia (gastric contents), near drowning
Signs and symptoms of ARDS
Acute onset with in 1 week of insult or worsening of resp status. Bilateral infiltrates with no other explanation. Edema not from fluid overload or CHF.
Clinical manifestations of ARDS
Acute dyspnea, hypoxemia despite O2 supplementation. In severe, multiorgan failure.
Dx and labs for ARDS
Chest xray shows bilateral diffuse pulm infiltrates, but spares costophrenic angles.
PaO2/FiO2 ratio less than 300.
PCWP less than 18 mm (will be greater than 18 in cardiogenic pulmonary edema)
Diagnosis of ARDS is made with
chest xray, labs, history (key is acute onset within 1 week of lung injury/insult/illness mentioned under causes and no other explanation for infiltrates or edema.
Management of ARDS
6Ps: PEEP management, Prone position (decreases mortality in 50% of cases, paralysis in some cases, peeing (fluid management), pulmonary vasodilators (nitrous oxide) or prostacyclins, perfusion (VV ECMO if refractory to other treatment options)
Foreign body aspiration
FB enters airway causing choking.
Most Common cause of FB aspiration
Food
Location of most FB aspirations
Main bronchus or lobar bronchus (R>L)
Risk factors for FB aspiration
Institutionalized, elderly, poor dentition, alcohol, sedative use
Clinical manifestations of FB aspiration
Inspiratory stridor if high in airway, wheezing, decreased breath sounds if low in airway
Dx/labs for FB aspiration
Chest xray may show expanded lungs, hyperinflation of affected side. ABG is necessary to follow progression and to assure proper ventilation.
Management of FB aspiration
Remove FB by bronchoscopy (rigid for kids, flexible for adults.
Complications of FB aspiration
Pneumonia, ARDS, asphyxia
Hyaline membrane disease
Common problem in preterm infants (less than 30 weeks GA) Deficiency in surfactant production in an immature lung resulting in high surface tension leading to instability of lung at end expiration, low lung volume, decreased compliance which then leads to hypoxemia due to atalectasis.
When is surfactant released in lungs
20 weeks gestation
Hist/PE/CM for Hyaline membrane disease
Preterm infant, tachypnea, nasal flaring, expiratory grunting, cyanosis, intercostal, subxiphoid, and subcostal retractions.
Dx Labs for Hyaline membrane disease
Chest XR shows low lung volume, diffuse reticulogranular ground glass appearance, air bronchograms
ABG hypoxemia that responds to O2
PCO2 initially normal to slightly elevated. Increases as disease worsens. Progresses to hyponatremia.
Management for hyaline membrane disease
Betamethasone antenatal IM x2. Initially use positive pressure (neonatal CPAP or NIPPV). Surfactant administration via endotracheal intubation.
Acute bronchiolitis Scientific concepts/definition
Infection or inflammation of the bronchioles. MCC viral infections like RSV, rhinovirus, influenza, parainfluenza, adenovirus. RSV MCC for 2 mos to 2 years old.
Risk factors for acute bronchiolitis
Premies (less than 37 weeks), No breastfeeding, less than 6 months old, smoke exposure, crowded living conditions.
CM/Hist/PE for acute bronchiolitis
Viral prodrome (fever, URI syx) for 1-2 days, then progresses to respiratory distress. Expiratory wheeze, crackles, hyperinflation, tachypnea, incr RR, grunting, intercostal retractions, nasal flaring.
Dx labs for acute bronchiolitis
clinical DX or nasal swab. CXR nonspecific: Incr bonchovascular markings, hyperinflation.
Management of acute bronchiolitis
Palivizumab (synagis) for children less than 29 weeks gestation birth for first year of life. Supportive care (fluids, suction, antipyretics, bronchodilators), cough may persist for weeks.
Acute bronchitis SC and definition
Lower respiratory infection characterized by inflammation of bronchi. MCC is viral (over 90% of cases), i.e. influenza A or B, parainfluenza, adenovirus, RSV, rhinovirus, coronavirus. Bacterial is about 6% with bordatella pertussis for unvaxxed, mycoplasma or chlamydia for vaxxed.
History/PE/CM for acute bronchitis
cardinal syx cough for 1-3 weeks with or without sputum, with or without wheeze or mild dyspnea, prolonged cough can lead to chest wall soreness. Acute bronchitis is MCC of hemoptysis (along with cancer). URI syx before and during including headache, congestion, sore throat, malaise.
Diagnostics/labs for acute bronchitis
clinical Dx: Acute onset but persistent cough without clinical findings suggestive of pneumonia (fever, tachypnea, rales). On CXR: only used to rule out pneumonia. Will often be normal or nonspecific with peribronchial thickening.
Management of acute bronchitis
Self limiting disease process. Supportive care, i e rest, fluids, analgesics, OTC cough meds, Antibiotics not indicated for most cases.
Acute epiglottitis SC/Definition
Potentially life threatening epiglottic inflammation. Most common in kids ages 3-6 years, males MC 2x more than females. RF: Diabetes mellitus in adults. Etiology: H flu (Hib) for unvaxxed, Strep species such as strep pneumo, or Group A strep in vaxxed. Cocaine use in adults.
Hist/PE/CM for acute epiglottitis
Three D’s: Dysphagia, drooling, distress. Fever, odynophagia, inspiratory stridor, dyspnea. Hoarseness, muffled “hot potato voice”, tripod position, retractions, cyanotic lips.
Dx/Labs for acute epiglottitis
Definitive laryngoscopy preferably when securing airway will show cherry red epiglottis with swelling. Lateral cervical x-ray “thumbprint sign”
Management of acute epiglottitis
Most important part is securing airway. Then dexamethasone for airway edema. Antibiotics: Ceftriaxone or cefotaxime with or without ampicillin, PCN, or vancomycin. To prevent: Rifampin to all close contacts, Hib vax.
Croup SC/Define
inflammation of larynx and subglottic aireay MC 6 mo to 6 YO especially in fall and winter. Etiologies: Parainfluenza type 1, mycoplasma, RSV 2nd MCC.
Hist/PE/CM of Croup
“seal-like” “barking cough”, inspiratory stridor, hoarseness, dyspnea, low-grade fever, URI syx (coryza) prior to or during or after.
Dx/Labs for croup
Clinical dx. AP cervical xray may show “steeple sign”
Management for croup
If mild: No stridor at rest, no resp distress, then supportive care (cool mist humidifier, O2 if less than 92%) with or without dexamethasone.
If mod: Stridor at rest with mild or moderate retractions: Dexamethasone PO or IM and supportive care. Nebulized epinephrine. observe 3-4 hours for improvement.
If severe: Stridor at rest with marked retractions: Dexamethasone plus supportive care, neb epi, hospitalize.
Influenza SC/Define
Viral Flu A more severe outbreaks than Flu B. Transmitted mostly by airborne resp droplets (cough, sneeze, talking, breathing) or contaminated surfaces. Incr risk age over 65, pregnant, immunocompromised. MC in kids. If over 65, at risk for complications.
Hist/PE/CM influenza
Abrupt onset, headache, fever, chills, malaise, URI syx, sore throat, pneumonia, myalgias.
Complications of influenza
pneumonia, resp failure, death, meningitis, encephalitis, rhabdomyolysis, kidney failure
Dx/Labs for influenza
Rapid flu swab, viral culture
Management of influenza
mild disease in otherwise healthy pt: Supportive care (tylenol, motrin, rest, fluids). Oseltamivir if within 72 hours of onset, also for age over 65, cardiovascular disease, pulmonary disease, immunosuppression, chronic liver disease, hemoglobinopathies. For prevention: VAX. Adverse drug reactions to vax: fever, myalgias, irritability. Vax contraindicated in: those allergic to vax, Guillian Barre w/in 6 weeks of previous vaccine, high fever, infants less than 6 MO.
Bordatella/Pertussis SC/Define
Gram-negative bacterial transmitted by droplet. PRevent with vax in DTAP at 2, 4, 6 months each visit, then once between 15 and 18 most, once between 4 and 6 years old.
Hist/PE/CM of bordatella/pertussis/Whooping cough
Catarrhal stage: Most contagious time: URI syx for 1-2 weeks. Paroxysmal phase: severe paroxysms of coughing fits with inspiratory whoop sound after cough. Many have post-tussive vomiting. Often lasts 2-4 weeks. Convalescent phase is when cough is resolving.
Dx/Labs for Whooping cough
throat culture rule out other illness. PCR swab. Lymphocytosis common.
Management of Whooping cough
supportive care, O2, nebulizers, mechanical ventilation if needed. Antibiotics: Azithromycin or erythromycin. Complications: Pneumonia.
Empyema SC/Define
Collection of pus in pleural space between lung and chest wall. Caused by bacterial infection spread from lungs or abscess, or surgery or trauma, TB.
Hist/PE/CM of empyema
Decreased tactile fremitus, decreased breath sounds, dullness to percussion, pleural friction rub. Fever, chest pain, SOB, cough, night sweats, malaise.
Dx/Labs for empyema
CXR, CT, pleural fluid analysis, blunting of the cosphrenic angle on XRAY/CT. Thoracentesis is therapeutic and diagnostic. LIghts criteria: 1. pleural fluid LDH >2/3 upper limits of normal serum LDH. 2. PLeural protein/serum >0.5. 3. Pleural LDH/Serum LDH >0.6.
community acquired pneumonia
Pneumonia acquired outside of hospital setting or within 48 hours of being admitted.
RF for CAP
Older age, tobacco use, excessive alcohol use, comorbid conditions (esp COPD), recent viral URI, immune suppression
Organism association: Streptococcal pneumoniae
Young adults, post-influenza
Org association: Haemophilus influenza
COPD, elderly
Org association: Moraxella cararrhalis
COPD, immune compromise
Org association: Klebsiella
alcoholics, diabetics
Org association: Staphyloccus aureus
Post-influenza
Org association: Mycoplasma
Kids, teens, colleges, military
Org association: Chalmydia pn
Kids, teens, military
Org association: Chlamydia psittaci
Exposure to birds
Org association: Legionella
air conditioning, hot tubs
Org association: Coxiella burnetti
Farm animals
Org association: Franciesella tulerensis
“tuleremia” rabbits
Org associations: Viral
RSV, CMV, influenza, parainfluenza, adenovirus, covid.
Signs and Sxs of CAP
Acute onset fever, cough with or without sputum, dyspnea
Hist/PE/CM for CAP
Tachycardia, tachypnea, crackles (rales) rhonchi. incr tactile fremitus, egophony, dullness to percussion.
Path assoc: Legionella
Atypical pneumonia, gram neg, 2-1 days incubation, fever, fatigue, then cough and SOB. GI sxs (NVD), hyponatremia, elevated liver enzymes, CRP >100
Path assoc: Mycoplasma
MCC atypical pneumo. School aged kids and adolescents, schools, colleges, prisons, military. Gradual onset, HA, malaise, low-grade fever +/- sore throat, cough +/- sputum, SOB, pleuritic CP, chest soreness from coughing, persistent cough. URI sxs of rhinorrhea, otitis media, sinusitis, cervical LAD
Path assoc: Mycoplasma in nonrespiratory disease
autoimmune hemolysis (Incr IgM cold aglutinins), erythema multiforme, JSJ, urticaria, mucositis; Cardiac (pericarditis, myocarditis), MSK (arthralgias, myalgias), mild elevations in liver enzymes.
Nosocomial pneumonia/HAP
Ventilator associated pneumonia/VAP
Hospital acquired pneumonia. Acquired >48 hours after admission.
VAP: Acquired >48 hours after endotracheal intubation.
Pathogens associated with HAP/VAP
Pseudomonas (cystic fibrosis), enterobacter, acinetobacter, S aureus (esp MRSA), strep pneumo
RF for HAP/VAP
Freq abx use, extended hospitalization >5 days.
To Diagnose HAP/VAP, you need
New lung infiltrate AND 2 or more clinical features of infection such as: New onset fever, leukocytosis, leukopenia, purulent sputum, decline in oxygenation.
Pseudomonas VAP RF:
IV Abx in last 90 days; structural lung disease like cystic fibrosis, bronchiectasis.
Sxs of pseudomonas VAP
Fever, cyanosis, hypotension, rapid cavitation <72 hours on CXR, green sputum
Dx/Labs for pneumonias
CBC: Leukocytosis w/left shift. CMP with incr ESR and CRP
Procalcitonin for pneumonia
<0.25 = viral; > or = 0.25 = bacterial
CXR for pneumonia
AP and lateral views will show lobar consolidation, interstitial infiltrates, cavitations
CXR for viral pneumonia
bilateral multifocal, patchy ground glass opacities. DENSE CONSOLIDATIONS, PLEURAL EFFUSIONS, AND ABSCESSES WILL BE ABSENT
CXR bacterial pneumo
dense lobar or alveolar consolidations
Sputum color assoc: Rust
Strep pneumo
Sputum color assoc: green
Pseudomonas or Hib
Sputum color assoc: current jelly
Klebsiella
CURB65 criteria for pneumonia
C= confusion
U=BUN >19 mg/dL or >7mmol/L urea +1
R=RR>30
B=SBP <90, DBP<=60 mmHg
65=age >=65
0-1 outpatient
2 admit
3 assess need for ICU, espec if score 4-5
Microbiology tests for pneumo (if inpatient)
Blood cultures x2, MRSA nasal PCR swab
Sputum gram stain and culture
pneumococcal urine antigen
influenza nasal swab (NAAT)
PCR for pneumonia (BioFire PN)
Respiratory BioFIre (viruses)
Management/Treatment for CAP outpatient
Amoxicillin plus macrolide is preferred. Can do doxycycline as macrolide alternative.
Mgt/Tx for CAP outpatient if any of the following are true: heart, liver, kidney dz, diabetes, alcoholism, malignancy, asplenia, immune suppression or use of other antibiotics in the last 3 months
Augmentin plus macrolide (doxy as macrolide alternative) OR respiratory fluoroquinolone monotherapy as alternative.
CAP inpatient NOT ICU
antipneumococcal beta lactam plus macrolide OR resp FQ monotherapy
CAP inpatient ICU
antipneumococcal beta lactam plus azithromycin preferred. can do antipneumococcal beta lactam plus resp FQ
If suspect MRSA CAP add
vancomycin or linezolid
If suspect pseudomonas CAP
Betalactam plus FQ but both have to have antipseudomonal coverage.
Nosocomial Pneumo Tx/Mgt
Need pseudomonas coverage
Zosyn or cefepime
If risk of MRSA, add vanco or linezolid
Anti-MRSA abx
Vancomycin or linezolid
Respiratory fluoroquinolones
Levofloxacin
Moxifloxacin
Gemifloxacin (PO)
Antipseudomonal FQ
ciprofloxacin
levofloxacin
antipseudomonal beta lactam
augmentin
Ampicillin sulbactam (Unasyn)
Ceftriaxone
Cefotaxime
Ertapenem
Antipneumo/antipseudomonal beta lactam
Piperacillin tazobactam (Zosyn)
Imipenem
Meropenem
Cefepime
Ceftazidime
Macrolides
Azithromycin
Clarithromycin
Histoplasmosis
Organism Histoplasma capsulatum
Transmitted through inhalation of moist soil that contains bird or bat droppings in Mississippi or Ohio river valley
Histoplasmosis RF
Immune compromise.
AIDS defining illness, esp if CD4 is less or equal to 100.
Hist/PE/CM Histoplasmosis
Most often asymptomatic. Could have flu like sxs. Atypical pneumonia may have fever, nonproductive cough, myalgias (mimics TB)
Dissemination (if immune compromised): Hepatosplenomegaly, fever, oropharyngeal ulcers, bloody diarrhea, adrenal insufficiency.
Dx/Labs for histoplasmosis
Increased ALP and LDH, pancytopenia.
CXR: pulmonary infiltrates, hilar or mediastinal LAD
Antigen PCR of sputum or urine
Cultures: Most specific + if disseminated or HIV.
Mgt/Tx for histoplasmosis
If asymptomatic: None.
Mild or moderate disease: itraconazole is first line
If severe: Amphotericin B
Cryptococcal pneumonia/cryptococcus
Etiology: inhaling pigeon or bird droppings, organism cryptococcus neoformans. AIDS defining illness.
Hist/PE/CM for cryptococcal pneumonia
meningoencephalitis. MCC of fungal meningitis. HA, neck stiffness, nausea/vomiting, photophobia
Pulmonary: Pneumonia (cough, peuritic CP, dyspnea, nodules, abscesses, pleural effusions)
Dx/Labs for cryptococcal pneumonia
LP: Fungal CSF pattern of incr WBC (lymphocytes), decr glucose, increased protein.
ELISA cryptococcal antigen.
India ink stain shows encapsulated yeast
Tx/MGt for cryptococcal pneumonia
meningoencephalitis: Amphotericin B plus flucytosine x2 weeks.
THEN PO fluconazole x10 weeks
HIV prophylaxis: fluconazole if CD4 <100
pneumocystis pneumonia
Interstitial pneumonia caused by the yeast-like fungal organism pneumocystis jerovecii. Transmitted airborne.
AIDS defining illness - CD4 < 200
RF: Immune compromised, chronic steroid therapy, malignancy such as leukemia or non Hodgkin lymphoma, maluntrition.
Hist/PE/CM Pneumocystis pneumonia
Gradual onset fever, dry cough, dyspnea, progressing over days to weeks. Fatigue, chills, CP, wt loss
5-10% of patients are asymptomatic. On PE, tachypnea, crackles and rhonchi, O2 less than 90%
Dx/Labs for pneumocystis pneumo
CD4 <200, incr LDH, Incr 1-3 beta D glucan.
Hypoxemia: Incr A-aO2 gradient (ref of 5-10 mmHg), decr PaO2, decr DLCO.
CXR: diffuse, bilateral perihilar infiltrates.
HiRES CT bilateral patchy or nodular ground glass opacities
Microbiologic ID via staining and or PCR of a respiratory specimen. PCR preferred.
Direct fluorescent antibody (DFA) stain: cystic or trophic forms.
Severity of illness pneumocystic pneuo
Mild to moderate PaO2 >/= 70 mmHg and A-a gradient <35
Mod-severe PaO2<70 mmHg and A-a gradient >/=35.
Mgt/Tx of pneumocystis pneumonia
TMP/SMX x21 days.
Alternatives:
1. Dapsone plus trimethoprim
2. PRimazuine plus clindamycin
If HIV + with moderate to severe PCP, add prednisone.
PCP prophylaxis indicated if CD4 less than 200: Low dose TMP SMX.
RSV
MCC of low respiratory infection in children worldwide. VIrtually all children will contract by age 3. Leading cause of pneumonia and bronchiolitis in infants.
Hist/PE/CM RSV
Rhinorrhea, wheezing, cough (can last months), low-grade fever, nasal flaring/retractions, nail bed cyanosis.
Dx/Labs for RSV
RSV antigen test by nasopharyngeal swab.
CXR diffuse infiltrates.
Tx/Mgt of RSV
Indications for hospitalizaion: Feeding difficulties, decreased O2, visible retractions.
Supportive care with albuterol nebs, antipyretics, humidified O2.
Steroids (controversial). Symptoms usually resolve 5-7 days.
PRevention of RSV
Palivizumab (synagis) for infants <12 months if premie <29 weeks gestation, chronic lung dz of prematurity, hemodynamically significant CHD, congenital airway abnormality or NMD that decreases ability to manage secretions.
Infants/children <24 mos old who also have chronic lung disease of prematurity requiring medical therapy such as O2, bronchodilators, diuretics, steroids, w/in 6 months prior to beginning of RSV season, cystic fibrosis, profound immune compromise, undergoing cardiac transplant during RSV season.
Tuberculosis
Mycobacterium tuberculosis
Bacilli = rod shaped
strict aerobe
Acid fast = won’t Gram stain.
Transmitted by air droplets.
RF: HC workers, immune compromised, drug use, homeless, crowded living conditions like prisons and nursing homes, close contact with persons with active TB, travel to endemic areas. NOT CONTAGIOUS
After primary infection, TB progresses three ways
- Latent TB infx: state of constant immune response stimulation due to TB.
- Active primary TB: Active TB occurring after first time exposure to TB. CONTAGIOUS. (1-5% of cases. This one can become progressive severe TB in patients with compromised immune systems, ie HIV, malnutrition, children.
- Reactivation TB (secondary infection). Active TB developing after endogenous reactivation of LTBI or exogenous re-infection. CONTAGIOUS.
Hist/PE/CM TB
Pulm TB: PRogressive cough: Dry to productive to hemoptysis. Pleuritic CP, fever, night sweats, anorexia, wt loss.
Extra-Pulmonary disease:
1. Vertebral: Osteolytic lesions on plain film.
2. Lymphadenitis (scrofula): single swollen nontender cervical lymph node.
3. Meningitis, ocular, renal, pericarditis, salpingitis, peritonitis, intestine.
Dx/Labs for TB
CXR: findings are variable and nonspecific.
1. Primary (middle and lower lobes) consolidation, hilar LAD, pleural effusion, Ghon complex (Ghon focus + hilar LAD).
2. Ranke complex: Calcified primary TB with Ghon complex.
3. Reactivation (post primary): Fibrocavitary lesions in upper lobes.
4. AIDS, CD4<200: Diffuse military, hilar, and mediastinal LAD.
DX/Labs for TB Biopsy
Caseating granulomas.
Dx/Labs for TB: Sputum
3 samples at least 8 hours apart and one must be early morning specimen. AFB smear/culture with NAAT.
+ NAAT with or without +AFB is considered sufficient for Dx of TB.
Definitive +sputum culture
Screening for TB
PPD skin test. Read at 48-72 hours. IGRA preferred if BCG vaccine given.
How to read TB skin test: >=5 mm induration
> = 5 mm is positive if HIV, immune suppression (ie TNF inhibitors, chemo, organ transplant, steroid therapy), close contact to active contagious case, abnormal CXR w/fibrotic changes consistent with TB infx.
How to read TB skin test: >= 10 mm induration
clinical conditions that increase risk of re-infection (silicosis, CKD on dialysis), diabetes mellitus, some cancers, underweight. IV drug use, bypass surgery, children under 4 YO, foreign from countries w/>25/100,000 cases annually. High risk settings such as prisons, health care facilities, homeless shelters.
How to read TB skin test: >=15 mm induration
Healthy individuals over 4 YO without risk factors.
Mgt/Tx TB
Traditional regimen: RIPE Intensive phase 2 months. Continuation phase RI 4 months
Rifampin
Isoniazid
Pyrazinamide
Ethambutol
Rifapetine - moxifloxacin based 4 mos regimen:
1. Intense phase (8 weeks) rifapentine, isoniazid, pyrazinamide, moxifloxacin.
2. Cont phase (9 weeks) rifapentine, isoniazid moxifloxacin
Adjunct treatment: Pyridoxine to prevent Vit B6 deficiency and neuropathy from isoniazid.
Criteria for stopping therapy for TB
2 consecutive cultures -AFB smear and culture.
Monitoring required during treatment for TB
baseline LFTs/screening and Q1 month throughout treatment due to risk of hepatotoxicity.
Latent TB infection treatment options
3HP: isoniazid, rifapetine Q1 week x3 months.
4R: Rifampin QD x4 months
3HR: isoniazid + rifampin QD x3 months
Postexposure protocol for TB
If positive skin test: CXR to exclude active TB. CXR normal, treat for latent TB. If CXR abnormal, work up for active TB.
If negative skin test: No further evaluation if >8-10 weeks from exposure. If less than 8-10 weeks from exposure and immune competent over 5 YO: No treatment, repeat screen at the 8-10 weeks from exposure time. If immune compromised or less than 5 YO, start tx for LTBI until repeat screen at 8-10 weeks after exposure. If repeat screen at that time is negative, discontinue treatment. If positive, CXR, then treat accordingly.
Rifampin
MOA inhibit bacterial DNA dependent RNA-polymerase, preventing transmission and inhibiting protein synthesis causing cell death (bactericidal). ADR: histamine release (flushing, rash, pruritus, flu-like sxs), red-orange body fluids (tears, saliva, urine, sweat), hepatitis.
Isoniazid
MOA: prodrug converted by bacterial catalase-peroxidase to its active metabolite, which prevents cell wall synthesis by inhibiting synthesis of mycolic acid. Pyroxidine supplement to prevent peripheral neuropathy. ADR: neurotoxicity (peripheral neuropathy), hepatotoxicity, cytochrome p450 inhibitor.
Pyrazinamide
MOA: Not fully understood. Prodrug converted into active form of pyrazinoic acid, most effective at acidic pH, bactericidal effect. ADR: hepatotoxicity, hyperuricemia (avoid in gout).
Ethambutol
MOA: inhibits arabinosyltransferase, which decreases carbohydrate polymerization and prevents mycobacterial cell wall synthesis (bacteriostatic). ADR: dose-dependent optic neuritis (decreases visual acuity, red-green color blindness), decreases urate excretion (exacerbates gout).
