Lower Respiratopry Tract Infections, TB, Fungi

Latent vs Active TB

Latent = asymptomatic, non‑contagious, walled‑off granulomas, positive TST/IGRA(Interferon gamma release assay)

Active=symptomatic, contagious, no longer “walling” off TB, AFB smear + culture

TB pathogenesis

Inhaled bacilli → survive in macrophages → T‑cell activation → granuloma formation → caseation necrosis

Nocardia characteristics

Weakly acid‑fast branching rods from soil/water

Actinomyces characteristics

Anaerobic branching rods, NOT acid‑fast

Endemic fungi pathogenesis

Mold in soil → inhaled spores → convert to yeast in tissue → granuloma formation

Aspergillus characteristics

Septated acute‑angle branching with septated hyphae

Mucormycosis characteristic

Broad aseptate right‑angle branching hyphae

Clinical manifestations: TB

Cavitary upper‑lobe disease, hemoptysis, fever, night sweats, weight loss

Clinical manifestations: NTM

MAC: nodular bronchiectasis, cavitary disease, disseminated infection in HIV

Clinical manifestations: Nocardia

Pulmonary nodules/cavities, cutaneous lesions, brain abscess (“lung‑brain syndrome”) (Nocardia= no heart= no brain or lungs bc no perfusion)

Clinical manifestations: Actinomyces

Cervicofacial abscesses with draining sinus tracts, lung abscesses, pelvic infections

Clinical manifestations: Histoplasma

Hilar lymphadenopathy, oral ulcers, pancytopenia, splenomegaly

Clinical manifestations: Blastomyces dermatitidis

Pneumonia, skin lesions mimicking SCC/BCC, bone, CNS, GU involvement

Clinical manifestations: Coccidioides

Valley Fever: fever, cough, fatigue, erythema nodosum

Clinical manifestations: Aspergillus

ABPA (asthma + eosinophilia), aspergilloma (fungus ball), chronic necrotizing disease, invasive aspergillosis (halo sign)

Clinical manifestations: Mucormycosis

Rhino‑orbital‑cerebral necrosis, black eschar, pulmonary necrosis

Clinical manifestations: Pneumocystis jirovecii pneumonia (PCP)

Subacute fever, dry cough, dyspnea on exertion, diffuse bilateral interstitial infiltrates, ↑LDH, ↑β‑D‑glucan

Management: TB

RIPE therapy (INH, rifampin, pyrazinamide, ethambutol)

Management: Nocardia

TMP‑SMX backbone + additional agents

Management: Actinomyces

High‑dose penicillin

Management: Endemic fungi

Itraconazole for most

Management: Aspergillus

Voriconazole is first‑line

Management: Mucormycosis

Surgical debridement + amphotericin B

Management: Pneumocystis (PCP)

TMP‑SMX for treatment and prophylaxis

Mycobacterium tuberculosis type of bacteria + components

acid fast bacilli, waxy cell envelope (mycolic acid + lipids)

Caseation and Granuloma def

Caseation=area of necrosis

Granuloma= rim of healthy macrophages

Tuberculin Skin Test measurements

5mm: severely immunocomprimised + sick

10mm: higher risk

15mm: No risk factors

TB drug that can cause optic neuritis

Ethambutol

TB drug that can cause peripheral neuropahty

Isoniazid (need to add B6)

TB drug that can cause gout flares

Pyrazinamide

TB drug that turns bodily fluids orange

Rifampin

This TB drug can cause a Lupus like syndrome

Isoniazid

TB drug with lots of drug-drug interactions

Rifampin

Cavitary lesion and abcess not getting better with antibiotics think:

TB, NTM, Nocardia, Actinomyces