Community-acquired acute pneumonia: B-Animal, or Environmental Exposure:

1- Legionella pneumophila pneumonia: Microscopy: -Gram’s negative rods (in nature) Coccobacillary; (in clinical specimens). -Facultative intracellular parasites. -Rods are motile by monotrichous flagella.

Transmission: inhalation of aerosols from contaminated water produced by showers, humidifiers, AC air condition.

N

Pathogenesis:-Infection of resident alveolar macrophage.-Inhibits phagosome-lysosome fusion.

-Formation of phagosome enveloped by endoplasmic reticulum; formation of replicative rod form; Autophage.-TNF-α, and INF-γ Production; monocytic infiltration of air spaces.-Alveolitis (Consolidation) and micro-abscess formation. -Bronchi are not affected.

N

Laboratory diagnosis:-Staining of specimens by Gram’s stain and Gimesa stain.-Grown on buffered charcoal yeast extract agar. (Enriched media: L-cysteine, iron, α-ketoglutarate).-Rapid identification: 1-Immunofluorescent microscopy 2-PCR.

Treatment:1-Macrolides: Azithromycin2-Fluoroquinolones: Levofloxacin.

N

2-Pneumonic tularemia: (granulomatous infection): : Francisella tularensis infection: Microscopy and Cultural characteristics: -Gram’s negative pleomorphic Coccobacillus with lipid- rich capsule. -Facultative intracellular parasite. -Obligate aerobic bacteria.

N

- Grown on buffered charcoal yeast extract agar. (Enriched media: L-cysteine, iron, α-ketoglutarate).

Transmission:1-Inhalation of infectious aerosols. 2-Blood sucking arthropods bite; vector (ticks, mites) from animals (rabbit, birds).

Pathogenesis and clinical presentation: -Infection of alveolar macrophage; granuloma of lung: Pneumonic tularemia.

N

Pathogenesis and clinical presentation:

N

-Infection of skin macrophage; ulcerative papule; transmitted to regional lymph nodes; lymphadenitis: Ulceroglandular tularemia ;(the most common presentation).

-Hematogenous dissemination to lung from other sites. (infection of APC of liver, spleen, bone marrow).

N

Treatment of Tularemia:1- Aminoglycosides: Gentamicin or Streptomycin.2-Ciprofloxacin and doxycycline.

3-Pneumonic Plague: Yersinia pestis infection: Microscopy, virulence, and cultural characteristics: - Gram’s negative coccobacillus. - In sputum: Gram’s negative bipolar-stained bacilli. -Encapsulated: F1, V, and W antigen; Antiphagocytic Ag. -Lipopolysaccharide (LPS) endotoxin. -Plasminogen activator: degrades fibrin.

N

Transmission: 1-Person-to-person: inhalation of droplets. 2-Vector-borne: insect bite(Fleas) from rodents (Rat).

Pathogenesis and clinical presentation: -Infective dose:100-500 cells.-Incubation: 2-8 days.-Primary: Bubonic plague: Swollen tender regional lymph node; bubo: lymphadenitis (Hemorrhagic necrosis). -Septicemic plague: DIC, Purpura and ecchymoses; Black).-Pneumonic plague: (Bronchopneumonia): A-Primary: Inhalation of droplets. B-Secondary: Hematogenous spread.

Transmission of Yersinia pestis (Plague): N

N

Treatment of Plague:-Pneumonic plague should be treated within 24 hours of appearance of symptoms, (mortality rate: 100%).-Aminoglycosides: Streptomycin, gentamicin.-Fluoroquinolones and doxycycline.

4-Inhalation anthrax: Woolsorter’s disease: Bacillus anthracis infection: -Caused by Gram’s positive aerobic spore-forming bacilli. -Transmission: inhalation of spores. -Not a true pneumonia. -Alveolar macrophage transfer the spore to mediastinal and peribronchial lymph nodes.

N

Clinical presentation of inhalation anthrax:-Hemorrhagic Mediastinal lymphadenitis.

-In 50% of inhalation cases; Anthrax meningitis ; extensive

hemorrhage of the leptomeninges; Dark-red “Cardinal’s

cap” appearance on autopsy.

Treatment:

-Only if multiple intravenous antibiotics and passive vaccine

administered prophylactically after spore exposure.

2- Hospital-acquired Pneumonia(Nosocomial):

Pneumonia acquired during or after hospitalization. It occurs at least 72 hour after admission.Who are at Risk?-Patients on mechanical ventilation ( ICU).-Immunocompromised patients. -Other factors: malnutrition, heart and lung diseases.

Causative agents:(Micro-aspiration of Oropharyngeal flora of hospitalized patients):MRSA, Pseudomonas, Enterobacter, Klebsella, Serratia, Acinetobacter (person-to person) and VRE.

Chronic and Subacute Pneumonias:

Chronic granulomatous pneumonia:1-Bacterial granulomatous pneumonia: Mycobacterium tuberculosis: -Acid-fast bacilli (Mycolic acid rich waxy capsule). -Non-motile aerobic rods resists drying. -Cultured on Lowenstein-Jensen agar. -Stained by Z.N stain.

N

Pathogenesis and Clinical presentation:

Primary Tuberculosis

90% Latent dormant tuberculosis

Living bacteria &granuloma

25% arrested granuloma

Fibrosis or Calcification.Enlarged Tracheobronchial lymph nodes .

75% Breaks down

granuloma

-Caseous material discharged; necrosis-Cavity creation.

Apical lung cavities

Tuberculous pneumonia

Lympho-Hemo

MeningitisOsteomyelitis

10% Progressive active infection

AIDS, Old, Children

Living- bacteria, granuloma

Diagnosis of Tuberculosis:

Clinical test:1-Tuberculin skin test. (DTH:48-72 hours). Mantoux test: (PPD: Purified Protein Derivative) Results: Intermediate reaction=5-9mm. Positive reaction=greater than 9mm. 2-Radiology.

Laboratory tests:1-Z.N stain (Low sensitivity). 2-Culture.3-PCR (highest sensitivity).

N

2-Fungal granulomatous pneumonia: (Endemic in America):

Transmission: Direct contact with birds and bats. A-Coccidioidomycosis. B-Histoplasmosis. C-Blastomycosis. D-Paracoccidioidomycosis.

Coccidioidomycosis: Caused by dimorphic fungi :Coccidioides immitis. Infective stage: Arthrospores generated by septate hyphae.Diagnostic stage: Spherule filled with many endospores.

Fungal Pneumonia in AIDS patients:

1-Pneumocystis Pneumonia: (The most common infection). -Caused by Pneumocystis jiroveci (P.carinii). -Yeast lacking ergosterol in cell membrane. -Can not be treated by Amphotericin. -Encysted forms infects alveoli; exudate; blocks gas exchange.

-Treatment: Sulfamethoxazole and trimethoprim. Cysts of Pneumocystis carinii ; Sliver stain.

N

2-Cryptococcosis: (The second common cause of Fungal pneumonia in AIDS pat.). -Causative agents: Cryptococcus neoformans. -Yeast transmitted to man from birds (pigeon). -Capsulated microbe. -Meningitis in Immunocompromised host. -Treatment: Fluconazole or amphotericin B.

The Budding capsulated yeast Cryptococcus neoformans as shown in India ink wet mount .