INFECTIOUS PULMONARY DISEASES

Module HPneumonia -Chapter 15 (pp. 224-241)

Lung Abscess - Chapter 16 (pp. 242-249)Tuberculosis – Chapter 17 (pp. 250-259)

Avian FluSARS

Fungal Diseases - Chapter 18 (pp. 260-271)

Pneumonia• Inflammatory Process

• Gas Exchange areas of the lung.

• Alveolar Consolidation• Alveoli become filled with fluid, RBC, WBC and

macrophages.

• 2 million cases/year with 40,000 to 70,000 deaths.• 6th leading cause of death• “Old Man’s Friend”

Etiology

• Bacteria

• Viruses

• Fungi

• Rickettsia

• Protozoa

• Anaerobic organisms

Pneumonia vs. Pneumonitis

• Pneumonia is an infection with an inflammatory response and consolidation of the lung parenchyma.

• Pneumonitis is an inflammatory response due to a non-infectious agent.

Aspiration Pneumonitis

• Etiology• Strokes• Neuromuscular disease• Decreased level of consciousness

• Alcoholics• Drug Abuse• Head Injury

• Chemical (Mendelson’s Syndrome)• Inhalation of gastric acid

Types of Pneumonia• Lobar Pneumonia

• Involves the entire lobe

• Segmental (Lobular)• Bronchopneumonia

• Alveoli contiguous to an bronchi

• Interstitial Tissues

• Double Pneumonia: Both lungs• Walking Pneumonia: Mild form of pneumonia

• Mycoplasma Pneumoniae

• Necrotizing Pneumonia

At Risk Patients• Elderly• Chronic Disease

• Diabetes, Renal Disease, Alcoholics

• Immunosuppressed Patients• Cancer patients• AIDS• Transplant patients• Malnutrition• Patients on steroids

• Burn victims• Leukemia• Drug abuse

Classification of Pneumonia

• Nosocomial • Diagnosed 48 hours after hospital admission.• Ventilator Associated Pneumonia (VAP) is a

subset of nosocomial infections.

• Community –Acquired Pneumonia • Outside a health care setting.

Pneumonia during Mechanical Ventilation

• Use of a modified Clinical Pulmonary Infection Score (CPIS)• If score is above 6, pneumonia is likely.

CPIS Points 0 1 2

Tracheal Secretions

Rare Abundant Abundant & Purulent

CXR Infiltrates No Infiltrate Diffused Localized

Temperature (ºC) > 36.5 and < 38.4 > 38.5 and < 38.9 > 39 or < 36

Leukocytes per mm3

> 4000 and

< 11,000

< 4000 or

> 11,000

< 4000 or > 11,000 with bands > 500

PF Ratio > 240 or ARDS < 240 and no evidence of ARDS

Microbiology Negative Positive

Bacterial Etiology – Gram +• Streptococcal (Pneumococcal)

Pneumonia• Most common (80%)• 80 different types• Pneumococcal Vaccine

• Staphylococcal Pneumonia• Staphylococcal aureus

• Primary causative agent• Methicillin-resistant (MRSA)

• Staphylococcal epidermidis • Normal flora

Bacterial Etiology – Gram -• Rare in “healthy” hosts

• Klebsiella pneumoniae (Friedlander’s Bacillus)

• Lobar Pneumonia• Older men and alcoholics

• Pseudomonas aeruginosa• Chronically ill, tracheotomized patients

• Haemophilus influenzae• Second most common community acquired

pneumonia (CAP) to Streptococcus pneumoniae• Secondary to viral infection• Type B is pathogenic

• HIB vaccine has reduced incidence

Bacterial Etiology – Gram -• Legionella pneumonphila

• American Legion in 1976• 30+ species

• Escherichia coli• GI tract normal flora

• Enterobacter sp.• Enterococcus sp.

• Normal flora in GI tract• Vancomycin Resistant Enterococcus (VRE)

• Proteus sp.• Serratia marcesens

Antibiotic Resistant Respiratory Bacterial

Pathogens

• Methacillian Resistant Staphylococcus Aureus (MRSA)• Treated with Vanomycin

• Vancomycin Resistant Enterococcus (VRE)• Normally found in GI tract• Nearly impossible to treat• Treated with teicoplanin & Synercid

Viral Pneumonia

• 90% of acute upper respiratory tract infections are caused by viruses.

• 50% of lower respiratory tract infections are due to viruses.

Types of Viral Pneumonias

• Influenza Virus• Types A and B are the most common• Winter months

• Respiratory Syncytial Virus (RSV)• Bronchiolitis in infants & pneumonias in elderly

• Parainfluenza Viruses• 5 types

• Type 1, 2, 3, 4A and 4B

• Type 1 is associated with croup infections

• Adenovirus

Types of Viral Pneumonias

• Varicella• Chickenpox & pneumonia

• Rubella• German Measles & pneumonia

• Rubeola• Measles

• Cytomegalovirus (CMV)• Member of the herpes virus• Usually seen in AIDS patients

Other Causes of Pneumonia• Mycoplasma Pneumoniae (Primary Atypical

Pneumonia)• Walking Pneumonia• Young (5 to 35 years of age)

• Rickettsiae• Rocky Mountain Fever, Typhus, Q fever• Transmitted by fleas, ticks, mites

• Chlamydia Psittaci (Psittacosis)• Found in respiratory tract and feces of a variety of

birds• Parrots, parakeets, cockatoos, chickens, pigeons

• Transmitted to humans via aerosol or direct contact• Chlamydia Pneumoniae

Other Causes of Pneumonia

•Pneumocystis carinii

•Opportunistic, often fatal, form of pneumonia seen in immunocompromised patients.

•Has been thought to be a protozoa but more recently, information suggests a fungus.

•Major cause of pneumonia in AIDS patients.

Fungal Infections

• AIDS patients and patients on steroids • Histoplasma capsulatum• Coccidioides immitis• Blastomyces dermatitidis• Candida albicans

• Oral thrush

• Aspergillus

• Treatment• Amphotericin B (IV)• Nystatin• Fluconazole

• Aspergilloma

Tuberculosis• One of the oldest diseases – 4,000 B.C.• 1.5 Billion cases worldwide

• 15 million of these are active

• TB is still prevalent in US• 15,000 cases/year – 50% occur in patients born

outside the US• Highest incidence in SE US, inner cities, homeless &

jails

• HIV infection is the greatest single medical risk factor (no defense mechanism)

• Age has traditionally been considered an independent risk factor (greater chance of exposure)

Tuberculosis• Chronic disease requiring months of treatment.

• Suboptimal treatment can result in drug-resistant TB.• TB can affect many organs in the body but most

common location is the lungs.• Brain Kidneys• Bones Genital tract

• TB is caused by mycobacterium tuberculosis.• Produces a tubercle (lesion) that undergoes caseation.• Highly aerobic & like to grow in areas with high oxygen

tension• Brain, lung apex

• TB has airborneairborne mode of transmission• Transmitted within aerosol droplets from cough/sneeze

& can remain suspended in the air for several hours

Tuberculosis• Initial infection results in no sickness, no

symptoms, and the individual is not contagious (Latent TB).

• Active TB occurs with immunosuppression.• AIDS, Young, Old, Cancer, substance abuse

• Treatment is multiple first line drug therapy for 6 or 9 months

• There is an emergence of drug resistant strains of TB (MDR-TB)• Cure rate is poor

Categories of Tuberculosis

• Primary TB

• Post-primary TB

• Disseminated TB

Primary TB

• First exposure to the pathogen• Bacilli implant in the alveoli & multiply over 3-4

weeks• Inflammatory reaction

• Leukocytes, macrophages move into the area to engulf (but not kill) the bacilli

• Alveolar Consolidation

• Positive TB reaction• WBC normal

TB Bacilli & Macrophages

Neutrophils

Fibroblasts Lymphocytes

Protective Cell Wall

Tubercle or granuloma

2-10 weeks

•Necrosis•Cottage Cheese

•Caseation

Caseous Lesion

Healing

•Fibrosis

•Calcification

•Retraction of lung tissue

Post-primary Tuberculosis

• Reactivation of the tuberculosis months or years after the initial infection

• Most patients recover completely but the live tubercle bacilli can remain dormant for decades• May reactivate in patients with weakened

immunity

• Positive TB test• Cavity formation and possible rupture

Disseminated Tuberculosis

• Bacilli escape from the tubercle and rapidly disseminate to other parts of the lung or other organs• Move via the lymphatics or bloodstream

• Miliary Tuberculosis• Small tubercles scattered throughout the body

via blood stream.

Symptoms

• General malaise• Cough with sputum production

• Minimal initially, gradually increasing

• Night sweats• Chills• Increasing dyspnea• Chest pain• Loss of appetite• Weight loss

CONSUMPTION

Chest x-ray

• Initial Lung Lesion is called a Ghon nodule

• Ghon nodule + involvement of lymph nodes in the hilar region is the Ghon Complex

• Multiple Nodules (supra- or retroclavicular)

• Pleural Effusions

• Cavity Formation

Diagnostic Testing• TB skin test

• Mantoux Test • 5 of purified protein derivative (PPD) in 0.1 mL of

solution is injected.• Induration of 10 mm or greater is positive test

• Sputum Cultures and Acid fast stain• Ziehl-Neelsen & Fluorescent Stain• Culture will differentiate M. Tuberculosis from other

acid fast organisms (6-8 weeks)• Sputum may show AFB but negative for TB

• Chest x-rays

Drug Therapy for Tuberculosis• First Line

• R – rifampin (Rimactane) (*)• I – isoniazid (INH) (+)• P – pyrazinamide (Tebrazid)• E – ethambutol (Myambutol) • R – rifapentine (Priftin) (*)• R – rifabutin (Mycobutin)

• Use if patient receiving antiretroviral

• Second Line• Streptomycin

• (*) Reduces efficacy of oral contraceptives.• (+) Liver toxicity when alcohol is used.

Treatment

• If a patient does not respond to treatment in 2-3 weeks, suspect:• Non-compliance with drug regimen• Multiple drug resistant organisms (MDR-TB)

• Oxygen

Prophylactic Treatment

• Isoniazid if often prescribed as a daily dose for one year in individuals exposed to TB• Positive TB skin Test

Safety Precautions

• Isolation• Keep door closed

• National Institute for Occupational Safety and Health (NIOSH) recommends particulate filter respirators for HCWs• Surgical masks are not very effective against

TB