Infectious Diseases and Pneumonia Chapter 30 Paauw

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Community acquired pneumonia is common, with over 4 million cases annually. What is the mortality rate?: Most patients are treated as outpatients with a mortality rate of 1%.

20% of patients require hospitalization, where death rates are as high as 25%.

PNA is the 6th leading cause of death overall.
What is pneumonia?: It is inflammation of lung parenchyma from infection.
What are the 3 routes by which bugs get into the lungs?: Organisims reach the lung by:

1. oropharyngeal aspiration
2. inhalation
3. hematogenous spread
Defects of host defenses often contribute to getting pneumonia. List some examples.: 1. impaired glottic reflex
2. insufficient cough
3. impaired ciliary function usually from smoking
4. deficient immunity
Risk Group: alcoholics What are specific likely organisms?: 1. Streptococcus pneumoniae
2. Anaerobes
3. Haemophilus influenzae
4. Klebsiella pneumoniae
5. Mycobacterium tuberculosis
Risk group: Alcoholics What are the mechanisms of acquiring pneumonia?: 1. decreased glottic reflex
2. seizures
3. stupor
4. aspiration of oral and gastric flora
5. poor WBC function and humoral immunity
Risk group: IVDU What are specific likely organisims?: 1. Streptococcus pneumoniae
2. Anaerobes
3. Staphylococcus aureus
4. Mycobacterium tuberculosis
Risk group: IVDU What are the mechanisims of acquiring pneumonia?: 1. Aspiration during times of altered consciousness (heroin) or seizures (cocaine)

2. septic pulmonary emboli (tricuspid endocarditis).
Risk group: Smokers What are specific likely organisims?: 1. Streptococcus pneumoniae
2. Haemophilus influenzae
3. Moraxella catarrhalis
4. Legionella
Risk group: Smokers What are the mechanisims of acquiring pneumonia?: 1. Impaired mucocillary transport
2. Colonized lower respiratory tract
3. Resistance due to prior frequent antibiotics
Risk group: HIV infection What are the likely organisims?: 1. Streptococcus pneumoniae
2. Haemophilus influenzae
3. Pneumocystis carinii
4. Pseudomonas aeruginosa
Risk group: HIV infection What are the likely mechanisms of acquiring pneumonia?: 1. Impaired cellular immunity
2. Prophylactic antibiotics and CD4 less than 100 make pseudomonal infection more likely
Risk group: Nursing home residence What are the likely organisims?: 1. Klebsiella pneumoniae
2. Staphylococcus aureus
3. Mycobacterium tuberculosis (reactivation or primary)
Risk group: Nursing home residence What are the likely mechanisms of acquiring pneumonia?: 1. Lower immunity
2. Predisposing illness
3. Institutional exposures
4. Neurologic disease or medication cause
4. Altered cognition and aspiration
5. Colonization with gram-negative rods
Risk group: Post-viral superinfection What are the likely organisisms?: 1. Streptococcus pnuemoniae
2. Staphylococcus aureus
3. Haemophilus influenza
Risk group: Post-viral superinfection What are the mechanisms of acquiring pneumonia?: 1. viral infections disrupt mucociliary function
2. viruses interfere with cell-mediated host defense mechanisms (influenza, CMV)
3. develops 7-19 days after viral infection
What organisms cause CAP?: Streptococcus pneumoniae, then H. influenzae are most common: both occur in patients with predisposing conditions, although these conditions are not always present.
What is the most common cause of PNA in young, otherwise healthy adults?: Mycoplasma pneumoniae
When do you see anaerobic pneumonias?: They occur with periodontal disease because anaerobes flourish amid rotting teeth and gums. Edentulous patients rarely get anaerobic infections. Anaerobic infections are also more common with aspiration of mouth flora during periods of unconsciousness or with swallowing disorders. Aspiration is a common cause for pneumonias in injection drug uses (heroin decreases the gag reflex, cocaine can cause seizures) and alcoholics.
Bacterial pneumonia can occur after viral upper respiratory infections, usually soon after symptoms of the viral infection begin to improve. Which are the most common causes of PNA after a preceding viral upper respiratory infection?: Pneumococcus and S. aureus.
How is hospital-acquired pnuemonia different from community acquired pneumonia?: Common culprits are gram-negative rods, often resistant to multiple antibiotics, and S. aureus, followed by anaerobes and S. pneumoniae. Gram-negative pneumonias carry a high mortality (40%) because the organisms are aggressive and concurrent underlying medical conditions complicate recovery.
Hospital-acquired PNA occurs in up to what percentage of hospitalized patients?: Up to 10% of hospitalized patients can get nosocomial pneumonia. Mortality in patients with nosocomial pneumonias can be as high as 50%, partially related to the presences and severity of comorbid conditions.
What are some uncommon causes of pneumonia?: 1. Legionella occurs sporadically or epidemically. Those with underlying lung disease are at greatest risk.

2. Consider psittacosis, Chlamydia psittaci, with exposure to birds, especially in pet shop workers or bird keepers.

3. Chlamydia pneumonia occurs in young adults.

4. Q-fever from inhalation of aerosolized Coxiella burnetii is seen in livestock handlers.
What causes pleural effusions in patients with pneumonia?: Exudative pleural effusion accompanies about 40% of pneumonias and is due to pleural inflammation. Most of these parapneumonic effusions are small, sterile and resolve with treatment of the pneumonia.

Some become infected, creating a purulent empyema, which can cause persistent infection, sepsis and permanent scarring if left untreated.
What is an empyema?: The presence of pus in a bodily cavity (as the pleural cavity)
What questions should I ask when I suspect pneumonia? Classic symptoms of bacterial pneumonia include cough producing bloody or purulent sputum, high fever many times accompanied by rigors or chills, dyspnea, and pleuritic chest pain.: What questions should I ask when I suspect pneumonia?

Classic symptoms of bacterial pneumonia include cough producing bloody or purulent sputum, high fever many times accompanied by rigors or chills, dyspnea, and pleuritic chest pain.

Patients with PNEUMOCOCCAL pneumonia classically present with a single shaking chill at onset followed by high fever, pleuritic chest pain, and cough productive of bloody or "rusty" sputum.

LEGIONELLA may cause myalgias, headache, confusion and diarrhea as well.

"Atypical" presentations are more subdued and suggest less inflammatory organisims such as VIRUSES, MYCOPLASMA, PNEUMOCYSTIS, CHLAMYDIA, and uncommonly Q-fever or PSITTACOSIS.

For atypical presentations, cough (when present) is usually NONPRODUCTIVE, fevers are LOW-GRADE, and myalgias or severe headache may be present.

Extra-pulmonary manifestations may be prominent with MYCOPLASMA, such as meningitis, cerebellar ataxia, and erythema multiforme.

Hoarseness or sore throat suggests CHLAMYDIA.

Ask about OCCUPATIONAL or ANIMAL exposure, especially when symptoms are atypical, an organism cannot be found, or the patient does not respond to empiric therapy for common organisms.

Foul-smelling sputum suggests anaerobes.

Weight loss, anorxeia, and night sweats are clues to TB infection.
In what situations might typical pneumonias present atypically? _______ patients may have few symptoms referable to the chest and the main finding is confusion, disorientation, or anorexia. _______ patients rarely have productive co: In what situations might typical pneumonias present atypically?

ELDERLY patients may have few symptoms referable to the chest and the main finding is confusion, disorientation, or anorexia.

NEUTROPENIC patients rarely have productive cough because there are no WBCs to produce sputum. Their earliest and most pronounced symptom of pneumonia is isolated fever.

Some LOWER LOBE pneumonias may occur with minimal chest symptoms and abdominal pain caused by irritation of the diaphragm.
What exam findings support a diagnosis of a typical lobar pneumonia? Tachypnea, tachycardia, and fever are common. With early lobar pneumonia, breath sounds may may be decreased over the affected parenchyma, although occasionally are louder du: What exam findings support a diagnosis of a typical lobar pneumonia?

Tachypnea, tachycardia, and fever are common. With early lobar pneumonia, breath sounds may may be decreased over the affected parenchyma, although occasionally are louder due to better transmission of tracheal airway sounds through consolidated lung, called bronchial breath sounds.

Always compare breath sounds from side to side to detect subtle asymmetry.

Dullness to percussion can represent CONSOLIDATION or PLEURAL EFFUSION.

RALES may be heard over the affected lobe and are most prominent with resolving pneumonia as air passages begin to open up again.
Definition of rhonchus or rales:: Wheeze is a clinical feature of bronchospasm, and is a sound occurring during breathing originating from turbulent flow of air through constricted bronchioles.

a whistling or snoring sound heard on auscultation of the chest when the air channels are partly obstructed
What exam findings support a diagnosis of a typical lobar pneumonia? Other signs of lobar consolidation include whispered pectoriloquy and tactile fremitus. Whispered pectoriloquy is elicited by having the patient whisper something: What exam findings support a diagnosis of a typical lobar pneumonia?

Other signs of lobar consolidation include whispered pectoriloquy and tactile fremitus.

Whispered pectoriloquy is elicited by having the patient whisper something such as their phone number. Transmission of sound is very good through CONSOLIDATED lung, and you can easily hear the whispered words when your stethoscope is placed over the area.

Elicit tactitle fremitus by having the patient say "toy boat" while you place your hand symmetrically on the chest. Vibrations are increased over areas of CONSOLIDATION and are decreased when FLUID or AIR is present in the pleural space. Use this technique when dullness to percussion is present to differentiate effusion from infiltrate.
What lab tests are warranted if I suspect pneumonia? Check O2 saturation, CBC, sputum Gram stain and culture, electrolytes, and kidney function. In typical bacterial presentations, the WBC count rises, often with a left shift (exces: What lab tests are warranted if I suspect pneumonia?

Check O2 saturation, CBC, sputum Gram stain and culture, electrolytes, and kidney function.

In typical bacterial presentations, the WBC count rises, often with a left shift (excess immature forms or bands).

In contrast, WBC count is often NORMAL in viruses, Mycoplasma, or Chlamydia.

LOW WBC in presence of pneumonia is a poor prognostic sign.
What lab tests are warranted if I suspect pneumonia? In particularly ill-appearing patients, consider ________ and _______ . ______________ occur in up to 25% of pneumococcal pneumonias and are associated with poorer prognosis (20%-: What lab tests are warranted if I suspect pneumonia?

In particularly ill-appearing patients, consider BLOOD CULTURES and ABG.

POSITIVE BLOOD CULTURES occur in up to 25% of pneumococcal pneumonias and are associated with poorer prognosis (20%-40% mortality).

ABG may reveal hypoxia and respiratory ALKALOSIS.
What lab tests are warranted if I suspect pneumonia? ______ is suggested by hemolytic anemia or cold agglutinins, seen in 50% of patients. Mycoplasma and Chlamydia are often treated empirically without confirming a diagnosis.: What lab tests are warranted if I suspect pneumonia?

MYCOPLASMA is suggested by hemolytic anemia or cold agglutinins, seen in 50% of patients.

Mycoplasma and Chlamydia are often treated empirically without confirming a diagnosis.

Confirm diagnosis by a rise in convalescent antibody titers.
What lab tests are warranted if I suspect pneumonia? Legionella causes _______ and a sputum Gram stain with ___________________. Diagnose Legionella by urinary antigen (type 1 only), DNA probe, direct fluorescent antiboy, culture,: What lab tests are warranted if I suspect pneumonia?

Legionella causes HYPONATREMIA and a sputum Gram stain with LEUKOCYTES BUT NO ORGANISMS.

Diagnose Legionella by urinary antigen (type 1 only), DNA probe, direct fluorescent antiboy, culture, or increase in convalescent antibody titer.

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