Pneumonia
Introduction
Pneumonia is the 5th most common cause of death and is a common infectious disease
of lung parenchyma. Pneumonia is loosely divided into community acquired and nosocomial
groups. Pneumonia that develops either during the hospital stay or within 4 to 6 weeks
after discharge from the hospital, in the nursing home or in long-term care facilities, is
considered nosocomial pneumonia. Pneumonia that develops in other settings is called
community acquired pneumonia. Community acquired pneumonia is further divided into acute
bacterial pneumonia and atypical pneumonia.
Etiology
The common causes of community acquired pneumonia are Pneumococcus, Hemophilus
influenzae, Legionella (bacterial), Mycoplasma, and Chlamydia. Other uncommon causes of
community acquired pneumonia are Group A Streptococcus, Staph aureus, gram-negative rods,
Moraxella catarrhalis (smokers), and anaerobes (aspiration). Other rare causes of
pneumonia based on endemic areas are Coccidiomycosis, histoplasmosis, Blastomycosis, and
Rickettsia. Finally consider Pneumocystis carinii pneumonia (PCP) and tuberculosis (TB) in
immunosuppressed patients.
Clues from the history and physical exam
With pleuritic type chest pain, suspect a pleural effusion; rigors are more common
with pneumococcal lung infection. Check the respiratory rate and observe the patient
closely if above 25. Check tilts to assess whether the patient is dehydrated. Check the
oxygen saturation. Hemoptysis (blood tinged sputum) is rare with Mycoplasma pneumonia but
is often seen with bacterial, TB, and fungal type lung infections. Severe coughing spells
and wheezing in a non-asthmatic is suggestive of chlamydia. Associated headache and GI
symptoms suggest Legionella.
Diagnosis
After gathering the history and performing the physical exam, request a CBC,
chemistry studies, CXR, and sputum smear. Always check a pulse oximetry. If a pulse
oximetry is not available, place the patient on oxygen. Initiate IV hydration.
A WBC of < 3,000/mm3 or > 25,000 is an ominous sign. A respiratory
rate >30, a diastolic blood pressure < 60 mmHg, and a BUN > 20 are other poor
prognostic signs. If you suspect tuberculosis based upon clinical and/or radiographic
features, ISOLATE the patient immediately. Do not hesitate when in doubt.
Perform a sputum gram stain. If the gram stain demonstrates gram positive organisms
suggestive of Pneumococcus or Streptococci, begin a third generation cephalosporin such as
Ceftriaxone or Cefuroxime. If either antibiotic is not available, penicillin may be given
at a dosage schedule of 2 million units every 4 hours (IV). If a sputum sample is not
available or the gram stain is not helpful, begin empiric therapy with
Ceftriaxone (or Cefuroxime) and Azithromycin. If the gram stain demonstrates gram-negative cocco-bacillary
forms, begin
Ceftriaxone, Cefuroxime or Septra.
Radiographic Red Flags
-
Volume loss This implies endobronchial obstruction (i.e.
foreign body, anatomical abnormalities, or tumor). The patient needs bronchoscopy and
isolation.
-
Pleural effusion Look at the costophrenic angle. If this is
obliterated, request lateral decubitus x-ray views. If the fluid layers out to more than
10mm, a thoracentesis should be performed to determine the cause. If clinical
deterioration occurs, tap the fluid even if it is <10mm.
-
Adenopathy - Hilar and mediastinal adenopathy signify an atypical
pneumonia. Suspicion for organisms such as tuberculosis or fungi should be high. Isolate
the patient and do an aggressive workup for diagnosis.
-
Cavitation The most common community acquired pneumonias
rarely cavitate except Staph aureus pneumonia. When cavitation is seen, isolate the
patient. Suspect tuberculosis, aspiration pneumonia, and a fungal infection.
-
Multilobar involvement When more than two lobes are
involved, this signifies high mortality in pneumonia.
-
Progression of pneumonia while on antibiotics Suspect TB,
fungal, PCP, or Legionella as the etiology.
RED FLAGS
require aggressive diagnostic, therapeutic management,
and early transfer or MEDEVAC.
Antibiotic therapy
The following description outlines empiric therapy for outpatient CAP:
-
Erythromycin 500mg , one PO, every 6 hours, or
-
Azithromycin 250mg, two PO initially, followed by one PO every day for
the remaining 4 more days, or
-
Clarithromycin 500mg, one PO BID for 7 to 14 days, or
-
Doxycycline 100mg, one PO BID.
In patients with comorbidities such as smoking, alcoholism or those
older than 60, consider coverage for H. influenzae with the addition of a second
generation cephalosporin:
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Cefuroxime (Ceftin) 500mg, one PO BID, or
-
Cefpodoxime (Vantin) 200mg, one PO BID, or
-
Augmentin 500mg, one PO TID, or 875mg, one PO TID, or
-
Septra
DS, one PO BID.
If the patient requires hospitalization, use the same antibiotic agents;
a macrolide with a second or third generation cephalosporin
such as
Ceftriaxone (Rocephin
2 gm IV QD), or Cefuroxime 1.5 gm IV, every 8 hours.
Specific Therapy
-
Empiric
Erythromycin; 500mg every 6 hours (with or without Cefuroxime TID or Septra
twice a day).
Add H. Influenza coverage for smokers and for patients older than 40. Strongly consider Doxycycline for wheezing pneumonias (as Chlamydia pneumonias frequently are).
-
Pneumococcus
Penicillin G IV 600,000-1.2 million units every 4 hours. If there are high rates of
Penicillin resistance in the area or if the organisms susceptibility (MIC) to PCN is
>0.1 micrograms/ml, IV Rocephin with Vancomycin (1 gm IV Q 12 hours) should be used.
The newer quinilones such as levofloxacin or trovofloxacin have good activity against PCN
resistant pneumococcus and can be used. Ciprofloxacin should not be used.
-
H. influenzae
Cefuroxime (Ceftin 500 mg) orally or IV. Intravenous
Ceftriaxone or Septra
DS one tab PO
BID (if the organism is sensitive) or Augmentin, orally or IV 500 mg TID should be
considered.
-
Chlamydia pneumoniae
Tetracycline 500 PO QID or Doxycycline
100 BID PO or IV. Macrolides
or flouroquinilones
can
also be used.
-
Moraxella catarrhalis
Usually causes acute bronchitis but is covered by macrolides such as Erythromycin, Azithromycin, or Clarithromycin.
Tetracycline, Septra, or Augmentin can also be used.
-
Staph aureus
Oxacillin or Nafcillin 2 gm IV every 6 hours or Vancomycin 1 gram every 12 hours IV (for
penicillin allergic patients).
-
Legionella pneumophila:
Erythromycin 1 gm IV every 6 hours with or Azithromycin 500 mg IV QD with or without
Rifampin 600mg PO BID.
-
Suspected Tuberculosis
Rifampin 600mg PO QD, INH 300mg PO QD, PZA 25mg/kg/day PO, Ethambutol 25mg/kg/day PO.
Assess the liver enzymes before and during therapy.
-
Pneumocystis carinii pneumonia (PCP)
Septra DS 2 PO QID, or Clindamycin (Cleocin) 600 mg PO QID plus Primaquine 26.3 mg PO QD,
or Dapsone 100 mg PO QD plus Trimethoprim 20 mg/kg PO daily, divided into a QID dosage
schedule.
Aspiration pneumonia
This can occur after dental work or drinking alcohol. Clues can include bad
smelling or tasting sputum, night sweats, and mild anemia. Treatment choices include
Timentin IV, Unisyn IV, Augmentin PO or Clindamycin
PO.
Re-evaluation
Once therapy is started, daily clinical reevaluation is necessary to ensure a good
response to therapy. The chest x-ray findings may lag behind the clinical response but
should be obtained in 2-3 weeks to ensure complete resolution of the infiltrate.
Reviewed by CAPT Angeline A. Lazararus, MC, USN, Pulmonary Specialty Leader,
Department of Internal Medicine, National Naval Medical Center, Bethesda, MD (1999).
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Preface
· Administrative Section
· Clinical Section
The
General Medical Officer Manual , NAVMEDPUB 5134, January 1, 2000
Bureau
of Medicine and Surgery, Department of the Navy, 2300 E Street NW, Washington, D.C.,
20372-5300
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