1 Cover the middle and right-hand columns and specify which bugs are associated with each type of infection and what type of empirical antibiotic should be used while waiting for culture results.

2 Cover the middle and right-hand columns and specify the empirical antibiotic of choice for each organism.

3 Cover the right-hand column and specify what each Gram stain most likely represents.

4 What is the gold standard for diagnosis of pneumonia?

Sputum culture. Obtain the culture before starting antibiotics, although many physicians treat empirically without culture in routine cases. Obtain blood cultures as well because bacteremia is common with pneumonia.

5 What is the most common cause of pneumonia? How does it classically present?

Streptococcus pneumoniae. Look for rapid onset of shaking chills after 1 to 2 days of upper respiratory infection symptoms (sore throat, runny nose, dry cough), followed by fever, pleurisy, and productive cough (yellowish-green or rust-colored from blood), especially in older adults. Chest radiograph shows lobar consolidation (Fig. 20-1), and the white blood cell count is high with a large percentage of neutrophils. Treat with a macrolide (e.g., azithromycin, clarithromycin), doxycycline, third-generation cephalosporin with a macrolide or doxycycline, or a fluoroquinolone that provides atypical coverage (e.g., levofloxacin, moxifloxacin).

6 What is the best prevention against S. pneumoniae?

Vaccination. Give pneumococcal vaccine to all children as well as adult patients over 65 years old, splenectomized patients, patients with sickle-cell disease (who have autosplenectomy) or splenic dysfunction, immunocompromised patients (human immunodeficiency virus (HIV), malignancy, organ transplant), and all patients with chronic disease (e.g., diabetes, cardiac disease, asthma and other pulmonary disease, renal disease, liver disease, or tobacco use).

7 How do you recognize and treat Haemophilus influenzae pneumonia?

H. influenzae is now uncommon in children because of vaccination, but is still an important cause of pneumonia in older adults and in those with underlying lung disease such as chronic obstructive pulmonary disease. Often it resembles pneumococcal pneumonia clinically, but look for gram-negative coccobacilli on sputum Gram stain. Treat with amoxicillin or a second- or third-generation cephalosporin.

8 Describe the hallmarks of Staphylococcus aureus pneumonia.

S. aureus tends to cause hospital-acquired (nosocomial) pneumonia and pneumonia in patients with cystic fibrosis (along with Pseudomonas sp.), patients who abuse intravenous drugs, and patients with chronic granulomatous disease (look for recurrent lung abscesses). Empyema and lung abscesses are relatively common with S. aureus pneumonia.

9 In what clinical situations do you tend to see gram-negative pneumonias?

Pseudomonas infection is classically associated with cystic fibrosis, Klebsiella infection may be found in patients who are homeless and/or suffer from alcoholism (watch for classic description of currant jelly sputum), and enteric gram-negative organisms (e.g., Escherichia coli) are associated with aspiration, neutropenia, and hospital-acquired pneumonia. These pneumonias often have a high mortality rate because often patients are already in poor health and the severity of the pneumonia (abscesses are common). Treat empirically with an antipseudomonal penicillin (e.g., ticarcillin, piperacillin) with or without a beta lactamase inhibitor (e.g., clavulanate, tazobactam). Alternatives include ceftazidime or ciprofloxacin.

10 How do you recognize Mycoplasma pneumonia?

Mycoplasma infection is most common in adolescents and young adults (the classic patient is a college student or soldier who lives in a dormitory/barracks and has sick contacts). It is one of the atypical pneumonias because it presents differently than a typical pneumonia due to S. pneumoniae. For example, it has a long prodrome with gradual worsening of malaise, headaches, dry, nonproductive cough, and sore throat; the fever tends to be low-grade. Chest radiograph shows a patchy, diffuse bronchopneumonia and classically looks impressive, although the patient often does not feel that bad. Look for positive cold-agglutinin antibody titers, which may cause hemolysis or anemia. Atypical pneumonia is treated empirically with a macrolide antibiotic (azithromycin), doxycycline, or broad-spectrum fluoroquinolone (e.g., levofloxacin, moxifloxacin).

11 What about chlamydial pneumonia?

Chlamydophila sp. is second only to Mycoplasma sp. as the cause of atypical pneumonia in adolescents and young adults. It presents similarly but has negative cold-agglutinin antibody titers. Treat with erythromycin in children younger than 8 years of age and either azithromycin or doxycycline in children older than 8 years of age, adolescents, and adults.

12 In what setting do you see Pneumocystis jiroveci pneumonia (PCP) and cytomegalovirus (CMV) pneumonia?

In HIV-positive patients with CD4 counts less than 200/mm³ (AIDS) and other severely immunosuppressed patients (e.g., organ transplant recipients taking powerful immunosuppressants, patients on cancer chemotherapy). In AIDS, PCP is the most common opportunistic pneumonia and may require bronchoalveolar lavage for diagnosis. PCP can be seen with silver stains and typically causes bilateral interstitial lung infiltrates. Treat with trimethoprim-sulfamethoxazole plus corticosteroids. CMV pneumonia is characterized by intracellular inclusion bodies. Treat with valganciclovir.

13 What is the best time to treat PCP?

Before it happens. PCP is acquired when the CD4 count is below 200/mm³. At that point you should institute PCP prophylaxis in an HIV-positive patient with trimethoprim-sulfamethoxazole. Alternatives include dapsone or atovaquone.

14 Cover the middle and right-hand columns and specify the organism after looking at the scenario associated with it.

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