• Community-acquired bacterial pneumonia: Streptococcus pneumoniae, (Pneumococcus) Gram stain, sputum

  • Most frequent cause: Streptococcus pneumoniae (pneumococci)

    • Chest X-RAY

    • > 30% of recent S. pneumoniae isolates:

      • relatively or highly resistant to penicillin and sometimes cephalosporins.

  •  Other pathogens:

    •  Haemophilus influenzae

    •  Staphylococcus aureus

    •  Klebsiella pneumoniae

    •  occasionally: other gram-negative bacilli and anaerobic mouth organisms

    • "Atypical" pathogens:

      • Legionella

      • Mycoplasma pneumoniae

      • Chlamydia pneumoniae

      • respiratory viruses

      • tuberculosis

      • Pneumocystis carinii

• Diagnosis

• Treatment: In Hospitalized Patients--

  • Pending culture results and susceptibility testing:

    •  Reasonable first-choice: cefotaxime or ceftriaxone

      •  Cefotaxime (Claforan), ceftriaxone (Rocephin), high-doses of penicillin (IV) effective in treating pneumococcal pneumonia (intermediate resistance)

    •   Vancomycin (Vancocin): high resistance

    •  Vancomycin (Vancocin) and cephalosporin: severe illness-- not responding to a beta-lactam.

    • A macrolide (erythromycin, azithromycin (Zythromax), or clarithromycin (Biaxin)) added to a fluoroquinone (good activity against S. pneumoniae --  levofloxacin (Levaquin), grepafloxacin and trovafloxacin) can be used to cover Legionella, Mycoplasma, chlamydia.

      • If aspiration pneumonia is a concern: clindamycin (Cleocin) or metronidazole (Flagyl) may be added.

• Treatment for Ambulatory Patients:

  • Treatment Recommended for otherwise healthy patients with pneumonia due to Mycoplasma or Chlamydia:

    • Oral macrolide ( erythromycin,  azithromycin (Zythromax), or  clarithromycin (Biaxin)),  doxycycline (Vibramycin, Doryx), or fluoroquinones with good anti-pneumococcal activity (levofloxacin (Levaquin), grepafloxacin, trovafloxacin)

    •  Penicillin-resistant pneumococci: may be resistant to a macrolide or doxycycline

    • Older patients or patients with underlying disease: recommendation --

      •  levofloxacin (Levaquin)

      •  grepafloxacin

      •  trovafloxacin

• Treatment for hospital-acquired bacterial pneumonia:

  • Most often cause by gram-negative bacilli:

    • Klebsiella

    • Enterobacter

    • Serratia

    • Acinetobacter AND

  • Pseudomonas aeruginosa

  • Staphylococcus aureus

  • The initial treatment: third-generation cephalosporin --

    •  cefotaxime (Claforan)

    •  ceftizoxime (Cefizox)

    •  ceftriaxone (Rocephin)

    •  ceftazidime (Fortax, Taxidime, Tazicef)

  • Or:

    •  cefepime (Maxipime)

    •  ticarcillin (Ticar)/ clavulanic acid

    •  piperacillin (Pipracil)/tazobactam

    •  meropenem (Merrem IV)

    •  imipenem

  • with or without the aminoglycoside {tobramycin (Nebcin), gentamicin (Garamycin), or amikacin (Amikin)}

  •  Considering third-generation cephalosporins:

    • Cefotaxime (Claforan), ceftizoxime (Cefizox), and ceftriaxone (Rocephin)} limited activity against Pseudomonas

    • Ceftazidime (Fortax, Taxidime, Tazicef)} more activity against staphylococci and other gram-positive cocci

  • In the intensive care unit -- nosocomial pneumonia due to highly resistant gram-negative bacteria and Pseudomonas aeruginosa:

    • Good first choices--

      • imipenem

      • meropenem (Merrem IV)

      • plus aminoglycoside

      • add vancomycin (Vancocin) in hospitals where methicillin (Staphcillin)-resistant staphylococci are common.

The Choice of Antibacterial Drugs (Abramowicz, M, ed) The Medical Letter of Drugs and Therapeutics, vol. 40 (Issue 1023), March 27, 1998