Pseudomonas Infections

Key Features

Essentials of Diagnosis

• Opportunistic infection

• Confirmed by cultures

General Considerations

• Pseudomonas aeruginosa is an important cause of infection in children with cystic fibrosis, neoplastic disease, neutropenia, or extensive burns and in those receiving antibiotic therapy

• Infections of the urinary and respiratory tracts, ears, mastoids, paranasal sinuses, eyes, skin, meninges, and bones are seen

• Pseudomonas pneumonia is a common nosocomial infection in patients receiving assisted ventilation

Clinical Findings

• Depend on the site of infection and the patient's underlying disease

• Patients with cystic fibrosis

  • Have a persistent bronchitis that progresses to bronchiectasis and ultimately to respiratory failure

  • During exacerbations of illness, cough and sputum production increases with low-grade fever, malaise, and diminished energy

• The purulent aural drainage without fever in patients with chronic suppurative otitis media is not distinguishable from that due to other causes

Diagnosis

• Sepsis with these organisms resembles gram-negative sepsis with other organisms, although the presence of ecthyma gangrenosum suggests the etiologic diagnosis

• Diagnosis is made by culture

• Pseudomonas infection should be suspected in neonates and neutropenic patients with clinical sepsis

Treatment

• Antibiotics effective against Pseudomonas include

  • Aminoglycosides

  • Ureidopenicillins (piperacillin)

  • β-Lactamase inhibitor with a ureidopenicillin (piperacillin-tazobactam)

  • Expanded-spectrum cephalosporins (ceftazidime and cefepime)

  • Imipenem, meropenem

  • Colistin has been used in some children with multidrug resistance

• For serious infections

  • Gentamicin or tobramycin (5.0–7.5 mg/kg/d, given intramuscularly or intravenously in three divided doses)

  • Amikacin (15–22 mg/kg/d, given in two or three divided doses) in combination with piperacillin (240–300 mg/kg/d, given intravenously in four to six divided doses) or with another antipseudomonal β-lactam antibiotic

  • Ceftazidime (150–200 mg/kg/d, given in four divided doses) or cefepime (150 mg/kg/d, given in three divided doses) has activity against susceptible strains; treatment should be continued for 10–14 days

• Aerosolized anti-pseudomonal antibiotics, tobramycin, and aztreonam have been very useful adjunctive therapy for patients with cystic fibrosis

• Pseudomonas osteomyelitis due to punctures requires thorough surgical debridement and antimicrobial therapy for 2 week.

• Chronic suppurative otitis media

  • Responds to intravenous ceftazidime (150–200 mg/kg/d in three or four divided doses) given until the drainage has ceased for 3 days

  • Twice-daily ceftazidime with aural debridement and cleaning given on an outpatient basis has also been successful

  • Swimmer's ear may be caused by P aeruginosa and responds well to topical drying agents (alcohol–vinegar mix) and cleansing

Outcome

Prevention

• Infections in burn patients can be inhibited by

  • Aggressive debridement

  • Topical treatment with 0.5% silver nitrate solution, 10% mafenide cream, or silver sulfadiazine

• Nosocomial infections can be minimized by careful maintenance of equipment and enforcement of infection control procedures

Prognosis

• Mortality rates in hospitalized patients exceed 50%, owing both to the severity of underlying illnesses in patients predisposed to ...