Pseudomonas, trach tubes, ICU issues

Pseudomonas aeruginosa is a gram-negative rod that can multiply in moist environments. It frequently enters the hospital on the clothes or skin of patients or hospital personnel, with plants or fruit brought into the hospital, and in the gastrointestinal tracts of patients. Colonization of any moist environment may ensue. Colonization of a patient's skin,
throat, nasal mucosa, and stool is low at admission to the hospital, but it increases to as high as 50% to 70% with prolonged hospitalization and the use of broad-spectrum antibiotics, chemotherapy, or mechanical ventilation. P aeruginosa historically has been found to contaminate ventilators, tubing, and humidifiers, but this is uncommon today with appropriate disinfection procedures and routine changing of equipment. Patients whose upper respiratory tracts are colonized are at risk of pneumonia if they aspirate P aeruginosa-contaminated secretions, which allows the  organism access to the lungs. P aeruginosa is found in the respiratory tracts of most patients who have cystic fibrosis; at death, more than 90% of patients are colonized with multiple strains of these bacteria. This bacterium is virtually specific for cystic fibrosis, and once acquired, generally is not eradicated from the respiratory tract.

Tracheostomy tubes frequently are colonized with P aeruginosa. When a child who is colonized is hospitalized for respiratory problems, it is important to distinguish Pseudomonas infection from colonization to prevent unnecessary use of potent antibiotics. Infection often is signaled by an increase in sputum production and a change in the character of the sputum from thin and white or clear to thicker and more purulent. If the child has symptoms suggestive of a serious Pseudomonas infection, therapy usually includes an antipseudomonal penicillin such as piperacillin or ticarcillin and/or an amino-glycoside antibiotic.

Other pathogens are colonizers in the intensive care unit. Skin flora such as noncoagulase-positive staphylococci may colonize venous catheters and can gain access to the bloodstream by this route, giving rise to catheter-related infections. Foley catheters frequently become colonized with fecal flora, and scrupulous care is required to prevent introduction of these organisms into the bladder via the catheter. Surgical wounds may become infected with Staphylococcus aureus or Streptococcus pyogenes, which are both colonizers of skin surfaces.

References:
Baltimore RS. Pseudomonas, Burkholderia, and Stenotrophomonas. In:
Behrman RE, Kliegman RM, Jenson HB, eds. Nelson Textbook of Pediatrics.
16th ed. Philadelphia, Pa: WB Saunders Co; 2000:862-865
Fisher MC. Clinical syndromes of device-associated infections. In: Long
SS, Pickering LK, Prober CG, eds. Principles and Practice of Pediatric
Infectious Diseases. New York, NY: Churchill Livingstone; 1997:684-698