Pulmonary infection in the immunocompromised host remains a major cause of morbidity and high mortality. It presents a tremendous challenge in cancer and palliative care settings in terms of clinical assessment, diagnosis, and treatment.
Lungs are a common site of infection in patients with cancer. The spectrum of pulmonary infection depends on the underlying immunological deficits. In neutropenic patients, Gram-negative bacterial infections, such as Pseudomonas, Klebsiella, predominate early, whereas fungal infections are common in persistent neutropenia.
In patients with impaired cellular immunity, viral, fungal, and atypical bacterial infections are commonly seen. Streptococcus pneumonia and Hemophilus influenzae are the primary bacterial infections encountered in patients with impaired humoral immunity.
Multiple simultaneous infectious processes are common. These may include dual infection with Pneumocystis jirovecii (formerly Pneumocystis carinii) and Cytomegalovirus, or superimposition of another process (lung injury or drug toxicity).
Sequential infection (e.g., viral infection preceding bacterial or fungal infection) is also common.
In patients with cancer, the incidence of infections caused by Pseudomonas aeruginosa is 1-2.5% among all the patients presenting with fever during neutropenia, and 5-12% among patients with microbiologically documented infections. The mortality rate is increased by 40% among immunocompromised patients with P. aeruginosa pneumonia.

A usual clinical presentation is of an acute illness with cough producing mucopurulent sputum, breathlessness, and wheezing, along with systemic features such as fever, leukocytosis, hypoxemia, and a significant elevation in the erythrocyte sedimentation rate and C-reactive protein over previous levels.

The following guidelines for the specific management of P. aeruginosa infections in immunocompromised patients and neutropenia:
1. Any suspicion of Pseudomonas infection should require a culture and sensitivity.
2. Therapy should be initiated as soon as clinical samples have been collected. Early therapy is associated with better outcomes and will usually include an antipseudomonal β-lactam associated with either an Aminoglycoside or a Fluoroquinolone.
3. Stepping down of treatment in de-escalation or modification of the therapy is mandatory once culture and sensitivity results are available.
4. The patient's condition should be reevaluated on a regular basis, with appropriate measurements to decide whether antibiotics should be continued.

In an inpatient setting, the recommendations are to use an antipseudomonal β-lactam (piperacillin-tazobactam, ceftazidime, cefepime, imipenem, or meropenem) plus ciprofloxacin or levofloxacin (750 mg dose) or β-lactam plus an aminoglycoside and azithromycin. In penicillin-allergic patients, β-lactam is substituted with aztreonam.
In an ambulatory patient not requiring inpatient or high-dependency admission, oral levofloxacin 750 mg daily is the recommended treatment.
A continuous infusion of β-lactam is considered for the treatment of resistant P. aeruginosa infections in immunocompromised patients when conventional antibiotic options are limited.

See reference for more information.

Adapted from Salins N, Vallath N, Prince V V. Pseudomonas bronchopulmonary infections in a palliative care setting. Indian J Palliat Care 2012;18:1-5. Internet. Accessed on October 5, 2016.