Fig 2. P. aeruginosa infection of a cancer patient hospitalized to receive hematopoietic cell transplantation evolved resistance to aztreonam in the course of therapy.

(A) Timeline shows clinical events: conditioning regimen (myeloablation), hematopoietic cell infusion, location in the hospital (bone marrow transplantation unit [BMT] or intensive care unit [ICU]), the period of neutropenia, antibiotics administered, the day (relative to the day of transplant, day 0) and body site of origin (rsw: rectal swab; spt: sputum; bld: blood) of the eight P. aeruginosa isolates analyzed here. (B) Antibiotic resistance profiles of blood isolates measured by the clinical microbiology laboratory as the infection progressed; the profiles informed clinicians that the infection was multi-drug-resistant but also that it was initially sensitive to aztreonam (isolates D+3bld, D+4bld and D+5bld). As the disease progressed to become life-threatening sepsis, the patient was transferred to the ICU and was given aztreonam; however, the isolate D+7bld demonstrated resistance to aztreonam. The patient died on day +8.