Bacteraemia in adults due to glucose non-fermentative Gram-negative bacilli other than P. aeruginosa

Glucose non-fermentative Gram-negative bacilli other than P. aeruginosa (NF) are emerging pathogens.

To evaluate the epidemiology, clinical characteristics, predictors of acquisition, and outcome of bacteraemia due to NF.

Retrospective analysis of prospectively recorded data.

We reviewed episodes of NF bacteraemia in patients older than 14 years, recorded through a blood culture surveillance program. Patients were identified at the time of their bacteraemia and prospectively followed.

Between January 1991 and December 2000, 296 episodes of NF bacteraemia were detected: 87% were due to Acinetobacter sp., Pseudomonas sp. other than P. aeruginosa, or Stenotrophomonas maltophilia. The global incidence (0.87 cases per 1000 discharges) remained stable during the study period. Patients were of all ages and both sexes, and 282/296 (95.3%) had some predisposing underlying disease or condition, the most common being haematological malignancies without transplantation (85/296, 28.7%), treatment with steroids (78/296, 26.3%), and transplantation (bone marrow or solid organ) (70/296, 23.6%). Fifty (16.9%) were neutropenic. The most common sources of bacteraemia were central venous catheter infection (117/296, 39.5%) and unknown primary site (97/296, 32.8%). Sixty-one episodes (20.6%) were community-acquired and 235 (79.4%) were nosocomial. Forty-three patients (14.5%) died. Pneumonia (RR 1.5, 95%CI 1.1-14.2), age<65 (RR 3.1, 95%CI 1.4-10.3), hospitalization in the intensive care unit (ICU) (RR 3.2, 95%CI 1.3-9.8), rapidly fatal disease (RR 4.9, 95%CI 3.1-12.6), and severe sepsis (RR 9.8, 95%CI 1.6-19.7) were independent predictors of death. Factors predicting the probability that an episode of nosocomial bacteraemia was due to NF included: rapidly fatal disease (RR 1.23, 95%CI 1.02-4.1), age<65 (RR 2.05, 95%CI 1.4-3), hospitalization in the ICU (RR 2.06, 95%CI 1.4-3, and pneumonia (RR 2.1, 95%CI 1.05-4.8).

NF bacteraemia mainly affects patients with malignant haematological disease, with and without transplantation, and patients in the ICU. The most common known source is a central venous catheter, though many sources are unknown. Mortality is relatively low, and depends on the severity of the underlying disease.