Bacteremia caused by Achromobacter and Alcaligenes species in 46 patients with cancer (1989-2003)

BACKGROUND. Achromobacter and Alcaligenes are emerging infectious gram-negative bacterial species that can affect immunosuppressed patients. The authors sought to determine the incidence and characteristics of bloodstream infections caused by these organisms in patients with underlying malignancies. METHODS. All consecutive episodes of hematogenous Achromobacter and Alcaligenes infections recorded from December 26, 1989, to July 27, 2003, were studied retrospectively. RESULTS. Fifty-two episodes occurred in 46 patients; 31 patients (67%) had hematologic malignancies, and 24 (52%) experienced neutropenia (< 500 cells/muL). Diabetes mellitus was present in 12 patients (26%), and high-dose corticosteroids were administered to 12 patients (26%). Seventeen of the 52 infectious episodes (33%) were nosocomial in origin, and 10 patients (22%) had sepsis syndrome. Achromobacter xylosoxidans was the most common cause of infection (47 of 52 episodes [94%]), followed by Ach. denitrificans (2 of 52 episodes [4%]) and Alcaligenes faecalis (1 of 52 episodes [2%]). Twenty-seven episodes (52%) were polymicrobial, and 3 patients (7%) had concurrent fungemia. Infected intravascular catheters were present in 13 of 52 cases (25%), pneumonia was encountered in 6 of 52 cases (12%), and urinary tract infections were present in 5 of 52 cases (10%). Most isolates exhibited in vitro susceptibility to carbapenems, antipseudomonal penicillins, and trimethoprim-sulfamethoxazole. Resistance to ciprofloxacin, levofloxacin, aminoglycosides, and monobactam was common. Seven deaths (15%) were attributable to Achromobacter species. Incidence rates for sepsis syndrome, multiorgan dysfunction (Acute Physiology and Chronic Health Evaluation [APACHE] II score > 16), and use of mechanical ventilation and pressor support were significantly higher in patients who died (P < 0.001). Logistic regression analysis revealed that sepsis syndrome and high APACHE II scores were predictors of increased 30-day mortality. CONCLUSIONS. Most infections caused by this group of nonfermentative gram-negative bacteria were attributable to Ach. xylosoxidans, and only one-third were acquired during hospitalization. The presence of sepsis syndrome has evolved as an independent predictor of poor outcome in patients with high-risk malignancies accompanied by Achromobacter bloodstream infections. (C) 2004 American Cancer Society.