In-hospital mortality rates for BSI caused by CASR A. baumannii were significantly higher than those for non-CASR A. baumannii-induced BSI (43% versus 20%; OR ‫؍‬ 3.0, 95% CI ‫؍‬ 1.60 to 5.23, P value < 0.001). However, after adjusting for potential confounders, the association between BSI caused by CASR A. baumannii and increased risk of in-hospital mortality was not significant (OR ‫؍‬ 1.15, 95% CI ‫؍‬ 0.51 to 2.63, P value ‫؍‬ 0.74). This study demonstrated that CASR A. baumannii had a distinct epidemiology compared to more susceptible A. baumannii strains; however, clinical outcomes were similar for the two groups. Admission with a rapidly fatal condition was an independent predictor for both CASR A. baumannii and in-hospital mortality.

Clostridium difficile is a leading cause of infectious diarrhea in hematopoietic stem cell transplant (HSCT) recipients. Asymptomatic colonization of the gastrointestinal tract occurs before development of C. difficile infection (CDI). This prospective study examines the rates, risk factors, and outcomes of colonization with toxigenic and nontoxigenic strains of C. difficile in HSCT patients. This 18-month study was conducted in the HSCT unit at the Karmanos Cancer Center and Wayne State University in Detroit. Stool samples from the patients who consented for the study were taken at admission and weekly until discharge. Anaerobic culture for C. difficile and identification of toxigenic strains by PCR were performed on the stool samples. Demographic information and clinical and laboratory data were collected. Of the 150 patients included in the study, 29% were colonized with C. difficile at admission; 12% with a toxigenic strain and 17% with a nontoxigenic strain. Over a 90-day follow-up, 12 of 44 (26%) patients colonized with any C. difficile strain at admission developed CDI compared with 13 of 106 (12%) of patients not colonized (odds ratio [OR], 2.70; 95% confidence interval [95% CI], 1.11 to 6.48; P = .025). Eleven of 18 (61%) patients colonized with the toxigenic strain and 1 of 26 (4%) of those colonized with nontoxigenic strain developed CDI (OR, 39.30; 95% CI, 4.30 to 359.0; P < .001) at a median of 12 days. On univariate and multivariate analyses, none of the traditional factors associated with high risk for C. difficile colonization or CDI were found to be significant. Recurrent CDI occurred in 28% of cases. Asymptomatic colonization with C. difficile at admission was high in our HSCT population. Colonization with toxigenic C. difficile was predictive of CDI, whereas colonization with a nontoxigenic C. difficile appeared protective. These findings may have implications for infection control strategies and for novel approaches for the prevention and preemptive treatment of CDI in the HSCT patient population.

bIdentifying patients at risk for bloodstream infection (BSI) due to Acinetobacter baumannii-Acinetobacter calcoaceticus complex (ABC) and providing early appropriate therapy are critical for improving patient outcomes. A retrospective matched casecontrol study was conducted to investigate the risk factors for BSI due to ABC in patients admitted to the Detroit Medical Center (DMC) between January 2006 and April 2009. The cases were patients with BSI due to ABC; the controls were patients not infected with ABC. Potential risk factors were collected 30 days prior to the ABC-positive culture date for the cases and 30 days prior to admission for the controls. A total of 245 case patients were matched with 245 control patients. Independent risk factors associated with BSI due to ABC included a Charlson's comorbidity score of >3 (odds ratio [OR], 2.34; P ‫؍‬ 0.001), a direct admission from another health care facility (OR, 4.63; P < 0.0001), a prior hospitalization (OR, 3.11; P < 0.0001), the presence of an indwelling central venous line (OR, 2.75; P ‫؍‬ 0.011), the receipt of total parenteral nutrition (OR, 21.2; P < 0.0001), the prior receipt of ␤-lactams (OR, 3.58; P < 0.0001), the prior receipt of carbapenems (OR, 3.18; P ‫؍‬ 0.006), and the prior receipt of chemotherapy (OR, 15.42; P < 0.0001). The median time from the ABC-positive culture date to the initiation of the appropriate antimicrobial therapy was 2 days (interquartile range [IQR], 1 to 3 days). The in-hospital mortality rate was significantly higher among case patients than among control patients (OR, 3.40; P < 0.0001). BSIs due to ABC are more common among critically ill and debilitated institutionalized patients, who are heavily exposed to health care settings and invasive devices.