Cluster of Enterobacter cloacae pseudobacteremias associated with use of an agar slant blood culturing system.

From 1 February through 12 October 1990, 27 blood cultures processed at Shiprock Hospital were positive for Enterobacter cloacae; only 3 had been reported in the preceding 12 months. Twenty (74%) of the cultures were obtained from patients without clinical evidence of gram-negative septicemia. The increase in E. cloacae-positive blood cultures was temporally associated with the introduction of a new blood culturing system. To evaluate potential risk factors for an E. cloacae-positive blood culture (case-culture), we conducted a case-control study. Case-cultures were compared with 81 randomly selected cultures that were processed during the epidemic period and that were not positive for E. cloacae (controls). Because several factors suggested the possibility of pseudoinfection, we limited our analysis to the 20 blood cultures that appeared to be contaminants. Blood samples received in the laboratory during the midnight shift (5 of 20 [25%] versus 5 of 81 [6%]; odds ratio, 5.1; 95% confidence intervals, 1.01 to 24.6; P = 0.02) or present in the incubator with other E. cloacae-positive samples (17 of 20 [85%] versus 29 of 81 [36%]; odds ratio, 10.2, 95% confidence interval, 2.6 to 57.3; P < 0.001) were at increased risk for contamination. During mock experiments of the procedures for processing blood samples for culture, several breaks in aseptic technique and leakage from the blood culturing system were observed. Cultures of samples obtained from several environmental sites in the laboratory and the hand washings of two laboratory technicians grew E. cloacae. Plasmid and restriction enzyme analyses of E. cloacae isolates recovered from the patients' blood cultures, the two technicians' hand washings, and environmental sites in the laboratory indicated that all had identical plasmid profiles. Our findings suggest that the breaks in aseptic technique and the environmental contamination that occurred in association with the use of the new blood culturing system resulted in contamination of the blood cultures. This outbreak highlights the importance of routine environmental cleaning, periodic quality control assessments, and adherence to aseptic practices in clinical laboratories, particularly when new methods or equipment are introduced and/or new personnel are hired.

Competency to stand trial: a conceptual model for its proper assessment.

The assessment of competency to stand trial is frequently fraught with conceptual confusion resulting from a failure to properly apply the data of the clinical examination to the relevant legal criteria. A basic question scheme that encompasses (1) the defendant's psychiatric status, (2) the effects of that status on his functioning, and (3) his apparent ability to participate in legal proceedings, is introduced to clarify the evaluation of fitness to stand trial. The way in which combinations of answers to three "basic questions" generate a scheme that clarifies the difficulties encountered in most competency evaluations is shown. Eight paradigm cases are generated. Five of these (competence, incompetence, mentally ill but competent, malingering, and impaired but competent) are frequently straightforward. However, the three possibilities in which a defendant meets criteria entailed by two of the three questions are inherently subject to controversy. These situations (circumscribed psychosis related to the charges, malingering in the context of mental illness, and functional deficits in the context of minor mental illness) are discussed in detail and illustrated with case material.

Olfactory acuity in the common raven (Corvus corax).

The efficacy with which ravens can locate concealed carrion and similar foods has been noted from antiquity. This ability has been claimed in folklore to indicate an acute sense of smell. Contemporary opinion among ornithologists is that the sense of smell is weak at best in passerines, and particularly so in corvids which lack developed olfactory apparatus. Four studies were performed to test whether ravens could find hidden food (fresh ground fish) under conditions where scent was presumed to be the sole cue. The subjects, captive juvenile ravens (five males and three females) capably chose which one in a pair of containers held food buried under 2.0 cm of No. 4 gravel, discovered food concealed under as much as 2.5 cm of gravel, and located as little as 1.0 g of food covered by 1.5 cm of gravel. The several findings are consistent with the possibility that ravens can use olfactory cues to find food.