Investigation and control of an outbreak of Achromobacter xylosoxidans bacteremia

To define the extent of an outbreak of Achromobacter xylosoxidans bacteremia, determine the source of the outbreak, and implement control measures.

An outbreak investigation, including environmental and infection control assessment, and evaluation of hypotheses using the binomial distribution and case control studies.

A 50-bed medical surgical unit in a hospital in Illinois during the period January 1-July 15, 2006.

Discontinuation of use of opioid delivery via patient-controlled analgesia (PCA) until the source of the outbreak was identified and implementation of new protocols to ensure more rigorous observation of PCA pump cartridge manipulations.

Calculations based on the binomial distribution indicated the probability that all 9 patients with A. xylosoxidans bacteremia were PCA pump users by chance alone was <.001. A subsequent case control study identified PCA pump use for administration of morphine as a risk factor for A. xylosoxidans bacteremia (odds ratio, undefined; P < .001). Having a PCA pump cartridge with morphine started by nurse C was significantly associated with becoming a case-patient (odds ratio, 46; 95% confidence interval, 4.0-525.0; P < .001).

We hypothesize that actions related to diversion of morphine by nurse C were the likely cause of the outbreak. An aggressive pain control program involving the use of opioid medication warrants an equally aggressive policy to prevent diversion of medication by staff.