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was made using matrix-assisted laser desorption/ionization time- of-flight mass spectroscopy (MALDI-TOF MS), and the sus- ceptibility tests in clinical samples were performed using a MicroScan system (Beckman Coulter, Brea, California, USA). The genetic relationship between the C. indologenes isolates was determined by pulsed-field gel electrophoresis (PFGE). We undertook a spatiotemporal analysis of cases by associat-
ing bed occupancy of confirmed case patients against each other and possible environmental reservoirs to identify possible routes of cross transmission or point sources. This analysis was reviewed against the sequential effect of the control measures implemented. Mortality attributable to infection was determined by clinical evaluation.
Results
We identified a total of 12 cases from April 4 through May 18 (a rate of 2.72 per 1,000 patient days). All patients had positive samples from the respiratory tract (1 patient also had a positive blood sample). Of these cases, 4 developed pneumonia, and 3 infected patients died. One of these deaths was attributable to the infection. Other clinical and demographical characteristics are displayed in Table 1. Most case patients had been previously receiving 3 or more broad-spectrum antibiotics. The previous mean lengths of stay in the hospital and in the ICU were 37 and 17 days, respectively (Table 1). This outbreak was controlled after a third tier of control measures (Figure 1). In total, 232 environmental samples were collected. All tap and
distilled water, aqueous chlorhexidine, dialysate solution, and intravenous infusions samples were negative for microorganisms. Tap water free residual chlorine levels were above 0.2 ppm. In addition to the isolates derived from the patients, C. indolo-
genes was recovered from 8 sinkholes of handwashing sinks in patient boxes; 5 of these related to patient cases. Also, C. indologenes was recovered from 3 air samples taken close to the sinks: 1 from the reprocessing room and 2 near handwashing stations in patient boxes. Only 5 of these environmental samples could be analyzed by PFGE typing due to overgrowth of other microorganisms. The PFGE results from all 12 patients showed a unique pattern indistinguishable from the isolate recovered from the air close to the reprocessing room sink (pattern 1). The other 4 environ- mental isolates had distinct PFGE patterns, except for a couple of samples from the same box (sinkhole and air close to the basin) sharing the same pattern (pattern 2). Furthermore, many other species of bacteria, mainly NFGNB
but also Enterobacteriaceae and fungi, were recovered from the water drainage system (ie, sinkholes and the hemodialysis draining trap). Most of these microorganisms where also recov- ered from air samples close to the sinks (Supplementary Table 1).
Discussion
We describe an outbreak of C. indologenes infections and colo- nizations that resulted in important morbidity and mortality in a critically ill population. In total, 12 patients acquired the micro- organism during a 6-week period; 33% of them developed serious infections, and 3 infected patients died (75%). We were able to control the outbreak after 6 weeks. Interventions to contain the outbreak started shortly after iden- tification of the first cases. They included reeducation of staff on
Mireia Cantero et al
Table 1. Characteristics of Patients Infected and Colonized by Chryseobacter- ium indologenes
Characteristics
Demographic Male sex
Age, median y (range) Surgical ICU
Clinical characteristics Infected cases
Main diagnosis Heart diseaseb
Solid organ transplantc Cystic fibrosis
Colorectal cancer Othersd
Hospital stay Hospital days before event, median (range) ICU days before event, median (range)
Invasive devices Mechanical ventilation Central line Hemodialysis
Previous antibiotic exposure Overall mortality, within 30 d Case fatality (infected patients) Death directly related to infection
Cases (N=12) No. (%)a
8 (66.6)
56 (35–78) 9 (75.0)
4 (33.3)
4 (33.3) 4 (33.3) 1 (8.3) 1 (8.3)
2 (16.6)
37 (3–110) 17 (3–96)
12 (100.0) 12 (100.0) 6 (50.0) 10 (83.3) 6 (50.0) 3 (75.0) 1 (25.0)
NOTE. ICU, intensive care unit. aUnless otherwise specified. bCardiac valvular disease (n=3), aortic aneurysm (n=1). cLung transplant (n=2), cardiopulmonary transplant (n=1), kidney transplant (n=1). dTraumatic brain injury (n=1), idiopathic pulmonary fibrosis (n=1).
Fig. 1. Epidemic curve and timing of control measures.
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