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Multiply Antibiotic Resistant Gram-Negative Bacilli in a Long Term Care Facility A Case Control Study of Patient rick Factors and Prior Antibiotic Use
Published online by Cambridge University Press: 02 January 2015
Abstract
To determine the relation between prior exposure to specific antimicrobials and acquisition of gram-negative bacilli resistant to multiple ß-lactam and aminoglycoside antibiotics among long-term-care patients.
Case-control study. Cases were patients from whom multiply resistant Enterobacteriaceae or Pseudomonas aeruginosa were isolated; controls were patients from whom nonresistant bacteria of the same species were isolated. Prospectively defined risk factors included underlying illness, activity level, presence of decu-bitus ulcers, presence of indwelling devices, and prior exposure to specific antimicrobial agents. Resistant and control isolates of P aeruginosa were compared using pulsed-field gel electrophoresis (PFGE) of genomic DNA after digestion with XbaI.
390-bed long-term Veterans' Affairs facility.
We identified 35 patients with multiply resistant Enterobacteriaceae and 24 patients with multiply resistant P aeruginosa. Of the resistant Enterobacteriaceae, 87% of isolates were resistant to piperacillin, 55% to ceftazidime, and 90% to gentamicin. Acquisition of multiply resistant Enterobacteriaceae was associated with presence of decubitus ulcers (odds ratio [OR], 12.2; 95% confidence interval [CI95], 3.3-44.2; P=.0002) and prior receipt of ampicillm (OR, 13.7; CI95, 2.2-84; P=.005). Of resistant isolates of P aeruginosa, 88% were resistant to piperacillin, 25% to ceftazidime, 42% to imipenem, and 67% to ciprofloxacin. Isolation of a multiply resistant P aeruginosa was associated with total days of antimicrobial exposure (OR, 1.07; CI95, 1.01-1.12; P=.011) and not with prior receipt of any individual agent. Eleven multiply resistant isolates shared a common PFGE pattern.
In our long-term-care facility, acquisition of multiply resistant Enterobacteriaceae was associated with the presence of decubitus ulcers and prior exposure to ampicillin. Acquisition of resistant P aeruginosa was associated with total antibiotic exposure. Molecular typing of P aeruginosa isolates implicated patient-to-patient transmission of a limited number of resistant strains.
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- Copyright © The Society for Healthcare Epidemiology of America 1997
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