Related Experiment Videos
Something's rotten: a nosocomial outbreak of malodorous Pseudomonas aeruginosa
J A Labarca1, D A Pegues, E A Wagar
1Department of Pathology, UCLA 90095-1713, USA.
Abstract:
From July 1994 through November 1996, a phenotypically unique strain of Pseudomonas aeruginosa producing a pungent, "rotten-potato" odor and a positive lysine decarboxylase reaction was isolated from 39 patients at UCLA Medical Center (Los Angeles). Most cases (95%) were in intensive care units and had clinical infections (72%). Most isolates (74%) were recovered from cultures of respiratory secretions. To determine risk factors for acquisition of the organism, 23 cases were compared with 23 randomly selected controls matched by service and isolate date. Multivariate analysis revealed that isolation of malodorous P. aeruginosa was associated with mechanical ventilation of > 24 hours' duration (odds ratio [OR] = 9.4; P = .001) and transfer from an outside hospital (OR = 5.7; P = .04). DNA from outbreak strains hybridized to P. aeruginosa-specific toxin A and phospholipase C gene probes and all outbreak isolates tested were found to be identical by use of pulsed-field gel electrophoresis. An unusual phenotypic characteristic of the strain led to the recognition of a nosocomial outbreak of P. aeruginosa infection associated with mechanical ventilation.
Insights
A unique Pseudomonas aeruginosa strain causing a "rotten-potato" odor was linked to a hospital outbreak. Mechanical ventilation and outside hospital transfers were key risk factors for this infection.
Area of Science:
- Microbiology
- Infectious Diseases
- Hospital Epidemiology
Background:
- A unique strain of Pseudomonas aeruginosa, characterized by a distinct odor and positive lysine decarboxylase reaction, was identified.
- This organism was isolated from 39 patients at UCLA Medical Center between July 1994 and November 1996.
Purpose of the Study:
- To identify risk factors associated with the acquisition of this malodorous P. aeruginosa strain.
- To characterize the outbreak and confirm the genetic relatedness of the isolates.
Main Methods:
- Case-control study comparing 23 infected patients with 23 matched controls.
- Multivariate analysis to determine independent risk factors.
- DNA hybridization with P. aeruginosa-specific gene probes and pulsed-field gel electrophoresis (PFGE) for strain typing.
Main Results:
- The malodorous P. aeruginosa strain was frequently isolated from intensive care unit patients (95%) with clinical infections (72%), primarily from respiratory secretions (74%).
- Mechanical ventilation exceeding 24 hours (odds ratio [OR] = 9.4; P = .001) and transfer from an outside hospital (OR = 5.7; P = .04) were significant risk factors.
- PFGE confirmed that all outbreak isolates were genetically identical, and DNA hybridized to toxin A and phospholipase C gene probes.
Conclusions:
- An unusual phenotypic characteristic, a distinct odor, facilitated the recognition of a nosocomial outbreak.
- The outbreak was strongly associated with mechanical ventilation and patient transfers, highlighting infection control challenges.