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Salmonellosis associated with marijuana: a multistate outbreak traced by plasmid fingerprinting
Abstract:
In January and February of 1981, 85 cases of enteritis caused by Salmonella muenchen were reported from Ohio, Michigan, Georgia, and Alabama. Initial investigation failed to implicate a food source as a common vehicle, but in Michigan 76 per cent of the patients, in contrast to 21 per cent of the control subjects, admitted personal or household exposure to marijuana (P less than 0.001, relative risk = 20). Marijuana samples obtained from patients' households contained as many as 10(7) S. muenchen per gram. The outbreak-related isolates of S. muenchen were sensitive to all antibiotics and were phenotypically indistinguishable from other S. muenchen. Plasmid fingerprinting, however, revealed that all isolates related to marijuana exposure contained two low-molecular-weight plasmids (3.1 and 7.4 megadaltons), which were absent in control strains. Plasmid analysis of the isolates showed that the outbreaks in Ohio, Michigan, Georgia, and Alabama were related, and analysis of isolates submitted from various other states demonstrated that cases associated with marijuana may have been dispersed as far as California and Massachusetts.
Insights
A Salmonella muenchen outbreak in 1981 was linked to marijuana use. Investigations revealed significant patient exposure to marijuana, which contained the bacteria, suggesting it as a transmission vehicle.
Area of Science:
- Microbiology
- Epidemiology
- Public Health
Background:
- An outbreak of enteritis caused by Salmonella muenchen occurred in early 1981 across multiple US states.
- Initial investigations did not identify a common foodborne source for the illness.
Purpose of the Study:
- To identify the source and transmission vehicle of the Salmonella muenchen outbreak.
- To determine the relationship between outbreak isolates and other strains.
Main Methods:
- Case-control study comparing patient and control subject exposures.
- Microbiological analysis of Salmonella muenchen isolates from patients and marijuana samples.
- Plasmid fingerprinting for bacterial strain characterization.
Main Results:
- A strong association was found between enteritis cases and personal or household exposure to marijuana (relative risk = 20).
- Marijuana samples from patients' households contained high levels of Salmonella muenchen.
- Plasmid fingerprinting revealed unique genetic markers in outbreak-related Salmonella muenchen strains linked to marijuana exposure, connecting outbreaks across states.
Conclusions:
- Marijuana was identified as a likely vehicle for Salmonella muenchen transmission during the 1981 outbreak.
- Plasmid analysis confirmed the relatedness of geographically dispersed outbreak cases.
- This highlights the potential for non-food items to serve as vehicles for bacterial transmission.