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Morphine increases susceptibility to oral Salmonella typhimurium infection
A S MacFarlane1, X Peng, J J Meissler
1Departments of Microbiology and Immunology, Temple University School of Medicine, Philadelphia, PA 19140, USA.
Abstract:
This study examined the effect of morphine on oral infection with virulent Salmonella typhimurium. Animals were treated with a 75-mg slow-release morphine pellet followed by inoculation with salmonellae. Morphine markedly sensitized mice to oral infection, as assessed by survival, mean survival time, and colony culture. By 24 h after Salmonella inoculation, morphine-treated mice had a 105-fold difference in number of organisms in the Peyer's patches, compared with controls. The opioid antagonist naltrexone significantly blocked Salmonella colonization in Peyer's patches and reduced Salmonella burden in other organs, indicating that morphine acts at least in part via an opioid receptor-mediated pathway. The data show that morphine markedly potentiates Salmonella infection at the gastrointestinal portal of entry and enhances subsequent dissemination of Salmonella organisms. The results have implications for potentiating gastrointestinal opportunistic infections in intravenous drug abusers and in opioid-medicated postsurgical patients.
Insights
Morphine significantly worsens Salmonella infection in mice, increasing bacterial load and reducing survival. This effect is mediated by opioid receptors and has implications for opportunistic infections in drug users and surgical patients.
Area of Science:
- Immunology
- Microbiology
- Pharmacology
Background:
- Opioid use is common in surgical patients and among intravenous drug abusers.
- Salmonella typhimurium is a common cause of bacterial gastroenteritis.
Purpose of the Study:
- To investigate the effect of morphine on oral Salmonella typhimurium infection.
- To determine the role of opioid receptors in morphine-induced potentiation of Salmonella infection.
Main Methods:
- Mice were treated with slow-release morphine pellets and orally inoculated with Salmonella typhimurium.
- Survival, survival time, and bacterial colonization were assessed.
- The effect of the opioid antagonist naltrexone was evaluated.
Main Results:
- Morphine significantly increased susceptibility to Salmonella infection, reducing survival and mean survival time.
- Morphine-treated mice showed a 105-fold increase in Salmonella in Peyer's patches.
- Naltrexone blocked Salmonella colonization, indicating opioid receptor involvement.
Conclusions:
- Morphine potentiates Salmonella infection at the gastrointestinal portal of entry.
- Morphine enhances Salmonella dissemination and has implications for opportunistic infections in specific patient populations.