A multistate Salmonella Typhimurium outbreak, which has sickened 41 people in 13 states since last November, has been linked to clinical and college and university teaching microbiology laboratories, according to a Centers for Disease Control and Prevention (CDC) investigation.
The CDC investigation reveals via laboratory testing that the outbreak strains are indistinguishable by PFGE pattern from commercially available Salmonella Typhimurium strains used in laboratory settings for teaching or quality control purposes. These commercially available strains are known to be present in several teaching laboratories associated with ill persons.
Information gathered from interviews from those infected shows eighteen (86%) of 21 ill persons interviewed reported being enrolled in either a human biology course or microbiology course. Fifteen (83%) of these 18 ill persons were students, and three (22%) were employees. Many ill persons reported several behaviors while they were working in the laboratory that would increase the risk of acquiring a Salmonella infection, including not wearing gloves or lab coats, lack of handwashing, and using the same writing utensils and notebooks outside of the laboratory. Additionally, many ill persons did not recall receiving laboratory safety training.
This is not the first reported outbreak linked to college laboratory classes. In 2011, a total of 109 illnesses with one of these same strains of Salmonella Typhimurium were linked to exposure to clinical and teaching microbiology laboratories. Findings of that investigation indicated that teaching and clinical microbiology laboratory instructors should enhance training of students and staff on biosafety measures necessary in the laboratory. For more infectious disease news and information, visit and “like” the Infectious Disease News Facebook page