A recent outbreak of a laboratory-derived strain of Salmonella typhimurium, the leading bacterial cause of food poisoning in the United States, has raised concerns over general lab safety. LSU Food science professor Dr. Marlene Janes dispels the misconception that proper safety protocol requires a high degree of effort and expertise. Indeed, laboratory managers and beginning microbiology students alike, including staff and students here at LSU, can safeguard against infection if certain basic rules are followed.
Laboratory safety is of especial concern to Dr. Janes, who works with food-borne pathogens including the ‘nasty’ Listeria Monocytogenes and other toxin-producing microbes on a daily basis. For this professor, the recent nation-wide outbreak of Salmonella typhimurium resonates at home. The outbreak, involving the infamous food-poisoning ‘bug’, occurred across 35 states from April to March 2011, causing 73 reported cases of severe illness and one reported death.
Investigations by the Centers of Disease Control and Prevention (CDC) found that among those who feel ill, a significant portion were students in microbiology teaching laboratories, employees in clinical laboratories, or children from the households of laboratory researchers, with multiple ill persons reporting previous laboratory handling of Salmonella typhimurium in particular (1). Children living with adults who handle bacteria at work are among the most vulnerable populations for infection due to laboratory contamination, said Lola Scott Russell, Senior Press Officer of CDC Media Relations.
In light of the outbreak, attributed to improper adherence to safety protocol in clinical and teaching laboratories, university safety committees and laboratory managers including Dr. Janes are taking extra precautions and cracking down on student researchers.
According to Dr. Janes, most graduate students researching food-borne and infectious diseases do not have adequate concerns over their own health and safety. “It amazes me, most of them don’t… think, and don’t care. They just want to get their research done, and get out. So they don’t think it’s that bad,” Dr. Janes said. “I’m constantly getting onto them about [safety]…”
Genevieve Edwards, a graduate student in Dr. Janes’ lab currently studying the effectiveness of various cooking methods in eliminating Salmonella from seafood, said that she simply does not worry about personal health risks that much. “My mom worries about it more than I do,” Edwards laughed. Following this year’s deadly outbreak of Listeria due to contaminated cantaloupe from Jensen Farms in Colorado, Edwards told of her mother worrying, ‘Oh my Gosh, I can’t believe you are working with that!‘" Edwards, however, doesn’t think about it that way: “I just think about it more as work, and I know I’m supposed to do this, so I do this.”
From April 20 to March 19, 2011, 73 individuals in the U.S. were infected with a strain of Salmonella typhimurium identified as one originating from clinical and teaching microbiology laboratories. Dr. Janes believes that this route of contamination, especially for a bacterium traditionally associated with contaminated food, is not only unacceptable, but also completely avoidable.
Salmonella typhimurium, a bacteria commonly found to contaminate poultry, seafood, and occasionally certain fruits and vegetables, causes gastroenteritis – a condition that involves vomiting, stomach cramps, and diarrhea which, in severe cases, can be fatal.
According to Dr. Janes, the April 2011 Salmonella outbreak could have been prevented with proper safety equipment and protocol. “My perspective is [that] any pathogen you work with should be handled under a hood, because it will safeguard you against contamination,” Dr. Janes said. A biological safety cabinet, colloquially a ‘hood’, is an enclosed and HEPA air-filtered laboratory workspace for the isolation of dangerous substances such as pathogenic bacteria (2). “[Students can prevent outbreaks] by doing all of their work under a hood, wearing their gloves, making sure their lab coats don’t leave the lab, not touching door knobs or leaving the lab before removing their gloves or washing their hands,” she said.
“If you touch doorknobs with gloves and it [the bacteria] is on the gloves, then the next person who touches that doorknob with their bare hand could be contaminated,” Dr. Janes explained. “… You have to be really careful not to walk around with your lab coat and gloves on outside of the lab – we have pretty strict policies about that,” she said.
Keeping the microbiology laboratory clean is also of utmost importance to prevent against accidental contaminations. Microbiologists use a method of ‘deep’ cleaning called autoclaving, a process that harnesses high pressures and temperatures to sterilize bacterial waste and contaminated equipment. “I am constantly getting on [my students] to autoclave,” Dr. Janes said. “We create a lot of waste in my lab, so it is something that has to be done almost every day.”
Another safeguard against outbreaks of laboratory strains of pathogenic bacteria such as Salmonella typhimurium is the use of harmless or non-pathogenic strains for teaching purposes. “For all of Dr. Janes’ courses [in food and industrial microbiology], we don’t use any pathogenic strains,” Edwards said. “Even for one of the labs we use E.coli, but we don’t use the O157:H7 strain – we are not going to bring that in there with all of these kids who don’t care, or don’t know what they are doing!”
“We act as if it could be harmful, just to teach them how to have proper safety technique in the lab setting, but they are not at any risk,” Edwards said. If the microbiology students were actually handling pathogenic strains, “I could definitely see something happening,” she admitted. “Some of [the students in those courses] just don’t care that much – they are not going to go on to be food microbiologists.” Dr. Janes admits that the ‘scare’ tactic sometimes seems to be the only way to motivate such students to follow safety protocols.
Dr. Janes strictly enforces safety rules in her laboratory, requiring extensive safety training for all of her students. Before her graduate students can even begin handling pathogenic bacteria such as Salmonella in the lab, they must complete an entire semester of extensive literature review, in order to learn more about the bacteria as well as the consequences of contamination. While the LSU department of Food Science conducts a safety training session every semester, Dr. Janes conducts an additional monthly safety meeting with her students in order to address any problems or breaches of protocol.
Edwards believes that if she follows all of Dr. Janes’ rules, contamination shouldn’t be a factor – at least not for herself. “You see people come in here with shorts on, open-toed shoes, not wearing a lab-coat, not washing their hands, or not wearing gloves – for them, I just think ’You’re crazy! I don’t know why you would do that!’” Edwards said.
However, rules alone may not suffice; students must actively care about each other and their friends and families at home, Edwards said, in order to stay sharp on safety. “I don’t want my stuff to contaminate someone else’s research, so I try to be careful – I don’t want to contaminate the whole lab with my bacteria. Then, nobody else could get any results!” she said.
“If you work with Salmonella, look for signs of infection,” said Russell, urging microbiology students and employees to seek medical attention for fever or diarrhea. She warns students to “be aware that certain items should not be brought into the lab if they are going to be used outside the lab, in other classrooms or at home.”
Edwards had a scare with her German Shepard just last week, when the dog licked a portion of her arm that had been splashed with her Salmonella-infected shrimp sample earlier that day. “I thought I was going to kill my poor dog!” Edwards said, as her pet threw up three times later that night. Although the German Shepard recovered by the next day, the scare served as a reminder to Edwards that, when working with pathogenic bacteria such as Salmonella, “You can’t get complacent. Sometimes you are tired, you just want to go home, but you just can’t ever get complacent … We are at risk, and we have to follow protocol.”
The Biosafety committee on the LSU campus is constantly changing rules and regulations in response to reported incidents. An incident in 2006, in which a student at Texas A&M contracted the Brucella virus as a result of inadequate personal protective equipment, “really got our university to start paying attention to what was going on inside the university,” Dr. Janes said. “They need to know who is doing what, and what cultures are being worked with, especially concerning ‘controlled’ substances.”
Today, Dr. Janes is required to teach her undergraduate microbiology courses in a different building than the one housing her research laboratories, in order to prevent un-certified students from gaining access to pathogenic bacteria. The agricultural chemistry professor even keeps her pathogen culture collection, stored in a – 70°C freezer, under lock and key. “That way I can keep track of what is going on in the lab,” she said. “For me, that is key, to make sure that [my students] are following protocol.”
(1) Multistate Outbreak of Human Salmonella Typhimurium Infections Associated with Exposure to Clinical and Teaching Microbiology Laboratories, Centers for Disease Control and Prevention, Atlanta, GA (April 28, 2011).
(2) High-Efficiency Particulate Air (HEPA)
(3) You-Tube Video by lsudiver2008 : http://youtu.be/98NDcZpoVlo