Researchers from the University at Buffalo in New York say two bacteria that cause many common infections in children and the elderly, such as strep throat and ear infections, can live outside the human body for long periods of time on various objects, including books, cribs and toys.
The investigators found that Streptococcus pneumoniae and Streptococcus pyogenes linger on many surfaces significantly longer than previously thought, opposing previous studies that suggest the bacteria quickly die once they have left the human body.
The researchers say their findings suggest that better strategies are needed to prevent infections, particularly in hospitals, schools and daycare centers.
S. pyogenes is a common cause of strep throat and skin conditions in school children, but the bacteria can also cause severe infections in adults.
S. pneumoniae is a leading cause of morbidity and mortality from respiratory tract infections in children and the elderly, and it is also a leading cause of ear infections.
Previous research from the team showed that certain bacteria develop biofilms when they colonize human tissues. A biofilm is a group of microorganisms that bind together on a surface.
The researchers found that this bacteria is stronger than other bacteria that do not form biofilms, leading them to believe that the bacteria may linger on surfaces.
To test if this was the case, the investigators analyzed a number of objects including books, stuffed toys and cribs in a child daycare center.
Potential for biofilm bacteria reservoirs
Even after cleaning, the researchers found that biofilms were able to survive for many hours on cribs, toys and books.
Many surfaces - including cribs - tested positive for S. pyogenes, while four out of five stuffed toys tested positive for S. pneumoniae.
The researchers note that this testing was done after the surfaces had been cleaned, and prior to the center opening in the morning, meaning it had been a long time since the surfaces and objects had human contact.
The investigators then tested 1-month-old biofilm of S. pyogenes and S. pneumoniae to see whether the bacteria was able to colonize. Results revealed that the biofilms could effectively colonize a mouse model.
Other experiments found that the biofilms were able to survive for many hours on human hands, books, hard and soft toys and surfaces, even after cleaning.
Commenting on the findings, Anders Hakansson, assistant professor of microbiology and immunology at the University at Buffalo School of Medicine and Biomedical Sciences, and senior author of the study, says:
"In all of these cases, we found that these pathogens can survive for long periods outside a human host.
Commonly handled objects that are contaminated with these biofilm bacteria could act as reservoirs of bacteria for hours, weeks or months, spreading potential infections to individuals who come in contact with them."
However, Hakansson notes that further research is needed to determine the exact circumstances in which this type of contact may lead to transmission between individuals, and the results may emphasize the need for new strategies to prevent infection.
"If it turns out that this type of spread is substantial, then the same protocols that are now used for preventing the spread of other bacteria, such as intestinal bacteria and viruses, which do persist on surfaces, will need to be implemented especially for people working with children and in healthcare settings," he adds.
Medical News Today recently reported on a study detailing a new method in which researchers say they could target and kill bacteria, such as E. coli.