Common Cold-Causing Bacteria Lingers Longer than Expected When Outside of the Body

Two common bacteria that are the source of colds, ear infections, strep throat and a variety of other infections have been shown to survive outside of the human body for much longer than expected.

The revelation suggests that the bacteria - Streptococcus pneumoniae and Streptococcus pyogenes - will sick around longer than anticipated on places like furniture, toys and books.

Writing in the journal Infection and Immunity, the researchers suggest that additional precautions may be necessary to prevent infections, especially in places like schools, daycare centers and hospitals.

"These findings should make us more cautious about bacteria in the environment since they change our ideas about how these particular bacteria are spread," said senior author Anders Hakansson, an assistant professor of microbiology and immunology in the University of Buffalo School of Medicine and Biomedical Sciences. "This is the first paper to directly investigate that these bacteria can survive well on various surfaces, including hands, and potentially spread between individuals."

Although the bacteria in question are common, they can lead to a number of unwanted medical conditions, Hakansson said. S. pneumoniae, which is widespread in daycare centers and a common cause of hospital infections, is a leading cause of ear infections in children and a common cause of deadly respiratory tract infections in both children and the elderly. Children with strep throat have likely been infected with S. pyogenes, which can also cause serious skin infections in children and adults.

Hakansson and is research team tested a daycare center for the bacteria, finding that four out of five stuffed toys tested positive for S. pneumonaie and S. pyogenes was found on numerous surfaces, including cribs. The researchers tested for the bacteria in the morning before the daycare center opened for business, which ensured that it had been many hours since the last contact.

"Bacterial colonization doesn't, by itself, cause infection but it's a necessary first step if an infection is going to become established in a human host," Hakansson said. "Children, the elderly and others with compromised immune systems are especially vulnerable to these infections."

The researchers also found that bacteria samples that remained outside of an organic hose for a month were able to readily colonize in mice, and that the bacteria's biofilm persisted on hands, toys and books even if they were thoroughly sanitized.

"In all of these cases, we found that these pathogens can survive for long periods outside a human host," Hakansson said.

"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," Hakansson added.

"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 health-care settings," he said.