Bacteria causing pneumonia can spread by rubbing the nose

Pneumococcus, the bacterium that can cause pneumonia, is known to be transmitted by the inhalation of airborne droplets containing the bacteria, for example during coughing and sneezing. This study is the first to show that transmission can also occur through contact between the nose and hands after exposure to pneumococcal bacteria.

The study found that bacteria can spread at the same rate, whether it is dry or wet, and at the same rate when a person selects himself or pricks his nose as when she rubs his nose. The findings suggest that ensuring good hand hygiene and keeping toys clean could help protect young children from the transmission and spread of the bacteria to other children and their elderly parents, who could be more susceptible to infections.

Principal investigator Dr. Victoria Connor, a clinical research investigator at the Liverpool School of Tropical Medicine and the Royal Liverpool Hospital, explained: "Pneumococcal infection is a leading cause of death in the world, and would be responsible for 1 , 3 million deaths in children under five years of age each year. Elderly people and people with other causes of impaired immunity, such as chronic diseases, also run an increased risk of becoming ill. pneumococcal infections.

"Our current understanding of pneumococcal transmission is inadequate, so we wanted to look at how this disease could spread in the community, and to better understand how this bacterium spreads will help better advise on how to reduce transmission," he said. there is greater prevention of pneumococcal infections ".

To assess the risk of nose-to-hand contact that could cause pneumococcal spread in the nose, 40 healthy adult volunteers were randomly assigned to four pneumococcal exposure groups using different methods of nose.

One group received a pneumococcal bacterium covered with water and then they were asked to sniff their hands ("wet sniffing"). A second group was asked to sniff out of the back of the hand an air – dried pneumococcal bacterium ("sniff dry"). The third and fourth groups were asked to bump their noses with a finger exposed to a wet pneumococcal bacterium ("wet poke") or an air-dried pneumococcal bacterium ("dry poke").

Two different detection methods were then used to test the pneumococcus, to confirm the presence of the bacteria in the participants' noses. These included a test to see if they could develop pneumococcal bacteria from participants' nose wash samples (culture) and whether they could detect the presence of bacterial DNA (qPCR).

The results showed that the highest bacterial spread rates were for the "wet poke" group, followed by the "wet sniff" group.

The researchers stated that participants were equally likely to get pneumococcal through the nose, that they were exposed with wet or dry samples, but that the total number of bacteria transmitted was higher in the wet groups; the authors suggest that it may be because the process of drying in the air leads to the death of certain bacteria.

The tests also showed that the same degree of transmission occurred when the participants touched the nose or took the nose compared to the one they rubbed their nose with the back of the hand.

Dr. Connor said, "It may not be realistic to get children to stop picking, pricking and rubbing their noses, and the presence of the bacteria can sometimes strengthen the system. immune to children and reduce their chances of wearing them later in life, so it is unclear whether reducing the number of pneumococci in children is the best solution.

"But for parents, as this study shows, it is possible for children to transmit pneumococci by the hands, which can be important when children are in contact with elderly parents or with a reduced immune system. it is essential to ensure good hand hygiene and the cleaning of toys is likely to reduce the transmission and risk of pneumococcal infection such as pneumonia. "

The researchers point out that the use of real people as part of the design of the study allowed them to test pneumococcal survival and viability of transmission methods in a safe and controlled manner.

Professor Tobias Welte, of the University of Hanover in Germany, is President of the European Respiratory Society and did not participate in the study. "This pilot study is the first to confirm that the pneumococcus bacteria can be spread by direct contact, rather than simply inhaling airborne bacteria.

"For clinicians, the results reinforce the message that we need to promote rigorous hand hygiene and basic infection control measures, such as avoiding the sharing of food, beverages and cell phones, to potentially reduce transmission of respiratory pathogenic bacteria such as pneumococcus is the best method to limit the spread of S. pneumoniae in the sinuses and lower respiratory tract, but vaccination rates are less than 50% for those for whom it is recommended. Improving it is one of the main tasks of health policy. "

The researchers noted that the bacteria samples used in the tests were administered at a dose that did not necessarily represent a real scenario. The results can therefore be treated with caution. They plan to watch how the pneumococcus is removed from the nose and if hand washing reduces the spread of the hand to the nose.

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More information:
Victoria Connor et al., The hands are vectors of Streptococcus pneumoniae transmission in a new controlled human infection study, European respiratory journal (2018). DOI: 10.1183 / 13993003.00599-2018