Doctors usually have to send samples away to diagnose bacterial or viral infections. The new test could provide a rapid way for doctors to test patients immediately.
The study, published in JAMA, found that the two genes, called IFI44L and FAM89A, only shifted to an "on" state when a bacterial infection was present. This knowledge could enable doctors to distinguish between bacterial and viral infections, and identify early cases of severe infections that could be deadly.
While viral infections are more common than bacterial infections, bacterial infections are often more serious.
Meningitis, septicemia, and pneumonia all occur as a result of a bacterial infection. Differentiating between these potentially life-threatening conditions and viruses can allow health providers to provide quicker, more accurate treatments.
Also, making a distinction between whether an individual has a viral or bacterial infection can prevent antibiotics being prescribed for viruses. Antibiotics are only effective against bacteria and do not fight infections caused by viruses like colds, flu, most sore throats, bronchitis, and many sinus and ear infections.
Ineffective prescribing of antibiotics for viral infections will not cure the infection, not prevent others from becoming ill, may cause unnecessary and harmful side effects, and may contribute to antibiotic resistance, which is when bacteria can resist the effects of an antibiotic and continue to cause harm.
Antibiotics are among the most commonly prescribed drugs. However, up to 50 percent of the time, the use of antibiotics is not needed, is incorrectly dosed, and is used for the wrong duration.
Every year in the United States, more than 2 million people become infected with bacteria that are resistant to antibiotics, and at least 23,000 people die as a direct result of these infections.
Many children are misdiagnosed with viruses
Currently, when a child visits the doctor or the emergency room with a fever, no quick method exists to determine if the child has a bacterial or viral illness.
Diagnosis relies on a blood sample or spinal fluid being taken, transferred to a lab, and waiting more than 48 hours to see if bacteria grow in the sample.
Prof. Michael Levin, from the Department of Medicine at Imperial College London, who led the study, explains: "Fever is one of the most common reasons children are brought to medical care. However, every year many children are sent away from emergency departments or doctors' surgeries because the medical team thinks they have a viral infection when in fact they are suffering from life-threatening bacterial infections - which are often only diagnosed too late."
"Conversely, many other children are admitted to hospital and receive antibiotics because the medical team is unable to immediately exclude the possibility of a bacterial infection - but in fact, they are suffering from a virus," he adds.
Levin, who works in the pediatric infectious disease division, continues to say that while the research is at an early stage, the findings show that bacterial infection can be distinguished from other causes of fever - including viral infection - using a pattern of genes that are switched on or off in response to the infection.
"The challenge is now to transform our findings into a diagnostic test that can be used in hospital emergency departments or GP surgeries, to identify those children who need antibiotics," Levin adds.
Two genes predict bacterial infection with 95-100 percent accuracy
Scientists studied 240 children arriving at hospitals with fever in the United Kingdom, Spain, the Netherlands, and the United States, with an average age of 19 months.
After traditional methods had been used to determine whether the child had a bacterial or viral infection, the researchers analyzed the genes that had been switched on in the children's white blood cells.
Using RNA microarrays - a method that measures changes in 48,000 genes simultaneously using only a small drop of blood - the team found two genes switched on during bacterial infections. Further investigation indicated that the two genes predicted bacterial infection with 95-100 percent accuracy.
Dr. Jethro Herberg, senior lecturer in pediatric infectious diseases at Imperial and co-author of the research, says: "We are facing a growing threat from antibiotic-resistant bacteria. A large proportion of antibiotic use is driven by our inability to reliably identify the small number of children with bacterial infection from the much larger number with viral infection, who do not need antibiotics."
"Fear of missing life-threatening infections like meningitis and septicemia result in doctors often prescribing antibiotics and undertaking investigations such as lumber punctures just to be safe. A rapid test based on the two genes we have identified could transform pediatric practice, and allow us to use antibiotics only on those children who actually have a bacterial infection."
Dr. Jethro Herberg
Vinny Smith, chief executive of Meningitis Research Foundation who supported the study, adds:
"This latest development is very exciting. Bacterial meningitis and septicemia can kill in hours, and can leave survivors with life-changing after-effects. Giving health professionals the tools to rapidly determine whether an infection is bacterial or viral will enable faster detection and treatment of meningitis and septicemia."