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About Sickkids
About SickKids

April 11, 2008

Scientists develops new model for determining optimal antibiotic use for treatment of community acquired pneumonia

A group of Toronto scientists including Dr. David N Fisman, a scientist in the Child Health Evaluative Sciences program at The Hospital for Sick Children (SickKids), have developed a theoretical model to guide the best use of antibiotics for treating infectious diseases. This model estimates the risk of a bad outcome (such as death), based on the use of antibiotics to which resistance may be emerging. The model can also take into account various risk probabilities of the infectious agent as well as the age and health of patients. Fisman and team tested this model using the best available data on pneumonia and antibiotic resistance in Canada , the US and Europe . The model was built because current guidelines for antibiotic use do not consider the size of changes in risk for patients when certain antibiotics are used despite the presence of resistance in bacteria. This research is published online and in the April 15 th issue of the journal Clinical Infectious Diseases.

Community-acquired pneumonia (CAP) is an infectious form of pneumonia which can be caused by bacteria or viruses that are transmitted from one person to another in a community setting. Most commonly, CAP is caused by the bacteria Streptococcus pneumoniae (which also causes ear infections, meningitis, and bloodstream infections) . In Canada , infections that may be caused by S. pneumoniae are often treated with microlide antibiotics such as erythromycin, azithromycin, clarithromycin, or Roxithromycin . A challenge is that S.pneumoniae , like many other types of bacteria, is rapidly becoming resistant to the antibiotics which are used to treat it. This is a growing public health concern, as increasing antibiotic resistance in bacteria means that the antibiotics currently in use are becoming less effective, leading to a higher probability of prolonged disease symptoms and hospitalization, bacterial infection and even death as a result of infection. As more antibiotics are prescribed for infected patients, bacteria become increasingly resistant, requiring even more antibiotics to treat it, and the cycle continues.

Guidelines for providing antibiotic treatment for CAP have been developed and published; however these guidelines don't provide estimates of the risk to patients associated with using macrolides as the frequency of resistance increases. The model developed by the research team considers the trade-offs between effectiveness and risk and also considers the age and health of the individual patient. “Using this model, we have determined that even a low frequency of antibiotic resistance, and strains that have 'weak‘ resistance to antibiotics, may result in considerable risk to patients treated with macrolides,” stated Fisman. “Current guidelines only consider situations of high level or 'strong‘ antibiotic resistance, and as a result can lead to a poorer patient outcomes as well as increased costs to the health system.”

The research team suggests that this model can be adapted to any other infectious disease that is treatable by antibiotics and where antibiotic resistance is an issue. Current treatment guidelines for various diseases do not take into account the rising rates of antibiotic resistance, and so this model can serve as a useful tool to help public health and medical organizations evaluate and make decisions about the best antibiotic to use for treatment of common infectious diseases in different geographic regions. As this model considers a variety of risk factors including patient health status, it can be adapted for use with a variety of different populations. Fisman anticipates that this model will influence future decisions about antibiotic use, and as a result, patient treatment for infectious diseases will improve.

For more information, please contact:

Public Affairs
The Hospital for Sick Children
555 University Avenue
Suite 1742, Public Affairs, First floor Atrium
Toronto, ON
M5G 1X8
Canada
Phone: 416-813-5058
Fax: 416-813-5328