Resistance to common antibiotics is becoming frequent in Australia and our response will require a multifaceted response, say experts in a clinical focus article published in the Medical Journal of Australia.
An emerging phenomenon is the rise of multidrug-resistant (MDR) gram-negative bacilli (GNB), particularly in commonly encountered bacteria belonging to the Enterobacteriaceae group (such as E. coli and Klebsiella). MDR GNB are microorganisms that may acquire genes that produce enzymes with the ability to negate the effects of antibiotics such as β-lactams (like penicillins, cephalosporins and carbapenems). Until recently we have relied up carbapenems (a broad- spectrum antimicrobial) for the treatment of many types of MDR GNB, but we are increasingly witnessing resistance to these 'last-line' drugs. Fatality rates attributed to serious infections caused by carbapenem-resistant Enterobacteriaceae are high (ranging from 19% to 48%).
MDR GNB exist at high rates in communities in the Asia-Pacific region. Travellers returning from these countries may carry resistant bacteria in their gastrointestinal tract and remain colonised for a considerable period of time. Should they develop an infection, they remain at significant risk of the bacteria being resistant to standard antbiotics.
Dr Patrick Harris, an infectious diseases physician and research scholar at the University of Queensland's Centre for Clinical Research, and coauthors wrote that the paucity of new antibiotic classes meant the nature of Australia's response to MDR GNBs was vital.
"[O]ur national response to these challenges will require a multifaceted approach, including widespread implementation of antimicrobial stewardship, enhanced surveillance, targeted screening of at-risk patients and improved infection control practices", the authors wrote.
"In the longer term, restriction of agricultural use of antibiotic classes critical to human medicine, removal of barriers to new drug development, and technological advances in rapid microbiological diagnostics will be required."
In Australia, rates of resistance in Escherichia coli to widely-used antibiotics (known as third- generation cephalosporins) have doubled in recent years, although remain low by international standards. Less than 2% were resistant in 2007 but an increase to just above 4% in 2012 has been observed in large national surveys. An exponential increase in Enterobacteriaceae with resistance to third-generation cephalosporins, as has occurred in Europe, is also likely in Australia if no appropriate action is taken.
Several risk factors for contracting an infection with or becoming a carrier of MDR GNB have been identified, but a key modifiable risk is recent antibiotic use. Hence the pressing need to limit unnecessary antibiotic exposure. Other risk factors include, residence in a long-term care facility, hospital admission in endemic areas, multiple medical comorbidities, presence of medical devices, extended hospital stay (especially ICU admission), exposure to other patients carrying MDR GNB, and a history of recent surgery.
The authors wrote that there were, nevertheless, causes for optimism, largely because antimicrobial stewardship programs are now standard in Australian hospital accreditation requirements.
"The public is increasingly aware of the risks of health care-associated infection and the overuse of antibiotics", they concluded.
"Although most health care providers understand these risks, applying this awareness to daily practice is a challenge that we all have to confront."