A new study reports a surge in drug-resistant strains of a dangerous type of bacteria in US hospitals: Acinetobacter strikes patients in Intensive Care Units (ICUs) and others and often causes severe pneumonias or bloodstream infection, some of which are now resistant to imipenem, an antibiotic that is reserved for last-line treatment.
The study is the work of researchers at the Extending the Cure project, led by Dr Ramanan Laxminarayan, of the Washington DC-based think-tank Resources for the Future, and appears as an electronically published paper in the December 23 issue of the journal Infection Control and Hospital Epidemiology. (Extending the Cure is supported by the Robert Wood Johnson Foundation’s Pioneer Portfolio).
As well as affecting ICU and other patients, Acinetobacter infections are arising in soldiers returning from the war in Iraq.
For the study Laxminarayan and colleagues looked at data from 300 hospitals around the US and analyzed trends in resistance to imipenem, a highly potent, broad spectrum antibiotic often reserved as a last-line treatment.
They found that between 1999 and 2006, there was a three-fold plus increase in the proportion of Acinetobacter cases resistant to the drug.
Laxminarayan, who is also a visiting scholar and lecturer at Princeton University, told the media the finding was troublesome because it suggests “this bacteria is becoming resistant to nearly everything in our arsenal”.
“There is a lot of attention on MRSA, but less on infections caused by bacteria like Acinetobacter for which there are fewer drugs in the development pipeline,” he said, adding that “while all drug resistance is of concern, it is particularly worrying in the case of bugs for which we have few treatment options.”
He and his co-authors said the US should adopt a comprehensive solution to the problem of antibiotic resistance. For example, there should be more infection control at a regional level, and drug companies should be encouraged to develop new antibiotics that attack and destroy the resistant strains.
According to the US Centers for Disease Control and Prevention (CDC), Acinetobacter bacteria are common in soil and water, and can also be found on the skin of healthy people, especially those working in the healthcare profession.
The bacteria cause a variety of diseases, ranging from pneumonia to serious blood or wound infections, with varying symptoms, and they can also colonize a patient without showing any signs of infection, especially in tracheostomy sites or open wounds.
While Acinetobacter poses little risk to healthy people, those with weakened immune systems, chronic lung disease, or diabetes may be more susceptible to infections, as are very ill hospitalized patients on ventilators, those with a prolonged stay, or those with open wounds.
The bacteria spread through person-to-person contact, contact with contaminated surfaces, or exposure in the environment.
“Increasing Resistance of Acinetobacter Species to Imipenem in United States Hospitals, 1999-2006.”
Marc S. Hoffmann, Michael R. Eber, Ramanan Laxminarayan.
Infection Control and Hospital Epidemiology, 2010;31:000-000; electronically published December 23, 2009.
Sources: Burness Communications/Robert Wood Johnson Foundation, CDC.
Written by: Catharine Paddock, PhD