Carbapenem-resistant Enterobacteriaceae (CRE) are a group of bacteria that have high levels of resistance to specific antibiotics known as carbapenems. Carbapenems are members of the beta lactam class of antibiotics, which kill bacteria by binding to the bacterial cell wall to prevent synthesis of the bacterial cell wall. Over time, CRE bacteria have developed the ability produce an enzyme known as carbapenemase that is able to break down the antibiotic before it is able to bind to the cell wall. Common CRE bacteria include Escherichia coli and Klebsiella pneumoniae.
Scientists in China have developed a paper strip test method that is more sensitive and faster than the method currently recommended by the Clinical and Laboratory Standards Institute (CLSI) for the detection of carbapenem-resistant Enterobacteriaceae. Credit: Science News
The good news is that most healthy people do not get CRE infections. However; hospital patients as well as individuals in nursing homes and other health care settings whose immune systems are not as strong are at risk. Of particular concern are those individuals that require the use of medical devices such as ventilators, urinary catheters, intravenous catheters, or other patients taking long courses of antibiotics.
In order to prevent the spread of CRE bacteria in healthcare settings, those patients carrying the bacteria should be identified so that control measures can be implemented. There are a number of tests that are currently used for the early detection of CPE in clinical laboratories including basic culture techniques that require the bacteria to grow for 18-24 hours before results can be acquired. The long turnaround time is a major limitation of these tests considering the bacteria can continue to spread while awaiting test results
According to a study published in the Journal of Clinical Microbiology this week, scientists in China have developed a rapid test for the detection of CRE bacteria that can provide results within 5 minutes. The test was also shown to be 11% more sensitive than the testing method that is currently used.
Researchers collected 213 CRE bacteria from patients at a hospital in Hong Kong, China from January 2016 to December 2016. Another 177 isolates that were not resistant to carbapenems were used as experimental controls. Of those 390 isolates, 149 were Escherichia coli, 138 were Klebsiella pneumoniae, 47 were Enterobacter cloacae, 16 were Citrobacter freundii, 19 were Enterobacter aerogenes, 8 were Klebsiella oxytoca, as well as 13 other Enterobacteriaceae.
The paper strip test was performed by rubbing a small amount of freshly grown bacteria onto a test strip that had been pre-moistened with a specific solution. Results were read by determining if there was a color change on the paper strips within 1 and 5 minutes. Test results were confirmed using an immunochromatographic test.
The authors of the study report that this strip test method can provide a simple and cost-effective method for the rapid detection of CRE-carrying patients in healthcare settings. It is more sensitive and faster than the current method that is recommended by the Clinical and Laboratory Standards Institute (CLSI). This new test has potential for routine implementation in healthcare settings for the control of CRE-related infections.
Sources: Journal of Clinical Microbiology; Centers for Disease Control and Prevention