At the recent meeting of the European Congress of Clinical Microbiology and Infectious Diseases (ECCMID), researchers from Streck Inc, La Vista, Neb, presented the results of a study on an improved methodology for the detection of antibiotic resistance in Gram-negative bacteria.1,2
Chris Connelly, Streck.
The poster presentation by Chris Connelly, PhD, director of research and development at Streck, highlighted study results indicating that the design of Streck’s ARM-D ?-lactamase kit enables the test to detect more antibiotic resistance determinants than comparable tests. According to Connelly, the study “highlights the need to have comprehensive panels for polymerase chain reaction (PCR)-based molecular tests, so antibiotic resistance does not go undetected.”
Antibiotic-resistant bacteria can complicate treatment choices in healthcare settings. Many mechanisms contribute to antibiotic resistance, but the most common causes involve ?-lactamases—enzymes produced by bacteria that result in resistance to such ?-lactam antibiotics as carbapenems, cephalosporins, cephamycins, and penicillins. As a strategy to complement phenotypic testing, PCR-based assays are being used to correctly and comprehensively identify the presence or absence of the genes associated with antibiotic resistance.
PCR-based tests utilize nucleic acid, which can be extracted from a number of different sample matrices. To retain their sensitivity and specificity, such tests should be designed to identify multiple genetic variants within a given resistance gene family. Additionally, the tests should include controls that mimic the patient sample, including the sample matrix, in order to verify the accuracy and precision of the entire analytical process.
The study presented at ECCMID provided a direct comparison of multiple commercially available real-time PCR-based assays, complete with controls, for the evaluation of Gram-negative bacteria isolates to detect the presence of genes imparting antibiotic resistance.
Results of the study support the use of Streck ARM-D kits as comprehensive screening tools for ?-lactamase-based resistance. Performance of the kits, for comparable detection targets, was found to be as good as, or better than, the performance of other commercial tests. In total, the data demonstrate that Streck ARM-D kits provide a suitable tool for the detection of antibiotic resistance.
In the ECCMID study, molecular controls, positive for each target, demonstrated the expected identification profile of organisms and resistance mechanisms using the ampC and ?-lactamase ARM-D kits from Streck; the FilmArray BCID test by BioFire Diagnostics, Salt Lake City; and the Xpert Carba-R test by Cepheid, Sunnyvale, Calif. Stability analysis demonstrated equivalent analytical performance when the controls were held for up to 150 days at 4° C.
Streck ARM-D kits are for research use only and are not intended for use in diagnostic procedures. To learn more, visit Streck.
References
- Torres M, Sobansky M, Cossette S, Scheer C, Lechner J, Connelly C. Improved methodology for detection of antibiotic resistance in Gram-negative bacteria [abstract P2293, online]. Poster presented at the annual European Congress of Clinical Microbiology and Infectious Diseases, Madrid, April 21–24, 2018. Available at: www.escmid.org/escmid_publications/escmid_elibrary/?q=p2293&id=2173&L=0&x=0&y=0. Accessed September 21, 2018.
- Alao E, Sobansky M, Torres MP, Cossette S, Lechner J, Connelly C. Improved methodology for detection of antibiotic resistance in Gram-negative bacteria [poster, online]. Poster presented at the annual European Congress of Clinical Microbiology and Infectious Diseases, Madrid, April 21–24, 2018. Available at: bit.ly/2xqvTcG. Accessed September 21, 2018.
