Richard Gu, Jennifer Parker, Bryan Davies
Over the last several decades, the prevalence of multi-drug resistant (MDR) bacteria has increased. One such type, known as extended-spectrum beta-lactamase (ESBL) -producing Enterobacteriaceae, is resistant to many common antibiotics, like penicillins. The last line of defense against these infections is a class of antibiotics known as carbapenems, but unfortunately their increase in use has led to the presence of carbapenem-resistant Enterobacteriaceae (CRE), which the CDC classifies as an Urgent Threat to public health. ESBLs and CRE both have various mechanisms through which they can gain resistance and new mechanisms are still being discovered. Strains may also contain more than one resistance mechanism or may be resistant to more than one class of antibiotics, further increasing the danger that they pose. In order to understand the types of MDR Enterobacteriaceae in Travis County, TX, a study was conducted to genetically characterize CRE and ESBLs isolated from patients at the Dell Seton Medical Center. Dell Seton is able to phenotypically identify CRE and ESBL isolates, but the genetic mechanisms of resistance are unknown. To uncover these mechanisms, genomic DNA was extracted from these isolates and molecular techniques were used to detect putative resistance genes and sequence the DNA of particular genes of interest. A mix of genetic resistance elements were found among these local CRE and ESBL isolates, such as ESBL genes being detected in CRE isolates previously assumed to not contain them. By more clearly defining what mechanisms are in circulation, Dell Seton Medical Center can refine drug use to target any prevalent or specific mechanisms, improving antibiotic stewardship.
