Challenge of Multidrug-resistant Strains of Enterobacteriaceae Isolated from Clinical Samples

Background: The rising level of antimicrobial resistance among bacterial pathogens is one of the most significant public health problems worldwide. Antibiotic resistance of clinically important bacteria, the types and levels of resistance and multidrug resistance (MDR) among pathogens is extremely important. With the rise of infections caused by ESBL-producing Enterobacteriaceae (ESBL-E) and with their co-resistance to many other antibiotic classes, carbapenems have been considered to be the last and life-saving agents against these life-threatening infections. The current study was carried out to determine the frequency, disease burden and therapeutic challenge of infections caused by multidrug resistant strains of Enterobacteriaceae with particular reference to Extended-Spectrum Beta-lactamase-producing Enterobacteriaceae (ESBL-E), Carbapenem-resistant Enterobacteriaceae (CRE) and the emerging infections caused by Extended-Spectrum Beta-lactamase-producing Carbapenem-resistant Enterobacteriaceae (ESBL-CRE) Methodology: This cross-sectional study was carried out in the Microbiology Department of Islamabad Diagnostic Centre over a period of two years, from January 2018 to December 2020. Enterobacteriaceae isolated on culture from clinical samples were identified using appropriate characterization tests including the selective use of API 20E. Antimicrobial susceptibility testing (AST) and ESBL detection was performed on Vitek 2 compact system by Minimum Inhibitory Concentration (MIC) methodology. Isolates that were resistant to more than one carbapenem were identified as Carbapenem-Resistant Enterobacteriaceae ( CRE). Results: Out of 7270 specimens that yielded the growth of Enterobacteriaceae, 2943 (40.5%) were ESBL positive (ESBL-E) and 487 (6.7%) were carbapenem resistant (CRE). Further analysis of CRE revealed 247/487 as non-ESBL-CRE and 240/487 as ESBL-producing CRE (ESBL-CRE). Maximum number of CRE isolates - both non-ESBL and ESBL CRE - were from urine specimens. Klebsiella species followed by Eschcerichia coli and Enterobacter were the dominant ESBL-CRE isolates. Admission to a health care facility was the major risk factor followed by advancing age. Conclusion: Besides ESBL-E, Carbapenum-resistant Enterobacteriaceae (CRE), particularly those co-producing Extended-Spectrum Beta-lactamase (ESBL-CRE), (wherein resistance mechanisms to both carbapenems as well as to beta-lactam antibiotics are concomitantly expressed in the same organism), have emerged as the major pathogens of concern. The later appears to have introduced a new dimension in the resistance profile of infections caused by multidrug-resistant enterobacteriaceae. Key words: Carbapenem Resistant Enterobacteriaceae, Extended-Spectrum Beta-Lactamase, ESBL-producing Carbapenem-resistant Enterobacteriaceae, Escherichia coli, Klebsiella, Multi-drug Resistant Enterobacteriaceae.