Phenotypic methods for screening carbapenem-resistant Enterobacteriaceae and assessment of their antimicrobial susceptibility profile

Abstract

Introduction:In this study, we used phenotypic methods to screen carbapenem-resistant Enterobacteriaceae (CREs) and evaluated their antimicrobial sensitivity profile. Methods: One hundred and seventy-eight CREs were isolated at a university hospital in south Brazil in a one-year period. Samples were assessed using disk diffusion tests with inhibitors of β-lactamases such as phenylboronic acid (AFB), cloxacillin (CLOXA), and ethylenediaminetetraacetic acid (EDTA). Strains with differences in zone diameters ≥ 5mm for disks supplemented or not were considered producers of carbapenemases. Results: Klebsiella pneumoniae was the most prevalent CRE, which appeared in 80.3% cases (n = 143). Among clinical materials, the rectal swab was responsible for 43.4% of the isolations (n = 62), followed by urine (18.9%; n = 27). Among the CREs identified in this study, the growth of 56.7% (n = 101) isolates, which were putative producers of Klebsiella pneumoniae carbapenemase (KPC), were inhibited by AFB, whereas 7.3% (n = 13) isolates were inhibited by both AFB and CLOXA and were considered as putative producers of plasmid-mediated AmpC; approximately 3.4% (n = 6) were inhibited by EDTA, which possibly produced metallo-β-lactamase. Lastly, 32.6% (n = 58) cases showed negative results for AFB, CLOXA, and EDTA sensitivity, and represented another class of β-lactamases and/or mechanism of resistance. Conclusions: Phenotypic screening of CREs is important for clinical laboratories that monitor outbreaks of resistant microbes. Phenotypic tests that use carbapenemase inhibitors and enhancers such as AFB, CLOXA, and EDTA are necessary since they are good screening methods for the detection of carbapenemases.

Characterization of KPC-Producing Serratia marcescens in an Intensive Care Unit of a Brazilian Tertiary Hospital

“…This is in line with other studies that have also reported MDR S. marcescens mainly to beta-lactam, aminoglycoside, and quinolone antibiotics groups (Stock et al, 2003), in hospital environment (Merkier et al, 2013), and particularly in critically ill patients and neonatal intensive care units (Maragakis et al, 2008). We also observed a significant resistance to colistin and tigecycline in several colonization sites, as shown by a previous study (Silva et al, 2017).…”

Assessment of the biological potential of diaryltriazene-derived triazene compounds

“…Studies by Silva et al 70 and Paraginski et al 35 corroborate the results of our study by showing that triazene exhibit antimicrobial activity against all tested Gram-positive and Gram-negative bacteria. In the study by Paraginski et al 35 , the majority of Gram-negative strains had significant resistance mechanisms that may have decreased percentage activity compared to gram-positive bacteria.…”

Prevalence and antimicrobial resistance patterns of nosocomial pathogens causing Surgical Site Infections in an Egyptian University hospital.

“…We observed that the most common carbapenem resistant Gram-ve isolates were K. pneumonia and P. aeruginosa followed by E. coli and Acinetobacter spp. This agreed with Silva et al [27] and partially agreed with Solanki et al [28] they found that K. pneumonia was the most prevalent carbapenem resistant isolates followed by E coli, Acenitobacter spp and P. aeruginosa. Hasanin et al [29] found that Acinetobacter accounted for (86%) of carbapenem resistant isolates, although the relatively small number of carbapenem resistant Acenitobacter isolates in our study, this number represent 100% of this bacterial species.…”