Clinical and laboratory standards institute versus European committee for antimicrobial susceptibility testing guidelines for interpretation of carbapenem antimicrobial susceptibility results for Escherichia coli in urinary tract infection (UTI)

Abstract

BACKGROUND:Carbapenems show excellent activity against resistant uropathogens, and they are the antibiotics of choice for urinary tract infections (UTIs). The choice of carbapenem prescription is strongly influenced by antimicrobial susceptibility testing (AST) report. With the publication of recent AST guidelines by the European Committee on AST (EUCAST), we were curious to evaluate the difference in results between Clinical and Laboratory Standards Institute (CLSI) and the EUCAST guidelines for the interpretation of carbapenems.METHODS:During a period of 1 year, midstream urine specimens received in the laboratory were cultured by conventional techniques and 2932 of them grew significant colony counts of Escherichia coli. Out of them, 501 E. coli isolates which were resistant to at least six first-line antibiotics were further subjected to second-line antimicrobials imipenem and meropenem, reported by E-tests (bioMerieux, France). The E-test results were interpreted by both CLSI 2016 and EUCAST 6.0 (2016) guidelines. Weighted kappa was used to determine absolute agreement, and McNemar's Chi-square test was used to test the difference in proportions of susceptibility between two methods, respectively.RESULTS:Taking CLSI guidelines as a gold standard, there was 100% sensitivity in a susceptible category by the EUCAST guidelines for both the carbapenems. Weighted kappa showed good and moderate agreement between them for imipenem and meropenem, respectively. However, McNemar Chi-square test in the nonsusceptible category between the two tests was 9.38% and 33.03% for imipenem and meropenem, respectively, and they were highly significant (P < 0.001).CONCLUSIONS:A laboratory can follow EUCAST guidelines as well and the guidelines are more useful in urinary concentrated antibiotics such as carbapenems. Further other antibiotics need to be evaluated by both these guidelines.

Impact of CLSI and EUCAST breakpoint discrepancies on reporting of antimicrobial susceptibility and AMR surveillance

“…Nineteen out of 20 articles reported significant discrepancies in one or more pathogen–antimicrobial combination, nearly always due to a reduction in susceptibility rates and/or increase in resistance rates when applying more restrictive EUCAST breakpoints. A notable exception was a study from India [8] that reported higher meropenem and imipenem susceptibility rates in urinary E. coli isolates using EUCAST breakpoints, underlining the lack of alignment between the two systems even for such important combinations. A trend of reduced susceptibility and/or higher resistance rates with EUCAST breakpoints was evident in the additional 53 articles where both EUCAST and CLSI breakpoints were used for susceptibility interpretation, many of which were reports of AMR surveillance data.…”

Antimicrobial resistance pattern in Salmonella enterica from clinical and poultry sources in Calabar, Nigeria

“…Other studies have also suggested that the in vitro resistance to nalixidic acid could be used as a pointer to the actual level of in vitro resistance to ciprofloxacin (Campioni et al, 2017;Klemm et al, 2018). According to the Clinical and Laboratory Standard Institute (CLSI) guidelines, the resistance to any antimicrobial agent in the fluoroquinolone drug class has an impact on the resistance of other antimicrobial agents within this drug class (Sahu et al, 2018). This implies that the resistance observed by the Salmonella enterica to nalidixic acid in this study is a pointer to the development of resistance to other members of the fluoroquinolone class of antimicrobial agents such as ciprofloxacin and norfloxacin in humans in the Calabar region.…”

Nystatin Profile on Candida Species in HIV/AIDS Patients with Oral Candidiasis: A Phenomenology Study

“…The diameter of inhibition zone was measured using caliper (Rosco Diagnostica, Taastrup, Denmark). We interpreted the inhibition zone diameter using CLSI 15 . This study used nystatin with a dose of 100,000 UI/ml (pharma chemistry Ltd, Bekasi, Indonesia) and fluconazole at a dose of 2 mg/ml (pharma chemistry Ltd, Bekasi, Indonesia)…”