Evaluation of phenotypic tests to detect carbapenem-resistant Enterobacteriaceae in colonized patients hospitalized in intensive care units

Abstract

In this study, we aimed to evaluate the performance of different phenotypic tests to detect carbapenem-resistant Enterobacteriaceae. Three different phenotypic methods were evaluated: (1) combined-disk test of meropenem plus phenylboronic acid or EDTA reading after 24h and 48h; (2) selective/chromogenic read after 24h and after 48h; and (3) overnight selective enrichment broth containing 10μg ertapenem disk followed by culture on MacConkey agar. A positive result in at least one of the methods was submitted to PCR for blaNDM-1, blaOXA-48, blaKPC, blaSPM-1, blaIMP, and blaGES detection. Carbapenem-resistant Enterobacteriaceae was detected in 31 (30.4%) of 102 rectal swabs evaluated. All isolates showed to be KPC-2-producing organisms. Results showed excellent agreement among the evaluated tests (positive and negative) (kappa=0.88). It is important to state that combined-disk test with phenylboronic acid is not suitable for bacterial identification/isolation. Conversely, selective/chromogenic agar after 48h of incubation showed to be a useful tool, with the advantage of presumptive bacterial identification.

Establishment and evaluation of an experimental rat model for high-altitude intestinal barrier injury

“…As a selective culture medium, MacConkey culture medium contains the nutrient substances suitable for intestinal bacteria, which can partially inhibit gram-positive bacteria and completely inhibit the migrating growth of Proteusbacillus vulgaris (26). The addition of a pH indicator, neutral red and lactose, allows the pathogenic enterobacteria to be identified (27).…”

Menacing Emergence of Fosfomycin Resistance Among Klebsiella pneumoniae Carbapenemase–2-Producing K. pneumoniae Driven by Prior Use in Critically Ill Patients

“…KPC-2-Kp was defined according to carbapenem resistance patterns, with phenotypic testing results determined as proposed by Clinical and Laboratory Standards Institute guidelines 6 and through bla KPC-2 gene detection by polymerase chain reaction as previously reported. 7 Cases were defined as patients from whom a fosfomycin-resistant isolate was recovered from urine and/or blood cultures more than 48 hours but less than 90 days after the day a urinary fosfomycin-susceptible isolate was collected. Data on antibiotic exposures between the first KPC-2-Kp isolation and the day on which a positive culture for a fosfomycinresistant isolate was obtained were recorded.…”

Emergence of Infections due to a Polymyxin B–Resistant KPC-2-Producing Klebsiella pneumoniae in Critically Ill Patients: What Is the Role of a Previous Colonization?

“…4 During the period of the study, 149 (24.3%) of the 613 patients were found to be colonized by CPE and in only 10 of them, a CPE was recovered in a clinical specimen, resulting in a 6.7% (10/149; 95% CI, 3.7%-11.9%) cumulative incidence rate of infection. Table 1 shows the 10 colonized patients with CPE who presented with a subsequent infection with the same microorganism.…”