Carbapenem-resistant Enterobacterales (CRE) are a growing public health concern due to resistance to multiple antibiotics and potential to cause health care-associated infections with high mortality. Carbapenemaseproducing CRE are of particular concern given that carbapenemase-encoding genes often are located on mobile genetic elements that may spread between different organisms and species. In this study, we performed phenotypic and genotypic characterization of CRE collected at eight U.S. sites participating in active population-and laboratory-based surveillance of carbapenem-resistant organisms. Among 421 CRE tested, the majority were isolated from urine (n = 349, 83%). Klebsiella pneumoniae was the most common organism (n = 265, 63%), followed by Enterobacter cloacae complex (n = 77, 18%) and Escherichia coli (n = 50, 12%). Of 419 isolates analyzed by whole genome sequencing, 307 (73%) harbored a carbapenemase gene; variants of bla KPC predominated (n = 299, 97%). The occurrence of carbapenemase-producing K. pneumoniae, E. cloacae complex, and E. coli varied by region; the predominant sequence type within each genus was ST258, ST171, and ST131, respectively. None of the carbapenemase-producing CRE isolates displayed resistance to all antimicrobials tested; susceptibility to amikacin and tigecycline was generally retained.
We identified transmission of mcr-1 in a United States acute care hospital that likely occurred via duodenoscope despite no identifiable breaches in reprocessing or infection control practices. Duodenoscope design flaws leading to transmission of multidrug-resistant organsisms persist despite recent initiatives to improve device safety. Reliable detection of colistin resistance is currently challenging for clinical laboratories, particularly given the absence of an FDA-cleared test; improved clinical laboratory capacity for colistin susceptibility testing is needed to prevent the spread of mcr-carrying bacteria in healthcare settings.
Eighty Gram-negative bacilli (54 Enterobacteriaceae and 26 nonfermenting Gram-negative bacilli) obtained from multiple institutions in the United States were distributed in a blinded manner to seven testing laboratories to compare their performance of a test for detection of carbapenemase production, the Carba NP test. The Carba NP test was performed by all laboratories, following the Clinical and Laboratory Standards Institute (CLSI) procedure. Site-versus-site comparisons demonstrated a high level of consistency for the Carba NP assay, with just 3/21 site comparisons yielding a difference in sensitivity (P Ͻ 0.05). Previously described limitations with bla OXA-48-like carbapenemases and bla OXA carbapenemases associated with Acinetobacter baumannii were noted. Based on these data, we demonstrate that the Carba NP test, when implemented with the standardized CLSI methodology, provides reproducible results across multiple sites for detection of carbapenemases.KEYWORDS carbapenemase, antimicrobial resistance, screening, Gram-negative bacilli C linical microbiology laboratories around the globe have instituted a range of rapid screening tests for detection of carbapenemase production in the rising tide of carbapenem-nonsusceptible Gram-negative bacilli (GNB). One method, the Carba NP test, offers a rapid and simple colorimetric method for the detection of carbapenemase activity in isolates of GNB. In principle, the test is similar to the classic -lactamase detection assays described by Escamilla and by Skinner and Wise in the 1970s, in which benzylpenicillin acidimetrically produced a red color after hydrolysis by Haemophilus influenzae -lactamase (1, 2). With the Carba NP test, hydrolysis of imipenem produces acid and drives the pH indicator, phenol red, from red to yellow.The Carba NP test has been studied by several investigators (3-14), including evaluations and comparisons to a commercial version (15)(16)(17)(18)(19)(20). However, the literature lacks consistency in the Carba NP methodology. The test has evolved several times, including alterations to reagents, and has gone from a microtiter plate-based format performed on bacterial protein extracts to a rapid tube-based test with abbreviated processing. Most studies have been single-laboratory evaluations; there is a lack of multicenter performance assessments utilizing a single, harmonized method.As part of an effort to standardize the method, the Clinical and Laboratory Standards Institute (CLSI) Subcommittee on Antimicrobial Susceptibility Testing
A surgical heater–cooler unit has been implicated as the source for
Mycobacterium chimaera
infections among cardiac surgery patients in several countries. We isolated
M. chimaera
from heater–cooler units and patient infections in the United States. Whole-genome sequencing corroborated a risk for these units acting as a reservoir for this pathogen.
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