Dataset Information

Environmental colonization and onward clonal transmission of carbapenem-resistant Acinetobacter baumannii (CRAB) in a medical intensive care unit: the case for environmental hygiene.

ABSTRACT: Background:In May 2015, we noticed an increase in carbapenem-resistant Acinetobacter baumannii (CRAB) infections in the Medical Intensive Care Unit (MICU). To investigate this, we studied the extent of environmental contamination and subsequent onward clonal transmission of CRAB. Methods:We conducted a one-day point prevalence screening (PPS) of the patients and environment in the MICU. We screened patients using endotracheal tube aspirates and swabs from nares, axillae, groin, rectum, wounds, and exit sites of drains. We collected environmental samples from patients' rooms and environment outside the patients' rooms. CRAB isolates from the PPS and clinical samples over the subsequent one month were studied for genetic relatedness by whole genome sequencing (WGS). Results:We collected 34 samples from seven patients and 244 samples from the environment. On the day of PPS, we identified 8 CRAB carriers: 3 who screened positive and 5 previously known clinical infections. We detected environmental contamination in nearly two-thirds of the rooms housing patients with CRAB. WGS demonstrated genetic clustering of isolates within rooms but not across rooms. We analysed 4 CRAB isolates from clinical samples following the PPS. One genetically-related CRAB was identified in the respiratory sample of a patient with nosocomial pneumonia, who was admitted to the MICU five days after the PPS. Conclusion:The extensive environmental colonization of CRAB by patients highlights the importance of environmental hygiene. The transmission dynamics of CRAB needs further investigation.

SUBMITTER: Ng DHL

PROVIDER: S-EPMC5891964 | biostudies-literature | 2018

REPOSITORIES: biostudies-literature

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Environmental colonization and onward clonal transmission of carbapenem-resistant <i>Acinetobacter baumannii</i> (CRAB) in a medical intensive care unit: the case for environmental hygiene.

Ng Deborah H L DHL Marimuthu Kalisvar K Lee Jia Jun JJ Khong Wei Xin WX Ng Oon Tek OT Zhang Wei W Poh Bee Fong BF Rao Pooja P Raj Maya Devi Rajinder MDR Ang Brenda B De Partha Pratim PP

Antimicrobial resistance and infection control 20180410

<h4>Background</h4>In May 2015, we noticed an increase in carbapenem-resistant <i>Acinetobacter baumannii</i> (CRAB) infections in the Medical Intensive Care Unit (MICU). To investigate this, we studied the extent of environmental contamination and subsequent onward clonal transmission of CRAB.<h4>Methods</h4>We conducted a one-day point prevalence screening (PPS) of the patients and environment in the MICU. We screened patients using endotracheal tube aspirates and swabs from nares, axillae, gr ...[more]

PMID: 29644052

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Project description:Objectives: Carbapenem-resistant Acinetobacter baumannii (CRAB) are one of the most difficult pathogen to treat. The only drug recently approved by the FDA that is active against CRAB is cefiderocol. However, recent studies have shown higher all-cause mortality rate in the group of patients treated with cefiderocol, that may be due to heteroresistance, a phenotype characterized by the survival of a small proportion of cells in a population seemingly isogenic. Previous studies showed that adding human fluids to CRAB cultures can lead to CFDC heteroresistance. To better understand the nature of this phenomenon, we carried out molecular and phenotypic analyses of CRAB heteroresistant bacterial subpopulations. Methods: The CRAB strain AMA40 was cultured in the presence of cefiderocol and human pleural fluid (HPF) to isolate heteroresistant variants. Two of them, AMA40 IHC_1 and IHC_2, were subjected to whole genome sequencing and transcriptomic analysis to identify the mutations and transcriptomic changes responsible for the development of cefiderocol resistance. The impact of mutations on the pharmacodynamic activity of cefiderocol was assessed by susceptibility testing, EDTA and Boronic acid inhibition analysis, biofilm formation, and static time-kill assays. Results: Variants AMA40 IHC_1 and IHC_2 had 53 mutations, forty of which were common to both heteroresistant strains. None of the mutations are located inside genes associated with iron-uptake systems or β-lactam resistance. However, pipA, a gene associated with iron homeostasis in other species, was mutated in heteroresistant strains. Transcriptomic analyses revealed modifications in levels of expression of genes associated with antibiotic resistance. The blaNDM-1, blaADC-2, pbp3, and pbp1 were expressed at higher levels. At the same time, the carO and ompA genes’ expression was reduced. Collateral resistance to amikacin was observed in the heteroresistant variants. Static time-kill assays showed that when CA-MHB was supplemented with human serum albumin, the main protein component of HPF, cefiderocol killing activity was considerably reduced in all three strains. Conclusions: We conclude that heteroresistance to cefiderocol in CRAB, when exposed to fluids containing high HSA, is caused by mutations and modifications in the expression of genes associated with resistance to β-lactams.

Dataset Information

Environmental colonization and onward clonal transmission of carbapenem-resistant Acinetobacter baumannii (CRAB) in a medical intensive care unit: the case for environmental hygiene.

Publications

Environmental colonization and onward clonal transmission of carbapenem-resistant <i>Acinetobacter baumannii</i> (CRAB) in a medical intensive care unit: the case for environmental hygiene.

Similar Datasets

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