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

Abstract

BackgroundIn 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.MethodsWe 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).ResultsWe 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.ConclusionThe extensive environmental colonization of CRAB by patients highlights the importance of environmental hygiene. The transmission dynamics of CRAB needs further investigation.

The role of hospital environment in transmissions of multidrug-resistant gram-negative organisms

“…The environment surrounding seventy of these patients demonstrated contamination across all study days [38]. In another study investigating the environmental contamination of CRAB in an endemic setting, investigators found that ICU rooms occupied by patients carrying CRAB were consistently colonized by genomically similar strains of CRAB [39]. The investigators also demonstrated persistence of CRAB in the environment and subsequent clinical infection, highlighting the need for carefully thought out IPC strategies to control MDRO in an endemic setting.…”

“…A recent study by Mody et al [40] demonstrated that contamination of patients' hands with MDRO is frequent and correlates with contamination of high-touch surfaces. Patients who were colonized or infected with CRAB were also shown to have higher environmental contamination with clonal CRAB compared to patients who were not [39,41]. The higher burden of MDRGN as usually observed in clinical infections, has been shown to increase environmental contamination [42,43].…”

Community-acquired in name only: A cluster of carbapenem-resistantAcinetobacter baumanniiin a burn intensive care unit and beyond

“…Indeed, a recent study found A. baumannii isolates collected from the same individual to differ by as many as 11 SNPs. 22 However, the analysis presented here does not distinguish whether the outbreak was the result of expansion from a single strain or, less likely, the result of the introduction of multiple highly related strains (eg, from an environmental reservoir).…”

Water as a Source of Antimicrobial Resistance and Healthcare-Associated Infections

“…The size, shape and biovolume of bacteria may influence the filterability of a sample and potentially lead to inaccurate findings, particularly if multiple species of bacteria are being investigated using the one pore diameter [ 96 ]. Alternative molecular techniques for bacterial detection such as qPCR and whole-genome sequencing (WGS) have been employed by 27 studies included in this review [ 13 , 14 , 17 , 18 , 20 , 25 , 26 , 34 , 37 , 40 , 43 , 45 , 46 , 51 , 52 , 56 , 57 , 59 , 60 , 63 , 64 , 65 , 97 , 98 , 99 , 100 , 101 ]. Molecular techniques have significant advantages such as rapid turnaround times and detection of non-culturable cells [ 102 ].…”