Evaluation of antibiotic resistant enterobacterales in the Irish environment
Hooban, Brigid
Hooban, Brigid
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Publication Date
2022-10-03
Type
Thesis
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Abstract
Antibiotic resistance represents a significant public health challenge of global magnitude. In particular, infections caused by extended spectrum beta-lactamase (ESBL) and carbapenemase producing Enterobacterales (CPE) rank highly in respect to prevalence and clinical consequences. The environmental aspect of the One Health triad is not routinely monitored for antibiotic resistance, and as such represents an important knowledge gap relating to its role as a route of transmission of antibiotic resistance. Therefore, the aim of this research was to address this knowledge gap by evaluating the literature and assessing environmental samples on a national scale in Ireland for the presence of antibiotic resistance. A scoping review was initially conducted to evaluate the literature examining the natural aquatic environment, free from direct point discharges, as a reservoir and potential route of dissemination of ESBL and carbapenemase producing Enterobacterales. This was followed by an initial point prevalence survey which included the collection and processing of 39 water and 25 sewage samples across the South, East and West of Ireland. This was subsequently followed by two additional sampling rounds in each area (118 water, 36 sewage samples) as part of the longitudinal study. The scoping review included 41 studies ranging across 19 different countries. ESBL and carbapenemase genes were reported in 70.7% and 31.7% of studies respectively, revealing widespread dissemination across uncontaminated aquatic environments. A total of 630 Enterobacterales (487 water, 143 sewage) were isolated from the point prevalence and longitudinal survey sampling rounds. ESBL detection was widespread across the majority of samples collected. One or more CPE were isolated from 32 individual sampling sites (23 water, 9 sewage) across all three rounds. This included the detection of isolates harbouring blaOXA-48 (n = 24), blaNDM (n = 16), blaKPC (n = 6), blaIMP (n=1) and blaOXA-484 (n = 1). Common sequence types detected included E. coli ST131, ST38 and ST10 along with Klebsiella ST405 and ST323. Highly similar isolates from different water samples, alongside water and sewage samples were identified using core genome MLST comparisons. Carbapenemase producing Enterobacterales are considered a public health emergency in Ireland, and so their detection in the environment is a significant public health concern. The detection of ESBL and CPE across all seasons highlights the need for regular monitoring of the aquatic environment for the presence of antimicrobial resistant organisms to adequately inform policies to protect public health. Further areas of research which were identified in this thesis include evaluation of the risk of colonisation and infection due to exposure to the environmental resistome through ingestion of resistant bacteria in water via recreational exposure.
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Publisher
NUI Galway