Intra Strain Variation of the Effects of Gram-Negative ESKAPE Pathogens on Intestinal Colonization, Host Viability, and Host Response in the Model Organism Caenorhabditis elegans

Abstract

In its native environment of rotting vegetation, the soil nematode Caenorhabditis elegans encounters a range of bacteria. This includes species from the ESKAPE group of pathogens that pose a clinical problem in acquired hospital infections. Here, we investigated three Gram-negative members of the ESKAPE group, Pseudomonas aeruginosa, Klebsiella pneumoniae, and Acinetobacter baumannii. Pathogenicity profiles as measured by time to kill adult C. elegans showed that P. aeruginosa was the most pathogenic, followed by K. pneumoniae, while C. elegans cultured on A. baumannii exhibited the same survival as those on the standard laboratory food source for C. elegans, Escherichia coli OP50. The pathogenicity was paralleled by a reduction in time that C. elegans resided on the bacterial lawn with the most pathogenic strains triggering an increase in the frequency of food-leaving. Previous reports indicate that gut colonization is a feature of pathogenicity, but we found that the most pathogenic strains were not associated with the highest level of colonization. Indeed, clearance of P. aeruginosa strains from the C. elegans gut was independent of bacterial pathogenicity. We show that this clearance is regulated by neuromodulation as C. elegans mutants in unc-31 and egl-3 have enhanced clearance of P. aeruginosa. Intriguingly this is also not linked to their pathogenicity. It is likely that there is a dynamic balance occurring in the C. elegans intestinal environment between maintaining a healthy, beneficial microbiota and removal of pathogenic bacteria.

Genomics and Virulence of Klebsiella pneumoniae Kpnu95 ST1412 Harboring a Novel Incf Plasmid Encoding Blactx-M-15 and Qnrs1 Causing Community Urinary Tract Infection

“…Our data form the first study that experimentally describes the virulence of K. pneumoniae ST1412 lineage. A comparison of its virulence phenotype with other reported K. pneumoniae virulence studies [ 47 , 48 ] is limited due to differences in the in vivo virulence assays used. Considering that KpnU95 was isolated from urine, we assessed the strain virulence in artificial urine and revealed that despite its tardy growth, the strain preserved its nematode killing ability, demonstrating its pathogenesis in urine conditions.…”

Adherent-Invasive and Non-Invasive Escherichia coli Isolates Differ in Their Effects on Caenorhabditis elegans’ Lifespan

“…In the scientific literature, there are a few studies of the virulence of a small number of strains from the same bacterial species. Strain specificity has been clearly linked to levels of virulence for Gram-positive Staphylococcus aureus [ 63 ] and Gram-negative Pseudomonas aeruginosa and Klebsiella pneumoniae [ 64 ]. Interestingly, the most pathogenic strains did not show the highest level of colonization.…”

Synthetic autotetraploidCaenorhabditis elegansresist severe cold stress by escaping cold induced death at the gravid adult stage

“…P. aeruginosa is an opportunistic pathogen of animals, insects, nematodes and plants. P. aeruginosa kills C. elegans in several ways, depending on the environment (Kirienko et al 2014;Scott et al 2020).…”

“…Experiments were performed at 25°C, according to (Kirienko et al 2014;Scott et al 2020). Fresh cultures of Pseudomonas aeruginosa PAO1 (<16h culture) were used to seed NGM plates.…”