Table 3.
Studied characteristics and their hypothesized association with epidemic capability.
| Trait/quality | Variables/factors used in this study | Relevance |
|---|---|---|
| Virulence genes | Number/type | Number of virulence genes may directly affect the strain’s potential to cause infections |
| Antibiotic resistances | Number/type | Antibiotic resistance can compromise treatment, thus causing prolonged infections and increase the time during which bacteria disperse |
| Growth rate/density | Max growth rate (r), Max growth density (K) | Faster and more dense growth may increase the bacterial load in the surrounding environment and thus its epidemic potential |
| Growth temperature | 22°C (room temperature), 37°C | Growth differences in room temperature vs 37°C may reflect trade-offs in within- and outside-host environments and thus its adaptation to the environment vs the host |
| Growth in different media | LB, DMEM, BHI | Potential to grow in different nutrient environments may provide bacteria more opportunities to proliferate in alternative habitats and thus provide possibilities to survive outside the host |
| Growth in different nutrient levels | 1, 10, 100% L | Potential to grow in varying nutrient levels may provide advantage in different environments and hence affect its dispersal to new hosts |
| Growth in varying pH | pH 3, pH 4, pH 5, pH 6, pH 7 | Bacteria may be exposed to different pH in the environment and the host (phagocytosis, skin, gastrointestinal tract) and the sensitivity to pH may decrease the changes for dispersal |
| Potential to compensate surrounding pH | pH 3, pH 4, pH 5 | Potential to modify the surrounding microenvironment may play a crucial role in the bacterial chances to adapt to fluctuating environmental pH and hence affect its dispersal |
| Resilience in EtOH | 20, 50, 75, 90% EtOH | Survival in the presence of alcohol containing sanitizers may directly affect the persistence of the strain in the environment and hence influence its potential to get transmitted |
| Survival in the absence of water | 14 days, 2 months, 6 months | The potential to withstand drought can increase the timespan during which pathogen remains viable in hospital environment and hence affect its changes to get transmitted to new hosts |
| Recovery after drought | 14 days, 2 months, 6 months | Faster recovery after drought can provide bacteria increased potential to colonize or infect new hosts |
| Growth in mixed/spatially structured population | 0 rpm, 230 rpm | Growth as a differently structured population may play a role in various stages of infection and persistence in the environment and may therefore affect the strain’s potential to disperse |
| Number of plasmids | Number/Inc-type | Plasmids often carry genes that benefit the bacterium in specific conditions and hence their number may be related to survival in various conditions inside and outside the host |
| Genomic prophages | Number/Inc-type | Activation of prophages may cause infections in competing K. pneumoniae strains and may therefore provide the prophage carrying strain an advantage in situations where several strains occupy the same environment |
| Strain-specific inhibition | Pairwise inhibition | Production of bacteriocins or other antimicrobials may inhibit the growth of competing strains and thus may hinder the potential for sensitive strains to disperse into environments or hosts with other K. pneumoniae strains |
| Short ORFs in the genome | Number of ORFs | Number of short open reading frames in the genome may reflect bacterial adaptive history and hence may be linked to epidemic potential |