The deviations from log-linearity that are often observed in bacterial survivor curves can be explained using different arguments, both biological and experimental. In this study, we used Bacillus subtilis as a model organism to demonstrate that the generally accepted vitalistic arguments (initial heterogeneities in the stress resistance of the cells in the population) may fail to describe microbial inactivation in some situations. In this sense, we showed how dynamic stress acclimation during an isothermal treatment provides an alternative explanation for survivor curves with an upwards curvature. We also provided an innovative experimental approach based on preadaptation experiments to evaluate which hypothesis is more suitable for the bacterial response. Furthermore, we used our experimental results to define bounds for the possible stress acclimation that may take place during dynamic treatments, concluding that the magnitude of stress acclimation may be larger for dynamic treatments than for isothermal experiments. We also evaluated the contribution of the SigB general stress response system to heat resistance by comparing the heat survival of wt and the ΔsigB mutant. Both strains survived better in 51, 52.5 and 55 °C when cells were pre-adapted at 48 °C than non-pre-adapted cells. However, ΔsigB was less resistant to heat than wt due to the missing SigB general stress system. Although these conclusions were based on B. subtilis as a model organism, this study can be the first step towards the development of a novel methodology able to estimate dynamic effects using only isothermal experiments. This would improve the models developed within the predictive microbiology community, improving our ability to predict microbial inactivation during industrial treatments, which are most often dynamic.

Background: Malaria is currently ranked as an important public health issue in Greece despite its initial eradication back in 1974. Given that the clinical picture is often nonspecific, the need for the implementation of targeted laboratory methodologies is imperative to ensure prompt Plasmodium identification and diagnosis. Methods: A total of 780 clinical samples from 763 suspected malaria cases from the National Malaria Reference Center were analyzed within a seven-year period (2017–2023). A composite laboratory reference standard methodology, including rapid diagnostic testing, microscopy, and polymerase chain reactions, was implemented for the purposes set by the current study in a group of 532 samples. A multivariable statistical analysis was implemented for the interpretation of the extracted data. Results: Microscopy and PCR successfully identified P. falciparum (111 vs. 131) and P. vivax (95 vs. 95) clinical samples. In addition, microscopy successfully identified selected cases of P. ovale (16) and P. malariae (nine), with current cases being confirmed by targeted, species-level real-time PCR protocols. Conclusions: The current study highlighted the importance of microscopic examination in malaria diagnostic procedures for Plasmodium species identification and typing. The combination of microscopy and PCR ensures a credible laboratory approach for submicroscopic clinical cases and patients with prior antimalarial treatment. This composite laboratory reference standard methodology is recommended by the Greek Malaria Reference Center for prompt identification of Plasmodium species in suspected malaria clinical cases.