High-risk clonal lineages among extended-spectrum β-lactamase producing Escherichia coli and Klebsiella pneumoniae from urban and rural stagnant water samples in Tunisia

This study sought to investigate the occurrence and subsequently to characterize extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae from urban and rural stagnant water samples during the wet season (December to February) in several regions of northern Tunisia. From 56 stagnant water samples, 14 ESBL-producing Enterobacteriaceae were recovered, including 9 Escherichia coli, 3 Klebsiella pneumoniae, and 2 K. oxytoca. Most isolates were multidrug-resistant, with ESBL production primarily encoded by blaCTX-M-15 (n = 8) and blaCTX-M-1 (n = 4) followed by blaCTX-M-55 (n = 1) and blaTEM-26 (n = 1). One K. pneumoniae isolate co-harbored blaKPC and blaCTX-M-15 genes. Class 1 integrons were detected in 4 isolates, however, sul1, sul2, and aac(6')-Ib-cr genes were detected in eleven, two, and four isolates, respectively. The nine E. coli isolates belonged to seven sequence types namely, B2/ST131 (3 isolates), A/ST164, A/ST10, A/ST224, A/ST38, A/ST155, and A/ST69 (each of them one isolate). The three K. pneumoniae isolates were assigned to three sequence types: ST101, ST405 (harboring CTX-M-15 and KPC), and ST1564. Overall, the phenotypic and genotypic traits of collected isolates mirror the molecular epidemiology of ESBL-producing enterobacteria in Tunisia and highlight the potential role of stagnant water in both urban and rural areas as a reservoir of ESBL-producing Enterobacteriaceae.

Ecological Predictors of Human Malaria Risk During Different Phases of the Elimination: An Analysis of Historical Data

To understand the evolutionary ecology of disease dynamics, it is crucial to identify the environmental factors that mediate the spread and abundance of parasites and their vectors. However, human-mediated changes in the biotic and abiotic environment and intervention programs are intensifying in the past 30-40 years at a rate that masks the causal effect of the original ecological predictors. In this study, we used archived epidemiological data spanning over 100 years on malaria risk in Hungary to demonstrate that different associations exist between infection risk and environmental predictors during different phases of the elimination program. In the early 20th century, when malaria was quite common in the country and no defense program was operating, as predicted, there was a positive relationship between the area of flooded habitats and the intensity of malaria infection. In contrast, this relationship was absent during middle of the century, when an effective elimination program was already in effect. Furthermore, malaria morbidity in a given year was predicted by the degree of stagnant water cover of the previous year when considering the period before the launch of a drastic mosquito control program by dichloro-diphenyl-trichloroethane (DDT), whereas such relationship could not be revealed for a latter period. Our results highlight that human-induced alterations of the socioecological environment considerably reorganizes the ecological landscape of pathogens and their vectors.

Gunshot residue detection in stagnant water: SEM-EDX or ICP-MS? A preliminary study

The identification of gunshot residue (GSR) on wounds enables the differentiation of entry and exit wounds. Unfortunately, studies analyzing GSR on degraded bodies have been poorly documented, and no data exist regarding GSR detection after stagnant water immersion. The aim of this preliminary experimental study was to detect GSR on wounds altered in stagnant water, using scanning electron microscopy coupled with energy-dispersive X (SEM-EDX) and inductively coupled plasma mass spectrometry (ICP-MS). Shots were performed on sheep limbs with a 22LR at a distance of 20 cm. The limbs were then submerged in stagnant water and analyzed on days 0, 6, and 14. SEM-EDX was performed on previously dehydrated wounds. For ICP-MS analysis, the wounds were rubbed with a cotton swab that was then analyzed. In the SEM studies, a higher number of particles were detected in entry wounds compared to exit wounds under every set of experimental conditions. Unfortunately, SEM-EDX failed to detect GSR particles, even on day 0. ICP-MS enabled the detection of Pb, Sb, and Ba at every stage with higher quantities on entry than in exit. These elements remained detectable following limb immersion. ICP-MS enabled differentiate entry from exit wounds, even after immersion in stagnant water. Nevertheless, when manually swabbing the wounds, quantities of matter collected is highly variable. ICP-MS is a more suitable technique than SEM-EDX for GSR identification of wounds after decomposition in stagnant water; however, standardization is needed.