Growth of Acinetobacter baumannii in Pellicle Enhanced the Expression of Potential Virulence Factors

BACKGROUND: Interestingly, Acinetobacter baumannii presents an enhanced capacity to form biofilms (also named pellicles) at the air-liquid interface as compared to the other Acinetobacter species. This characteristic questions the contribution of this phenotype to an increased risk of clinical infections by this pathogen. METHODOLOGY/PRINCIPAL FINDINGS: By a proteomic approach using 2-D gel electrophoresis-LC-MS/MS mass spectrometry, we compared the membrane protein patterns of A. baumannii 77, a pellicle-forming clinical isolate, grown in planktonic and in sessile modes. We identified 52 proteins with a differential expression, including 32 up-regulated and 20 down-regulated in the pellicle state. Several proteins, differentially expressed during pellicle development, were of particular interest. We determined the over-expression of four siderophore iron uptake systems including the acinetobactin and enterobactin receptors and confirmed that the development of this type of biofilm is promoted by ferric ions. Two over-expressed proteins, CarO and an OprD-homologue, putative carbapenem-resistance associated porins, would be involved in the transport of specific compounds, like ornithine, a biosynthesis precursor of a siderophore from the hydroxamate family. We evidenced the overexpression of a lipase and a transporter of LCFA that may be involved in the recycling of lipids inside the pellicle matrix. Finally, we demonstrated both by proteomic and by AFM studies that this particular type of biofilm required multiple pili systems to maintain this cohesive structure at the air-liquid interface; two of these systems have never been described in A. baumannii. CONCLUSIONS/SIGNIFICANCE: Our study demonstrated that several proteins, overexpressed at a late state of pellicle development, could be potentially involved in virulence processes. Therefore, regarding the number of potential virulence factors that are over-expressed in this growth mode, the pellicle-forming clinical isolates should be kept under survey

A bioinspired peptide scaffold with high antibiotic activity and low in vivo toxicity

Bacterial resistance to almost all available antibiotics is an important public health issue. A major goal in antimicrobial drug discovery is the generation of new chemicals capable of killing pathogens with high selectivity, particularly multi-drug-resistant ones. Here we report the design, preparation and activity of new compounds based on a tunable, chemically accessible and upscalable lipopeptide scaffold amenable to suitable hit-to-lead development. Such compounds could become therapeutic candidates and future antibiotics available on the market. The compounds are cyclic, contain two D-amino acids for in vivo stability and their structures are reminiscent of other cyclic disulfide-containing peptides available on the market. The optimized compounds prove to be highly active against clinically relevant Gram-negative and Gram-positive bacteria. In vitro and in vivo tests show the low toxicity of the compounds. Their antimicrobial activity against resistant and multidrug-resistant bacteria is at the membrane level, although other targets may also be involved depending on the bacterial strain

Pathogenic Acinetobacter species including the novel Acinetobacter dijkshoorniae recovered from market meat in Peru

Species of the Acinetobacter calcoaceticus-Acinetobacter baumannii complex are important human pathogens which can be recovered from animals and food, potential sources for their dissemination. The aim of the present study was to characterise the Acinetobacter isolates recovered from market meat samples in Peru. From July through August 2012, 138 meat samples from six traditional markets in Lima were cultured in Lysogeny and Selenite broths followed by screening of Gram-negative bacteria in selective media. Bacterial isolates were identified by MALDI-TOF MS and DNA-based methods and assessed for their clonal relatedness and antimicrobial susceptibility. Twelve Acinetobacter isolates were recovered from calf samples. All but one strain were identified as members of the clinically-relevant Acinetobacter calcoaceticus-Acinetobacter baumannii complex: 9 strains as Acinetobacter pittii, 1 strain as A. baumannii, and 1 strain as the recently described novel species A. dijkshoorniae. The remaining strain could not be identified at the species level unambiguously but all studies suggested close relatedness to A. bereziniae. All isolates were well susceptible to antibiotics. Based on macrorestriction analysis, six isolates were further selected and some of them were associated with novel MLST profiles. The presence of pathogenic Acinetobacter species in human consumption meat might pose a risk to public health as potential reservoirs for their further spread into the human population. Nevertheless, the Acinetobacter isolates from meat found in this study were not multidrug resistant and their prevalence was low. To our knowledge, this is also the first time that the A. dijkshoorniae species is reported in Peru

DYRK1A promotes dopaminergic neuron survival in the developing brain and in a mouse model of Parkinson's disease

In the brain, programmed cell death (PCD) serves to adjust the numbers of the different types of neurons during development, and its pathological reactivation in the adult leads to neurodegeneration. Dual-specificity tyrosine-(Y)-phosphorylation regulated kinase 1A (DYRK1A) is a pleiotropic kinase involved in neural proliferation and cell death, and its role during brain growth is evolutionarily conserved. Human DYRK1A lies in the Down syndrome critical region on chromosome 21, and heterozygous mutations in the gene cause microcephaly and neurological dysfunction. The mouse model for DYRK1A haploinsufficiency (the Dyrk1a +/− mouse) presents neuronal deficits in specific regions of the adult brain, including the substantia nigra (SN), although the mechanisms underlying these pathogenic effects remain unclear. Here we study the effect of DYRK1A copy number variation on dopaminergic cell homeostasis. We show that mesencephalic DA (mDA) neurons are generated in the embryo at normal rates in the Dyrk1a haploinsufficient model and in a model (the mBACtg Dyrk1a mouse) that carries three copies of Dyrk1a. We also show that the number of mDA cells diminishes in postnatal Dyrk1a +/− mice and increases in mBACtg Dyrk1a mice due to an abnormal activity of the mitochondrial caspase9 (Casp9)-dependent apoptotic pathway during the main wave of PCD that affects these neurons. In addition, we show that the cell death induced by 1-methyl-4-phenyl-1,2,3,6 tetrahydropyridine (MPTP), a toxin that activates Casp9-dependent apoptosis in mDA neurons, is attenuated in adult mBACtg Dyrk1a mice, leading to an increased survival of SN DA neurons 21 days after MPTP intoxication. Finally, we present data indicating that Dyrk1a phosphorylation of Casp9 at the Thr125 residue is the mechanism by which this kinase hinders both physiological and pathological PCD in mDA neurons. These data provide new insight into the mechanisms that control cell death in brain DA neurons and they show that deregulation of developmental apoptosis may contribute to the phenotype of patients with imbalanced DYRK1A gene dosage

Lessons Learned from the Investigation of an Anomalous Termination of BETTII

The Balloon Experimental Twin Telescope for Infrared Interferometry (BETTII) mission launched from Palestine, Texas in June 2017. After an exciting launch and successful cruise, the BETTII gondola suffered an anomalous event at termination. BETTII separated from its parachute and free-fell 136,000 feet into the west Texas desert. This event was classified as a "close-call" and investigated as such. We present here the recovery effort required to find the payload and extract the payload from its impact site. We also present lessons learned from the event and results from the investigation, the design for the next BETTII gondola, and a path forward for return to flight

Análisis etnoarqueológico del valor social del producto en sociedades cazadoras-recolectoras

This work was formulated as a consequence of considering the necessity of a value theory (that is, an economical theory), in archaeology. From our materialist perspective, that would allow us to set the basis for an objective analysis of past societies, understanding that only through the knowledge of their material life conditions and their social organization we would be able to know their historical becoming. We were reaching a common index that would make possible to compare different occupations and sites in Tierra del Fuego. This index would be used to make inferences about the amount of work invested in every occupation, amount of work that could be understood as the duration of the occupation or as the amount of people in that camp-site. On the other hand, on the basis of the Main Contradiciton formulation, we could establi sh a mechanism to quantify different participation in the production cycle and the existing differences in the access to the consumption of what has been produced. This will drive us to the formulation of a method to identify social explotation.Este trabajo surgió como consecuencia de varias preocupaciones. En primer lugar, considerábamos, desde hacía ya tiempo, la necesidad de una teoría del valor (económica, por tanto), en Arqueología; preocupación compartida con otros investigadores/as. Desde nuestra perspectiva materialista, ello nos había de permitir sentar las bases para un análisis objetivo de las sociedades prehistóricas, entendiendo que tan sólo a través delconocimiento de Las condiciones materiales de vida, y de la estructuración u organización de las relaciones sociales, podremos llegar a conocer el devenir histórico de las mismas. Buscábamos un índice, un común denominador, que nos permitiera poder comparar diferentes ocupaciones y yacimientos actualmente (y desde hace ya más de una década) en estudio en Tierra del Fuego (Argentina). Este índice debería permitirnos, por un lado realizar inferencias sobre la cantidad de trabajo invertida en cada ocupación de los diferentes asentamientos Yámana. Lo cual podría ser interpretado en clave de ti empo de ocupación o de cantidad de personas ocupando el sitio. Y por otro lado, y sobre la base de la formulación de la Contradicción Principal, podría establecer un mecanismo que nos permitiera cuantificar la participación diferencial en la producción y las disimetrías en el acceso al consumo de lo producido, estableciendo un «cálculo» para la identificación de la explotación. Este último interés tiene mucho que ver con el aceptado concepto de «sociedades igualitarias » aplicado a las sociedades cazadoras recolectoras, concepto cuestionable en tanto que surge de una aproximación androcéntrica. Este trabajo ha sido posible, en el caso de la sociedad Yámana, gracias a la exhaustiva y variada información etnográfica confrontada a una completa información arqueológica. El objetivo final es conseguir generar propuesta metodológica contrastada que nos permita este tipo de acercamientos a sociedades cazadoras-recolectoras prehistóricas

Excess mortality among older adults institutionalized in long-term care facilities during the COVID-19 pandemic: a population-based analysis in Catalonia

Objectives: To assess excess mortality among older adults institutionalized in nursing homes within the successive waves of the COVID-19 pandemic in Catalonia (north-east Spain).Design: Observational, retrospective analysis of population-based central healthcare registries.Setting and participants: Individuals aged >65 years admitted in any nursing home in Catalonia between January 1, 2015, and April 1, 2022.Methods Deaths reported during the pre-pandemic period (2015-2019) were used to build a reference model for mortality trends (a Poisson model, due to the event counting nature of the variable mortality), adjusted by age, sex, and clinical complexity, defined according to the adjusted morbidity groups. Excess mortality was estimated by comparing the observed and model-based expected mortality during the pandemic period (2020-2022). Besides the crude excess mortality, we estimated the standardized mortality rate (SMR) as the ratio of weekly deaths' number observed to the expected deaths' number over the same period.Results: The analysis included 175,497 older adults institutionalized (mean 262 days, SD 132), yielding a total of 394,134 person-years: 288,948 person-years within the reference period (2015-2019) and 105,186 within the COVID-19 period (2020-2022). Excess number of deaths in this population was 5,403 in the first wave and 1,313, 111, -182, 498, and 329 in the successive waves. The first wave on March 2020 showed the highest SMR (2.50; 95% CI 2.45-2.56). The corresponding SMR for the 2nd to 6th waves were 1.31 (1.27-1.34), 1.03 (1.00-1.07), 0.93 (0.89-0.97), 1.13 (1.10-1.17), and 1.07 (1.04-1.09). The number of excess deaths following the first wave ranged from 1,313 (2nd wave) to -182 (4th wave). Excess mortality showed similar trends for men and women. Older adults and those with higher comorbidity burden account for higher number of deaths, albeit lower SMRs.Conclusion: Excess mortality analysis suggest a higher death toll of the COVID-19 crisis in nursing homes than in other settings. Although crude mortality rates were far higher among older adults and those at higher health risk, younger individuals showed persistently higher SMR, indicating an important death toll of the COVID-19 in these groups of people

Spread of ST348 Klebsiella pneumoniae producing NDM-1 in a peruvian hospital

The aim of this study was to characterize carbapenem-resistant Klebsiella pneumoniae (CR-Kp) isolates recovered from adults and children with severe bacteremia in a Peruvian Hospital in June 2018. Antimicrobial susceptibility was determined by disc/gradient diffusion and broth microdilution when necessary. Antibiotic resistance mechanisms were evaluated by PCR and DNA sequencing. Clonal relatedness was assessed using pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). Plasmid typing was performed with a PCR-based method. Thirty CR-Kp isolates were recovered in June 2018. All isolates were non-susceptible to all -lactams, ciprofloxacin, gentamicin and trimethoprim-sulfamethoxazole, while mostly remaining susceptible to colistin, tigecycline, levofloxacin and amikacin. All isolates carried the blaNDM-1 gene and were extended spectrum -lactamase (ESBL) producers. PFGE showed four different pulsotypes although all isolates but two belonged to the ST348 sequence type, previously reported in Portugal. blaNDM-1 was located in an IncFIB-M conjugative plasmid. To our knowledge, this is the first report of an New Delhi metallo- -lactamase (NDM)-producing K. pneumoniae recovered from both children and adults in Lima, Peru, as well as the first time that the outbreak strain ST348 is reported in Peru and is associated with NDM. Studies providing epidemiological and molecular data on CR-Kp in Peru are essential to monitor their dissemination and prevent further spread

Placebo-controlled trial of nimodipine in the treatment of acute ischemic cerebral infarction

Nimodipine is a 1,4-dihydropyridine derivative that shows a preferential cerebrovascular activity in experimental animals. Clinical data suggest that nimodipine has a beneficial effect on the neurologic outcome of patients suffering an acute ischemic stroke. Our double-blind placebo-controlled multicenter trial was designed to assess the effects of oral nimodipine on the mortality rate and neurologic outcome of patients with an acute ischemic stroke. One hundred sixty-four patients were randomly allocated to receive either nimodipine tablets (30 mg q.i.d.) or identical placebo tablets for 28 days. Treatment was always started less than or equal to 48 hours after the acute event. The Mathew Scale, slightly modified by Gelmers et al, was used for neurologic assessment. Mortality rate and neurologic outcome after 28 days were used as evaluation criteria. We considered 123 patients to be valid for the analysis of efficacy. Mortality rates did not differ significantly between groups. Neurologic outcome after 28 days of therapy did not differ between groups. However, when only those patients most likely to benefit from any intervention (Mathew Scale sum score of less than or equal to 65 at baseline) were analyzed separately in post hoc-defined subgroups, the nimodipine-treated subgroups showed a significantly better neurologic outcome. This result suggests that some patients with acute ischemic stroke will benefit from treatment with nimodipine tablets

Epidemiology and molecular characterization of multidrug-resistant Escherichia coli isolates harboring blaCTX-M group 1 extended-spectrum β-lactamases causing bacteremia and urinary tract infection in Manhiça, Mozambique

Background: The emergence and spread of extended-spectrum β-lactamases (ESBLs), especially CTX-M, is an important public health problem with serious implications for low-income countries where second-line treatment is often unavailable. Knowledge of the local prevalence of ESBL is critical to define appropriate empirical therapeutic strategies for multidrug-resistant (MDR) organisms. This study aimed to assess and characterize the presence of ESBL and especially CTX-M-producing Escherichia coli MDR isolates from patients with urinary tract infections (UTIs) and bacteremia in a rural hospital in Mozambique. Materials and methods: One hundred and fifty-one E. coli isolates from bacteremia and UTI in children were screened for CTX-M, TEM, SHV and OXA β-lactamases by polymerase chain reaction and sequencing. Isolates carrying CTX-M group 1 β-lactamases were further studied. The resistance to other antibiotic families was determined by phenotypic and genotypic methods, the location of the blaCTX-M gene and the epidemiology of the isolates were studied, and extensive plasmid characterization was performed. Results: Approximately 11% (17/151) of E. coli isolates causing bacteremia and UTI were ESBL producers. CTX-M-15 was the most frequently detected ESBL, accounting for 75% of the total isolates characterized. The blaCTX-M gene is located in different plasmids belonging to different incompatibility groups and can be found in non-epidemiologically related isolates, indicating the high capacity of this resistance determinant to spread widely. Conclusion: Our data suggest the presence of a co-selection of third-generation cephalosporin-resistant determinants in the study area despite limited access to these antibiotics. This highlights the importance of continuous surveillance of antimicrobial resistance of both genetic elements of resistance and resistant isolates in order to monitor the emergence and trends of ESBL-producing isolates to promote adequate therapeutic strategies for the management of MDR bacterial infections