Revista Argentina de microbiologia最新文献

This study is the first report on mycosynthesis of silver nanoparticles (NPs) using psychrotrophic Antarctic filamentous fungi, and the first report regarding Tulasnella (Basidiomycota). In this work, the ability to synthesize silver NPs from cell free filtrates of strains of Tulasnella albida isolated from Antarctica was assessed. All fungal filtrates were capable of synthesizing silver NPs with the addition of AgNO₃. UV–vis spectroscopy, TEM and SEM microscopy analyses were performed to characterize the synthesized NPs. ATR-FTIR and Micro Raman spectroscopy analyses were conducted to find functional groups responsible for the reduction of AgNO₃ and to detect the presence of silver oxide on the AgNPs. Theoretical calculations of optical absorption based on core-shell Ag–Ag₂O were used to characterize the experimental absorption spectra of silver NPs colloids. Spherically shaped silver NPs, typically 2–3 nm in diameter, were obtained. The largest ones showed a capping shell around them, which could be associated with the formation of small silver NPs. Functional groups corresponding to amides and alcohols were detected, confirming the presence of proteins as possible intermediates in the synthesis of AgNPs. On the other hand, the Micro Raman analysis confirms the presence of silver oxide on the surface of the AgNPs. This work presents a simple procedure for the synthesis of silver NPs using a psychrotrophic organism that could be interesting for the industry.

This study aimed to assess the impact of the implementation of a rapid multiplex molecular FilmArray Respiratory Panel (FRP) on the medical management of immunocompromised patients from a community general hospital. We conducted a single-center, retrospective, and before–after study. Two periods were evaluated: before the implementation of the FRP (pre-FRP) from April 2017 to May 2018 and after the implementation of the FRP (post-FRP) from January to July 2019. The inclusion criteria were immunocompromised patients over 18 years of age with suspected acute respiratory illness tested by conventional diagnostic methods (pre-FRP) or the FilmArray™ Respiratory Panel v1.7 (post-FRP). A total of 142 patients were included, 64 patients in the pre-FRP and 78 patients in the post-FRP. The positive detection rate was significantly higher in the post-FRP (63% vs. 10%, p < 0.01). There were more patients receiving antimicrobial treatment in the pre-FRP compared with the post-FRP period (94% vs. 68%, p < 0.01). A decrease in beta-lactam (89% vs. 61%, p < 0.01) and macrolide (44% vs. 13%, p < 0.01) prescriptions were observed in the post-FRP. No differences were observed in oseltamivir use (22% vs. 13%, p = 0.14), changes in antimicrobial treatment, hospital admission rate, days-reduction in droplet isolation precautions, hospital length of stay (LOS), admission to intensive care unit (ICU), LOS in ICU, treatment failure and 30-day mortality. The implementation of the FRP impacted patient care by improving diagnostic yield and optimizing antimicrobial treatment in immunocompromised adult patients.

There is currently an extensive record of scientific studies on the general characteristics of filamentous fungus Trichoderma spp., which demonstrates its wide range of interrelation in ecosystems and its fungal activity that benefits the agricultural sector and agroindustry, as well as its importance in the preservation and restoration of the soil microbiota. The success of the biological and ecological benefits of Trichoderma is due to its reproductive capacity, as well as its efficiency in the use of soil nutrients; the efficacy of the genus has been reported against a variety of phytopathogenic fungi, as well as the potential to synthesize and release enzymes (cellulases, xylanases, and chitinases) that have been implemented in agroindustrial bioprocesses. It has also been reported that various species of Trichoderma spp. can produce auxins and gibberellin-type growth regulators, reported as growth promoters of some agricultural crops; however, their most relevant fact is their ability to prevail at certain doses of ‘agrotoxic’ active ingredients and contribute studies regarding processes for obtaining biofuel and bioremediation of the agricultural soil. In this overview, a general description of the current and relevant studies of the different subspecies of Trichoderma and their contribution in agriculture is made, presenting results obtained in vitro, in greenhouses and in the field. This analysis will serve as a starting point for future research in Mexico, specifically on the genus Trichoderma and its benefits for the Mexican countryside.

Bacillus thuringiensis is an entomopathogen belonging to the Bacillus cereus clade. We isolated a tetracycline-resistant strain called m401, recovered it from honey, and identified it as Bacillus thuringiensis sv. kumamotoensis based on the average nucleotide identity calculations (ANIb) comparison and the analysis of the gyrB gene sequences of different B. thuringiensis serovars. Sequences with homology to virulence factors [cytK, nheA, nheB, nheC, hblA, hblB, hblC, hblD, entFM, and inhA] and tetracycline resistance genes [tet(45), tet(V), and tet(M)/tet(W)/tet(O)/tet(S) family] were identified in the bacterial chromosome. The prediction of plasmid-coding regions revealed homolog sequences to the MarR and TetR/AcrR family of transcriptional regulators, toxins, and lantipeptides. The genome mining analysis revealed 12 regions of biosynthetic gene clusters responsible for synthesizing secondary metabolites. We identified biosynthetic gene clusters coding for bacteriocins, siderophores, ribosomally synthesized post-translationally modified peptide products, and non-ribosomal peptide synthetase clusters that provide evidence for the possible use of Bt m401 as a biocontrol agent. Furthermore, Bt m401 showed high inhibition against all Paenibacillus larvae genotypes tested in vitro. In conclusion, Bt m401 owns various genes involved in different biological processes, such as transductional regulators associated with antibiotic resistance, toxins, and antimicrobial peptides with potential biotechnological and biocontrol applications.

In Argentina, hemolytic uremic syndrome (HUS) caused by Shiga toxin-producing Escherichia coli (STEC-HUS) infection is endemic, and reliable data about prevalence and risk factors have been available since 2000. However, information about STEC-associated bloody diarrhea (BD) is limited. A prospective study was performed during the period October 2018–June 2019 in seven tertiary-hospitals and 18 referral units from different regions, aiming to determine (i) the frequency of STEC-positive BD cases in 714 children aged 1–9 years of age and (ii) the rate of progression of bloody diarrhea to HUS. The number and regional distribution of STEC-HUS cases in the same hospitals and during the same period were also assessed. Twenty-nine (4.1%) of the BD patients were STEC-positive, as determined by the Shiga Toxin Quik Chek (STQC) test and/or the multiplex polymerase chain reaction (mPCR) assay. The highest frequencies were found in the Southern region (Neuquén, 8.7%; Bahía Blanca, 7.9%), in children between 12 and 23 month of age (8.8%), during summertime. Four (13.8%) cases progressed to HUS, three to nine days after diarrhea onset. Twenty-seven STEC-HUS in children under 5 years of age (77.8%) were enrolled, 51.9% were female; 44% were Stx-positive by STQC and all by mPCR. The most common serotypes were O157:H7 and O145:H28 and the prevalent genotypes, both among BD and HUS cases, were stx_2a-only or -associated. Considering the endemic behavior of HUS and its high incidence, these data show that the rate of STEC-positive cases is low among BD patients. However, the early recognition of STEC-positive cases is important for patient monitoring and initiation of supportive treatment.

Listeria monocytogenes is an opportunistic foodborne pathogen. It can resist stress conditions by adapting through the production of biofilms, which represents a serious problem for the food industry. It is classified into 14 serotypes, although only four (1/2a, 1/2b, 1/2c, and 4b) account for 89.0-98.0% of listeriosis cases worldwide. The objective of this study was to detect and serotype L. monocytogenes isolated from different food matrices from processing plants in Argentina. In the period 2016-2021, 1832 samples (meat, ready-to-eat foods, ice cream, dairy foods, and frozen vegetables) were analyzed, of which 226 (12.34%) isolates compatible with L. monocytogenes were detected. At the same time, environmental and surface samplings were performed in processing plants for ready-to-eat foods, sausages and dairy products, where environmental contamination with L. monocytogenes was detected in numerous critical points of the process, yielding a positivity rate of 22.7%. The molecular analysis of serogroups was performed, where it was observed that serogroup IIb was the most frequent with 66.5% (n = 107), and in descending order IIc with 22.3% (n = 36), and IIa (n = 9) and IVb (n = 9) with 5.6%. The serogroup mostly isolated in environmental monitoring was IIb. This work highlights the importance of the detection and serotyping of L. monocytogenes for taking actionable measures and identifying outbreaks, and is the first study in Argentina to describe an extensive study in food matrices.

The usefulness of the combined use of MALDI-TOF MS from a subculture with 3-5 h of incubation and the BCID2 panel (FilmArray) for the identification of microorganisms from positive blood cultures and its importance in the adjustment of antimicrobial therapy was analyzed. Overall identification with BCID2 was 90.4% (142/157) and with Maldi-TOF MS 83.4% (131/157) (p = 0.0858); in 23 polymicrobial episodes (47 strains), the BCID2 panel identified 45 (95.7%) and MALDI-TOF MS 24 (51.1%) (p < 0.0000). BCID2 detected the presence of the resistance genes mecA/C (n = 16), bla_KPC (n = 8); bla_CTX-M (n = 17), bla_NDM (n = 8), bla_OXA-48 (n = 1), and vanA/B (n = 2). The median time to report a result was 2.0 h for BCID2 and 4.0 h for MALDI-TOF MS (p < 0.0000). Of 124 episodes analyzed, the rapid result of BCID2 led to 82.3% (102/124) therapeutic changes.