Revista Argentina de microbiologia最新文献

Human listeriosis is an infectious disease caused by Listeria monocytogenes. The invasive form of this disease leads to a high rate of hospitalizations and fatality. The main mode of transmission is through contaminated ready-to-eat foods such as dairy, vegetables and meat products. The knowledge of the diversity and population dynamics of isolates collected from human and food sources is essential for the detection of clusters and the identification of common sites of infection. The aim of this study was the molecular characterization of L. monocytogenes isolates in Argentina. We sequenced a total of 63 isolates, 35 from human and 28 from food sources, collected between 2018 and 2023. Our genomic study divided the isolates into two lineages, four serogroups, 17 sequence types and 15 clonal complexes (CCs). The hypervirulent clone CC1 (lineage I; serogroup IVb) predominated in human and food samples. The phylogenomic analysis showed a high and possible epidemiological relationship between isolates from human and/or food sources, suggesting the presence of transmission chains in our country. These findings highlight the need to strengthen genomic surveillance of L. monocytogenes in Argentina. The identification of geographic distribution and characteristics of predominant and emerging clones from human and food sources might help to focus action plans and public health policies better directed at the control and prevention of listeriosis.

In recent years the relationship between the intestinal microbiota, the host and chronic non-communicable diseases has brought interest into the study of its formation and maintenance in the host. Lactic acid bacteria (BAL) are Gram-positive bacteria with probiotic activity, which have been associated with many health benefits, such as decreased body fat mass and lower risk of type II diabetes mellitus. One of the main colonization mechanisms and bacteria survival strategies is the production of biofilms and the use of prebiotics as substrates to achieve a balance within intestinal microbiota. However, there is not enough evidence to demonstrate the biofilm formation in the presence of agave fructans (AF). This study aimed to evaluate in vitro the biofilm formation in a consortium of lactic acid bacteria: Lactobacillus delbrueckii ssp. lactis, Lactobacillus delbrueckii ssp. bulgaricus y Streptococcus thermophilus in the presence of AF at different concentrations: 0%, 0,1%, 4%, 8% y 16%. The addition of 0,1% of AF correlates with the best capacity for biofilm formation. The findings imply the possibility of modulating the biofilm formation of lactic acid bacteria with AF. These results can contribute positively to the host, by generating intestinal homeostasis, colonization resistance, stability to food digestion and chemical modifications of drugs and carry out beneficial functions to the health.

The first autochthonous case of rickettsiosis is reported here. The case occurred in the Costanera Sur Ecological Reserve, a protected area of the City of Buenos Aires, in August 2022, where 4 species of ticks were found, namely Amblyomma aureolatum, Ixodes auritulus sensu lato, Rhipicephalus sanguineus sensu stricto and Amblyomma triste.

The epidemiological, ecological, clinical and laboratory aspects that allowed timely diagnosis and appropriate treatment are also described.

Cildáñez stream (in Matanza-Riachuelo basin, Buenos Aires) is one of the most polluted watercourses of Argentina, containing a mixed contamination from agricultural and industrial wastes. The application of water bioremediation processes for this kind of effluent will require microorganisms with a high tolerance to contamination. In this sense, obtaining higher contaminant-resistant microalgae lines is widely desired. In this study, adaptive laboratory evolution (ALE) and random mutagenesis were used to obtain Chlorella vulgaris LMPA-40 strains adapted to grow in polluted water from the Cildáñez stream. The ALE process was performed by 22 successive subcultures under selective pressure (Cildáñez wastewater alone or with the addition of phenol or H₂O₂) while random mutagenesis was performed with UV-C radiation at 275 nm. Not all the cell lines obtained after ALE could adapt enough to overcome the stress caused by the Cildáñez wastewater, indicating that the process is quite random and depends on the stressor used. The best results were obtained for the Cildáñez wastewater adapted cells (Cild 3 strain) that were more resistant than the original strain. The concentration of protein, Chlorophyll A, Chlorophyll B, and carotenoids in the Cild 3 ALE evolved strain was higher than that of the control strain. However, this strain exhibited half of the lipid content compared to the same control strain. Interestingly, these alterations and the acquired tolerance may be reversed over time during storage. These findings suggest that the acquisition of novel cell lines could not be permanent, a fact that must be considered for future trials.

Understanding the proportion of SARS-CoV-2 patients with Mycoplasma pneumoniae coinfection is crucial for treating patients suffering from coronavirus disease (COVID-19), help to ensure responsible use of antibiotics and minimize the negative consequences of overuse. In addition, this knowledge could have an impact on empirical antibiotic management guidelines for patients with COVID-19. This systematic review aimed to identify the prevalence of M. pneumoniae in patients with coronavirus disease 2019 (COVID-19).

A bibliographic search of studies published in Spanish or English was conducted using the PubMed search engine. Fourteen articles from different continents (America, Asia and Europe) were included, involving a total of 5855 patients in these studies. The mean age of COVID-19 patients with M. pneumoniae was 48 years old (range 1–107), most of whom were male. The detection of laboratory-confirmed M. pneumoniae infection varied between 0 and 33.3%. Most of patients referred fever, cough, and dyspnea, and received empirical antibiotic treatment. Bacterial coinfection was not associated with increased ICU admission and mortality. The prevalence of coinfection showed extremely dissimilar figures according to the population studied and diagnostic criteria. However, it is important to develop Latin American studies, given the heterogeneity observed in the studies conducted in different countries. Standardized definitions should be developed in order to be able to assess the impact of coinfections in patients with a diagnosis of COVID-19.

The actinobacterium Arthrobacter sp. UMCV2 promotes plant growth through the emission of N,N-dimethylhexadecilamine (DMHDA). The Medicago–Sinorhizobium nodulation has been employed to study symbiotic nitrogen fixation by rhizobia in nodulating Fabaceae. Herein, we isolated three Sinorhizobium medicae strains that were used to induce nodules in Medicago truncatula. The co-inoculation of M. truncatula with Arthrobacter sp. strain UMCV2 produced a higher number of effective nodules than inoculation with only Sinorhizobium strains. Similarly, the exposure of inoculated M. truncatula to DMHDA produced a greater number of effective nodules compared to non-exposed plants. Thus, we conclude that Arthrobacter sp. UMCV2 promotes nodulation, and propose that this effect is produced, at least partly, via DMHDA emission.

Candida bloodstream infections in children are of special concern in neonatal and pediatric intensive care and patients with comorbidities. This study aimed to estimate the incidence and risk factors associated with mortality in candidemia cases occurring in a public children's hospital in Ribeirao Preto, Brazil. It is a retrospective transversal study. Every patient under the age of 18 admitted to the study facility from January 1, 2013, to December 31, 2019, was considered potentially eligible to be included if they had candidemia. We collected clinical data from medical records. We included 113 blood cultures yielding positive results for Candida. The incidence rate was 2.12 per 1000 admissions. The most common Candida species was Candida parapsilosis. Septic shock during the candidemia episode was the only clinical outcome associated with a relative risk-adjusted (RRa) of 2.77 with an interval >1 (1.12–6.85). Our findings show that the incidence rate and mortality rates of candidemia are in line with those in other children's services in Brazil. We found a global mortality rate of 28.31% (32/113) from candidemia episodes. We highlight the predominance of non-albicans Candida species including C. parapsilosis. Septic shock was the most important factor showing a significant risk of mortality.

Multidrug-resistant Shigella sonnei ST152, global lineage III, is a high-risk clone, whose dissemination has limited therapeutic options for shigellosis. This study aimed to characterize two isolates of S. sonnei, which were recovered in Lima, Peru, during November 2019, exhibiting resistance to extended-spectrum cephalosporins and quinolones, and concurrently harboring bla_CTX-M-15 and qnrS1 genes, in addition to mutations in gyrA-S83L. These isolates were resistant to ceftriaxone, ciprofloxacin and trimethoprim/sulfamethoxazole. The molecular analysis showed that both isolates belonged to lineage III, sublineages IIIa and IIIb. The bla_CTX-M-15 gene was located in the same genetic platform as qnrS1, flanked upstream by ISKpn19, on a conjugative plasmid belonging to the IncI-γ group. To the best of our knowledge, this would be the first report on S. sonnei isolates carrying the bla_CTX-M-15 gene in Peru. The global dissemination of S. sonnei ST152, co-resistant to β-lactams and quinolones, could lead to a worrisome scenario in the event of potential acquisition of genetic resistance mechanisms to azithromycin.

Air and surfaces in the hospital environment are a potential source of exposure to filamentous fungi (FF) that could cause invasive fungal diseases (IFD) in severely immunocompromised patients. The prevalent FF in IFD are species from the genera Aspergillus, Fusarium, Scedosporium, and those within the order Mucorales. We have compiled regulations and described the procedures used in the clinical mycology laboratory to assess the presence of FF in areas at risk for the development of IFD. The infection control committees of each establishment implement hospital policies to regulate and control processes aimed at preventing infections. Fungal load monitoring is an important step in this process to validate air quality in order to ensure a clean and protected environment for severely immunocompromised patients.