Revista Argentina de microbiologia最新文献

The high load of agrochemicals and antibiotics present in agricultural aquatic environments represents a risk for wildlife. Since enteric bacteria, which play a key role in the physiological functioning of their hosts, are sensitive to a wide variety of pollutants, their study allows to evaluate the health of organisms. This study aimed to evaluate the effects of commercial formulations of a glyphosate-based herbicide (GBH) and the antibiotic ciprofloxacin (CIP), individually and in mixture, on the bacterial diversity of the intestinal content of common toad (Rhinella arenarum) tadpoles. The diversity of cultivable fast-growing bacteria with low nutritional requirements was evaluated using classic microbiological tests and matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry identification. Bacterial diversity varied among treatments. Taxa diversity increased in the GBH-treated group but decreased in the CIP-treated group. Remarkably, Yersinia spp. and Proteus spp. were only found in the GBH-treated group. The prevalence of Klebsiella spp. and Pseudomonas spp. decreased in the intestinal microbiota of the GBH-CIP-treated group. To our knowledge, this is the first report on the alteration of cultivable enteric bacteria of autochthonous tadpoles due to two pollutants of emerging concern. Our results demonstrate that R. arenarum tadpoles can be used as non-conventional model organisms for environmental pollution monitoring. Our preliminary findings would contribute to understanding how the presence of GBH and CIP in freshwaters may represent a threat to wildlife and human health by causing enteric dysbiosis of part of the bacterial community.

Escherichia coli O157:H7 is a foodborne pathogen implicated in numerous outbreaks worldwide that has the ability to cause extra-intestinal complications in humans. The Enteropathogens Division of the Central Public Health Laboratory (CPHL) in Paraguay is working to improve the genomic characterization of Shiga toxin-producing E. coli (STEC) to enhance laboratory-based surveillance and investigation of foodborne disease outbreaks. Whole genome sequencing (WGS) is proposed worldwide to be used in the routine laboratory as a high-resolution tool that allows to have all the results in a single workflow. This study aimed to carry out for the first time, the genomic characterization by WGS of nine STEC O157:H7 strains isolated from human samples in Paraguay. We were able to identify virulence and resistance mechanisms, MLST subtype, and even establish the phylogenetic relationships between isolates. Furthermore, we detected the presence of strains belonging to hypervirulent clade 8 in most of the isolates studied.

At present, different reports have shown that children reach similar SARS-CoV-2 viral load (VL) levels compared to adults; however, the impact of VL on children remains ambiguous when asymptomatic versus symptomatic cases are compared. Thus, the aim of this study was to assess VL at the time of diagnosis in asymptomatic and symptomatic SARS-CoV-2 infected children. VL analysis was retrospectively carried out from nasopharyngeal swabs on 82 SARS-CoV-2 infected children, from March to October 2020. Of the 82 children, 31 were asymptomatic. Symptomatic patients had significantly higher VL values compared to asymptomatic ones (median = 7.41 vs 4.35 log10 copies/ml, respectively). Notwithstanding, 8 out of 31 asymptomatic children had high VL levels, overlapping levels observed above the first quartile in the symptomatic group. Analysis of different age groups revealed that median VL values were higher in the symptomatic groups, although there was only a significant difference in children younger than 5 years of age. On the other hand, there was no significant difference between the VL values from the 82 SARS-CoV-2 infected children according to age, sex, underlying disease, symptoms or severity of COVID-19 related disease. This study emphasizes the importance of VL analysis in SARS-CoV-2 infected children, who could contribute to viral spread in the community. This concern could be extended to healthcare workers, who are in contact with children.

Candida albicans is a commensal of the mammalian microbiome and the primary pathogenic fungus of humans. It becomes a severe health problem in immunocompromised patients and can cause a wide variety of mucosal and systemic infections. The interaction between C. albicans and host cells is characterized by the expression of virulence factors such as adhesins and invasins, the secretion of hydrolytic enzymes, a transition from yeast to filamentous hyphae form, and the ability to form biofilms; these features collectively result in cell adhesion, invasion, and damage. This review describes complex commensal interactions of C. albicans with host cells and the cellular events that it triggers in a pathogenic environment. We also review the host immune response induced by C. albicans antigens and the mechanisms developed by this fungus to avoid the action of antifungal agents.

Bovine pestiviruses are the causative agents of bovine viral diarrhea, a disease that causes severe economic losses in cattle. The aim of this study was to improve their diagnosis by developing a RT-qPCR to detect bovine pestiviruses A, B and H; and to set up a protocol for collecting, shipping and preserving bovine pestiviral RNA on filter papers. The developed RT-qPCR showed high sensitivity in detecting these viruses in different matrices: viral stocks, semen and serum samples. With regard to the possibility of using the technique to test serum pools, it was possible to identify a positive serum sample within a pool containing 30 sera. In addition to evaluating the qPCR from fresh samples, the use of filter papers to sow bovine samples was analyzed. The sampling method on two different filter papers using bovine blood drops was a useful alternative for diagnostic purposes and allowed to preserve pestiviral RNA for up to 12 months under refrigeration.

Legionnaires’ disease (LD) is severe acute pneumonia that occurs in sporadic or epidemic form, and generally requires hospitalization. The objective of this work was to describe the experience in the LD laboratory diagnostic approach in Argentina during the period 2016–2021. The laboratory analyzed 168 clinical specimens from 93 cases of suspected LD pneumonia. Laboratory tests included the detection of the soluble antigen of Legionella pneumophila serogroup 1 in urine sample, detection of DNA of Legionella spp. in lower respiratory secretions by conventional and commercial molecular methods and isolation in selective medium. LD was confirmed in 12 patients. The urinary antigen allowed the diagnosis for 8 patients. L. pneumophila was isolated from the respiratory material of 6 patients suffering from health care-associated pneumonia, who had been previously diagnosed using the commercial molecular method. Fifty percent of these cases did not show detectable urinary antigen. A single patient did not shows neither detectable antigenuria nor isolation of Legionella from the respiratory sample and was diagnosed as a confirmed case of LD by the detection of DNA of Legionella spp. by PCR directly from the respiratory secretion and the epidemiological link with another case of confirmed LD by culture. Urinary antigen detection is the first-line diagnostic test. However, the incorporation of complementary molecular methods has proved to avoid false negatives and contributed to a better understanding of the true incidence of the disease.

Leptospirosis is a neglected zoonosis that is widely distributed in the world. Although it is endemic in Argentina, prevalence remains unknown. The aims of the study were: (i) to determine the prevalence of leptospirosis in humans from a rural community in Tandil Argentina, (ii) to identify infecting Leptospira spp. serogroups, (iii) to identify factors associated with the infection, (iv) to estimate the population attributable fraction (PAF) of the risk factors and (v) to determine the spatial patterns of disease presentation and related risk factors. Blood samples from 202 participants were collected. A survey was conducted to obtain clinical and epidemiological data. Serological testing was performed by the microscopic agglutination test (MAT). Univariate and multivariate methods were applied to evaluate associations. Spatial clusters were investigated for seroprevalence and risk factors. Antibodies were found in 32.2% of participants (95% CI: 25.8–39.1). The most prevalent serogroup was Hebdomadis followed by Sejroe; Icterohaemorrhagiae; Tarassovi and Canicola. Living at lower altitudes (OR: 13.04; 95% CI: 2.60–65.32); not having access to water supply network (OR: 2.95; 95% CI: 1.30–6.69); living close to flooded streets (OR: 2.94; 95% CI: 1.14–7.69) and practicing water sports (OR: 3.12; 95% CI: 1.12–8.33) were associated with seropositivity. Factors related with housing characteristics, services and infrastructure had the higher PAF (from 17% to 81%). A spatial cluster with higher rates of positivity and of the main risk factors was determined. This work contributes useful data for specific preventive measures that should be implemented for the control of the disease.

We report an autochthonous case of Rickettsia parkeri rickettsiosis occurred in June 2018 in a forested area of the Urugua-í Provincial Park, Misiones, Argentina. No previous records of this disease in humans have been previously reported in this region. The epidemiological, ecological, clinical, and laboratory features required for a proper diagnosis and adequate treatment are described here. The fact of considering rickettsiosis as a differential diagnosis in a patient with exanthematic acute febrile syndrome is highlighted, being the epidemiological history of exposure to the vector (ticks of the genus Amblyomma) an essential element.

Abuse and misuse of antimicrobial agents has accelerated the spread of antimicrobial-resistant bacteria. The association between antimicrobial-resistant infections in humans and antimicrobial use in agriculture is complex, but well-documented. This study provides a systematic review and meta-analysis of the dissemination of antimicrobial resistance (AMR) to antimicrobials defined as critically important by the WHO, in swine, chicken, and cattle from intensive and extensive production systems in Argentina. We conducted searches in electronic databases (MEDLINE-PubMed, Web of Science, SciELO, the National System of Digital Repositories from Argentina) as well as in the gray literature. Inclusion criteria were epidemiological studies on AMR in the main food-transmitted bacteria, Salmonella spp., Campylobacter spp., Escherichia coli and Enterococcus spp., and mastitis-causing bacteria, isolated from swine, chicken, dairy and beef cattle from Argentina. This study gives evidence for supporting the hypothesis that AMR of common food-transmitted bacteria in Argentina is reaching alarming levels. Meta-analyses followed by subgroup analyses confirmed the association between the prevalence of AMR and (a) animal species (p < 0.01) for streptomycin, ampicillin and tetracycline or (b) the animal production system (p < 0.05) for streptomycin, cefotaxime, nalidixic acid, ampicillin and tetracycline. Moreover, swine (0.47 [0.29; 0.66]) and intensive production (0.62 [0.34; 0.83]) showed the highest pooled prevalence of multidrug resistance while dairy (0.056 [0.003; 0.524]) and extensive production (0.107 [0.043; 0.240]) showed the lowest. A research gap regarding beef-cattle from feedlot was identified. Finally, there is an urgent need for political measures meant to coordinate and harmonize AMR surveillance and regulate antimicrobial use in animal production.