Revista Argentina de microbiologia最新文献

Infectious bovine keratoconjunctivitis (IBK) is an ocular disease that affects bovines and has significant economic and health effects worldwide. Gram negative bacteria Moraxella bovis and Moraxella bovoculi are its main etiological agents. Antimicrobial therapy against IBK is often difficult in beef and dairy herds and, although vaccines are commercially available, their efficacy is variable and dependent on local strains. The aim of this study was to analyze for the first time the genomes of Uruguayan clinical isolates of M. bovis and M. bovoculi. The genomes were de novo assembled and annotated; the genetic basis of fimbrial synthesis was analyzed and virulence factors were identified. A 94% coverage in the reference genomes of both species, and more than 80% similarity to the reference genomes were observed. The mechanism of fimbrial phase variation in M. bovis was detected, and the tfpQ orientation of these genes confirmed, in an inversion region of approximately 2.18 kb. No phase variation was determined in the fimbrial gene of M. bovoculi. When virulence factors were compared between strains, it was observed that fimbrial genes have 36.2% sequence similarity. In contrast, the TonB-dependent lactoferrin/transferrin receptor exhibited the highest percentage of amino acid similarity (97.7%) between strains, followed by cytotoxins MbxA/MbvA and the ferric uptake regulator. The role of these virulence factors in the pathogenesis of IBK and their potential as vaccine components should be explored.

Bovine respiratory syncytial virus (BRSV) affects both beef and dairy cattle, reaching morbidity and mortality rates of 60–80% and 20%, respectively. The aim of this study was to obtain a recombinant MVA expressing the BRSV F protein (MVA-F) as a vaccine against BRSV and to evaluate the immune response induced by MVA-F after systemic immunization in homologous and heterologous vaccination (MVA-F alone or combined with a subunit vaccine), and after intranasal immunization of mice. MVA-F administered by intraperitoneal route in a homologous scheme elicited levels of neutralizing antibodies similar to those obtained with inactivated BRSV as well as better levels of IFN-γ secretion. In addition, nasal administration of MVA-F elicited local and systemic immunity with a Th1 profile. This study suggests that MVA-F is a good candidate for further evaluations combining intranasal and intramuscular routes, in order to induce local and systemic immune responses, to improve the vaccine efficacy against BRSV infection.

Water kefir is a sparkling, slightly acidic fermented beverage made from sugar, water, and water kefir grains, which are a mixture of yeast and bacteria. These grains produce a variety of fermentation compounds such as lactic acid, acetaldehyde, acetoin, ethanol and carbon dioxide. In this study, a high-throughput sequencing technique was used to characterize the bacterial composition of the original water kefir from which potential probiotics were obtained. We studied the bacterial diversity of both water kefir grains and beverages. DNA was extracted from three replicate samples of both grains and beverages using the Powerlyzer Microbial Kit. The hypervariable V1–V2 region of the bacterial 16S ribosomal RNA gene was amplified to prepare six DNA libraries. Between 1.4 M and 2.4 M base-pairs were sequenced for the library. In total, 28 721 971 raw reads were obtained from all the samples. Estimated species richness was higher in kefir beverage samples compared to grain samples. Moreover, a higher level of microbial alpha diversity was observed in the beverage samples. Particularly, the predominant bacteria in beverages were Anaerocolumna and Ralstonia, while in grains Liquorilactobacillus dominated, with lower levels of Leuconostoc and Oenococcus.

Although the bacterial diversity in kefir grains was low because only three genera were the most represented, all of them are LAB bacteria with the potential to serve as probiotics in the artificial feeding of bees.

Waterborne diseases can have different origins, micro-organisms such as bacteria and parasites being the most important ones. In this study, two recreational aquatic environments were studied in the province of Salta, Argentina. Water samples collected from three different locations, two from a creek and one from the outlet of a thermal complex, were monitored at four time points. Physicochemical and microbiological characterization of each point was conducted, as well as a search for parasites and amebae. Parasites were identified through optical microscopy observations and free-living amebae (FLA) were isolated by spiking in Petri dishes followed by subsequent molecular identification. Water samples from the outlet of the thermal complex showed different physicochemical characteristics from those of the creek. Bacterial indicators of contamination were detected at all points; however, the creek water had a significantly higher concentration of Pseudomonas sp. Sporadically, creek samples exhibited Ascaris spp. eggs, Giardia sp. cysts, and ancylostomid eggs. The presence of FLA was observed in all samples, 15 of which were isolated and identified as Acanthamoeba sp., mostly belonging to the T4 genotype. Parasite surveillance in recreational aquatic environments is an important complement to traditional microbial indicators for assessing water quality. The identified parasites represent a potential health risk for people using these environments.

Entamoeba infections occur worldwide, with higher frequency in countries of low socioeconomic status and poor public health. Since Entamoeba histolytica has long been recognized as the only pathogenic species, making a differential diagnosis of other morphologically identical Entamoeba is important. This study aimed to determine the prevalence of Entamoeba species in two populations from Argentina, make a differential diagnosis by PCR and characterize Entamoeba isolates at the SSU rRNA gene. A total of 493 serial fecal samples were obtained from individuals in the provinces of Buenos Aires (n = 210) and Misiones (n = 283). Samples were examined by conventional methods (formalin–ethyl acetate and Willis flotation) and specific PCRs to differentiate Entamoeba species. Entamoeba isolates were characterized by sequencing a fragment of the SSU rRNA gene. The overall prevalence of Entamoeba infection was 12.4%, being more prevalent in Buenos Aires than in Misiones (14.8% vs. 10.6%). A case of E. histolytica confirmed by PCR and sequence analysis was reported for the first time in Buenos Aires. Moreover, new genetic data on Entamoeba coli and Entamoeba dispar were recorded. The phylogenetic analysis revealed a congruence between morphological characteristics and SSU rRNA gene sequences. This study increases the amount of information on the distribution of these species in Argentina and the region of the Americas.

The aim of this study was to compare the performance of two MALDI-TOF MS systems in the identification of clinically relevant strict anaerobic bacteria. The 16S rRNA gene sequencing was the gold standard method when discrepancies or inconsistencies were observed between platforms. A total of 333 isolates were recovered from clinical samples of different centers in Buenos Aires City between 2016 and 2021. The isolates were identified in duplicate using two MALDI-TOF MS systems, BD Bruker Biotyper (Bruker Daltonics, Bremen, Germany) and Vitek MS (bioMèrieux, Marcy-l’Etoile, France). Using the Vitek MS system, the identification of anaerobic isolates yielded the following percentages: 65.5% (n: 218) at the species or species–complex level, 71.2% (n: 237) at the genus level, 29.4% (n: 98) with no identification and 5.1% (n: 17) with misidentification. Using the Bruker Biotyper system, the identification rates were as follows: 85.3% (n: 284) at the species or species–complex level, 89.7% (n: 299) at the genus level, 14.1% (n: 47) with no identification and 0.6% (n: 2) with misidentification. Differences in the performance of both methods were statistically significant (p-values <0.0001). In conclusion, MALDI-TOF MS systems speed up microbial identification and are particularly effective for slow-growing microorganisms, such as anaerobic bacteria, which are difficult to identify by traditional methods. In this study, the Bruker system showed greater accuracy than the Vitek system. In order to be truly effective, it is essential to update the databases of both systems by increasing the number of each main spectrum profile within the platforms.

In Argentina, hemolytic uremic syndrome (HUS) caused by EHEC has the highest incidence in the world. EHEC infection has an endemo-epidemic behavior, causing 20–30% of acute bloody diarrhea syndrome in children under 5 years old. In the period 2016–2020, 272 new cases per year were notified to the National Health Surveillance System. Multiple factors are responsible for HUS incidence in Argentina including person-to-person transmission. In order to detect possible EHEC carriers, we carried out a preliminary study of the frequency of kindergarten teachers with anti-LPS antibodies against the most prevalent EHEC serotypes in Argentina. We analyzed 61 kindergarten teachers from 26 institutions from José C. Paz district, located in the suburban area of Buenos Aires province, Argentina. Fifty-one percent of the plasma samples had antibodies against O157, O145, O121 and O103 LPS: 6.4% of the positive samples had IgM isotype (n = 2), 61.3% IgG isotype (n = 19) and 32.3% IgM and IgG (n = 10). Given that antibodies against LPS antigens are usually short-lived specific IgM detection may indicate a recent infection. In addition, the high percentage of positive samples may indicate a frequent exposure to EHEC strains in the cohort studied, as well as the existence of a large non-symptomatic population of adults carrying pathogenic strains that could contribute to the endemic behavior through person-to-person transmission. The improvement of continuous educational programs in kindergarten institutions could be a mandatory measure to reduce HUS cases not only in Argentina but also globally.

Interaction between severe acute respiratory coronavirus 2 (SARS-CoV-2) and IIEB remains under investigation. Objective: to compare IIEB incidence before and during COVID-19 pandemic, and assess incidence of coinfection with COVID-19 and case fatality. A cross-sectional study was performed on data from a centralized microbiology laboratory serving a network of healthcare centers comprising 713 pediatric and adult inpatient beds, expanded by 20% during the pandemic. Three periods were evaluated: (1) pre-pandemic: March 1, 2019–February 29, 2020; (2) pandemic year 1: March 1, 2020–February 28, 2021; (3) pandemic year 2: March 1, 2021–July 31, 2021. Descriptive statistical analysis was performed. 56 502 samples (96% blood cultures) from 27 224 patients were analyzed. Of these, 54 samples (from 54 patients) were positive for encapsulated bacteria. IIEB incidence was: 167.4, 32.6, and 50.4 per 100 000 samples for periods 1, 2, and 3, respectively. Twelve IIEB episodes occurred during the pandemic period: 10 Streptococcus pneumoniae, and 2 Haemophilus influenzae, of which 7 were SARS-CoV-2/S. pneumoniae coinfections, with an incidence of 5.68 per 10 000 COVID-19-related hospitalizations (0.056%). IIEB case fatality was 31%, 29%, and 60% for each period, respectively, 3/7 patients with coinfection died (43%). Case fatality for invasive pneumococcal disease (IPD) in patients without COVID-19, was 32.5%. Significant reduction in IIEB incidence was observed during the pandemic, coinciding with implementation of containment measures. The incidence of SARS-CoV-2/S. pneumoniae coinfection was low, with higher case fatality than IPD patients without COVID-19.

Blepharitis is a very common disease in ophthalmology, dermatology and allergy practice. It generally follows a chronic course and is frequently associated with objective and/or subjective symptoms such as epiphora, red eye, dandruff, gritty sensation, itching, burning, photophobia, and blurred vision. The purpose of this study is to analyze the prevalence of Demodex spp. in patients with symptoms of chronic blepharitis. An analytical cross-sectional study was conducted in the period between 2016 and 2020. All patients with symptoms of chronic blepharitis who underwent a parasitological test of eyelashes (Rapitest) in the Dermatology Department of the Hospital Italiano de Buenos Aires were included. Those with previously established blepharitis due to another infectious cause were excluded. We analyzed 972 patients. Sixty percent (n = 585) underwent a positive Rapitest for the presence of Demodex spp. Seventy five percent (n = 728) were women. There were no significant differences in the prevalence associated with sex (p = 0.38). Among the patients positive for Demodex spp., 65% (n = 628) were older than 60 years old. The most frequently associated symptom was itching, present in 35% (n = 342). A statistically significant decrease in the number of consultations was observed during the cold months of the year (May–June–July–August). Our results show a high prevalence of Demodex spp. in patients with chronic blepharitis. As its presence reveals a direct association with age, we recommend looking for this parasite in this age group.