Shiga toxin-producing Escherichia coli (STEC) is a group of pathogenic enterobacteria of significant public health importance due to their association with highly prevalent human diseases. STEC is ubiquitous in livestock environments, and its presence in the environment emphasizes the importance of properly managing agricultural effluents to reduce health risks from contamination. In order to detect STEC in the effluent treatment systems of two dairy farms ("A" and "B") in the southwest of Buenos Aires province, samples ("A", n=88; "B", n=72) were taken at two different times of the year (winter and spring) and at various points in the treatment systems. Analysis markers for virulence genes (stx, eae, saa, and ehxA) revealed the presence of STEC in 13.1% of the samples, showing an increase in spring and differences between dairy farms possibly related to their maintenance conditions. After manure, sediments showed the highest proportion of STEC-positive samples, which is relevant due to the ability of these strains to survive in the environment through biofilm formation. Eight genetic profiles were identified among all STEC-positive samples, which are associated with STEC strains that can cause hemolytic uremic syndrome (HUS) and other gastrointestinal diseases. This demonstrates the role of dairy farm environments in the region as reservoirs of pathogenic STEC strains and their impact on public health.

Pseudomonas aeruginosa is a Gram-negative bacillus capable of developing in humid environments and animal tissue. The interest in this bacterium lies in its ability to cause opportunistic diseases in patients with cystic fibrosis and healthcare-associated infections (HAIs). The objective of our study was to characterize the resistance profile of strains causing HAIs isolated in hospitals within our community, from January 2019 to December 2021. This descriptive, prospective, and cross-sectional study involved the isolation of strains from January 2019 to December 2021 at the Autonomous University of Baja California (UABC). The identification of the strains was carried out using Matrix-Assisted Laser Desorption/Ionization-Time of Flight (MALDI-TOF) mass spectrometry, and the detection of beta-lactam resistance was performed according to the criteria of the Clinical and Laboratory Standards Institute as stipulated in the CLSI M100-S27 document. A total of 649 samples were obtained from January 2019 to December 2021, including sputum (335 samples), urine (119 samples), and wounds (91 samples). Resistance to carbapenems was 38.94% for meropenem and 21.97% for imipenem. For cephalosporins, there was a 21.05% resistance rate for cefepime, 22.9% for ceftazidime, and 24.78% for ceftolozane-tazobactam. The prevalence of antimicrobial resistance has increased over time, which is attributable to both selective pressure and the evolution of the microorganisms themselves.

Salmonella spp. is one of the most important zoonotic pathogens that causes foodborne diseases. It is divided into two species (Salmonella bongori and Salmonella enterica) including around 2600 serovars, being S. enterica serovar Enteritidis one of the most frequent in Argentina. Serovar identification is generally conducted by somatic and flagellar agglutination sera assays, and molecular biology techniques can also be performed. As efforts are being made worldwide to differentiate Salmonella serovars, our aim was to evaluate the utility of two specific biomarkers, previously reported for differentiating S. Enteritidis with MALDI-TOF MS. A panel of 105 S. enterica local isolates, belonging to different serovars and characterized by sera agglutination and PCR, was included in this study. Two specific S. Enteritidis biomarkers, at m/z 3016±3Da and 6034±3Da, were visually detected showing a sensitivity of 54% and 98%, respectively, and a specificity of 100% for both peaks. Concordance between serotyping and identification by PCR of S. Enteritidis and the blind search of biomarkers in a subset of isolates was 98%. Visual detection of these S. Enteritidis biomarkers using MALDI-TOF MS can be used as a fast and easy screening method for serovars differentiation at the microbiology clinical laboratory.

This is the first report of a cutaneous infection in an immunocompromised domestic cat caused by Setosphaeria turcica. The investigation encompasses an assessment of its virulence factors and susceptibility to antifungal drugs. The isolated strain originated from a domestic cat displaying cutaneous lesions that tested positive for feline leukemia virus (FeLV) infection. Identification procedures employed both microscopic and molecular techniques, with molecular identification relying on ITS DNA sequencing. Enzymatic assays targeting lipase, phospholipase, protease, and keratinase yielded negative results, suggesting the prevalence of alternative virulence mechanisms. Successful treatment of the infection was achieved with itraconazole, and susceptibility testing confirmed its sensitivity to azoles and polyene antifungal drugs.

In 2021, avian influenza A (H5N1) clade 2.3.4.4b virus spread to North America and then to Central and South America in October 2022, extending from Colombia to Chile in three months. During 2023, several countries, mostly in the Americas, reported outbreaks in poultry, wild birds and mammals, as well as the emergence of two cases in humans (one in Ecuador in January and one in Chile in March). As of September 20th, 2023, 17 countries in the Americas Region have recorded cases of A (H5N1) in birds and mammals. On February 14th, 2023, Argentina confirmed the first case of avian influenza in wild birds, which was later detected in backyard and commercial poultry, and in the South-American sea lion (Otaria flavescens) in Tierra del Fuego, in the south of the country. So far, 21 suspected cases have been recorded in humans; however, all of them tested negative for Influenza A virus. Hemagglutinin sequence data of animal viruses analyzed in this report showed that Argentinian viruses clustered together with those isolated in other countries of the region. Epidemiological data suggested the possibility of multiple simultaneous entries of the avian virus, highlighting the role of migratory avian populations in the introduction and dissemination of the disease in Argentina. Continued comprehensive surveillance of these viruses in animals and people worldwide, along with ongoing preparedness efforts, are critical to determine the public health risk.

Microbial contaminations pose a significant concern within the brewing industry, exerting negative effects on the organoleptic quality of the product and leading to substantial economic losses. The exponential proliferation of craft breweries in Argentina in recent years has heightened the demand for constant improvements in processes to ensure excellence in beer production. However, the stringency of microbiological quality controls remains a vulnerable area. This study assesses the prevalence of beer contaminants in samples from 10 breweries located in Buenos Aires City (CABA) and Greater Buenos Aires area (GBA). The results revealed the presence of microorganisms in 70% of the analyzed samples. Fifteen bacteria and 19 yeasts were successfully isolated, with bacteria belonging to the genera Acetobacter and Staphylococcus, and yeasts to the genera Saccharomyces, Lodderomyces, Candida, and Pichia. Accurately identifying these microorganisms provides producers with the necessary information for formulating action plans to improve cleaning and sanitization protocols in their facilities. This proactive approach not only has the potential to mitigate economic losses associated with microbial contamination but also contributes to maintaining and elevating quality standards in regional craft beer production.

We describe here the first isolation in Argentina of a lactose-fermenting and lysine decarboxylase-negative non-Typhi Salmonella enterica from a blood culture of a patient with systemic lupus erythematosus. The microorganism was identified as S. enterica (score: 2.148) by mass spectrometry, as "Salmonella group" (discrimination: 86%) by the VITEK® 2 system and as Citrobacter freundii complex by biochemical tests. The serological test using the OMA antiserum for the somatic antigen was positive. The identification was confirmed as Salmonella subsp. I 4,[5],12:i:- atypical at the National Reference Center ANLIS Dr. Carlos G. Malbrán. Mass spectrometry is especially useful in microbial identification in the presence of atypia, while biochemical tests can lead to misidentification in these cases. This study warns about the circulation of this strain in Argentina.

Bartholinitis is the inflammation and infection of the Bartholin's glands that results from the accumulation of mucus in their ducts, the most frequent causal microorganisms being anaerobic and aerobic bacteria and those responsible for sexually transmitted infections. Those caused by agents not belonging to the genital microbiota are less frequent. Likewise, in most cases the diagnosis is clinical. Here, we describe the case of a 42-year-old heterosexual woman with a Bartholin's gland abscess caused by Neisseria meningitidis, isolated through culture and identified by VITEK®2. For molecular characterization and subtyping, the sequence type and clonal complex were determined using the multiple locus sequence typing technique. The antigenic profile was studied by amplification and sequencing of the genes coding for PorA, fHbp, NHBA and NadA and the susceptibility profile was assessed by MIC. Molecular diagnosis led to the confirmation of N. meningitidis as the pathogen responsible for bartholinitis.

Brucellosis is a zoonotic disease with a worldwide distribution that causes significant productive losses and negative impacts on public health. The aim of this work was to identify the risk factors associated with the presence of brucellosis in mixed farms (cattle/goats) in the central-western region of the province of Formosa. Sixty seven mixed farms with 7,855 animals (2,943 cattle and 4,912 goats) were randomly sampled during 2022/2023. The samples were serologically analyzed (BPA + FPA) to determine which animals were positive. Likewise, in each farm, a confidential survey was carried out to evaluate potential associated variables. The statistical analysis was performed using Generalized Linear Mixed Models (GLMM) with binomial distribution, logarithmic link function, and farm as a random variable. The estimated prevalence of brucellosis in mixed farms was 9%, while the joint prevalence per animal (cattle and goats) was 2.75%. The prevalence of brucellosis in cattle and goats was explained by the presence of animals with reproductive signs (odds ratio, OR=40), the occurrence of abortions in the last term of gestation and the birth of weak offspring (OR=5.3), incorrect treatment of abortions (OR=8), the introduction of animals from other farms (OR=5.9), and not having a negative brucellosis certificate (OR=9.6). The management practices conducted in each farm such as preventive measures, sanitation practices for the pens, and prevention measures for the workers, are important for the control of brucellosis.

The brown dog tick (Rhipicephalus sanguineus) is the vector of Rickettsia rickettsii, the causative agent of Rocky Mountain spotted fever (RMSF) in Northern Mexico and Southwestern United States. The immune response to a tick protein in the sera of humans or animals may reveal the zones with a high propensity to acquire RMSF, and vector control strategies may be focused on these zones. Arginine kinase (AK) is a highly antigenic invertebrate protein that may serve as a marker for tick exposure. We used R. sanguineus recombinant AK in an indirect ELISA assay with RMSF-positive patient sera. The response to AK was significantly higher against the sera of RMSF patients than the control sera from healthy participants without contact with dogs. To validate the antigenicity of tick AK, we mutated one predicted conformational epitope to alanine residues, which reduced the recognition by RMSF patients' immunoglobulins. This preliminary result opens a perspective towards the development of a complimentary technique based on RsAK as an antigen biomarker for vector serological surveillance for Rickettsia RMSF prevention.

Bovine mastitis poses a significant threat to global dairy production, resulting in substantial losses in milk production. Streptococcus bacteria, particularly Streptococcus uberis, Streptococcus agalactiae, and Streptococcus dysgalactiae, are commonly implicated in this condition. An accurate diagnosis is crucial for implementing effective treatment and minimizing its impact on production. This study examined 115 Streptococcus strains isolated from bovine mastitis cases in Uruguay using PCR for species identification. Additionally, the resistance to tetracycline, erythromycin, and penicillin was assessed in 81 of the bacterial strains under study. Significant disparities between phenotypic and genotypic detection were evident across all three species, with only 31% of strains identified phenotypically aligning with PCR results. Phenotypic prevalence indicated S. dysgalactiae as the most prevalent (44.35%), followed by S. uberis (24.34%) and S. agalactiae (6.09%). However, the genotypic identification revealed S. uberis as the most prevalent, followed by S. dysgalactiae, while S. agalactiae remained the least prevalent. The high sensitivity and speed of PCR suggest its potential routine implementation for diagnosing bovine mastitis caused by Streptococcus in any laboratory. Although, penicillin resistance was practically nonexistent, tetracycline and erythromycin exhibit higher resistance levels across all three species studied. In conclusion, the study underlines the importance of early diagnosis, highlights variations in bacterial prevalence, and proposes PCR as a valuable diagnostic tool for Streptococcus species responsible for bovine mastitis.

Tackling the dissemination of antibiotic resistance is one of the main global challenges. Manures from animal production are a recognized source of antibiotic resistance genes (ARGs) and mobile genetic elements (MGEs) requiring appropriate treatment methods. One of the main approaches for manure treatment is anaerobic digestion (AD). Meta-analyses have demonstrated that AD can significantly reduce the load of ARGs. However, antibiotics, ARGs and MGEs still remain in the final product (digestate). A sustainable agricultural use of digestates under the One Health framework requires wide assessments of their effects in the soil resistome. The objective of this review was to present the state of the art of digestate effects on ARGs of agricultural soils, focusing exclusively on digestates from animal manures. A systematic review was conducted. The examination of the resulting literature indicated that although temporal decays are observed for a variety of ARGs in single-application and repeated-applications experiments, for certain ARGs the pre-treatment or control levels are not restored. However, the low number of studies and the heterogeneous experimental conditions preclude a clear understanding of the fate of ARGs in soil and their risk for agroecosystems. The inclusion of multiple MGEs and the assessment of the long-term influence of digestates on soil properties and microbial communities could be keystones for a better understanding of the risks associated with digestate-induced changes in the soil resistome.

The aim of this study was to determine the impact of Kluyveromyces marxianus VM004 culture conditions on the cell wall (CW) structure and its influence on aflatoxin B binding. The yeast was inoculated into two types of culture media: yeast extract-peptone-dextrose (YPD) broth and dried distiller's grains with solubles (DDG). The CW was extracted from the biomass produced in these media. AFB (150ng/ml) adsorption tests using the biomass (1×10cells/ml) and the CW (0.001g) were performed at pH 2 and pH 8. Transmission electron microscopy (TEM) evaluated the CW thickness, and infrared spectroscopy (IR) determined the CW composition. Biomass production in YPD was higher than that in DDG. Cell diameter (μm) and CW thickness (μm) increased in the DDG medium. The CW percentage obtained in DDG was higher than that in YPD. The absorbance of carbohydrates by IR was higher in YPD. pH influenced AFB adsorption, which was lower at pH 8. The proportion of β-glucan and chitin present in CW was higher in the YPD medium. The IR method allowed to study the CW carbohydrate variation under the influence of these carbon sources. In conclusion, the culture media composition influenced the β-glucan and chitin composition and consequently, AFB adsorption.

Norovirus (NoV) is the leading cause of outbreaks of acute gastroenteritis worldwide. These are non-enveloped viruses that are classified into 10 genogroups, of which genogroup I (GI), II (GII), IV (GIV), VIII (GVIII), and IX (GIX) are the ones that infect humans. Two outbreaks (A and B) of acute gastroenteritis that occurred in a nursery school are described. The first outbreak (A) occurred in November 2018, and the second (B) in February 2020. The detection of viral and bacterial pathogens was performed to study both outbreaks. Additionally, an epidemiological investigation of the outbreaks was conducted. In the analyzed fecal and vomit samples from both children and adults in the nursery school, NoV GII.4 [P16] Sydney 2012 and NoV GI.3 [P13] were detected in outbreaks A and B, respectively. Since the study of acute gastroenteritis outbreaks is underestimated in Argentina, it is necessary to design prevention, study, and control protocols, as well as to improve the outbreak notification system in our country.

Intestinal parasitic diseases constitute a cosmopolitan public health concern, with greater prevalence in developing countries, and mainly affecting children. The aim of this study was to develop an educational intervention aimed at mothers/guardians of children attending three child development centers (CDI) in Santa Fe, Argentina, during 2018. An educational intervention was conducted using a descriptive, quasi-experimental design, with pre- and post-intervention assessment. This intervention included 36 mothers, and was carried out in three stages: diagnosis, intervention and final evaluation. Simultaneously, a coproparasitological study was performed on 48 children under 5 years of age, who were assisted in the CDI, with the aim to understand and address the parasitic infections prevalent in the child population. It was possible to compare the correct answers before and after the educational intervention, observing a statistically significant increase (p=0.008742) in the average number of correct answers. Enteroparasites were identified in 54% of the population of children analyzed, 10% were biparasitized and 6% had more than two parasitic species. The most frequently detected parasites were Blastocystis spp., Giardia intestinalis and Ascaris lumbricoides. The educational intervention was positive, resulting in an improvement in the level of knowledge related to intestinal parasitosis and its prevention. This educational intervention experience highlights the importance of ongoing education in promoting a healthy lifestyle and preventing parasitosis in vulnerable populations.

Rectal swabs (122) from pediatric patients were analyzed by polymerase chain reaction (PCR) for the detection of EPEC and STEC. STEC isolates were tested for the presence of stx1, stx2, eae, saa and ehxA. All eae-positive samples were tested for the presence of bfpA, and antigen O was determined using the agglutination test. Int1 and Int2 were detected to identify the presence of integrons class 1 and 2, respectively. Escherichia coli was detected in 68% of the samples, of which 18.8% were STEC (2.45%) and EPEC (16.3%). Serogroups STEC O145 and EPEC O130, O113 and O157 were observed, while three strains were non-typable. None of the EPEC strains carrying tbfpA and class 1 and 2 integrons was detected in any of the samples. The results obtained are important considering the virulence profiles found in the isolated EPEC and STEC strains and the serogroups associated with disease in humans.

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 HO) while random mutagenesis was performed with UV-C radiation at 275nm. 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.

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.

Lysinibacillus sphaericus is a bacterium that, along with Bacillus thuringiensis var. israelensis, is considered the best biological insecticide for controlling mosquito larvae and an eco-friendly alternative to chemical insecticides. It depends on peptidic molecules such as N-acetylglucosamine to obtain carbon sources and possesses a phosphotransferase system (PTS) for their incorporation. Some strains carry S-layer proteins, whose involvement in metal retention and larvicidal activity against disease-carrying mosquitoes has been demonstrated. Alterations in the amino sugar incorporation system could affect the protein profile and functionality. Strain ASB13052 and the isogenic mutant in the ptsH gene, which is predominant in the PTS signaling pathway, were used in this study. For the first time, the presence of N-glycosylated S-layer proteins was confirmed in both strains, with a variation in their molecular weight pattern depending on the growth phase. In the exponential phase, an S-layer protein greater than 130 kDa was found in the ptsH mutant, which was absent in the wild-type strain. The mutant strain exhibited altered and incomplete low quality sporulation processes. Hemolysis analysis, associated with larvicidal activity, showed that the ptsH mutant has higher lytic efficiency, correlating with the high molecular weight protein. The results allow us to propose the potential effects that arise as a result of the absence of amino sugar transport on hemolytic activity, S-layer isoforms, and the role of N-acetylglucosamine in larvicidal activity.