Methicillin-susceptible Staphylococcus aureus (MSSA) clonal complex CC398 carrying ermT has emerged as a prevalent lineage in human bloodstream infections in South America. We analyzed 77 S. aureus isolates from processed foods in Misiones and northern Corrientes, Argentina, from a retrospective (2009-2010, n=36) and a prospective cohort (2020-2024, n=41). Antimicrobial susceptibility was determined by disk diffusion and the D-test. Based on a two-step phenotypic selection (methicillin susceptibility and the D-test), 20 MSSA-iMLSb positive isolates were identified, of which 14 were analyzed by PCR for the presence of the sau1-hsdS1 and ermT genes. All 14 isolates tested positive for both markers, consistent with their assignment to CC398. A marked increase in the iMLSb phenotype was observed between cohorts: 2.8% (1/36) in 2009-2010 versus 46% (19/41) in 2020-2024. This is the first report of CC398-MSSA-ermT+ in processed foods from northeastern Argentina, with evidence of its circulation dating back to at least 2009-2010.
OBJECTIVE:Human herpesvirus-8 (HHV-8) causes lymphoproliferative diseases, but recent studies suggest it may also be linked to neuropsychiatric disorders. This study aimed to determine HHV-8 IgG seroprevalence in individuals with schizophrenia and blood donors, as well as to evaluate whether HHV-8 constitutes a risk factor for schizophrenia. A total of 135 patients diagnosed with schizophrenia based on DSM-V criteria and 200 healthy blood donors were included. HHV-8 IgG antibodies were analyzed using ELISA, and molecular detection of HHV-8 DNA was performed by real-time PCR. The seropositivity rates between the groups were statistically compared. HHV-8 IgG positivity was detected in 6.7% of schizophrenia patients (9/135, CI: 3.1-12.3) and 5.0% of blood donors (10/200, CI: 2.4-9.0) (p=0.518). HHV-8 DNA was not detected in any of the serum samples that tested positive for HHV-8 IgG. No statistically significant association was observed between HHV-8 seropositivity and schizophrenia (OR=1.36; 95% CI: 0.53-3.43; p=0.519). Brief Psychiatric Rating Scale (BPRS) total scores were similar between IgG-positive (median 27, IQR 17-42; mean 47.0±13.3) and IgG-negative patients (median 26, IQR 20-34; mean 45.0±10.8) (p=0.678). Although some BPRS parameters appeared higher in IgG-positive patients, none were statistically significant after multiple testing correction. In this study, HHV-8 IgG seroprevalence was similar between schizophrenia patients and blood donors, and no statistically significant association was observed between HHV-8 seropositivity and schizophrenia. To enhance the generalizability of the findings, larger studies with increased sample size, as well as comparative, regional, and multicenter designs, are needed.
Carnivore protoparvovirus 1 (CPPV-1) is a significant pathogen of domestic carnivores, but its occurrence and genomic diversity in South American wildlife remain poorly characterized. Here we report the first detection and complete-genome characterization of an FPV-like CPPV-1 strain in a Procyon cancrivorus from Northeastern Argentina. Viral DNA was sequenced using tiling-tailed amplicons and NGS (95.4% genomic coverage, mean depth >1700×). Phylogenetic analysis of global genomes indicated that the P. cancrivorus strain clustered robustly within the FPV-like clade and was closely related to FPV variants circulating in domestic cats in Argentina. The CPPV-1 positive individual was clinically healthy, suggesting subclinical spillover at the wildlife-domestic interface. These findings extend the recognized host range of FPV-like parvoviruses in South America and underscore the need for genomic surveillance to monitor cross-species transmission at the wildlife-domestic interface.
Domestic pigeons (Columba livia domestica) are potential reservoirs of opportunistic yeasts that may pose health risks to humans, particularly in urban environments. This study aimed to investigate the prevalence, seasonal distribution, and molecular identification of Candida species in pigeon feces across Riyadh, Saudi Arabia. Fecal samples were collected from 64 pigeons across four regions of Riyadh during all four seasons. Yeasts were isolated using selective Sabouraud dextrose agar and CHROMagar Candida, purified, and preserved. Species-level identification was performed via morphological analysis, MALDI-TOF mass spectrometry (MS), and molecular techniques targeting the ITS1-5.8S-ITS2 region. Phylogenetic analysis was conducted on confirmed Candida albicans isolates. Overall, 20.31% (n=13) of the samples were positive for fungal isolation. The predominant species were C. albicans, Pichia kudriavzevii, and Clavispora lusitaniae. Seasonal analysis revealed the highest prevalence in spring (7.81%), while the central region of Riyadh showed the highest regional prevalence (7.81%). MALDI-TOF MS successfully identified C. lusitaniae and P. kudriavzevii, whereas C. albicans was confirmed via PCR and ITS sequencing (GenBank: OR467467 and OR467468). Phylogenetic analysis placed C. albicans isolates in a well-supported monophyletic clade. Environmental factors such as temperature and humidity influenced fungal prevalence. Cryptococcus neoformans was not detected. Domestic pigeons in Riyadh serve as environmental reservoirs of pathogenic Candida species, highlighting potential public health risks, particularly for immunocompromised individuals. These findings emphasize the need for monitoring urban bird populations to mitigate opportunistic fungal transmission.
The spread of ESBL-producing Escherichia coli strains among different hosts, including humans, domestic animals, and synanthropic animals, has become a current public health challenge. A comprehensive analysis of bacterial isolates in animals and meat products throughout South America is essential to improve the understanding of their distribution and the different mechanisms of resistance in developing countries. This review aims to evaluate the different studies on ESBL-producing E. coli in animals and meat products in South America, from 2020 to 2024. A systematic search was conducted in databases such as PubMed, SciELO, and Latindex from January 1, 2020 to May 1, 2024. Studies published in English, Spanish, and Portuguese on ESBL-producing E. coli from animal sources (dogs, cats, chickens, pigs, cows, rats, and meat products) were conducted across South America. Eighty percent of the included articles reported blaCTX-M genes, with the blaCTX-M-2 gene being the most common with 48.2%. This gene was found mainly in chickens, followed by dogs, cows and pigs. The ST10 clone was the most prevalent, reported in 40% of the included studies, while ST155 was evidenced in 30%. Other clones, such as ST117 and ST131, were identified in 20% of the studies. The increasing prevalence of blaCTX-M resistance genes in E. coli in South American countries highlights the need for effective surveillance and control measures in the animal environment. The inappropriate use of antibiotics in livestock requires multidisciplinary approaches, such as the One Health approach, to address this problem.
Endophytes, microorganisms that inhabit internal plant tissues without causing harm, are increasingly recognized as valuable sources of bioactive metabolites with industrial, agricultural, and pharmaceutical relevance. This study aimed to isolate, identify, and evaluate the antimicrobial and antioxidant activities of endophytic and rhizospheric bacteria associated with medicinal plants from North Shewa, Ethiopia. This study hypothesized that endophytic and rhizospheric bacteria associated with medicinal plants from North Shewa, Ethiopia, produce bioactive compounds with significant antimicrobial and antioxidant potential. We hypothesized that these bacterial communities synthesize metabolites capable of inhibiting test microorganisms and scavenging free radicals. Isolation was carried out from sterilized leaves and roots, as well as from root washes, on nutrient agar at 30°C for 72h. The isolates were first screened via the perpendicular method and then via the disc diffusion method. Fermented broths were extracted via solvents. Among the 104 isolated microbes, including 89 endophytic and 15 rhizospheric microbes, 29 showed antibacterial activity. The main bioactive-producing isolates were Pseudomonas oleovorans, Ligilactobacillus salivarius, Bacillus subtilis, and Pseudomonas fluorescens. Notably, P. oleovorans was effective against Streptococcus epidermidis (13.7mm) and Staphylococcus aureus (12mm), with inhibition zones ranging from 8 to 13.7mm for all the tested organisms. The antioxidant activity ranged from 15.42% to 22.57%, with the highest value observed for P. oleovorans (22.57%). These findings highlight the potential of endophytic and rhizospheric bacteria as promising and sustainable sources of bioactive compounds.
Carbapenem-resistant Acinetobacter baumannii (CRAB) is a critical global threat, particularly in Latin America and Argentina, where carbapenem resistance exceeds 85%. Treatment options are limited and controversial. This article presents a successful case of a patient with ventilator-associated pneumonia caused by extensively drug-resistant (XDR) CRAB, successfully treated with a combination of ampicillin/sulbactam (AMS) and ceftazidime/avibactam (CAZ/AVI). The CRAB isolate was resistant to multiple antibiotics. In vitro testing confirmed that avibactam restored the strain's susceptibility to sulbactam, demonstrating crucial synergy in regions without access to newer drugs. This case highlights the potential of combining AMS and CAZ/AVI as a viable therapeutic strategy for severe CRAB infections, especially XDR strains, offering a valuable alternative where options are limited.
Clinical mastitis (CM) is one of the main causes of antimicrobial use (AMU) in dairy cattle, and strategies that support selective therapy are essential to promote responsible antimicrobial stewardship. This study evaluated the use of a commercial on-farm culture (OFC) system supported by an artificial intelligence-based mobile application to describe pathogen prevalence, assess AMU, and characterize treatment practices on dairy farms in Argentina. A retrospective longitudinal study was conducted using data generated between April 2022 and June 2025 from dairy farms implementing the OFC system. Only new mild and moderate CM cases were included in the analysis. Microbiological diagnoses and antimicrobial treatments administered via intramammary and/or parenteral routes were descriptively analyzed. A total of 26546 CM were evaluated. No bacterial growth was the most frequent diagnosis, followed by non-aureus staphylococci, Staphylococcus aureus, environmental streptococci, and Gram-negative bacteria. Overall, approximately half of the cases did not receive antimicrobial treatment. When antimicrobials were used, intramammary administration was the most common route, although parenteral treatments were still applied in a considerable proportion of mild and moderate cases. Critically important antimicrobial groups (macrolides and aminoglycosides) were frequently used for intramammary therapy, and combined antimicrobial formulations predominated. The implementation of OFC provided relevant microbiological information to support therapeutic decision-making and contributed to a substantial reduction in AMU. Strengthening collaboration between farmers and veterinarians is essential to improve antimicrobial stewardship and align mastitis treatment practices with microbiological evidence and international recommendations.
This study evaluates the antibacterial activity of Apis mellifera honey (in fresh form and in extracted fractions) and its effects on the outer membrane permeability of Enterococcus faecalis and Staphylococcus epidermidis. Five honey samples from four municipalities in the Midwest of Brazil (Mato Grosso state) were evaluated in this study. Samples of fresh honey and its hexane, ethyl acetate, and n-butanol fractions were prepared by the fractional extraction method in a separating funnel using each fraction's solvent. Antibacterial activities were assessed using the broth microdilution method with serial dilution of the samples ranging from 1000 to 1.95μg/ml. Outer membrane permeability was determined by the broth microdilution method with a combination of honey or solvent extract fraction (80-0.15mg/ml) and clarithromycin and erythromycin (20-0.04μg/ml) prepared in a checkerboard. Time-kill assays were performed at 2, 4, 8 and 24h. At a concentration of 1000μg/ml, no antibacterial activity was observed, with inhibition below 24% for two bacteria. Honey 1 (80mg/ml) and its n-butanol fraction increased the outer membrane permeability of E. faecalis when combined with clarithromycin (20μg/ml), but no effect on membrane permeability of E. faecalis was observed for the remaining r four honey samples and their fractions. None of the samples affected the membrane permeability of S. epidermidis. We concluded that honey 1 increase the antibacterial activity of clarithromycin and erythromycin against E. faecalis, possibly due to the action of flavonoids.
This study evaluated the effects of probiotic administration on growth performance, health status, and fecal microbiota in Holstein calves. Thirty animals were assigned to two groups: the treated group of animals, from 2 to 30 days of age, received a daily oral capsule containing Lactobacillus johnsonii, Ligilactobacillus murinus, Limosilactobacillus mucosae and Ligilactobacillus salivarius (1×109CFU per capsule), whereas the control group received placebo. Health status was monitored using the Wisconsin scoring system, and body weight was recorded at 2 and 60 days of age. Fecal microbiota was characterized at 30±3 days through 16S rRNA gene sequencing. No significant differences were observed between groups regarding diarrhea incidence, weight gain, or microbiota structure. A higher relative abundance of Lactobacillus and Collinsella was observed in the treated group.
The study of vaginal dysfunction in women using various contraceptive methods is relevant, since each method modifies the vaginal microbiota and the host immune response differently. The aims of this study were: (1) To evaluate the prevalence of different contraceptive methods. (2) To evaluate vaginal imbalance, prevalence of bacterial vaginosis (BV), yeasts, trichomoniasis and vaginal inflammatory response (VIR). (3) To characterize Lactobacillus species in patients using different contraceptive methods (oral contraceptive pills (OCPs), condom, copper intrauterine device (Cu-IUD) and tubal ligation (TL). A total of 1326 patients underwent clinical examination and collection of vaginal fornix to study basic vaginal states (BVS) and culture; of these,1303 patients were finally included and divided into five groups: Group 1 (G1) OCs (n=314), Group 2 (G2) condom (n=385), Group 3 (G3) Cu-IUD (n=92), Group 4 (G4) tubal ligation (n=26), Group 5 (G5) control (n=486). The prevalence of vaginal imbalance was higher in G3, 48.9% (OR 1.57, p=0.05) compared to control. G3, 41.3% (OR 1.56, p=0.03) and G4, 50% (OR 2.21, p=0.05) were the groups with higher BV prevalence. The groups with the highest yeast prevalence were G3, 31.5% (OR 1.89, p=0.01) and G4, 38.5% (OR 2.56, p=0.02). Inflammatory states were present in 82.8% (OR 3.8, p=0.01) of G3 with yeasts. G3 had a higher prevalence of VIR of 58.7% (OR 1.71, p=0.01). Group 1 (31.6%) had a prevalence of Lactobacillus crispatus similar to that in the control group. A greater vaginal imbalance, prevalence of BV and yeasts was observed in Cu-IUD users. The microbiota balance and prevalence of L. crispatus was higher in OCP users. Cu-IUD users presented higher VIR.
Dysgonomonas spp. is a microorganism that is occasionally isolated in patients with gastroenteritis, although its clinical relevance remains uncertain. It has also been reported in association with other underlying conditions, especially in immunocompromised individuals. However, the exact role of Dysgonomonas spp. requires further investigation. Our objective was to link the pathogenesis of Dysgonomonas spp. with the clinical context in pediatric patients, evaluating its significance in gastroenteritis and related diseases. This was a retrospective and descriptive prevalence study involving the isolation of Dysgonomonas spp. from the fecal samples of pediatric patients presenting with digestive symptoms (from September 2019 to December 2023). The strains were isolated on a selective medium for Campylobacter spp., identified using the MALDI-TOF method, and their antibiotic sensitivity was assessed. Cases in which other gastrointestinal pathogens were isolated alongside Dysgonomonas spp. were excluded. Fifty cases of patients with Dysgonomonas spp. infection were analyzed, of which 45 (41 D. capnocitophagoides; four D. gadei) met the inclusion criteria. Among these, 77.8% were isolated episodes of gastroenteritis, whereas 22.2% were cases of persistent gastroenteritis (PG). Eighty percent (80%) of the cases occurred in the context of associated pathologies. All strains were sensitive to clindamycin and co-trimoxazole. In cases of alteration of the intestinal microbiota, usually related to specific underlying pathologies and other concomitant factors, Dysgonomonas spp. may act as an opportunistic pathogen.
This study investigates the efficacy of spray-dried Lactiplantibacillus plantarum CIDCA 83114 in a murine model of giardiasis. Mice (C57BL/6) were divided into four groups: control, Giardia-only, probiotic-only, and a combined (probiotic+Giardia, PG) group. Probiotic treatment started one week pre-infection with Giardia intestinalis H7 and continued throughout the study. Infection was monitored through trophozoite counts, intestinal histology, cytokine expression and microbiome analysis. Histology revealed that the administration of strain CIDCA 83114 prior to infection, increases villus/crypt ratios compared with control infected animals. In addition, trophozoite counts in the small intestine were lower in probiotic-treated mice than in infected control animals. Probiotic-treated infected mice showed significantly higher IL-10 expression than untreated controls. Expression of the IL-12 gene was diminished in animals administered with strain CIDCA 83114 (both infected and non-infected with Giardia). In addition, Giardia infection led to a decrease in IFN-γ expression, even when the probiotic-treated animals. Expression of TNF-α increased in the groups treated only with strain CIDCA 83114 and in infected animals. Notably, the PG group exhibited lower values of TNF-α expression, potentially due to the elevated IL-10 levels detected in this group. Dysbiosis associated with Giardia infection led to an increase in Epsilonproteobacteria and Clostridium. These changes were abrogated in the group that received the probiotic strain, which, as expected, showed an increase in Lactobacillaceae. This study demonstrates that spray-dried probiotic L. plantarum CIDCA 83114 has a positive impact on key aspects of Giardia infection, supporting its potential as a preventive or therapeutic strategy for giardiasis.
While Burkholderiales and Eubacteriaceae are associated with colorectal cancer, a causal relationship has not yet been fully established. This study aimed to assess their causal effects and associated plasma metabolites on colorectal cancer. Summary statistics from genome-wide association studies were analyzed for gut microbiota (n=7738), 1400 plasma metabolites (n=8299), and colorectal cancer (n=321040). Genetic correlations were estimated using linkage disequilibrium score regression. Causal relationships were assessed using Mendelian randomization. Furthermore, a two-step mediation analysis was performed to estimate the proportion of the effect of Burkholderiales and Eubacteriaceae on colorectal cancer mediated by plasma metabolites. The inverse variance weighted method was primarily used to estimate the effect. Our results suggested the causal effects of 13 Burkholderiales and eight Eubacteriaceae taxa on colorectal cancer. The positive effect of Oxalobacteraceae, Oxalobacter and Oxalobacter formigenes was potentially mediated by dihomo-linolenoylcarnitine, while the protective effect of Eubacterium siraeum may involve 1-linoleoyl-GPE. Sensitivity analyses indicated no significant heterogeneity or pleiotropy. This study suggests the potential causal effects of the Burkholderiales and Eubacteriaceae taxa on colorectal cancer, with effects potentially mediated by the metabolites dihomo-linolenoylcarnitine and 1-linoleoyl-GPE, respectively. It should be emphasized that these findings are inherently observational in nature and do not establish definitive causality, which is a limitation of the study due to the relaxed statistical threshold for instrumental variable selection and the restriction of the analysis to populations of European ancestry. Further experimental and clinical studies are required to elucidate these mechanistic relationships.
Superficial mycoses are prevalent worldwide. This study analyzed their epidemiology and etiological agents in a general hospital in Buenos Aires. A descriptive, retrospective, and observational study was conducted, including 1584 patients and 1726 samples processed between September 2021 and June 2024. Overall, 57.5% of the samples were positive. Dermatophytosis accounted for 91.3% of the isolates, mainly affecting adult women and pediatric patients. The most frequent clinical manifestations were onychomycosis (66%), tinea corporis (17%), and tinea capitis (14.5%). The predominant species were Trichophyton rubrum (50.1%), Trichophyton tonsurans (36.0%), and Microsporum canis (10.6%). In children, tinea capitis predominated, associated with T. tonsurans and linked to barbershop-related exposure, while in adults, onychomycosis caused by T. rubrum was most common. These findings highlight the need to strengthen epidemiological surveillance and optimize diagnostic and preventive strategies to reduce the impact on the population.
Bloodstream infections (BSIs) are a major cause of morbidity and mortality in immunocompromised hosts, particularly those with malignancies, transplants, or autoimmune diseases. Epidemiologic surveillance is critical to optimize empirical antimicrobial therapy. Our aims were to describe the frequency, clinical and microbiological characteristics of BSIs in immunocompromised patients treated at two hospitals in Córdoba, Argentina. We conducted a retrospective study at two tertiary care centers in Córdoba, Argentina, including adult immunocompromised patients with microbiologically confirmed BSIs between January 2019 and December 2022. Underlying immunosuppression included malignancy, neutropenia, transplantation, or immunosuppressive therapy. Clinical data were analyzed over a 30-day period, and microbiological isolates were characterized. A total of 181 BSI episodes were included; 97 (53.6%) were hospital-acquired (HA-BSI) and 84 (46.4%) community-acquired (CA-BSI). Median age was 62 years (IQR 54.5-71.5), and 101 (55.8%) were male patients. Active malignancy was the most common immunosuppressive condition (n=124, 68.5%). Primary bacteremia occurred in 51 cases (28.2%). Urinary (n=34, 18.8%), intra-abdominal (n=30, 16.6%), and catheter-related infections (n=24, 13.3%) were the leading sources. Gram-negative bacilli (GNB) predominated (n=150, 75.8%), with Escherichia coli (n=71, 35.9%) and Klebsiella pneumoniae (n=30, 15.2%) being the most frequent isolates. Multidrug-resistant organisms (MDRO) were identified in 67 (33.8%) episodes, more commonly in HA-BSI than CA-BSI (37 [46.3%] vs 15 [21.4%], p=0.001). The overall 30-day mortality rate was 24.8% (n=45). This study demonstrated that, in this cohort of immunocompromised adults, BSIs were slightly more often hospital-acquired and associated with substantial mortality. One-third of the isolates were multidrug-resistant organisms (MDROs).
