Part Of Human Microbiota Research Articles

Finegoldia magna: An Infrequent Guest in Orthopedic Infections.

Background: Finegoldia magna is a species of anaerobic gram-positive coccus considered part of human microbiota. It has been described as a cause of skin and soft tissue infections, but it is not a common cause of operation-related infections. Objectives: Describe the characteristics, treatment, and results of musculoskeletal infection by F. magna treated in our center. Methods: We performed a descriptive, retrospective observational study. Clinical records of all musculoskeletal surgical infections treated in our department between 2012 and 2022 were reviewed. We selected the patients with a positive culture for F. magna. Risk factors for infection, patient's medical records, previous operation performed, time from surgical procedure to infection, susceptibility tests, antibiotic and surgical treatment for the infection, and recovery rate were registered for the analysis. Results: Twenty patients have positive cultures for F. magna, representing 15.5% of the anaerobic infections. Eleven of them were arthroplasties, three fracture synthesis, two foot operations, two spinal operations, and two soft tissue operations. All patients underwent operation and antibiotic treatment. The most commonly used antibiotic scheme was amoxicillin followed by amoxicillin-rifampicin. Eighty percent of the patients achieved a complete clinical recovery with a mean of 2.1 surgical procedures. Patients with polymicrobial infections required twice the number of operations (p = 0.047) and exhibited a failure rate of 36% compared with 0% for monomicrobial cases (p = 0.043). Conclusions: Orthopedic infections caused by F. magna are infrequent, but they usually have good outcomes. Polymicrobial infection with F. magna exhibits poorer clinical results and requires a greater number of operations compared with monomicrobial ones.

Distribution and antifungal susceptibility of clinical Trichosporon spp. isolates: 10 years of single-center experience

Purpose: The genus Trichosporon, which is a yeast-like basidiomycete, is ubiquitous in nature and a part of human microbiota. It’s an oppurtunistic fungal pathogen, which was once rare, but increasing dramatically recently, leading to fatal infections. The aim of this study was to determine the prevalence, and antifungal susceptibility of clinical Trichosporon spp. isolates, and to determine whether there was a change in incidence during the COVID-19 Pandemic. 
 Materials and Methods: This was a retrospective cross-sectional descriptive study, conducted between January 1, 2013 and February 5, 2023. Cultures which Trichosporon spp. isolated (n=125) were screened, and those met the eligibility criteria were included (n=77). Identification, antifungal susceptibility test results, age, gender records were identified from Microbiology Laboratory Information Management System. 
 Results: 97.4% of the isolates were Trichosporon asahii, and 2.6% were Trichosporon mucoides. The most frequent isolation period was the 2016 and 2019 year group (71.4%), not during the COVID-19 Pandemics (19.5%). The most common sample type was urine (58.4%), of whom predominantly (58.4%) hospitalized in the Intensive Care Unit. Amphotericin B MICs were ≤1µg/ml in 68.9% of the isolates. Fluconazole and voriconazole MICs were ≤1µg/ml in 20.0% and 94.8%, respectively. 59.7% of the isolates had a MIC of ≥4µg/ml for flucytosine. Micafungin and caspofungin MICs were ≥4µg/ml in 88.3% and 92.2% of the isolates, respectively. Voriconazole had the strongest in vitro activity, and amphotericin B had lower MICs than expected. The combination therapy of voriconazole and amphotericin B could be a therapeutic option in this setting, as well as monotherapy of voriconazole.
 Conclusion: Trichosporon spp. isolated in clinical specimens and their antifungal susceptibility depend on the geographic region and the anatomic site. Identifying local data will contribute to both the management of these patients, and surveillance studies.

Elizabethkingia miricola: an opportunistic pathogen in ICU

Abstract Background The Elizabethkingia genus is formed by a group of bacteria which are widely distributed in nature. Elizabethkingia is not part of human microbiota, therefore is considered to be an opportunistic pathogen. In the last years, it has become a cause of potentially fatal disease, becoming an emerging bacteria of increasing relevance. The objective of this study is to describe the impact of Elizabethkingia bacteria in infected patients in the ICU of a hospital in Granada. Methods Descriptive study. Patients who have been isolated in a biological sample of Elizabethkingia miricola throughout the year 2.021 in the ICU of San Cecilio University Hospital in Granada. Date and place of isolation were registered. Other variables registered were sex, age, length of ICU stay, days between ICU admission and bacterium isolation, days between bacterium isolation and death, infection, cause of admission or cause of death. Results Bacterium was isolated in 15 patients. Cause of admission was COVID-19 in 73.3% of patients. 73.3% were men and 26.6% women.The average age was 56.9 years. The average length of ICU stay was 43.8 days. 4 patients were diagnosed with ventilator-associated pneumonia and 5 patients were diagnosed with tracheobronchitis.The average days between ICU admission and bacterium isolation was 26,4 days. The average days between mechanical ventilation and bacterium isolation was 25.9 days. 53.3% of patients died. The average days between bacteria isolation and death was 18.2 days. Conclusions Elizabethkingia miricola is an emerging bacterium under special vigilance due to its capacity to cause major morbidity and mortality in admitted patients in ICU. The rapid identification and the study of the antibiotic susceptibility is considered of special relevance so they can be correctly managed to avoid infections and complications resulting from this microorganism. Key messages • Elizabethkingia is a special surveillance bacterie due to its morbidity and mortality effects. • Elizabethkingia could be a severity indicator in admitted patients to the ICU.

Emerging enterococcus pore-forming toxins with MHC/HLA-I as receptors

Enterococci are a part of human microbiota and a leading cause of multidrug resistant infections. Here, we identify a family of Enterococcus pore-forming toxins (Epxs) in E.faecalis, E.faecium, and E.hirae strains isolated across the globe. Structural studies reveal that Epxs form a branch of β-barrel pore-forming toxins with a β-barrel protrusion (designated the top domain) sitting atop the cap domain. Through a genome-wide CRISPR-Cas9 screen, we identify human leukocyte antigen class I (HLA-I) complex as a receptor for two members (Epx2 and Epx3), which preferentially recognize human HLA-I and homologous MHC-I of equine, bovine, and porcine, but not murine, origin. Interferon exposure, which stimulates MHC-I expression, sensitizes human cells and intestinal organoids to Epx2 and Epx3 toxicity. Co-culture with Epx2-harboring E.faecium damages human peripheral blood mononuclear cells and intestinal organoids, and this toxicity is neutralized by an Epx2 antibody, demonstrating the toxin-mediated virulence of Epx-carrying Enterococcus.

Impact of tobacco smoking on oral microbiota – a case-control study.

Oral microbiota is a vital part of human microbiota, including bacterial, protozoa, viral and fungal species. Beneficial microbes form biofilms to form a first-line defense against harmful microorganisms. Tobacco smoking is considered a major environmental factor affecting the orodental microbiota. Smokers harbor more pathogenic microbes than non-smokers. In fact, cigarette smoking exposes the oral cavity to a large number of toxicants, perturbing the oral microbial ecology through various mechanisms. In Saudi Arabia, research on the impact of tobacco smoking on oral microbiota is still lacking. Therefore, this case-control study is an important addition to the literature in terms of tobacco use and its effects on oral microbiota and oral hygiene. 130 men were recruited for this study, including 65 smokers and 65 non-smokers. The following parameters were recorded for all 130 participants – age, weight, height and education. The aim of this study was to investigate and compare the effect of tobacco smoking on the oral microbiome of smokers and non-smokers. The majority of the smokers were young adults between the ages of 21 and 30 inclusive (n=27). The results show that excessive microorganism growth was seen in smokers to a greater degree than non-smokers (38.5% of smokers vs. 8.8% of non-smokers). Not surprisingly, a significant majority (85.3%) of non-smokers had moderate microorganism growth compared to only 53.8% of smokers. cigarette smoking facilitates excessive growth of oral microorganisms, predisposing smokers to various periodontal diseases. In fact, smoking perturbs the balance of oral microbiota, producing a viable environment for microbes to cause diseases. Further large scale prospective studies are required to determine the exact mechanism that causes tobacco to affect oral microbiota.

ANTIMICROBIAL SUSCEPTIBILITY OF ENTEROBACTERIACAEISOLATED FROM INTESTINAL MICROBIOTA OF RESIDENTS OF THE REPUBLIC OF GUINEA AND RUSSIA (SAINT PETERSBURG)

It is known that resistant Enterobacteriacaestrains can be a part of human microbiota. While colonizing the body of a healthy person, resistant strains do not cause diseases, while the healthy person becomes carrier and source of such strains or the resistance genes to the external environment. The aim of the study was to compare the antimicrobial susceptibility of opportunistic Enterobacteriacaeisolated from feces of residents of the Republic of Guinea (121 strains) and Russia, Saint Petersburg (897 strains). The antimicrobial susceptibility was determined by the disc-diffusion method according to the national russian Clinical Guideline “Antimicrobial susceptibility testing of microorganisms” using discs and Muller-Hinton agar manufactured by Oxoid. Resistance mechanisms were tested in bacterial strains non-susceptible to beta- lactams using confirmatory phenotypic and molecular tests. Resistant strains were detected significantly more often in the intestinal microbiota of residents of the Republic of Guinea, than of Saint Petersburg (83.5 and 28.7 per 100 strains studied, respectively), including strains with multidrug resistance (47.9 and 11.1, respectively). The residents of the Republic of Guinea have a high frequency of isolation of Enterobacteriacaeresistant to “old” antibiotics, which were often used in the 1970s, but rarely used in Russia and other European countries: tetracyclines (63.2), trimethoprim/ sulfamethoxazole (59.5) and aminopenicillins (48.4). The frequency of detection of strains resistant to modern clinically significant antibiotics (extended spectrum cephalosporins, f luoroquinolones, aminoglycosides) was the same in residents of the Republic of Guinea and Saint Petersburg. Resistance to beta-lactams in Enterobacteriacaestrains isolated both from the residents of the Republic of Guinea and from Saint Petersburg is due to the same mechanism — the production of beta-lactamases — broadspectrum and extended spectrum- of various genetic families. This data corresponds to world global trends in the antimicrobial resistance in Enterobacteriacae: resistance to aminopenicillins in E. coliis due to the production of broad-spectrum beta-lactamases TEM-1 (80% of strains from residents of the Republic of Guinea and 86.5% from Saint Petersburg), and resistance to extended spectrum cephalosporins — the production of extended spectrum beta-lactamases of the CTX-M1 genetic group (72.7 and 67.6% respectively). Our research has shown that the intestinal microbiota of the inhabitants of different continents (Europe and Africa) contains the strains (Klebsiella pneumoniae and Escherichia coli) resistant to clinically significant antibiotics (beta-lactams) due to single mechanism globally spread in Enterobacteriacae.

Archaea associated with human surfaces: not to be underestimated.

Over 40 years ago, Carl Woese and his colleagues discovered the existence of two distinctly different groups of prokaryotes-Bacteria and Archaea. In the meantime, extensive research revealed that several hundred of bacterial species are intensely associated with humans' health and disease. Archaea, originally identified and described to occur mainly in extreme environments, have been shown to be ubiquitous and to appear frequently and in high numbers as part of human microbiota in recent years. Despite the improvement in methodologies leading to increased detection, archaea are often still not considered in many studies focusing on the interdependency between members of the microbiota and components of the human immune system. As a consequence, the knowledge on functional role(s) of archaeal species within the human body is mainly limited to their contribution to nutrient degradation in the intestine, and evidence for immunogenic properties of archaea as part of the human microbiota is generally rare. In this review, the current knowledge of human mucosa-associated archaeal species, their interaction with the human immune system and their potential contribution to humans' health and disease will be discussed.