Change in Tissue Microbiome and Related Human Beta Defensin Levels Induced by Antibiotic Use in Bladder Carcinoma.

It is now generally accepted that the success of antitumor therapy can be impaired by concurrent antibiotic therapy, the presence of certain bacteria, and elevated defensin levels around the tumor tissue. The aim of our current investigation was to identify the underlying changes in microbiome and defensin levels in the tumor tissue induced by different antibiotics, as well as the duration of this modification. The microbiome of the tumor tissues was significantly different from that of healthy volunteers. Comparing only the tumor samples, no significant difference was confirmed between the untreated group and the group treated with antibiotics more than 3 months earlier. However, antibiotic treatment within 3 months of analysis resulted in a significantly modified microbiome composition. Irrespective of whether Fosfomycin, Fluoroquinolone or Beta-lactam treatment was used, the abundance of Bacteroides decreased, and Staphylococcus abundance increased. Large amounts of the genus Acinetobacter were observed in the Fluoroquinolone-treated group. Regardless of the antibiotic treatment, hBD1 expression of the tumor cells consistently doubled. The increase in hBD2 and hBD3 expression was the highest in the Beta-lactam treated group. Apparently, antibiotic treatment within 3 months of sample analysis induced microbiome changes and defensin expression levels, depending on the identity of the applied antibiotic.

Rapid detection of CTX-M-type ESBLs and carbapenemases directly from biological samples using the BL-DetecTool.

BACKGROUND: Lateral flow immunoassays (LFIA) have shown their usefulness for detecting CTX-M- and carbapenemase-producing Enterobacterales (CPEs) in bacterial cultures. Here, we have developed and validated the BL-DetecTool to detect CTX-M enzymes and carbapenemases directly from clinical samples. METHODS: The BL-DetecTool is an LFIA that integrates an easy sample preparation device named SPID (Sampling, Processing, Incubation and Detection). It was evaluated in three University hospitals on urine, blood culture (BC) and rectal swab (RS) specimens either of clinical origin or on spiked samples. RS evaluation was done directly and after a 24 h enrichment step. RESULTS: The CTX-M BL-DetecTool was tested on 485 samples (154 BC, 150 urines, and 181 RS) and revealed a sensitivity and specificity of 97.04% (95% CI 92.59%-99.19%) and 99.43% (95% CI 97.95%-99.93%), respectively. Similarly, the Carba5 BL-DetecTool was tested on 382 samples (145 BC, 116 urines, and 121 RS) and revealed a sensitivity and specificity of 95.3% (95% CI 89.43%-98.47%) and 100% (95% CI 98.67%-100%), respectively. While with the Carba5 BL-DetecTool five false negatives were observed, mostly in RS samples, with the CTX-M BL-DetecTool, in addition to four false-negatives, two false-positives were also observed. Direct testing of RS samples revealed a sensitivity of 78% and 86% for CTX-M and carbapenemase detection, respectively. CONCLUSIONS: BL-DetecTool showed excellent biological performance, was easy-to-use, rapid, and could be implemented in any microbiology laboratory around the world, without additional equipment, no need for electricity, nor trained personnel. It offers an attractive alternative to costly molecular methods.

Interactions between immune system and the microbiome of skin, blood and gut in pathogenesis of rosacea.

The increasingly wide use of next-generation sequencing technologies has revolutionised our knowledge of microbial environments associated with human skin, gastrointestinal tract and blood. The collective set of microorganisms influences metabolic processes, affects immune responses, and so directly or indirectly modulates disease. Rosacea is a skin condition of abnormal inflammation and vascular dysfunction, and its progression is affected by Demodex mites on the skin surface. When looking into the effects influencing development of rosacea, it is not only the skin microbiome change that needs to be considered. Changes in the intestinal microbiome and their circulating metabolites, as well as changes in the blood microbiome also affect the progression of rosacea. Recent research has confirmed the increased presence of bacterial genera like Acidaminococcus and Megasphera in the intestinal microbiome and Rheinheimera and Sphingobium in the blood microbiome of rosacea patients. In this review we discuss our current knowledge of the interactions between the immune system and the skin, gut and blood microbiome, with particular attention to rosacea diagnostic opportunities.

High prevalence of group B streptococcus ST17 hypervirulent clone among non-pregnant patients from a Hungarian venereology clinic.

BACKGROUND: Although Streptococcus agalactiae is the leading causative agent of neonatal sepsis and meningitis, recently it is increasingly isolated from non-pregnant adults. The relation between its presence in the genitourinary tract and manifested clinical symptoms of STD patients remains an open question. In this study, a complex epidemiological investigation of GBS isolates from a venerology clinic was performed. METHODS: Ninety-six GBS isolates were serotyped and their genetic relatedness determined by PFGE. MLST was also performed for a subset of 20 isolates. The antibiotic susceptibility was tested with agar dilution. Surface proteins and the ST-17 hypervirulent clone was detected by PCR. RESULTS: The serotype prevalence was the following: V (29.2%), III (27.1%), Ia (22.9%), IV (10.4%), II (5.2%) and Ib (4.2%). A strong association was demonstrated between surface protein genes and serotypes. All isolates were fully susceptible to penicillin, but erythromycin and clindamycin resistance was high (41.7 and 35.4%, respectively), and 8 phenotypically macrolide sensitive isolates carried the ermB gene. 21.9% of all strains belonged to the hypervirulent ST17 clone, most being of serotype III and all were rib +. We found a few serotype IV isolates belonging to several STs and one serotype V/ST110 strain, containing a 44-bp deletion in the atr allele. CONCLUSIONS: The presence of silent ermB genes is of worry, as their expression upon macrolide exposure could lead to unforeseen therapeutic failure, while clindamycin is used for intrapartum antibiotic prophylaxis, in case of penicillin allergy. The other alarming result is the high prevalence of ST17 among these strains from STD patients, who could be sources of further infections. This is the first report from Hungary providing both serotyping and genotyping data of GBS isolates. These results could be helpful for vaccine production as the major vaccine candidates are capsular antigens or surface proteins.

Clinical and microbiological characteristics and outcomes of community-acquired sepsis among adults: a single center, 1-year retrospective observational cohort study from Hungary.

BACKGROUND: Community-acquired sepsis is a life-threatening systemic reaction, which starts within ≤72 h of hospital admittance in an infected patient without recent exposure to healthcare risks. Our aim was to evaluate the characteristics and the outcomes concerning community-acquired sepsis among patients admitted to a Hungarian high-influx national medical center. METHODS: A retrospective, observational cohort study of consecutive adult patients hospitalized with community-acquired sepsis during a 1-year period was executed. Clinical and microbiological data were collected, patients with pre-defined healthcare associations were excluded. Sepsis definitions and severity were given according to ACCP/SCCM criteria. The primary outcome was in-hospital all-cause mortality. Secondary outcomes were intensive care unit (ICU) admittance, length-of-stay (LOS), source control and bacteraemia rates. Statistical differences were explored with classical comparison tests, predictors of in-hospital all-cause mortality were modelled by multivariate logistic regression. RESULTS: 214 patients (median age 60.0 ± 33.1 years, 57% female, median Charlson score 4.0 ± 5.0) were included, 32.7% of them (70/214) had severe sepsis, and 28.5% (61/214) had septic shock. Prevalent sources of infections were genitourinary (53/214, 24.8%) and abdominal (52/214, 24.3%). The causative organisms were dominantly E. coli (60/214, 28.0%), S. pneumoniae (18/214, 8.4%) and S. aureus (14/214, 6.5%), and bacteraemia was documented in 50.9% of the cases (109/214). In-hospital mortality was high (30/214, 14.0%), and independently associated with shock, absence of fever, male gender and the need for ICU admittance, but source control and de-escalation of empirical antimicrobial therapy were protective. ICU admittance was 27.1% (58/214), source control was achieved in 18.2% (39/214). Median LOS was 10.0 ± 8.0, ICU LOS was 8.0 ± 10.8 days. CONCLUSIONS: Community-acquired sepsis poses a significant burden of disease with characteristic causative agents and sources. Patients at a higher risk for poor outcomes might be identified earlier by the contributing factors shown above.

Clinical and microbiological characteristics of adult invasive Haemophilus influenzae infections: results of a 14-year single-center experience from Hungary.

To describe the characteristics of adult invasive H. influenzae disease, 34 patients diagnosed at a single tertiary center between 2004 and 2017 were analyzed in a retrospective case series study. The annual estimated incidence was 0.1 cases/100.000 inhabitants. Dominant source of infection was pneumonia accompanied by sepsis (62%) and caused by nontypeable strains (74%) with low ampicillin resistance (14%). Survival (94%) and complication rates were high (35%). Main empirical treatments were ceftriaxone or levofloxacine.

Transdermally administered proline-arginine-rich host defense peptides show systemic efficacy in a lethal mouse bacteremia model.

Host defense peptides are preferably administered as topical therapeutic agents. We have investigated whether peptide A3-APO can enter the circulation when applied to the ear skin. Efficacy of peptide monotherapy as transdermal administration option was assessed in a systemic mouse Acinetobacter baumannii model. A3-APO reduced mortality and demonstrated a statistically significant reduction of blood bacterial counts, regardless whether it was administered prior or after bacterial challenge. The peptidic metabolite of A3-APO was efficacious when applied to the ear or tail.

Pharmacokinetics and in vivo efficacy of optimized oncocin derivatives.

OBJECTIVES: To evaluate the efficacy of antimicrobial peptide Onc112 in a lethal Escherichia coli infection model and the pharmacokinetics of Onc72 and Onc112 administered intravenously or intraperitoneally in mice. METHODS: Onc72, Onc112 and their major metabolites in blood, kidneys, liver, brain and urine were quantified by MS using multiple reaction monitoring (MRM) and isotope-labelled peptides. RESULTS: Onc112 rescued all animals when administered intraperitoneally at a dose of 2.5 mg/kg and was thus slightly more efficient than Onc72. The MRM method provided limits of quantification in plasma, urine and kidney, liver and brain homogenates of 7-80 µg/L, well below the MICs of 2-4 mg/L. Onc72 and Onc112 reached all organs within 10 min when administered intraperitoneally (5 mg/kg). Their initial concentrations in plasma were 11.9 and 22.6 mg/L, respectively, with elimination t1/2 values of ∼14 and 21 min. The peptide concentrations in blood remained above their MICs for 20 min for Onc72 and 80 min for Onc112. The highest peptide concentrations were detected in kidney homogenates, which also contained the highest content of metabolites, indicating, together with the results from analysis of urine samples, that both peptides are cleared through the kidneys. CONCLUSIONS: Onc72 and Onc112 reach organs, including the brain, within 10 min after intravenous and intraperitoneal administration. Onc112 remained in blood at concentrations above its MIC for 80 min. The pharmacokinetic profiles explain the high in vivo efficacies in models of systemic infection and indicate the potential use of these agents for the treatment of urinary tract infections.

Polyvinyl alcohol nanofiber formulation of the designer antimicrobial peptide APO sterilizes Acinetobacter baumannii-infected skin wounds in mice.

Native and designer cationic antimicrobial peptides are increasingly acknowledged as host defense molecules rather than true antimicrobials. Due to their ability to activate the innate immune system, these structures are used to treat uninfected and bacterially-infected wounds, including those harboring Acinetobacter baumannii. Previously we documented that when administered intramuscularly or topically in liquid formulations, the proline-rich host defense peptide dimer A3-APO accelerates uninfected wound re-epithelization and eliminates systemic and local A. baumannii, methicillin-resistant Staphylococcus aureus and other pathogen load from infected lesions better than conventional antibiotics. In the current study we sought to produce and characterize a novel delivery system, suitable for immediate and convenient application in non-hospital environments. The APO monomer was incorporated into polyvinyl alcohol nanofibers and the complex was polymerized into a solid patch dressing. Mice were subjected to skin abrasion where the wounds were either left uninfected or were inoculated with a near lethal dose of multidrug resistant A. baumannii strain. Analyzed after 3 days, APO monomer-containing patches improved wound appearance significantly better than polymer patches without antibiotics. When compared to colistin, the APO patches accelerated wound healing, and statistically significantly reduced wound size and wound bacterial load. The in vivo antimicrobial effect was more extensive than after intramuscular administration of the peptide drug, by using only one tenth of the active pharmaceutical ingredient. These data suggest that the APO monomer-impregnated nanofiber dressing can be developed as an economical first-line treatment option to skin injuries in general and battlefield burn and blast injuries in particular.

Emerging azithromycin-resistance among the Neisseria gonorrhoeae strains isolated in Hungary.

BACKGROUND: In the 1990s, azithromycin became the drug of choice for many infectious diseases but emerging resistance to the drug has only been reported in the last decade. In the last 5 years, the National Neisseria gonorrhoeae Reference Laboratory of Hungary (NNGRLH) has also observed an increased number of N. gonorrhoeae strains resistant to azithromycin. The aim of this study was to determine the most frequent sequence types (ST) of N. gonorrhoeae related to elevated levels of azithromycin MIC (minimal inhibitory concentration). Previously and currently isolated azithromycin-resistant strains have been investigated for the existence of molecular relationship. METHODS: Maldi-Tof technic was applied for the identification of the strains isolated from outpatients attending the reference laboratory. Testing antibiotic susceptibility of azithromycin, cefixime, ceftriaxone, tetracycline, spectinomycin and ciprofloxacin was carried out for all the identified strains, using MIC strip test Liofilchem(®). N. gonorrhoeae multiantigen sequence typing (NG-MAST) was performed exclusively on azithromycin-resistant isolates. A phylogenetic tree was drawn using MEGA6 (Molecular Evolutionary Genetics Analysis Version 6.0) Neighbour-Joining method. RESULTS: Out of 192 N. gonorrhoeae isolates, 30.0 % (58/192) proved resistant to azithromycin (MIC > 0.5 mg/L). Of the azithromycin-resistant isolates, ST1407, ST4995 and ST11064 were the most prevalent. Based on the phylogenetic analysis, the latter two STs are closely related. CONCLUSIONS: In contrast to West-European countries, in our region, resistance to azithromycin has increased up to 30 % in the last 5 years, so the recommendation of the European Guideline -500 mg of ceftriaxone combined with 2 g of azithromycin as first choice therapy against N. gonorrhoeae- should be seriously considered in case of Hungary.

[Yeast species in vulvovaginitis candidosa]. / Vulvovaginitis candidosában eloforduló sarjadzógomba-speciesek.

INTRODUCTION: Vulvovaginal candidiasis is the most common mycosis, however, the available information about antifungal susceptibilities of these yeasts is limited. AIM: To compare the gold standard fungal culture with a new molecular identification method and report the incidence of yeast species in vulvovaginitis candidosa. METHOD: The authors studied 370 yeasts isolated from vulvovaginal candidiasis and identified them by phenotypic and molecular methods. RESULTS: The most common species was Candida albicans (85%), followed by Candida glabrata, and other Candida species. CONCLUSION: At present there are no recommendations for the evaluation of antifungal susceptibility of pathogenic fungal species occurring in vulvovaginal candidiasis and the natural antifungal resistance of the different species is known only. Matrix Assisted Laser Desorption Ionization Time of Flight identification can be used to differentiate the fluconazole resistant Candida dubliniensis and the sensitive Candida albicans strains.

[Antimicrobal resistance of Neisseria gonorrhoeae strains in Hungary]. / Neisseria gonorrhoeae törzsek rezisztenciaadatai Magyarországon.

INTRODUCTION: European guidelines on the treatment of Neisseria gonorrhoeae are based mostly on Western European data, although these recommendations may not be optimised for the circumstances in Hungary. AIM: The aim of the authors was to assess current antimicrobial resistance of Neisseria gonorrhoeae strains in order to enhance gonococcal antimicrobial surveillance in Hungary. Neisseria gonorrhoeae strains were isolated at the National Center of Sexually Transmitted Infections at the Department of Dermatology, Venerology and Dermatooncology of Semmelweis University in the period between January 2011 and June 2014. METHOD: Antimicrobial resistance was determined with minimum inhibitory concentration measurement. Neisseria gonorrhoeae Multiantigen Sequence typing was used as molecular typing method. RESULTS: Resistance to the currently recommended extended spectrum cephalosporins is rare in Hungary, but there is an emerging azithromycin resistance among the Neisseria gonorrhoeae strains. CONCLUSIONS: Revision of the national treatment guideline must consider that the most frequent sequence types of Neisseria gonorrhoeae strains causing infections in Hungary are mainly resistant to azithromycin.

[Lymphogranuloma venereum: the first Hungarian cases]. / Lymphogranuloma venereum: elso hazai esetek.

Lymphogranuloma venereum is a sexually transmitted infection caused by the Chlamydia trachomatis serovars L1-3. It has been found to be endemic in tropical countries. In the last decades several cases have been reported in Western Europe, particularly in men who have sex with men population infected with human immunodeficiency virus. The authors present three cases of lymphogranuloma venereum infections, observed at their department in 2013 and 2014. The three human immunodeficiency virus infected patients who belonged to men who have sex with men population had casual sexual contacts in Western Europe. The symptoms included urethral discharge, discomfort and inguinal lymphadenomegaly in two patients, and rectal pain, discharge and perianal ulceration in one patient. The diagnosis was confirmed by nucleic acid amplification test performed in samples obtained from urethral discharge and exudate of perianal ulcer; lymphogranuloma venereum 2b serovars were demonstrated in two patients and serovar 2 in one patient. Doxycyclin (daily dose of two times 100 mg for 21 days) resolved the symptoms in all cases. The authors conclude that lymphogranuloma venereum is a diagnostic challenge in Hungary, too. It is important to be aware of the altered clinical features of this disease to prevent complications and spreading.

[Development of new magistral method for the preparation of artificial tears]. / Korszeru tartósítási módszer fejlesztése magisztrálisan eloállítható mukönnyhöz.

Nowadays, large part of the population in Hungary is affected by the dry eye disease or symptom. Most of these magistral pharmaceuticals (FoNo VI) compared to the industrial products have disadvantages. They are not compatible with contact lenses, because of the preservatives and after opening they can be used only for seven days. In our experiments we used sodium-perborate as preservative, which could be a solution for the problems mentioned above. Our results indicate that the sodium-perborate sterilized the solution and resists against microbiological contamination. Its preservative effect maintained for more than four weeks. Our further purpose is to develop a new pharmacy drug preparation method to find an effective solution for the microbiological stability-related problems of artificial tears.

The designer leptin antagonist peptide Allo-aca compensates for short serum half-life with very tight binding to the receptor.

The leptin receptor antagonist peptide Allo-aca exhibits picomolar activities in various cellular systems and sub-mg/kg subcutaneous efficacies in animal models making it a prime drug candidate and target validation tool. Here we identified the biochemical basis for its remarkable in vivo activity. Allo-aca decomposed within 30 min in pooled human serum and was undetectable beyond the same time period from mouse plasma during pharmacokinetic measurements. The C max of 8.9 µg/mL at 5 min corresponds to approximately 22% injected peptide present in the circulation. The half-life was extended to over 2 h in bovine vitreous fluid and 10 h in human tears suggesting potential efficacy in ophthalmic diseases. The peptide retained picomolar anti-proliferation activity against a chronic myeloid leukemia cell line; addition of a C-terminal biotin label increased the IC50 value by approximately 200-fold. In surface plasmon resonance assays with the biotin-labeled peptide immobilized to a NeutrAvidin-coated chip, Allo-aca exhibited exceptionally tight binding to the binding domain of the human leptin receptor with ka = 5 × 10(5) M(-1) s(-1) and kdiss = 1.5 × 10(-4) s(-1) values. Peptides excel in terms of high activity and selectivity to their targets, and may activate or inactivate receptor functions considerably longer than molecular turnovers that take place in experimental animals.

Semisynthetic teicoplanin derivatives as new influenza virus binding inhibitors: synthesis and antiviral studies.

In order to obtain new, cluster-forming antibiotic compounds, teicoplanin pseudoaglycone derivatives containing two lipophilic n-octyl chains have been synthesized. The compounds proved to be poor antibacterials, but, surprisingly, they exhibited potent anti-influenza virus activity against influenza A strains. This antiviral action was related to inhibition of the binding interaction between the virus and the host cell. Related analogs bearing methyl substituents in lieu of the octyl chains, displayed no anti-influenza virus activity. Hence, an interaction between the active, dually n-octylated compounds and the lipid bilayer of the host cell can be postulated, to explain the observed inhibition of influenza virus attachment.

Incidence and antimicrobial susceptibility of Neisseria gonorrhoeae isolates from patients attending the national Neisseria gonorrhoeae reference laboratory of Hungary.

BACKGROUND: The Hungarian national guidelines for the treatment of gonorrhoea were published in 2002 but are now widely considered to be outdated. Improved knowledge is needed with respect to the epidemiology and antimicrobial susceptibility of Neisseria gonorrhoeae strains currently circulating in Hungary not least for the construction of updated local recommendations for treating gonorrhoea. European guidelines are based mostly on western European data raising concerns locally that recommended treatments might not be optimised for the situation in Hungary. We report our recent study on the distribution of antibiotic resistance in various Hungarian (East European) Neisseria gonorrhoeae strains isolated from patients with gonorrhoea over the past four years. METHODS: Between January 2010 and December 2013, isolates of N. gonorrhoeae were obtained from sexually active individuals during medical examination at the STD Center of Semmelweis University in Budapest. The minimal inhibitory concentrations (MIC) of azithromycin, cefixime, ceftriaxone, ciprofloxacin, penicillin, tetracycline and spectinomycin were determined to establish the antimicrobial susceptibility of the strains currently circulating in patients that attend our clinic. RESULTS: Among the 9097 patients tested, 582 had an N. gonorrhoeae infection as detected by culture. The isolates were all sensitive to ceftriaxone and spectinomycin and 581/582 strains were sensitive to cefixime. In contrast, the number of detected strains with elevated azithromycin MIC did increase over the time period examined to approximately 16% in 2013. There was a high percentage of detected resistance to penicillin (77%), tetracycline (86%), and ciprofloxacin (66%) in the isolates examined in this study. CONCLUSION: Current European guidelines recommend 2 g azithromycin in addition to 500 mg ceftriaxone as first choice therapy for gonorrhoea. For the purposes of revising the Hungarian national treatment guidelines, apparent increasing resistance to azithromycin during the last four years should be accounted for. It is also clear that penicillin, tetracycline and ciprofloxacin are inappropriate treatment measures at least locally. We also recommend that culture should form part of the diagnostic pathway of gonorrhoea, followed by antibiotic susceptibility testing with MIC determination. This will provide valuable continued monitoring of antibiotic resistance development in strains of Neisseria gonorrhoeae circulating in Hungary.

[Purulent keratoconjunctivitis due to Neisseria gonorrhoeae and Chlamydia trachomatis coinfection]. / Conjunctivitis gonorrhoica szövodése Chlamydia trachomatis-infekcióval.

Gonococcal conjunctivitis is a rare infection induced by Neisseria gonorrhoeae and it usually manifests as a hyperacute purulent conjunctivitis. Ocular access of the infectious secretion during sexual intercourse is the way of transmission among adults. Inclusion conjunctivitis caused by the serovars D-K of Chlamydia trachomatis also affects the sexually active population. Authors present a case of a 33-year-old homosexual man who was treated for late latent syphilis formerly. Clinical symptoms were yellow purulent discharge for 3 weeks without any urological or upper respiratory tract symptoms. Conjunctival Neisseria gonorrhoeae and Chlamydia trachomatis infection was identified using cultures and polymerase chain reaction; pharyngeal swab culture and polymerase chain reaction showed positive results for both pathogens. The patient was probably under influence of party drugs at the time of sexual abuse when he became infected. After parenteral and oral cephalosporin and azithromycin therapy the patient had complete recovery within three weeks.

NADH and NADPH peroxidases as antioxidant defense mechanisms in intestinal sulfate-reducing bacteria.

Animal and human feces typically include intestinal sulfate-reducing bacteria (SRB). Hydrogen sulfide and acetate are the end products of their dissimilatory sulfate reduction and may create a synergistic effect. Here, we report NADH and NADPH peroxidase activities from intestinal SRB Desulfomicrobium orale and Desulfovibrio piger. We sought to compare enzymatic activities under the influence of various temperature and pH regimes, as well as to carry out kinetic analyses of enzymatic reaction rates, maximum amounts of the reaction product, reaction times, maximum rates of the enzyme reactions, and Michaelis constants in cell-free extracts of intestinal SRB, D. piger Vib-7, and D. orale Rod-9, collected from exponential and stationary growth phases. The optimal temperature (35 °C) and pH (7.0) for both enzyme's activity were determined. The difference in trends of Michaelis constants (Km) during exponential and stationary phases are noticeable between D. piger Vib-7 and D. orale Rod-9; D. orale Rod-9 showed much higher Km (the exception is NADH peroxidase of D. piger Vib-7: 1.42 ± 0.11 mM) during the both monitored phases. Studies of the NADH and NADPH peroxidases-as putative antioxidant defense systems of intestinal SRB and detailed data on the kinetic properties of this enzyme, as expressed by the decomposition of hydrogen peroxide-could be important for clarifying evolutionary mechanisms of antioxidant defense systems, their etiological role in the process of dissimilatory sulfate reduction, and their possible role in the development of bowel diseases.

Specific nasopharyngeal Corynebacterium strains serve as gatekeepers against SARS-CoV-2 infection.

The SARS-CoV-2 virus is still causing a worldwide problem. The virus settles primarily on the nasal mucosa, and the infection and its course depend on individual susceptibility. Our aim was to investigate the nasopharynx composition's role in the individual susceptibility. During the first phase of SARS-CoV-2 pandemic, nasopharyngeal microbiome samples of close contact unvaccinated patients were investigated by 16S rRNA analysis and by culturing. The whole genome of cultured Corynebacteria was sequenced. The relative expression of ACE2, TMPRSS2, and cathepsin L on Caco-2 cells and the strength of S1-ACE2 binding were determined in the presence of Corynebacteria. From 55 close contacts exposed to identical SARS-CoV-2 exposure, 26 patients became infected and 29 remained uninfected. The nasopharyngeal microbiome analysis showed significantly higher abundance of Corynebacteria in uninfected group. Corynebacterium accolens could be cultivated only from uninfected individuals and Corynebacterium propinquum from both infected and uninfected. Corynebacteria from uninfected patient significantly reduced the ACE2 and cathepsin L expression. C. accolens significantly reduced the TMPRSS2 expression compared to other Corynebacteria. Furthermore, Corynebacterium spp. weakened the binding of the S1-ACE2. Most C. accolens isolates harbored the TAG lipase LipS1 gene. Based on these results, the presence of Corynebacterium spp. in the nasopharyngeal microbiota, especially C. accolens strains, could reduce the individual susceptibility to SARS-CoV-2 infection by several mechanisms: by downregulation the ACE2, the TMPRSS2 receptors, and cathepsin L in the host; through the inhibition of S1-ACE2 binding; and lipase production. These results suggest the use of C. accolens strains as probiotics in the nasopharynx in the future.