Genotypic, phenotypic and redox characteristics of group B streptococci isolated in Serbia

Група Б стрептокока (ГБС) је један од најчешћих узрочника неонаталног морбидитета и морталитета широм света, значајан узрочник инвазивних инфекција пацијента старије животне доби и имунокомпромитованих, али и асимптоматски колонизатор урогениталног и гастроинтестиналног тракта код 10 до 30% здравих људи и трудница. Циљ: Циљ студије је да се испитају фенотипови и генотипови резистенције на антибиотике инвазивних и неинвазивних изолата ГБС, одреде капсуларни типови, утврди повезаност капсуларних типова са фенотиповима и генотиповима резистенције на макролиде и тетрациклин и испита редокс статус изолата ГБС. Материјал и методе: Тест осетљивости на антибиотике је извршен диск-дифизионом методом антибиограма и тестом дифузије антибиотика у градијенту концентрације по EUCAST стандардима. Испитивање генетичке основе резистенције, капсуларна типизација и детекција хипервирулентног клона III/ST17 су обављене PCR методом, а испитивање клоналне повезаности, PFGE профилисањем. Параметри редокс статуса су квантитативно одређени у бактеријским лизатима употребом одговарајућих спектрофотометријских метода. Резултати: Процењена учесталост колонизације трудница је износила 15,6%, а инциденција инвазивних неонаталних инфекција 0,18/1000 живорођене деце. Заступљености резистенције на еритромицин (26,7%), клиндамицин (22,1%) и тетрациклин (85,2%) су имали тренд пораста. Доминатан фенотип резистенције на макролиде је био cMLS (60,8%), посредован ermB геном. Већину CPS типова (51,8%) су чинили типови V и III, од којих је тип III био доминантан међу инвазивним сојевима (51,3%), а тип V међу неинвазивним (26,3%). Хипервирулентни клон III/ST17 је био заступљенији међу инвазивним сојевима (35%) са трендом пораста. Резултати редокс статуса указују на већи антиоксидативни капацитет неинвазивних сојева, повећану оксидацију сојева резистентних на макролиде и смањену ензимску заштиту сојева III/ST17. Закључак: Високе стопе резистентних сојева и клона III/ST17 са значајним трендовима пораста указују на неопходност континуираног праћења и спровођења мера за спречавање даљег раста. Редокс параметри нам дају додатан увид у патогенезу различитих клиничких облика сојева ГБС.Group B streptococcus (GBS) is one of the most common causes of neonatal morbidity and mortality worldwide, a significant cause of invasive infections in elderly and immunocompromised patients, and also an asymptomatic colonizer of the urogenital and gastrointestinal tract in 10 to 30% of healthy people and pregnant women. Aim: The study aims to examine phenotypes and genotypes of antibiotic resistance of invasive and noninvasive GBS isolates, determine capsular types, determine the association of capsular types with phenotypes and genotypes of resistance to macrolides and tetracycline and examine the redox status of GBS isolates. Material and methods: The antibiotic susceptibility testing was performed by the disk diffusion method and antimicrobial gradient method according to EUCAST standards. Determination of resistance genetic basis, capsular typing, and detection of hypervirulent clone III/ST17 were performed by PCR method and clonal association testing by PFGE profiling. Redox status parameters were quantified in bacterial lysates using appropriate spectrophotometric methods. Results: The estimated frequency of colonization of pregnant women was 15.6%, and the incidence of invasive neonatal infections was 0.18/1000 live births. The prevalence of erythromycin resistance (26.7%), clindamycin (22.1%), and tetracycline (85.2%) had an increasing trend. The dominant macrolide resistance phenotype was cMLS (60.8%), mediated by the ermB gene. The majority of CPS types (51.8%) were V and III, of which type III was dominant among invasive strains (51.3%) and type V among non-invasive (26.3%). Hypervirulent clone III/ST17 was more prevalent among invasive strains (35%) with an increasing trend. The redox status results indicate the higher antioxidant capacity of noninvasive strains, increased oxidation of macrolide-resistant strains, and decreased enzyme protection of III/ST17 strains. Conclusion: High rates of resistant strains and clone III/ST17 with significant growth trends indicate the need for continuous monitoring and implementation of measures to prevent further growth. Redox parameters give us additional insight into the pathogenesis of different clinical forms of GBS strains

Cinnamon essential oil and its emulsion as efficient antibiofilm agents to combat Acinetobacter baumannii

Acinetobacter baumannii is an emerging nosocomial pathogen resistant to a wide spectrum of antibiotics, with great potential to form a biofilm, which further aggravates treatment of infections caused by it. Therefore, searching for new potent agents that are efficient against A. baumannii seems to be a necessity. One of them, which has already been proven to possess a wide spectrum of biological activities, including antimicrobial effect, is cinnamon essential oil. Still, further increase of antibacterial efficacy and improvement of bioavailability of cinnamon oil is possible by emulsification process. The aim of this study was comparative analysis of cinnamon essential oil and its emulsion against biofilm forming A. baumannii clinical isolates. Furthermore, the investigation of toxicological aspects of possible applications of essential oil and emulsion was done as well. Gas chromatography–mass spectrometry of essential oil indicated trans-cinnamaldehyde as the most abundant component. The cinnamon emulsion was synthesized from cinnamon essential oil by combining modified low- and high- energy methods. Synthesized emulsion was characterized with Fourier-transform infrared spectroscopy and photon correlation spectroscopy. Both substances exhibited significant antibacterial (minimal inhibitory concentrations in the range 0.125–0.5 mg/ml) and antibiofilm effects (inhibitions of formation and reduction of pre-formed biofilm were 47–81 and 30–62%, respectively). Compared to essential oil, the efficacy of emulsion was even stronger considering the small share of pure oil (20%) in the emulsion. The result of biofilm eradication assay was confirmed by scanning electron microscopy. Even though the cytotoxicity was high especially for the emulsion, genotoxicity was not determined. In conclusion, strong antibacterial/antibiofilm effect against A. baumannii of the cinnamon essential oil and the fact that emulsification even potentiated the activity, seems to be of great significance. Observed cytotoxicity implicated that further analysis is needed in order to clearly determine active principles being responsible for obtained antibacterial/antibiofilm and cytotoxic properties. Copyright © 2022 Ganić, Vuletić, Nikolić, Stevanović, Kuzmanović, Kekić, Đurović, Cvetković and Mitić-Ćulafić

Antimicrobial Susceptibility Testing: A Comprehensive Review of Currently Used Methods

Antimicrobial resistance (AMR) has emerged as a major threat to public health globally. Accurate and rapid detection of resistance to antimicrobial drugs, and subsequent appropriate antimicrobial treatment, combined with antimicrobial stewardship, are essential for controlling the emergence and spread of AMR. This article reviews common antimicrobial susceptibility testing (AST) methods and relevant issues concerning the advantages and disadvantages of each method. Although accurate, classic technologies used in clinical microbiology to profile antimicrobial susceptibility are time-consuming and relatively expensive. As a result, physicians often prescribe empirical antimicrobial therapies and broad-spectrum antibiotics. Although recently developed AST systems have shown advantages over traditional methods in terms of testing speed and the potential for providing a deeper insight into resistance mechanisms, extensive validation is required to translate these methodologies to clinical practice. With a continuous increase in antimicrobial resistance, additional efforts are needed to develop innovative, rapid, accurate, and portable diagnostic tools for AST. The wide implementation of novel devices would enable the identification of the optimal treatment approaches and the surveillance of antibiotic resistance in health, agriculture, and the environment, allowing monitoring and better tackling the emergence of AMR

Correction to: Redox Status and Antioxidative Cofactor Metals Influence Clinical and Pathological Characteristics of Papillary Thyroid Carcinoma and Colloid Goiter (Biological Trace Element Research, (2020), 197, 2, (349-359), 10.1007/s12011-019-01995-x)

Papillary thyroid carcinoma (PTC) is the endocrine neoplasm that occurs the most often worldwide, and its molecular pathophysiology is still not well characterized. Redox status is recognized as an important factor of carcinogenesis, but its influence on the PTC's clinical course needs to be better elucidated. The aim of this research was to determine the tissue redox status of 65 PTC and 45 colloid goiter (CG) patients together with antioxidative cofactor metal profiling. The malondialdehyde (MDA) concentration was used to access the prooxidation level, while antioxidant mechanisms were estimated by assaying the activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and glutathione reductase (GR). The antioxidative cofactor metals included quantification of Se, Cu, Zn, and Mn concentration. PTC tissues had normal prooxidation levels and increased GPx and GR activity. The activity of SOD has been significantly reduced in multicentric PTC dissemination and increased in smokers. SOD activity was directly dependent on MDA levels in CG tissues. CG patients with retrosternal goiter had reduced MDA concentration and SOD activity. Numerous correlations between redox parameters in PTC tissues reveal good co-activation of antioxidative mechanisms and cooperative response on prooxidation. PTC tissues had decreased Se levels and increased concentration of Cu and Mn in comparison to other tissues. MDA concentration and SOD activity were significant predictors of PTC's multicentric dissemination and for the existence of lymph node metastases, respectively. Particularly, the concentration of Cu predicted the retrosternal localization in CG patients. Significant findings presented in this study provide a possibility for development of novel prognostic molecular biomarkers of PTC and CG.The contribution corrects an equation from the paper: Rovcanin, B.; Stojsavljevic, A.; Kekic, D.; Gopcevic, K.; Manojlovic, D.; Jovanovic, M.; Knezevic, S.; Zivaljevic, V.; Diklic, A.; Paunovic, I. Redox Status and Antioxidative Cofactor Metals Influence Clinical and Pathological Characteristics of Papillary Thyroid Carcinoma and Colloid Goiter. Biol Trace Elem Res 2020, 197 (2), 349–359. [https://doi.org/10.1007/s12011-019-01995-x

Supplementary information for the article: Kabic, J., Novovic, K., Kekic, D., Trudic, A., Opavski, N., Dimkic, I., Jovcic, B., & Gajic, I. (2023). Comparative genomics and molecular epidemiology of colistin-resistant Acinetobacter baumannii. Computational and Structural Biotechnology Journal, 21, 574–585. https://doi.org/10.1016/j.csbj.2022.12.045

Related to published version: [https://imagine.imgge.bg.ac.rs/handle/123456789/1784]Supplementary data associated with this article can be found in the online version at doi:[10.1016/j.csbj.2022.12.045.

Cinnamon essential oil and nanoemulsion: antibiofiIm activity on Acinetobacter baumannii clinical isolates

Objective: Acinetobacter baumannii is a pathogenic species which presents a danger to healthcare facilities due to the rapid spread of antibiotic resistance. Plants are currently being explored as a potential source of bioactive compounds that could be used to combat infectious diseases. Cinnamon is used as a food spice, but essential oil has been proven for antimicrobial activity. Due to reduced stability and solubility of essential oil, nanoemulsion (NE) synthesis could provide stronger antimicrobial effects. Investigation and comparison of antimicrobial activity of cinnamon (Cinnamomum zeylanicum L.) bark essential oil (EO) and NE on the A. baumannii ATCC19606 and clinical isolates. Effect of EO and NE on biofilm formation and biofilm eradication. Methods: GC/MS was performed in order to determine chemical composition of commercially purchased EO (P0125285, Frey + Lau, GmbH, Henstedt-Ulzburg, Germany). Droplet/particle size and polydispersity index of NE was determined by photon correlation spectroscopy (PCS). Minimal inhibitory concentration of EO and NE were defined using MIC assay. Effects of EO and NE were also examined on biofilm formation and eradication. Crystal violet staining was used for biofilm biomass quantification. Results: GC/MS analysis determined that the most common compound was trans-Cinnamaldehyde (61.9%). NE droplet/particles had multimodal distribution, shown by PCS. MIC values for EO were in range 0.25mg/mL — 0.5mg/mL, and for NE 0.125mg/mL — 0.25mg/mL. Both tested substances showed good effect on biofilm eradication, and destroyed biofilm biomass up to 64%, whilst the inhibition of biofilm formation was up to 70%. Conclusion: Taking all the results into account, it is a good start for further investigations of both EO and NE as a potential antimicrobial agent. Deeper knowledge about the mechanisms of actions of both of these tested substances could help us to understand the best and the most effective way to use them, in order to combat against Acinetobacter baumannii

Influence of subinhibitory antibiotic concentration on Streptococcus pyogenes adherence and biofilm production

In this study, the focus was on the effects of sub-MICs of the antibiotics on adherence, hydrophobicity, and biofilm formation by two groups of Streptococcus pyogenes strains, which were responsible for different clinical cases. The aim of this study was to explore the effects of sub-MICs of penicillin, ceftriaxone, erythromycin, and clindamycin on adherence, surface hydrophobicity, and biofilm biomass in two selected collections of group A streptococcus (GAS): strains isolated from carriers (CA) and strains isolated from patients with tonsillopharyngitis (TPh). Isolates were tested for hydrophobicity to xylene, adherence, and biofilm production in uncoated microtiter plates before and after treatment with 1/2 and 1/4 MICs of antibiotics. Penicillin reduced adherence and biofilm production in TPh strains, whereas ceftriaxone diminished adherence and biofilm formation in CA group. On the contrary, clindamycin enhanced adherence and biofilm production in both groups of strains. Erythromycin did not significantly alter adherence, but triggered biofilm production in both groups of isolates. Hydrophobicity of both groups of strains was significantly reduced after exposure to all antibiotics. Beta-lactams displayed anti-biofilm activity; penicillin diminished both adherence and biofilm production in TPh strains, whereas ceftriaxone reduced it in strains isolated from CA

Isolation, Characterization, Genome Analysis and Host Resistance Development of Two Novel Lastavirus Phages Active against Pandrug-Resistant Klebsiella pneumoniae

Klebsiella pneumoniae is a global health threat and bacteriophages are a potential solution in combating pandrug-resistant K. pneumoniae infections. Two lytic phages, LASTA and SJM3, active against several pandrug-resistant, nosocomial strains of K. pneumoniae were isolated and characterized. Their host range is narrow and latent period is particularly long; however, their lysogenic nature was refuted using both bioinformatic and experimental approaches. Genome sequence analysis clustered them with only two other phages into the new genus Lastavirus. Genomes of LASTA and SJM3 differ in only 13 base pairs, mainly located in tail fiber genes. Individual phages, as well as their cocktail, demonstrated significant bacterial reduction capacity in a time-dependent manner, yielding up to 4 log reduction against planktonic, and up to 2.59 log on biofilm-embedded, cells. Bacteria emerging from the contact with the phages developed resistance and achieved numbers comparable to the growth control after 24 h. The resistance to the phage seems to be of a transient nature and varies significantly between the two phages, as resistance to LASTA remained constant while resensitization to SJM3 was more prominent. Albeit with very few differences, SJM3 performed better than LASTA overall; however, more investigation is needed in order to consider them for therapeutic application

Genotypic, phenotypic and redox characteristics of group B streptococci isolated in Serbia

Група Б стрептокока (ГБС) је један од најчешћих узрочника неонаталног морбидитета и морталитета широм света, значајан узрочник инвазивних инфекција пацијента старије животне доби и имунокомпромитованих, али и асимптоматски колонизатор урогениталног и гастроинтестиналног тракта код 10 до 30% здравих људи и трудница. Циљ: Циљ студије је да се испитају фенотипови и генотипови резистенције на антибиотике инвазивних и неинвазивних изолата ГБС, одреде капсуларни типови, утврди повезаност капсуларних типова са фенотиповима и генотиповима резистенције на макролиде и тетрациклин и испита редокс статус изолата ГБС. Материјал и методе: Тест осетљивости на антибиотике је извршен диск-дифизионом методом антибиограма и тестом дифузије антибиотика у градијенту концентрације по EUCAST стандардима. Испитивање генетичке основе резистенције, капсуларна типизација и детекција хипервирулентног клона III/ST17 су обављене PCR методом, а испитивање клоналне повезаности, PFGE профилисањем. Параметри редокс статуса су квантитативно одређени у бактеријским лизатима употребом одговарајућих спектрофотометријских метода. Резултати: Процењена учесталост колонизације трудница је износила 15,6%, а инциденција инвазивних неонаталних инфекција 0,18/1000 живорођене деце. Заступљености резистенције на еритромицин (26,7%), клиндамицин (22,1%) и тетрациклин (85,2%) су имали тренд пораста. Доминатан фенотип резистенције на макролиде је био cMLS (60,8%), посредован ermB геном. Већину CPS типова (51,8%) су чинили типови V и III, од којих је тип III био доминантан међу инвазивним сојевима (51,3%), а тип V међу неинвазивним (26,3%). Хипервирулентни клон III/ST17 је био заступљенији међу инвазивним сојевима (35%) са трендом пораста. Резултати редокс статуса указују на већи антиоксидативни капацитет неинвазивних сојева, повећану оксидацију сојева резистентних на макролиде и смањену ензимску заштиту сојева III/ST17. Закључак: Високе стопе резистентних сојева и клона III/ST17 са значајним трендовима пораста указују на неопходност континуираног праћења и спровођења мера за спречавање даљег раста. Редокс параметри нам дају додатан увид у патогенезу различитих клиничких облика сојева ГБС.Group B streptococcus (GBS) is one of the most common causes of neonatal morbidity and mortality worldwide, a significant cause of invasive infections in elderly and immunocompromised patients, and also an asymptomatic colonizer of the urogenital and gastrointestinal tract in 10 to 30% of healthy people and pregnant women. Aim: The study aims to examine phenotypes and genotypes of antibiotic resistance of invasive and noninvasive GBS isolates, determine capsular types, determine the association of capsular types with phenotypes and genotypes of resistance to macrolides and tetracycline and examine the redox status of GBS isolates. Material and methods: The antibiotic susceptibility testing was performed by the disk diffusion method and antimicrobial gradient method according to EUCAST standards. Determination of resistance genetic basis, capsular typing, and detection of hypervirulent clone III/ST17 were performed by PCR method and clonal association testing by PFGE profiling. Redox status parameters were quantified in bacterial lysates using appropriate spectrophotometric methods. Results: The estimated frequency of colonization of pregnant women was 15.6%, and the incidence of invasive neonatal infections was 0.18/1000 live births. The prevalence of erythromycin resistance (26.7%), clindamycin (22.1%), and tetracycline (85.2%) had an increasing trend. The dominant macrolide resistance phenotype was cMLS (60.8%), mediated by the ermB gene. The majority of CPS types (51.8%) were V and III, of which type III was dominant among invasive strains (51.3%) and type V among non-invasive (26.3%). Hypervirulent clone III/ST17 was more prevalent among invasive strains (35%) with an increasing trend. The redox status results indicate the higher antioxidant capacity of noninvasive strains, increased oxidation of macrolide-resistant strains, and decreased enzyme protection of III/ST17 strains. Conclusion: High rates of resistant strains and clone III/ST17 with significant growth trends indicate the need for continuous monitoring and implementation of measures to prevent further growth. Redox parameters give us additional insight into the pathogenesis of different clinical forms of GBS strains

In Search for Reasons behind Helicobacter pylori Eradication Failure–Assessment of the Antibiotics Resistance Rate and Co-Existence of Helicobacter pylori with Candida Species

Helicobacter pylori eradication is characterized by decreasing successful eradication rates. Although treatment failure is primarily associated with resistance to antibiotics, other unknown factors may influence the eradication outcome. This study aimed to assess the presence of the antibiotics resistance genes in H. pylori and the presence of Candida spp., which are proposed to be endosymbiotic hosts of H. pylori, in gastric biopsies of H. pylori-positive patients while simultaneously assessing their relationship. The detection and identification of Candida yeasts and the detection of mutations specific for clarithromycin and fluoroquinolones were performed by using the real-time PCR (RT-PCR) method on DNA extracted from 110 gastric biopsy samples of H. pylori-positive participants. Resistance rate to clarithromycin and fluoroquinolone was 52% and 47%, respectively. Antibiotic resistance was associated with more eradication attempts (p < 0.05). Candida species were detected in nine (8.18%) patients. Candida presence was associated with older age (p < 0.05). A high rate of antibiotic resistance was observed, while Candida presence was scarce, suggesting that endosymbiosis between H. pylori and Candida may not be a major contributing factor to the eradication failure. However, the older age favored Candida gastric mucosa colonization, which could contribute to gastric pathologies and microbiome dysbiosis