Currently, one of the most serious threats to public health is the rapid spread of multidrug–resistant (MDR) and highly virulent Klebsiella pneumoniae (hvKp). In these strains, various antibiotic resistance genes (ARGs) are frequently detected, including several novel ones first identified in this bacterial species, such as carbapenemases of the KPC, NDM–1, and OXA–48 types. The widespread prevalence of environmental ARGs, which can be transferred between microbiota, particularly among clinical pathogens and human commensals, has significantly contributed to the emergence of antimicrobial resistance (AMR) in K. pneumoniae. Resistance is caused by mechanisms such as drug inactivation, increased efflux, or altered binding to target sites. Moreover, this resistance is further enhanced by the production of various beta-lactamases, mainly extended–spectrum beta-lactamases (ESBLs), or by biofilm formation. Particularly concerning in K. pneumoniae, the main species representing the carbapenemase–producing Enterobacterales (CPE) group, is the emergence of plasmid–mediated resistance to carbapenems and polymyxins, which are considered “last–resort drugs” for treating infections caused by these pathogenic microorganisms. The growing resistance of K. pneumoniae to antibiotics and other antimicrobial agents remains one of the most important problems in epidemiological surveillance, microbiological diagnostics, and the global treatment of infections. The high mortality rate among infected patients and the difficulty in treating infections caused by MDR K. pneumoniae have led to this bacterium being classified as one of the most common and dangerous human pathogens in both Polish and global healthcare. This article characterizes the factors determining antibiotic resistance in K. pneumoniae, both in terms of biochemical mechanisms and molecular features. In addition, the current epidemiological situation regarding the spread of invasive, resistant K. pneumoniae isolates in Europe and Poland is described, and treatment regimens for infections caused by these high–alert pathogens are presented.
Candidemia is the most common form of invasive fungal infection, and is associated with high mortality rates particularly in intensive care patients. In this study, 50 C. albicans strains isolated from blood samples were genotyped by 25S intron analysis, and the presence of virulence genes was investigated by PCR. Genotyping revealed that 28 isolates (56%) were genotype A, 14 (28%) genotype B, and eight (16%) genotype C. The SAP1 gene was detected in 96% of isolates, SAP2 and SAP4 in 98%, ALS1 and HWP1 in 92%, and PLB1 in 94%. A comprehensive understanding of Candida virulence factors, particularly in C. albicans which is the most prevalent Candida species acting as both a commensal organism and an opportunistic pathogen, is essential for improving diagnostic methods, and guiding the design of novel antifungal agents targeting virulence mechanisms.
Recent studies have shown that the Taabo, Kossou, and Faé reservoirs are contaminated by faecal pollutants, which could pose health risks to users due to a potentially high abundance of pathogenic bacteria. Accordingly, a monitoring study was planned to assess variation in pathogen abundance, including Pseudomonas aeruginosa (P. aeruginosa) and Staphylococcus aureus (S. aureus), in these reservoirs. Water sampling was conducted between February and October of the same year along a linear transect in each reservoir. Pathogenic bacteria were analyzed using culture and polymerase chain reaction (PCR) methods. The primer pairs PA-SS-F/PA-SS-R were used for P. aeruginosa, and 16S rRNA-F/16S rRNA-R were used for S. aureus. Overall, the median concentrations of P. aeruginosa and S. aureus ranged from 0.97 and 2.57 Log CFU/100 mL. The highest concentrations of these bacteria were generally recorded during the rainy periods in June, July, September, and October. Spatially, the highest concentrations were found in the shore areas of the different reservoirs. The results indicated weak correlations between the concentrations of these pathogenic bacteria. To preserve the integrity of these hydroelectric reservoirs, it is advisable to establish safety zones around them and to treat wastewater prior to discharge.
Antibiotics are pivotal for treating Staphylococcus aureus infections, but overuse has led to multidrug-resistant (MDR) strains, necessitating alternative strategies. Targeting virulence factors, rather than bacterial survival, offers a promising approach to combat resistance. This study evaluated the in vitro effects of native, non-insecticidal Bacillus thuringiensis (Bt) parasporal crystal proteins (PCPs), in protoxin (PT) and trypsin-activated (AT) forms, on S. aureus virulence gene expression and biofilm formation. Fourteen Bt PCPs were isolated and prepared as PT and AT forms. Their impact was assessed using LacZ promoter fusion assays for hla (alpha-hemolysin), spa (protein A), and RNAIII (a key virulence regulator), supplemented by quantitative β-galactosidase assays. Biofilm formation was quantified and normalized to planktonic growth (Normalized Biofilm Index, NBI) to distinguish specific antibiofilm activity from growth inhibition. AT-PCPs from Bt strains M11, M78, M91, M154t1, and A11 significantly downregulated hla, spa, and RNAIII expression (log2 fold changes up to −4.88, p < 0.001) and reduced biofilm formation (NBI reduction up to 57%, p < 0.001). AT proteins exhibited no hemolytic activity and had MIC values >100 μg/mL, confirming antivirulence effects at sub-inhibitory concentrations. PCR screening revealed the absence of cyt1 genes in four of five active isolates, supporting Cry-mediated targeting. These in vitro findings suggest that trypsin-activated PCPs can disrupt critical virulence pathways in S. aureus. Trypsin-activated Bt PCPs attenuate virulence and biofilm formation in S. aureus in vitro, highlighting their potential as leads for novel antivirulence strategies. These proteins show potential as candidates for standalone or adjuvant strategies alongside conventional antibiotics in the fight against MDR infections, pending further validation. Further research is needed to elucidate their mechanisms, assess their efficacy in vivo, and evaluate enzymatic activation by host-derived proteases. These in vitro results highlight the potential of Bt-derived PCPs as novel virulence-targeting leads, though further research is needed to identify the active component(s), elucidate mechanisms, and evaluate efficacy in vivo.
The urinary tract microbiota (urobiota) in healthy individuals remains understudied, particularly in men. Methods: Expanded quantitative urine cultures were performed on 40 asymptomatic, presumably healthy males (18-40 years). Results: 88% of samples showed bacterial growth, predominated by Firmicutes (Streptococcus, Staphylococcus, Corynebacterium). Sexual behavior influenced diversity. Conclusions: The male urinary tract harbors a complex microbiota, challenging the "sterile urine" paradigm.
Bacterial vaginosis (BV) is an inflammatory condition of the vagina with a polyetiological origin, most commonly associated with an overgrowth of anaerobic bacteria such as Gardnerella vaginalis or Prevotella spp. Pathogens compromise the protective barrier of the vagina through multiple mechanisms. Sialidases, key virulence factors of BV pathogens, desialylate vaginal glycans, altering their structure and function. Point-of-care tests based on sialidase activity are available for diagnostics. This work reviews the role of sialidases in BV pathophysiology, focusing on their effects on mucosal integrity and biofilm formation, as well as their potential diagnostic and therapeutic applications.
The MALDI-TOF MS technique is now playing a major role in improving microbial diagnostics by enabling rapid and accurate identification of pathogens from minimal amounts of biological material. In recent years, its application has been extended to the detection of antimicrobial resistance trough diverse approaches (e.g., MALDIxin test, MBT-ASTRA, MBT-RESIST, FLAT or DOT-MGA). These strategies allow phenotypic assessment of resistance by measuring antibiotic degradation, identifying resistance-associated spectral peaks, or monitoring bacterial growth in the presence of antimicrobials, thereby providing clinically relevant results. This review critically discusses current evidence on MALDI-TOF MS-based detection of resistance to key antibiotic classes in major pathogens. It also highlights a typical performance metrics, antibiotic- and species-dependent variability, and focuses on remaining gaps in coverage of important resistance mechanism.
Human papillomavirus (HPV) can cause asymptomatic infections, making it part of the human microbiota. Some HPV types cause benign proliferative lesions, such as warts or condylomas, while highly oncogenic types, in the context of chronic infection, can induce lesions that may progress to cancer. The article presents current knowledge on HPV biology, carcinogenesis, and risk factors modulated by co-infections with other viruses or bacteria. The paper also reviews contemporary diagnostic strategies, ranging from cytology (conventional and LBC) and DNA/mRNA (E6/E7) tests to highly sensitive NAAT and sequencing methods. Prevention through available vaccination programs is discussed. From a public health perspective, the importance of adolescent vaccination programs and screening tests, which effectively reduce the incidence of infection and mortality associated with HPV-related cancer, is emphasized.
The Burkholderia cepacia complex (Bcc) consists of multiple opportunistic pathogens capable of causing serious infections, especially in individuals with cystic fibrosis (CF). Some patients may develop "cepacia syndrome," a rapidly worsening and often deadly complication. Treatment is difficult because Bcc naturally resists many antibiotic classes and can form biofilms, which help it persist and shield bacteria from the immune system. These issues have made traditional antibiotic treatments mostly ineffective, highlighting the urgent need for alternative solutions.Phage therapy has shown promise as a potential strategy, but its use against Bcc remains limited. Isolating strictly lytic phages is challenging because most available Burkholderia phages are temperate and have narrow host ranges. So far, only a few phages with activity against clinically relevant isolates have been identified. Evidence from compassionate use cases indicates that phage therapy can be safe and well-tolerated, but solid clinical data are still missing. Important gaps in knowledge include the limited availability of phages, the need for standardized protocols, and the optimization of delivery methods, such as aerosolization for lung infections. Solving these issues will be crucial for making phage therapy a practical treatment option for multidrug-resistant Bcc infections.
The ability of microorganisms to form biofilm structures is at the root of many diseases of the oral cavity. Biofilm - in particular its abnormal growth in combination with other factors, such as impaired functioning of specific and non-specific defence mechanisms of the human body or disorders in the quantitative and qualitative composition of the oral microbiota - may lead to the development of caries, gingivitis or periodontitis. Treatment of this type of infections is a challenge for modern dentistry, also due to the increasing resistance of microorganisms. The above requires a search for alternative therapeutic methods.This paper presents a general characteristics of antimicrobial peptides, briefly characterizes oral diseases and provides basic information on infection therapy in dentistry. It also discusses the possibilities of therapeutic use of natural and synthetic antimicrobial peptides in dentistry.
Previous research has confirmed that Candida spp. incubated with the folic acid pathway inhibitor methotrexate can develop multidrug resistance to azoles. However, it remains unclear whether this phenomenon also occurs with other antifoliate agents. The aim of this study was to assess whether a different antifolate —pemetrexed— can induce resistance to azoles among endogenous yeast strains. For this purpose, 15 strains of Candida and 3 strains of Nakaseomyces were stimulated twice with either methotrexate or pemetrexed. Subsequently, minimum inhibitory concentration for fluconazole for each strain was determined before and after stimulation. Susceptibility to fluconazole increased in 7 strains, decreased in 10 strains and did not change in case of 1 strain after exposure to pemetrexed. After exposure to methotrexate susceptibility to fluconazole increased in 7 strains, decreased in 5 strains and did not change in case of 6 strains. One strain of Candida albicans became resistant to fluconazole after stimulation with either methotrexate or pemetrexed.
Virus-like particles (VLPs) are multiprotein structures that mimic the conformation of infectious virus particles and are therefore potent inducers of immune responses in mammals. Because they are non-infectious and non-replicative, VLPs are attractive options for developing safer vaccines. Modular VLPs are composed of proteins that display universal attachment sites, allowing further functionalization with antigens of interest. These systems are especially useful for creating multivalent vaccines, quickly adaptable vaccines in pandemic scenarios, or vaccines targeting challenging pathogens where traditional methods have failed. Besides vaccines, modular VLPs are also being studied as carriers for targeted cell delivery and as protective shells for fragile biological cargo. In this review, I discuss current strategies for designing modular VLPs, focusing on the types of anchoring sites and attachment techniques used.
Beehive products have been known since ancient times and are used in medicine, food, and beverages. Honey, bee bread, propolis, pollen, royal jelly, and beeswax are valuable sources of active compounds that contribute to modern apitherapy and help combat civilization-related diseases. However, there is growing attention to the microbiota of beehive products, which vary among different products and depend on several factors, such as the environment surrounding the hive, the collection process of bee products, and their subsequent processing. Culture-dependent and culture-independent methods have been used to investigate the microbiota of bee products. Commonly identified microorganisms include lactic acid bacteria, spore-forming Bacillus species and related genera, osmophilic yeasts, and xerophilic molds. The microbiota of bee products holds underexplored potential for applications in industry and medicine, including as potential probiotics, sources of antimicrobial agents, and enzyme producers.
The antibacterial properties of nanomaterials are well-known and have been extensively studied. On the other hand, bacterial responses to these structures are largely unknown. Notably, defense mechanisms that stimulate physiological features are frequently omitted. Studies on these effects indicate that nanomaterials may stimulate the production of primary and secondary metabolites. The stimulation effects range from cell agglomeration to the secretion of pigments. Contact with nanostructures changes the expression of genes responsible for responding to reactive oxygen species, efflux pumps, and virulence factors. These findings can be potentially used in biotechnology and bioprocess engineering, using nanostructures as stimulants for the biological production of valuable metabolites. On the other hand, the potential stimulation of virulence factors or the risk associated with increased transfer of antibiotic resistance may limit the use of nanomaterials in medical devices that have direct contact with patients. In that manner, more transcriptomic and metabolomic studies are necessary to fully assess the stimulative potential of nanomaterials in biotechnology and medicine.
Introduction Psychrobacter sanguinis is a rarely reported Gram-negative organism, usually linked to cold environments, but it is increasingly being recognized as an opportunistic pathogen.Materials and methods Two blood culture isolates from hospitalized patients in Limanowa, Poland, were identified using MALDI-TOF MS and confirmed with 16S rRNA sequencing. Antimicrobial susceptibility testing was conducted via the gradient diffusion method.Results Both P. sanguinis strains showed low MICs for fluoroquinolones, extended-spectrum cephalosporins, and carbapenems, suggesting possible treatment options.Conclusion These cases highlight the growing clinical importance of P. sanguinis. Reliable molecular identification and systematic research are necessary to understand its pathogenic potential, resistance determinants, and epidemiological impact.
Octenidine dihydrochloride (OCT) is an antiseptic used for the prevention of wound infections, treatment of wounds and for treating oral infections. The spectrum of OCT’s activity includes Gram-positive and Gram-negative bacteria, as well as fungi, including multidrug-resistant (MDR) strains. For most species, it exhibits activity at concentrations ranging from approximately 1 to several μg/mL. OCT also exhibits strong antibiofilm activity, both against biofilm formation and mature biofilms. The compound has limited virucidal and antiparasitic activity. The Clinical Efficiency of MIC (CEMIC) index for most pathogens is classified as excellent, meaning that the MIC is much lower than the clinical concentration. The required contact time for OCT microbicidal action is fast, at just 1 minute. The possibility of adaptation to OCT has been described; however, the Karpinski Adaptation Index (KAI) for most species is below 0.2, indicating a very low or low risk of developing clinical resistance. Only in some isolates of Proteus mirabilis and Pseudomonas aeruginosa the risk of resistance development considered moderate. According to guidelines (Statement of the Polish Wound Management Association, German Consensus on Wound Antisepsis, and International Consensus Document “Use of wound antiseptics in practice”), OCT is the first-choice antiseptic for critically colonized wounds, infection-prone wounds, burns, wounds colonized by multidrug-resistant (MDR) pathogens or infected wounds, and for the prevention of surgical site infections (SSI). OCT is also used in umbilical stump care, the treatment of oral infections, skin and mucosal candidiasis, and bacterial vaginosis.
Akkermansia muciniphila is a gut bacterium that has recently attracted considerable attention in microbiota research. Its presence in the gut is associated with improved metabolic health, enhanced gut barrier integrity, and modulation of the immune system. However, potential risks related to its abundance under certain pathological conditions have also been noted. As A. muciniphila emerges as a candidate for next-generation probiotics, evaluating whether current data support its therapeutic use is crucial. In this review, we analyze the available literature to outline the beneficial effects of A. muciniphila on the host and critically assess its potential as a probiotic.
Irritable bowel syndrome (IBS) is a chronic gastrointestinal disorder with an increasing global prevalence. The International Classification of Diseases (ICD) system typically categorizes IBS into four subtypes based on symptomatology. The objective of this review is to provide a concise synthesis of the most current information regarding IBS, encompassing widely accepted diagnostic criteria, etiology, epidemiological data and the significance of gut microbiota (GM) in pathogenesis of this disorder. Additionally, it will explore future perspectives. Recent studies have demonstrated that the GM in healthy individuals primarily consists of four main bacterial phyla: Firmicutes spp., Bacteroidetes spp., Actinobacteria spp., and Proteobacteria spp. Dysbiosis or an imbalance in these bacteria may be a contributing factor to the IBS development. It is imperative to acknowledge the multifaceted role of the GM in several essential biological processes, including: immunomodulation, intestinal barrier integrity, gut microbiota-gut-brain axis (GBA) or nutrient absorption. The composition of GM is subject to variation depending on the IBS subtype. Many therapeutic strategies have been devised for the treatment of patients with IBS, comprising antibiotics, probiotics, prebiotics, synbiotics and fecal microbiota transplantation (FMT). Although FMT has shown promise, clinical trials outcomes remain still inconsistent. Dietary interventions and psychological support are also vital components of IBS management.Despite the advances in understanding the GM-IBS relationship, there is still a lack of knowledge regarding specific microbial markers for each IBS subtype. Consequently, a definitive microbiota pattern has yet to be delineated. However, emerging evidence underscores the microbiome's role in IBS pathophysiology.
In recent years the field of probiotics, prebiotics, synbiotics and postbiotics has been extensively studied. Preparations including live and inanimate microorganisms, their parts and substances that selectively stimulate their growth, are promising in treatment or amelioration of symptoms in many diseases. The aftermath of the COVID-19 pandemic has forced us to face complications such as post-acute COVID-19 syndrome and a general decrease in population immunity, for which treatment with probiotics, prebiotics, synbiotics and postbiotics is promising. The use of such preparations can have a positive effect on the immune system and has also shown positive effects in major depressive disorder. Due to the rapid development in the field a lot of confusion and misconceptions emerged, especially regarding the use of terms and definitions. This article aims to present a clear classification of these products according to International Scientific Association of Probiotics and Prebiotics (ISAPP) guidelines as well as basic mechanisms of action and efficacy of selected preparations. Authors of this article use the term ‘biotic(s)’ to refer collectively to probiotics, prebiotics, synbiotics and postbiotics. While this term has not been officially established, it is used by other authors in the scientific literature. The taxonomic nomenclature used in this article has been updated according to the most recent taxonomic reclassification.
In the context of escalating microbial resistance to antibiotics, antiseptics are gaining prominence as a critical component of infection prevention. Concurrently, the widespread and increasing use of these biocides, particularly within healthcare settings, has prompted concerns regarding their potential contribution to the emergence of reduced microbial susceptibility to them and the phenomenon of cross-resistance to antibiotics. This review focuses on four widely utilized antiseptics: chlorhexidine, octenidine, povidone-iodine, and alcohols. It was discusses their antimicrobial activity, mechanisms of action, and applications, including available preparations and the minimum effective concentrations required for reliable pathogen eradication. Current evidence regarding the mechanisms underlying decreased susceptibility to these agents is summarized. Furthermore, the review presents data from studies investigating the impact of prolonged exposure to subinhibitory concentrations of antiseptics on the induction of reduced antimicrobial efficacy and the potential for co-selection of antibiotic resistance. Furthermore, the review presents methods of adaptation of bacteria and fungi to increasing concentrations of antiseptics, including techniques using liquid media - gradient method and incremental method, as well as methods based on solid media. Findings from recent studies suggest that long-term exposure of microorganisms to subinhibitory concentrations of antiseptics may result in reduced effectiveness of these agents and selection of mutants with changed sensitivity to antibiotics.
