Pathogenicity Of Bacterial Strains Research Articles

Deep-Learning Resources for Studying Glycan-Mediated Host-Microbe Interactions

Glycans, the most diverse biopolymer, are shaped by evolutionary pressures stemming from host-microbe interactions. Here, we present machine learning and bioinformatics methods to leverage the evolutionary information present in glycans to gain insights into how pathogens and commensals interact with hosts. By using techniques from natural language processing, we develop deep-learning models for glycans that are trained on a curated dataset of 19,299 unique glycans and can be used to study and predict glycan functions. We show that these models can be utilized to predict glycan immunogenicity and the pathogenicity of bacterial strains, as well as investigate glycan-mediated immune evasion via molecular mimicry. We also develop glycan-alignment methods and use these to analyze virulence-determining glycan motifs in the capsular polysaccharides of bacterial pathogens. These resources enable one to identify and study glycan motifs involved in immunogenicity, pathogenicity, molecular mimicry, and immune evasion, expanding our understanding of host-microbe interactions.

Genetic and biochemical characterization of staphylococci occurring in Novosibirsk, Russia

Staphylococci are capable of penetrating many human tissues and organs, causing superficial and deep purulent infections, respiratory and urinary tract infections, food poisoning and intoxication. Last years, coagulase­negative staphylococci were the cause of infection in many cases. Infectious agents, namely Staphylococcus epidermidis, Staphylococcus haemolyticus, and Staphylococcus hominis, were detected more often as nosocomial infections. A particular danger of these infections is a high virulence and pathogenicity of bacterial strains and their resistance to various anti ­ biotics. Methicillin­resistant staphylococci are especially difficult to treat. The correct identification of staphylococci and their sensitivity to antibiotics are important for clinical diagnosis and appointment of adequate drug therapy. Rapid and accurate identification of Staphylococcus species and detection of their sensitivity to antibiotics is quite important. The aim of this study was to study staphylococci isolated in Novosibirsk from human, animal and environmental samples. A collection of 100 staphylococcus strains was analyzed. Staphylococcus species were identified by sequencing the 16S rRNA gene. Eleven staphylococcus species were identified. Among the strains obtained from hospitalized patients, Staphylococcus aure us dominated (79.1 %), Staphylococcus epidermidis amounted to about 12.5 %. However, S. aureus and S. epi dermidis strains were isolated in an approximately equal proportion from community­associated samples. Identification of coagulase positive strains was performed using a standard biochemical method and by real­time PCR of the coa gene. 100 % coincidence between the presence of the gene and coagulase activity for S. aureus strains was recorded, which suggests that detection of the coa gene can be used as a correct method for S. aure us identification. A high coincidence rate (99 %) was reveal ed between the phenotypic resistance to oxacillin and the presence of the staphylococcal mecA gene. The study of staphylococci for the presence of the mecA gene can be considered as an alternative to the phenotypical method for identification of methicillin­resistant strains of staphylococci.

Identification and pathogenicity of bacterial strains carried by American pine wood nematodes

To confirm that pine wood nematodes carrying attenuated bacterial strains could alleviate pine wilt disease，bacteria were isolated from two nematodes native to America. Bacterial virulence and pathogenicity were tested with pine seedlings，and preliminary identification of predominant strains was determined using bacterial staining reactions and morphology combined with 16S rDNA sequence analysis. Results of the isolation experiment showed that the predominant bacteria which American nematodes carried were strains MG4 （Delftia tsuruhatensis），MG5 （Pseudomonas putida），MG8 （Stenotrophomonas maltophilia），and MG9 （Pantoea sp.） Virulence and pathogenicity results demonstrated that compared with the high virulent bacteria strains（Pseudomonas fluorescence） isolated from Chinese nematodes，toxicity and pathogenicity of bacterial strains from America were relatively low. Thus，the bacteria carried by American nematodes should be considered the candidates for biological control agents.［Ch，2 fig. 3 tab. 20 ref.］

Effect of Antibiotics on Cell Surface Hydrophobicity of Bacteria Causing Orthopedic Wound Infections

Background: Despite antibiotic prophylaxis and treatment, the incidence of wound infections in orthopedic surgery is significant. Postoperative wound infection is a multifactorial process, which can be modified by several bacterial factors. Cell surface hydrophobicity of bacteria is a very important physicochemical feature, which has a great influence on the ability of bacteria to adhere to the surface of host cells or medical implants. Methods: In this study, the hydrophobic properties of thirteen bacterial strains (coagulase-negative staphylococci, Staphylococcus aureus and Pseudomonas aeruginosa) isolated from patients with postoperative deep wound infections following orthopedic procedures were determined by the salt aggregation test. Results were compared to the hydrophobicity of three Hungarian standard bacterial strains. The modifying effect of four antibiotics (cefuroxime, cefotaxime, amoxicillin combined with clavulanic acid and amikacin) – applied most often in our Department for prophylaxis and treatment of patients – were analyzed. Results: The cell surface hydrophobicity of certain strains showed considerable changes after antibiotic treatment. These alterations indicated the decrease in hydrophobicity. Supra-inhibitory concentrations (2× minimum inhibitory concentrations, MIC) of the antibiotics were able to induce more frequent alterations in hydrophobicity than sub-inhibitory (0.5× MIC) levels. Conclusions: Alterations in cell surface hydrophobicity caused by antibiotics can modify the adhesion process and thus the pathogenicity of bacterial strains. These changes should be taken into consideration in the management of proper antibiotic prophylaxis and in the treatment of orthopedic patients.