Volumen 58 (2019): Heft 2 (January 2019)

The stringent response is a form of bacterial response to adverse environmental conditions. Its effectors are guanosine tetraphosphate and guanosine pentaphosphate [(p)ppGpp], which are synthetized by RelA, SpoT and their homologs (RSH). RelA, a (p)ppGpp synthase, is activated when there is a shortage of amino acids, whereas SpoT, which has the ability to synthetize and hydrolyze (p)ppGpp, responds to fatty acids, iron and carbon limits. Accumulation of (p)ppGpp causes an inhibition of translation, replication, a decrease in the transcription of many genes, e.g. rRNA, tRNA, encoding ribosomal proteins, and an increase in the transcription of genes whose proteins are important in bacterial stress response. The stringent response alarmones are crucial for bacterial resistance to oxidative stress and antibiotics. They also regulate the production of specific molecules, the so-called quorum sensing autoinducers, which help bacteria communicate the density of their own population, which enables them to adjust their metabolism to the prevailing conditions, to form a biofilm – a community of microorganisms attached to a certain surface, ensuring them appropriate conditions to survive in an unfavourable environment, and to colonize new niches. (p)ppGpp has a positive impact on biofilm formation not only via the regulation of quorum sensing, but also by stimulating the synthesis of potential elements of the biofilm. It also appears that the stringent response alarmones decrease the ability of Agrobacterium tumefaciens bacteria to transform plants and thus their potential to cause disease. (p)ppGpp enables the bacteria to perform swarming motility, a movement that increases their resistance to adverse environmental factors.

1. Introduction. 2. RelA, SpoT and RSH proteins – enzymes that metabolize the alarmones of the stringent response. 2.1. The regulation of transcription via stringent response alarmones in Gram-negative bacteria. 2.2. The regulation of transcription via (p)ppGpp in Gram-positive bacteria. 2.3. The influence of stringent response alarmones on translation and replication. 3. The role of the stringent response in the regulation of other physiological processes. 3.1. The role of the stringent response in the production of siderophores and antibiotics. 4. Bacterial cell resistance to stress and the stringent response. 4.1. The participation of the stringent response in quorum sensing regulation. 4.2. The regulation of exopolysacharide production and biofilm formation dependent on the stringent response. 4.3. The role of the stringent response in the regulation of bacterial swarming motility. 5. Summary

Diffusely adhering E. coli strains (DAEC) is one of the seven pathovars of pathogenic E. coli causing intestinal infections in humans. DAEC is a diverse group of strains producing fimbrial or afimbrial adhesins that are responsible for their pathogenicity specific diffuse adherence pattern for epithelial cells. DAEC isolates are detected not only in humans, but also in various groups of animals (dogs, calves, cattle, poultry, pigs). A large variation in the genes that encode the adhesins contributes to the omission of DAEC in the routine diagnosis of gastrointestinal and urinary tract infections.

1. Introduction. 2. The Afa/Dr family of adhesins. 3. The division of DAEC strains. 4. Other virulence factors of DAEC. 5. The pathogenicity of DAEC. 5.1. Urinary tract infections. 5.2. Gastrointestinal tract infections. 6. Immunological response in DAEC infections. 7. The pathomechanism of infections caused by DAEC. 7.1. The internalization of DAEC. 8. The epidemiology of DAEC. 9. Diagnosis. 10. Summary

The genus Lyssavirus spp. currently includes 14 species that are responsible for causing rabies, rabies-like and rabies-related diseases. The first symptoms of infection are similar to a cold and mainly include fever, headache and general fatigue. Then comes brain dysfunction and acute neurological symptoms, and ultimately – in most cases – death. Lyssaviruses are spread mainly through direct contact with the carrier that contains the viral reservoir. The gold standard in diagnostics is the method of direct immunofluorescence, through which viral antigens are detected – mainly in the saliva of a patient. Currently, rabies treatment is an experimental form of therapy according to the Milwaukee protocol.

1. Introduction. 2. Systematics. 2.1. Lagos bat virus. 2.2. Mokola virus. 2.3 Duvenhage virus. 2.4. European bat 1 lyssavirus. 2.5. European bat 2 lyssavirus. 2.6. Australian bat lyssavirus. 3. Characteristics. 3.1. Molecular structure. 3.2. Genome and gene expression. 3.3. Life cycle. 4. Pathogenicity. 4.1. Pathogenesis. 4.2. Rabies symptoms. 5. Prevention, prophylaxis, diagnostics, treatment. 5.1. Vaccinations. 5.2. Postexposure prophylaxis. 5.3. Diagnostics. 5.4. Experimental treatment. 6. Summary

Dermatophytoses are skin diseases related to the infection of surface layers of skin and other keratinised structures such as hair and nails, caused by fungi referred to as dermatophytes. The scientific literature provides descriptions of over 50 dermatophytic species classified in the Trichophyton, Epidermophyton, Nannizzia, Arthroderma, Lophophyton, and Paraphyton genera. Dermatophytes are regarded as pathogens; they are not a component of skin microbiota and their occurrence in animals and humans cannot be considered natural. The review of the scientific literature regarding the occurrence and prevalence of dermatomycoses in companion animals revealed significant differences in the prevalence of the infections. Two main factors are most frequently assumed to have the greatest epidemiological importance, i.e. the animal origin and the type of infection. In this aspect, interesting data are provided by investigations of the fungal microbiota present in cat and dog fur. Interestingly, an anthropophilic species Trichophyton rubrum was found to be one of the species of dermatophytes colonising the skin of animals that did not present symptoms of infection. Is the carrier state of this species important in the epidemiology of human infections? Additionally, animal breeders and veterinarians claim that only certain breeds of dogs and cats manifest high sensitivity to dermatophyte infections. The pathomechanism of dermatophyte infections has not yet been fully elucidated; however, three main stages can be distinguished: adhesion of arthrospores to corneocytes, their germination and development of mycelium, and fungal penetration into keratinised tissues. Importantly, the dermatophyte life cycle ends before the appearance of the first symptoms of the infection, which may pose an epidemiological threat. Dermatophyte virulence factors include various exoenzymes, mainly keratinase, protease, lipase, phospholipase, gelatinase, and DNase as well as toxins causing haemolysis responsible for nutrient supply to pathogens and persistence in the stratum corneum of the host. Clinical symptoms of the infection are external manifestations of the dermatophyte virulence factors.

1. Introduction. 2. Dermatophytoses in dogs and cats. 2.1. Diagnostic problems in zoophilic dermatophytoses. 2.2. The prevalence of dermatophytosis in dogs and cats. 2.3. Factors predisposing to dermatophytosis. 2.4. Breed predilections in dermatophyte infections. 3. Pathogenesis and dermatophyte virulence factors. 3.1. Development of dermatophyte infection. 3.2. The pathogenesis of infection. 3.3. Dermatophyte virulence factors. 3.4. Clinical symptoms in canine and feline dermatomycoses. 3.5. Host immune response. 4. Summary

Presently, the overuse of antibiotics is a great problem all over the world. The reason for this phenomenon is both primary and secondary resistance. Primary resistance is a congenital feature of microbes and does not depend on its contact with a drug. It is chromosomally coded and cannot be transmitted to other species of bacteria. Secondary resistance, on the other hand, develops as a result of contact with the antibiotic substance. Genes located in plasmids are responsible for the formation of this type of resistance. One plasmid often contains resistance genes for several different antibiotics. Plasmids can transfer gene-encoded resistance from one bacterial cell to another by conjugation and transduction. As a result of the overuse of antibiotics in humans and animals, a growing number of infections – such as pneumonia, salmonellosis, tuberculosis, and gonorrhea – are becoming more troublesome to treat. Antibiotic resistance leads also to longer hospital stays, higher medical costs and finally increased mortality. Now people are finally becoming aware of the consequences of the overuse of antibiotics. Thus, interest in natural bacteriostatic materials, such as plant essential oils, has observably grown. A number of scientific studies have confirmed the antimicrobial activity of plant-derived essential oils against pathogenic bacteria, including Pseudomonas aeruginosa. A very important advantage of plant oils is the fact that they are active in low, sub-lethal concentrations, without provoking the acquisition resistance mechanisms in bacteria. The aim of this review was to explain the mechanisms of antibiotic resistance formation on the example of Pseudomonas aeruginosa and to demonstrate that it is worth looking for alternative treatment methods which can lead to limiting the use of antibiotics. Finally, this work tries to explain how the oils work.

1.Introduction. 2. The characteristics of Pseudomonas genus. 2.1. Pseudomonas aeruginosa. 3. The mechanisms of antibiotic resistance in Pseudomonas spp. 3.1. Intrinsic resistance. 3.2. Adaptive resistance. 3.3. Plasmid resistance. 4. The most common resistances of clinical P. aeruginosa strains to antibiotics. 4.1. Resistance to aminoglycosides. 4.2. Resistance to fluoroquinolones. 4.3. Resistance to cephalosporins. 5. Essential oils from plants as a natural alternative for antibiotics. 5.1. Antibacterial activity of plant EOs against Pseudomonas spp. 5.2. How EOs work on the bacteria cell. 6. Summary

Exopolysaccharides (EPS) are one of the classes of extracellular biopolymers synthesized by bacteria. Some strains of lactic acid bacteria (LAB) used in the dairy industry are able to synthesize EPS (EPS(+) strains). EPS may be secreted by a cell in the form of capsule or slime. Our review describes the factors influencing the activity of EPS production by LAB, the impact of the use of EPS(+) strains on the quality of fermented milk products (yoghurt, cheeses, etc.) and pro-health properties of EPS produced by LAB. The capability to synthesize EPS by LAB depends on many factors, e.g., affiliation to species and characteristics of strain, growth stage, composition of culture medium (type of carbon and nitrogen sources, and presence of other nutrients), temperature, pH, and presence of adjuvant microflora. The presence of EPS synthesized by LAB strains has a significant effect on changes in various properties of dairy products, including: yoghurt, kefir and many other fermented milk drinks, sour cream and cheeses. The EPS act as thickening, emulsifying and gelling agents, hence the use of EPS(+) strains may become a certain alternative to the use of thickeners in, e.g., fermented milks. During formation of a casein milk curd, EPS are able to bind water and thus reduce syneresis. The high water holding capacity of EPS has a positive effect on increasing viscosity and improving texture of low-fat cheeses. EPS are claimed to have health-promoting properties, like: anticarcinogenic, antioxidative, immunomodulatory and reducing blood cholesterol.

1. Introduction. 2. General characteristics of exopolysaccharides. 3. Factors affecting exopolysaccharides synthesis by lactic acid bacteria. 4. Effect of exopolysaccharides on the quality of fermented milk products. 4.1. Effect of EPS on the quality of yoghurts. 4.2. Effect of EPS on the quality of other fermented milk drinks. 4.3. Effect of EPS on the quality of cheeses. 5. Health-promoting properties of exopolysaccharides. 6. Conclusions

In each laboratory, a quality assurance program should be developed in order to obtain reliable results and to fulfil the requirements of quality standards in the field of microbiological laboratory tests. Microbiological diagnostics makes it possible to determine the etiological agent of infection and allow the selection of an appropriate therapy. The quality of test results are affected by pre-laboratory, laboratory and post-laboratory steps, which should be checked regularly. Constant internal quality control of performance in the laboratory and participation in external quality control programmes may ensure the quality of results. Internal quality control of the tests at all stages of routine microbiological diagnostics in the laboratory facilitates constant monitoring of the quality of results. Participation in interlaboratory external quality control programmes permits the quality of performance of tests routinely used in a laboratory to be assessed.

1. Introduction. 2. Quality assurance programme. 2.1. Factors affecting quality. 3. Internal quality control. 3.1. Quality control of identification tests. 3.2. Internal quality control of antimicrobial susceptibility testing and detecting resistance mechanisms. 3.3. Internal quality control of automated systems for identification and susceptibility testing. 4. External quality control. 4.1. External quality assurance programme participation rules. 5. Summary