Extra-intestinal pathogenic Escherichia coli - threat connected with food-borne infections

Infections caused by extra-intestinal pathogenic Escherichia coli (ExPEC) are a serious public health problem worldwide. The most troublesome are urinary tract infections, severe neonatal meningitis, serious intraabdominal infections, and more rarely, pneumonia, intravascular-device infections, osteomyelitis, soft-tissue infections or sometimes bacteraemia. These strains are also able cause significant economic losses in animal husbandry. A thorough understanding of ExPEC ecology, reservoirs, chains and dynamics of transmission can greatly contribute to a reduction in the burden of ExPEC-associated disease. The ability of E. coli (including ExPEC) to exist and survive in various ecological niches impedes the precise recognition and indication of transmission routes most important for individual infections cases. Among many identified ExPEC reservoirs, animal companion and animals providing food seem to be important sources of infection for human; however, the real level of risk connected with potential transmission of these bacteria remains unclear. Food is indicated as one of potential ways of transmission. Despite a quite high number of reports, many of the uncertainties are expected to be reliably elucidated. This review presents most important data on the current state of knowledge concerning the potential role of food in ExPEC transmission. The possible consequences of ExPEC infections in human and animals are briefly described.

Streptococcus suis: a re-emerging pathogen associated with occupational exposure to pigs or pork products. Part II - Pathogenesis

Streptococcus suis is a re-emerging zoonotic pathogen that may cause severe disease, mostly meningitis, in pigs and in humans having occupational contact with pigs and pork, such as farmers, slaughterhose workers and butchers. The first stage of the pathogenic process, similar in pigs and humans, is adherence to and colonisation of mucosal and/or epithelial surface(s) of the host. The second stage is invasion into deeper tissue and extracellular translocation of bacterium in the bloodstream, either free in circulation or attached to the surface of monocytes. If S. suis present in blood fails to cause fatal septicaemia, it is able to progress into the third stage comprising penetration into host's organs, mostly by crossing the blood-brain barrier and/or blood-cerebrospinal fluid barrier to gain access to the central nervous system (CNS) and cause meningitis. The fourth stage is inflammation that plays a key role in the pathogen esis of both systemic and CNS infections caused by S. suis. The pathogen may induce the overproduction of pro-inflammatory cytokines that cause septic shock and/or the recruitment and activation of different leukocyte populations, causing acute inflammation of the CNS. Streptococcus suis can also evoke - through activation of microglial cells, astrocytes and possibly other cell types - a fulminant inflammatory reaction of the brain which leads to intracranial complications, including brain oedema, increased intracranial pressure, cerebrovascular insults, and deafness, as a result of cochlear sepsis. In all stages of the pathogenic process, S. suis interacts with many types of immunocompetent host's cells, such as polymorphonuclear leukocytes, mononuclear macrophages, lymphocytes, dendritic cells and microglia, using a range of versatile virulence factors for evasion of the innate and adaptive immune defence of the host, and for overcoming environmental stress. It is estimated that S. suis produces more than 100 different virulence factors that could be classified into 4 groups: surface components or secreted elements, enzymes, transcription factors or regulatory systems and transporter factors or secretion systems. A major virulence factor is capsular polysaccharide (CPS) that protects bacteria from phagocytosis. However, it hampers adhesion to and invasion of host's cells, release of inflammatory cytokines and formation of the resistant biofilm which, in many cases, is vital for the persistence of bacteria. It has been demonstrated that the arising by mutation unencapsulated S. suis clones, which are more successful in penetration to and propagation within the host's cells, may coexist in the organism of a single host together with those that are encapsulated. Both 'complementary' clones assist each other in the successful colonization of host's tissues and persistence therein. S. suis has an open pan-genome characterized by a frequent gene transfer and a large diversity. Of the genetic determinants of S. suis pathogenicity, the most important are pathogenicity islands (PAI), in particular, a novel DNA segment of 89 kb length with evident pathogenic traits that has been designated as 89K PAI. It has been estimated that more than one-third of the S. suis virulence factors is associated with this PAI. It has been proved that the virulent S. suis strains possess smaller genomes, compared to avirulent ones, but more genes associated with virulence. Overall, the evolution of the species most probably aims towards increased pathogenicity, and hence the most significant task of the current research is an elaboration of a vaccine, efficient both for humans and pigs.

Streptococcus suis: a re-emerging pathogen associated with occupational exposure to pigs or pork products. Part I - Epidemiology

Streptococcus suis (ex Elliot 1966, Kilpper-Bälz & Schleifer 1987) is a facultatively anaerobic Gram-positive ovoid or coccal bacterium surrounded by a polysaccharide capsule. Based on the antigenic diversity of the capsule, S. suis strains are classified serologically into 35 serotypes. Streptococcus suis is a commensal of pigs, commonly colonizing their tonsils and nasal cavities, mostly in weaning piglets between 4-10 weeks of age. This species occurs also in cattle and other mammals, in birds and in humans. Some strains, mostly those belonging to serotype 2, are also pathogenic for pigs, as well as for other animals and humans. Meningitis is the primary disease syndrome caused by S. suis, both in pigs and in humans. It is estimated that meningitis accounted for 68.0% of all cases of human disease reported until the end of 2012, followed by septicaemia (including life-threatening condition described as 'streptococcal toxic shock-like syndrome' - STSLS), arthritis, endocarditis, and endophthalmitis. Hearing loss and/or ves tibular dysfunction are the most common sequelae after recovery from meningitis caused by S. suis, occurring in more than 50% of patients. In the last two decades, the number of reported human cases due to S. suis has dramatically increased, mostly due to epidemics recorded in China in 1998 and 2005, and the fulminant increase in morbidity in the countries of south-eastern Asia, mostly Vietnam and Thailand. Out of 1,642 cases of S. suis infections identified between 2002-2013 worldwide in humans, 90.2% occurred in Asia, 8.5% in Europe and 1.3% in other parts of the globe. The human disease has mostly a zoonotic and occupational origin and occurs in pig breeders, abattoir workers, butchers and workers of meat processing facilities, veterinarians and meat inspectors. Bacteria are transmitted to workers by close contact with pigs or pig products, usually through contamination of minor cuts or abrasions on skin of hands and/or arms, or by pig bite. A different epidemiologic situation occurs in the Southeast Asian countries where most people become infected by habitual consumption of raw or undercooked pork, blood and offal products in the form of traditional dishes. Prevention of S. suis infections in pigs includes vaccination, improvement in pig-raising conditions, disinfection and/or fumigation of animal houses, and isolation of sick animals at the outbreak of disease. Prevention of human infections comprises: protection of skin from pig bite or injury with sharp tools by people occupationally exposed to pigs and pig products, prompt disinfection and dressing of wounds and abrasions at work, protection of the respiratory tract by wearing appropriate masks or repirators, consulting a doctor in the case of febrile illness after exposure to pigs or pork meat, avoidance of occupations associated with exposure to pigs and pork by immunocompomised people, avoidance of consumption of raw pork or pig blood, adequate cooking of pork, and health education.

Occurrence and characterisation of MRSA and extended-spectrum ß-lactamases producing Escherichia coli isolated from mastitic cows’ milk

The aim of study was the preliminary evaluation of the occurrence of methicillin-resistant Staphylococcus aureus (MRSA) and extended spectrum ß-lactamases (ESBL) - producing Escherichia coli in 650 milk and inflammatory secretions from cows with clinical or subclinical mastitis. One millilitre of the sample was added to Mueller-Hinton broth supplemented with 6.5% NaCl, Tryptone Soya Broth with cefoxitin and aztreonam, and then to MRSA ID agar. Presumptive MRSA colonies were analysed for the presence of mecA gene. Parallel to MRSA identification, the samples were incubated in buffered peptone water, lauryl tryptose broth and McConkey agar supplemented with cefotaxim for ESBL-producing E. coli isolation. These bacteria were identified using API Rapid 32 E and the ability of ESBL production was initially established using disc test D68C and confirmed by MIC technique using Sensititre ESBL plates. The primers (blaCTX, blaTEM, blaSHV, and blaCMY-2-group) for the detection of some of the genes encoding ESBL production were used. The 45 strains of S. aureus with mecA gene and 41 strains of E. coli with blaTEM gene were detected.

Occurrence of Leptospira DNA in water and soil samples collected in eastern Poland

Leptospira is an important re-emerging zoonotic human pathogen, disseminated by sick and carrier animals, water and soil. Weather calamities, such as flooding or cyclones favour the spreading of these bacteria. To check a potential role of natural water and soil in the persistence and spread of Leptospira on the territory of eastern Poland, 40 samples of natural water and 40 samples of soil were collected from areas exposed to flooding, and 64 samples of natural water and 68 samples of soil were collected from areas not exposed to flooding. Samples of water were taken from various reservoirs (rivers, natural lakes, artificial lakes, canals, ponds, farm wells) and samples of soils were taken at the distance of 1-3 meters from the edge of the reservoirs. The samples were examined for the presence of Leptospira DNA by nested-PCR. Two out of 40 samples of water (5.0%) collected from the area exposed to flooding showed the presence of Leptospira DNA, while all 40 samples of soil from this area were negative. All samples of water and soil (64 and 68, respectively) collected from the areas not exposed to flooding were negative. No significant difference were found between the results obtained in the areas exposed and not exposed to flooding. In conclusion, these results suggest that water and soil have only limited significance in the persistence and dissemination of Leptospira in eastern Poland.

Leptospirosis--current risk factors connected with human activity and the environment

Leptospirosis is a widespread although recently neglected zoonosis recognized worldwide. The disease seems to be underestimated, especially in countries located in the temperate climatic zone. The presented article concerns the main characteristics of leptospirosis and describes formerly known and recently observed environmental, occupational and recreational risk factors significant in the spreading and pathogenesis of the disease. The aspects of epidemiology significant in the temperate climatic zone are emphasized. The majority of cited articles present cases of the disease reported from Europe or North America. Climatic changes (warming) and extreme weather events such as floods are potential risk factors of leptospirosis. Also, some socio-economic phenomena, such as the intensive migration of people resulting in the transfer of the infections acquired in tropical countries, or worsening of economic status in the cities, increase the probability of disease. Apart from the danger connected with rodents, which are the main vectors of leptospires, occurrence of the disease in dogs and cats can generate a higher risk of infection for humans. Infections may also be acquired during various types of agricultural work and during recreational activities, such as swimming. The results of recent investigations show that ticks are also potential vectors of leptospires. The more frequent emergence of leptospirosis in countries located in the temperate climatic zone emphasize the need to verify knowledge related to the risk of its appearance, and to consider this disease during diagnostic processes.

Seroprevalence of leptospirosis in rural populations inhabiting areas exposed and not exposed to floods in eastern Poland

Blood serum samples collected from randomly selected groups of 100 persons inhabiting rural community 'A' located in eastern Poland and exposed to floods by the Vistula river, and 98 persons inhabiting rural community 'B', also located in eastern Poland, but in the area not exposed to floods were examined by the microscopic agglutination test (MAT) for the presence of antibodies against 18 Leptospira serovars. Positive results showed 3% of serum samples collected from community 'A', while the seroprevalence in community 'B' was 9.2%, being insignificantly higher than in community 'A'. For both examined communities (n=198), a significant positive correlation was found between the prevalence and titer of seropositive response and age of examined people (r=0.145, p=0.042). No significant differences were found between the prevalence of positive reactions in males and females (p>0.05). The reactions with 10 serovars of Leptospira (Australis, Autumnalis, Hebdomadis, Hardjo, Sejroe, Zanoni, Bataviae, Bratislava, Canicola and Grippotyphosa), belonging to 3 species (L. interrogans, L. borgpetersenii, L. kirschneri), were found in the examined communities. From both communities, of 12 persons demonstrating positive results in MAT, 9 showed reaction with one serovar, 2 with two serovars and 1 with three serovars. The highest titers found during the examination did not exceeded 800. In conclusion, our results suggest that there is only a slight, if any, hazard of an leptospirosis epidemic after the flood that afflicted eastern Poland in the year 2010 and the general epidemiological situation of leptospirosis in eastern Poland. Although there does not seem to be any cause for concern, further research is needed.

[Leptospirosis--current problems]

Leptospirosis has been known for more than one hundred years zoonosis, caused by pathogenic spirochetes of the genus Leptospira. It occurs most often in tropical countries where the infections of humans are acquired from animals or from environment contaminated by leptospires. In temperate climatic zone main source of infections are animals. In spite of not common occurrence of leptospirosis in temperate climate the disease is still difficult for recognition and treatment. Laboratory diagnosis needs quick and precise methods allowing detect and differentiate leptospires directly in clinical samples. The efficacy of carrier state eradication methods in humans and animals are still unsatisfied. There are also not available vaccines, which enable protection against infections caused by all or majority of pathogenic Leptospira serovars. Furthermore, some climatic and socioeconomic phenomena observed in the last decades can increase the range of favourable circumstances for transmission of Leptospira infections from animals to men. Selected reports concerning cases of leptospiral infections connected with mentioned above phenomena noted in countries located in temperate climatic zone are quoted in the article. Known for many decades sources of infections are also still dangerous and the real scale of this hazard is not precisely estimated. Current data concerning serological screenings among selected species of domestic animals and wildlife as well as examples of described in European countries cases of Leptospira infections transmitted from animals to man are quoted in the article.