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57 Cards in this Set
- Front
- Back
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Describe the structure of enterobacteriacea.
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Non-motile and motile via peritrichous flagella. non spore forming. facultative anaerobes to produce acid and gas (some lactose), catalase positive and oxidase negative. Some have capsules.
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How are entereobacteriaceae identified?
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Based on the O, H, and K antigens. This is detected by the antibody agglutination.
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What are the general enterobacteriaceae virulance factors?
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Endotoxin, capsule, phase variation, Type III secretion system, Sederophores, Resistance to killing serum, and Antimicrobial resistance.
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Describe how the Type III secretion system works.
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A molecular syringe injects virulence factors into the host cell. This manipulates the host cell and enables the bacteria to attach or phagocytize the bacterial cell.
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What are siderophores and cite some examples.
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They sequester iron from the environment. enterobactin and aerobactin.
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How does enterobacteriaceae resist to serum killing?
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grows resistant to complement inactivation via capsule and O side chains.
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Where is Escherichia coli located?
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in the GI tract of warm-blooded animals, most of it is harmless.
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What type of contamination is Estcherichia coli indicitive of?
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Fecal contaimination due to its proximity to the GI tract.
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If Escherichia coli is not pathogenic, then why is it harmful?
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It has evolved to become harmful.
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What are the three disease Escherichia coli is associated with?
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neonatal meningitis, UTI's, and gastroenteritis.
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Describe extraintestinal Escherichia coli.
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They can colonize, survive, and cause disease outside of the intestine. They have specific virulence factors that enable this.
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What causes neonatal meningitis.
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Caused by K-1 capsular antigen extraintestinal Escerechia coli. K-1 capsular antigen may aid in crossing blood braind barrier.
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What is the critical virulence factor if UTI's?
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P-pili. and siderophores.
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What is the role of P-pili?
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attach to specific receptors in the urinary tract to susceptible individuals. This resists being washed away upon urination.
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Where is the UTI infection usually acquired?
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from within/self inoculation.
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What are the five different types of intestinal E. coli?
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Enteropathogenic, Enterohemorrhagic, Enterotoxigenic, Enteroinvasive, and Enteroaggregative.
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Describe the Enteroinvasive form of intestinal E. coli.
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EIEC causes foodbourne outbreaks in developing countries. EIEC invade colonic epithelial cells.
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Describe the Enteroaggregative form of intestinal E. coli.
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EAEC causes foodbourned outbreaks in developing countries.
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Describe the symptoms of the Enteropathogenic form of intestinal E. coli.
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EPEC causes diarrhea in infants in underdeveloped countries. they form attaching and effacing lesions to the host.
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What is effacement?
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The destruction of microvilli.
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Describe how attachment of the Enteropathogenic intestinal E. Coli to the host cell occurs.
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Bundle forming pilli initiate a loose attachment, destruction of microvilli occur (effacement), TTSS injects Translocated intimin receptor (Tir) into host cell, which serves as a receptor for intimin on host cell. This results for a more intimate attachment to the host cells. Finally, a pedestal forms at the attachment site.
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Where is enterohemmorhagic E. Coli most common?
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Developed countries.
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What is the most common Enterohemmorhagic E. coli serotype in the US?
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O157:H7
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What is Enterohemmorhagic E. coli associated with?
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Undercooked meat, unpasteurized milk and juices, fruits, vegetables, and water.
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What can develop in about half the patients with Enterohemmorhagic E. coli?
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Hemmorhagic colitis, or bloody diarrhea. Hemolytic Uremic Symdrome can occur in children ( 3-5% die ) and some produce lesions similar to EPEC.
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What are the toxins produced by Enterohemmorhagi E. coli?
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Shiga toxin 1 and Shiga toxin 2.
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When is Enterotoxigenic E. coli most commonly seen?
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In developed countries, usually in the travelers.
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What are the two toxins that Tenterotoxigenic E. coli produces?
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Heat stable toxin and a Heat Labile toxin.
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Where do salmonella invade?
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They invade and replicate in intestinal epithelial cells.
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Describe how the pathogenic pattern of somonella.
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inject salmonella secreted invasion proteins in host cell using TTSS. These stimulate host to phagocytize salmonella. Salmonella then replicate, and some can transport to other sites of the body.
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What do salmonella typhi and salmonella paratyphi cause?
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typhoid and paratyphoid. Can also cause the systemic disease enteric fever.
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Where are salmonella typhic and salmonella paratyphi found?
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In humans in developing countries.
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How long can salmonella be shed?
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Up to a year after symptoms resolve. (low infectious dose)
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What does non-typhoidal salmonella cause?
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salmonellosis
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Describe Salmonellosis.
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Can infect a variety of animals, primarily foodbourne, big problem in developed countries, high infectious dose, can be shed for weeks after symptoms dissolve.
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What are the four species of Shigella?
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S. dysenteriae, S. flexneri, S. boydii, S. Sonnei.
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Where does Shigella attach?
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To intestinal epithelial cells.
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How does Shigella attach?
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Initiates phagocytosis using TTSS.
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How does Shigella evade the immune system?
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replicates in the cytoplasm to evade the phagosome.
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What toxin is produces by Sigella?
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The shiga toxin.
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Describe Shigellosis.
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Caused bye Shigella, Characterized by bloody stools, transmitted via fecal oral route, low infectious dose, young children are at a high risk.
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What is the bloody diarrhea of Shigellosis a result of?
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Destruction/invasion of epithelial cells.
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What does Y. pestis cause?
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The bubonic plague, The black death, systemic diseases.
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What is caused by Y. enterocolitica Y. pseutotuberculosis?
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Entercolitis.
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What is a zoonic pathogen and what is an example?
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One spread from animals to humans, an example is Y pestis.
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Describe the Sylvatic cycle.
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Transmission along the rodent population. Spread primarily from wild rodents to humans via the bite of an infected flea.
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Describe the Urban Cycle.
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Transmission in an urban setting. Spread primarily from rats to humans via the bite of an infected flea.
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Describe the Yersernia pestis pathogenisis.
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Enter following a flea bite, phagocytized by macrophages. replicate in macrophages and released, replicated cells are resistant to phagocytosis (mediated by TTSS and antiphagotic capsule), bacteria can spread through lymph nodes.
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What are two ways that Yersernia pestis resists phagocytosis?
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TTSS, injects cytotoxic proteins into host phagocyte cells, and an antiphagocytic protein capsule that is plasmid mediated.
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What are the two diseases that Yersernia pestis can cause?
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Bubonic and Pneumonic.
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Describe the bubonic infection caused by Yersinia pestis.
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High fever and swollen, painful bulbo. If untreated, bacteremia can develop followed by pneumonic plague.
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Describe the pneumonic infection caused by Yersinia pestis.
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Can be a primary or secondary infection with the bubonic plague. highly infections with a 90% mortality rate.
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Describe Yersinia enterocolitica
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Foodborne pathogen associated with meats, milk or water. pshycotroph, can grow at 4 degrees C. Can also be transmitted during blood transfusions.
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Why is enterobacteriaceae hard to treat?
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Antibiotic resistance is a big problem, and it spreads easily among enterobacteriaceae members. Antibiotic therapy can make some cases worse! (E. coli O157:H7)
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For which enterobacteriaceae is there a vaccine for?
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S. Typhi, it is recommended for people traveling to high-risk areas, but the vaccine can be overcome by bacterial load.
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How is the number of Salmonella cases being brought down in the US and other countries?
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By strict food regulations.
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How is the number of Shigella cases brought to a minimum?
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hygiene education
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