Test Questions on Microbiology Exam 1 – Flashcards
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| infectious disease |
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| a disease in which a pathogen invades a susceptible host and carries out at least part of their lifecycle in the host. |
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| endogenous infection |
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| something's that part of the body, part of the normal flora but it can become an infection in large enough numbers ex) yeast infection, e coli, staff infection |
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| exogenous infection |
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| something from outside the body, may be part of the normal flora, but more typically is something that isn't part of the normal flora ex) herpes |
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| resistance to antibiotics, pathogens that mutate, population density (easier to spread), travel (exposure to more pathogens), people not getting vaccinated |
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| why is there an increase in death from infectious disease? |
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| microparasite |
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| replicate inside the host and typically produce a large # of progeny and potentially a serious infection ex) bacteria, viruses, fungi, and protazoa |
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| macroparasites |
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| typically have one infectious stage maturing into a reproducing stage, with the offspring exiting the host to continue the cycle. The level of the infection is dependent on the number of organisms that entered the body. ex) arthropods, worms, helminthes |
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| intracellular pathogens |
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| have access to the host's nutrient supply, genetic material, and can avoid the host's immune system and antimicrobial protective mechanisms. |
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| extracellular pathogens |
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| can feed on host cells or take up nutrients from tissue fluids or gut contents. many can spread rapidly through extracellular fluids or over host surfaces |
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| vector |
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| term used to refer to an organism which itself does not cause disease but allows the transmission of disease causing microbes |
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| pathogen |
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| protazoa that directly causes disease |
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| false |
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| true or false bacteria are more advanced than protazoa with respect to their metabolic function. |
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| nucleus |
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| bacteria are prokaryotes. pro means before and karyote means... |
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| bacteria |
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| single celled prokaryotes DNA is in a long circular molecule devoid of an envelope but found in the region called the nucleoid the cell wall is complex and there is often a thick capsule no organelle other than ribosomes some possess flagella for motility pili function in the passage of DNA from one organism to another fimbriae function in the attachment to other bacteria or a host a mesosome is a coiled cytoplasmic membrane that anchors chromosomes |
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| bacterial "sex" via the transfer of DNA from one bacterium to another |
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| a bacterial pilus is an organelle that functions in... |
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| intracellular pathogens |
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| have access to the host's nutrient supply, genetic material, and can avoid the host's immune system and antimicrobial protective mechanisms. |
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| obligate aerobes |
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| require oxygen to live |
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| obligate anaerobes |
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| unable to use oxygen for energy yielding reactions. are harmed by oxygen |
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| facultative anaerobes |
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| can use oxygen when it is present but are able to continue growth via fermentation or anaerobic respiration when oxygen isn't available |
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| bacteria are heat fixed or dried on a slide stained with crystal violet and Gram's iodine excess stain is removed by washing with acetone-based decolorizer and water red counterstain (safranin) is added |
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| process of gram staining |
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| gram positive bacteria |
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| thick multilayered cell wall made mainly of peptidoglycan around the cell membrane peptidoglycan can block phagocytosis and induce fever degraded with lysozymes may contain teichoic and lipoteichoic acids and polysaccarides outer membrane: no lysozyme: sensitive cell wall: thicker lipopolysaccaride: no endotoxin: no |
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| gram negative bacteria structurally and chemically more complex than gram positive cell walls |
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| outer membrane is hydrophilic but also hydrophobic due to lipids special pores made of proteins (porins) allow passage of nutrients LPS confers antigenic and toxic properties outer membrane: yes lysozyme: resistant cell wall: thinner lipopolysaccarides: yes endotoxin: yes |
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| starved cells old cells in the stationary stage treated with antibiotics mycobacteria (waxy outer shell), mycoplasmas (no peptidoglycan) |
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| when does gram staining not work? |
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| spherical rod shaped spiral |
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| coccus bacillus spirillum |
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| transformation |
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| bacteria take up fragments of naked DNA and incorporate them into their genome some species are competent, naturally taking up exogenous DNA |
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| conjugation |
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| a one way transfer of DNA from a donor (male) to a recipient (female) cell through the sex pilus |
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| transduction |
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| the transfer of genetic material from one bacteria to another via a bacteriophage (bacterial viruses with extrachromosomal genetic elements). once in a cell, a transposon can jump between plasmid to plasmid or plasmid to chromosome. |
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| 1) production of the basic building block (UDP-acetylmuramyl-pentapeptide), takes place inside the cell. Cycloserine, a rather toxic antibiotic that is employed rarely in the treatment of mycobacterial infections, inhibits the terminal reactions in this sequence. 2) the precursor unit is carried from inside the cell membrane to outside. During this process, a number of modifications occur in the chemical structure of the basic repeating unit; they are linked covalently to the pre-existing cell wall. Vancomycin and bacitracin act during this second stage. 3) takes place entirely outside the cell membrane and consists of a variety of reactions that cross link and modify the wall components (the cross linking enzymes and some of the modifying enzymes are inhibited by penicillins and cephalosporins) |
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| cell wall synthesis can be divided into these 3 stages |
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| D-Alanine terminal |
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| repeating unit of cell wall synthesis has a common terminal in all bacteria (gram - or +) |
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| 1) initiation: involves formation of an initiation complex. In bacteria, the first aa is formylmethionine. Formylmethionine and its appropriate tRNA are first united under the direction of an aminoacyl-tRNA-synthetase to form the aminoacyl-tRNA 2) elongation: at the end of initiation, the ribosome is ready to translate the reading frame associated with the initiation codon. Elongation is accomplished by the sequential repetition of three reactions with each aa. 3) termination: the elongation process continues until a termination sequence containing code triplets UAA, UGA, or UAG in the mRNA signals that the protein chain is complete. The termination codon is not an aminoacyl-tRNA. The ribosome binds a protein called "termination release factor" which recognize the termination codon in the A site. The peptidal transferase works now as an esterase that releases the peptide. The ribosome is released. in each stage a different set of protein factors is utilized by the ribosome. These factors cycle on and off the ribosome and allow the ribosome to interact with them sequentially at a single site. |
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| 3 stages of protein synthesis (process of mRNA translation) |
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| given to patients who have a suspected infection |
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| empiric antibiotic therapy |
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| very specific for the identified pathogen |
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| definitive antibiotic therapy |
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| patient doesn't have infection, but may have the risk |
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| prophylaxis antibiotic therapy |
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| Staphylococcus aureus |
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| gram positive bacteria shape: cocci clusters coagulase + (coagulase is a protein produced by some microorganisms) |
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| Staphylococcus epidermidis and Staphylococcus saprophyticus |
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gram positive bacteria shape: cocci clusters coagulase negative (coagulase is a protein produced by some microorganisms) |
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| Streptococcus pneumoniae and Streptococcus viridians |
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| gram positive bacteria shape: cocci chains alpha-hemolysis (the agar is dark or green) |
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| Streptococcus pyogenes and Streptococcus agalactiae |
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| gram positive bacteria shape: cocci chains beta-hemolysis (the agar is yellow) |
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| Vibrio and Aeromonas |
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| gram negative bacteria shape: bacillus respiration: aerobic glucose fermentation (lactose +) |
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| E. coli, Klebsiella, and Salmonella |
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| gram negative bacteria shape: bacilli respiration: aerobic glucose fermentation (lactose -) |
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| virus |
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| aren't living obligate intracellular parasites must be infectious to survive in nature cannot make energy or proteins independent of a host cell contain RNA OR DNA (whereas living organisms contain RNA and DNA) have to be able to use host processes to produce proteins, viral mRNA, identical copies of the genome. single (ss) or double stranded (ds), linear or circular DNA or RNA within a capsule (capsid) may only be a nucleocapsid or it may have an outer membrane or envelope (derived from the host cell) [image] |
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| [image] host specificity is due to the ability of the virus to attach to the host cells receptor molecules |
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| stages in the infection of a host cell and the replication of the virus |
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| lytic infection |
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| viral infection where the virus replicates, produces new viruses, and they are released when the cell lyses. |
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| persistent infection |
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| viral infection where the cell survives and releases particles slowly |
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| latent infection |
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| viral infection where the virus is quiescent (dormant) with the DNA or RNA existing in the host's cytoplasm (herpes) or in the host's genome (retrovirus) replication takes place when some type of activation occurs. |
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| biochemical properties: mode of replication structure: size, morphology, nucleic acid associated disease mode of transmission host cell: animal, plant, bacterium target tissue or organ |
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| methods of classifying viruses |
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| [image] |
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| modes or viral transmission |
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| fungal cell ergosterol in the cell wall instead of cholesterol different antifuncals are going to target different parts of the cell or the cell cycle |
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| [image] |
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| multicellular, branching filamentous (hyphae) forms or as unicellular yeast filamentous forms, mass of hyphae is called a mycelium; asexual reproduction results in spores yeasts reproduce by budding or fission (division) |
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| fungal morphology |
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| superficial |
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| fungal infection of the body surface (skin, hair) |
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| cutaneous or subcutaneous |
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| fungal infection of the nails or subcutaneous area of the skin |
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| systemic |
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| fungal infection of the internal organs |
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| opportunistic |
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| fungal infection that causes disease in immune compromised hosts |
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| protozoa |
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| single celled animals cytoplasm enclosed by a cell membrane and many organelles (ex. nucleus, ER, vacuoles) move via pseudopods, flagella, cilia |
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| usually asexual (binary or multiple division) sexual (rare) in an arthropod vector |
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| methods of protozoal reproduction |
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| protozoan infections |
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| most common in tropical, subtropical regions but many in temperate intracellular parasites infect RBCs, macrophages, brain, muscle, and epithelial cells. Nutrient uptake from host cells. Extracellular pathogens infect the blood, intestines, urinary or reproductive tracts. Feed by nutrient uptake from host cells or ingest the whole cell. |
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| ingestion of cysts in contaminated food or drink (Giardia) sexual contact; reside in urogenital tract arthropod vectors (malaria); reside in blood or other tissues |
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| modes of transmission for protozoa |
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| some can: continuously change their surface antigens develop into a cyst form in harsh conditions consume compliment at the cell surface intracellular protozoa can evade intracellular enzymes facultative anaerobes for example: Giardia lamblia has a cyst form and it has a ventral sucker that allows it to attach to human intestines |
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| protozoan survival mechanisms |
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| cestoda |
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| helminth flatworm tapeworm has suckers/hooks |
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| trematoda |
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| helminth flatworm fluke has suckers/hooks |
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| nematoda |
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| helminth roundworm no attachment organs |
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| parasitic worms all organs in the body can become infected larvae are macroscopic adults are macroscopic (cm-m) anaerobic respiration (predominantly) flatworms do have attachment organs roundworms do not have attachment organs many lack a digestive system (flukes absorb food via the cuticle) they have a simplified and reduced nervous system their means of movement are dramatically reduced they have a complex reproductive system in which they produce large numbers of eggs for infection |
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| characteristics of helminthes |
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| [image] risk factors: low sanitation, walking barefoot, eating uncooked or undercooked meat, insect bites |
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| modes of helminth transmission |
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| simple tapeworm lifecycle |
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| [image] |
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| complex life cycle goes through humans and it can go through an intermediate host (2 loops) |
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| [image] |
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| arachnida: spiders, ticks, mites insecta: mosquitoes, fleas, lice |
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| 2 phylum of arthropods that cause infectious disease |
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| directly by feeding on host's tissue/blood indirectly via transmission |
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| modes of disease transmission for arthropods |
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| malaria from mosquitoes lyme disease from ticks plague from fleas |
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| examples of disease transmitted by arthropods |
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| host |
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| provides an environment for another organism |
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| pathogen |
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| utilizes the environment of the host for nutrients |
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| In the respiratory tract there are macrophages in the alveoli that will get rid of a pathogen through phagocytosis. In the GI tract bacteria can attach to the epithelium, but the body blocks this attachment by increasing acid and mucous production. In the urinary tract, the acidity of urine kills some pathogens and urine can also flush out pathogens. |
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| How does the body respond to or get rid of extracellular bacteriarespiratory tractGI tracturinary tract? |
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| infection |
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| presence of a particular type of microorganism in a part of the body not normally found. |
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| flora members of normal flora can be harmful if they enter sterile areas of the body |
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| microorganisms that are colonized in the body that do not produce disease. |
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| commensalism |
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| parasite/bacteria may benefit but the host may not be affected |
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| mutualism |
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| a relationship with mutual benefits, both the host and the parasite benefit |
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| parasitism |
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| a relationship where only the parasite/bacteria benefit at the expense of the host |
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| 1) the microbe must be present in every case of the disease 2) the microbe must be isolated from the diseased host and grown in pure culture 3) the disease must be reproduced when a pure culture is introduced into a non-diseased susceptible host 4) the microbe must be recoverable from an experimentally infected host exceptions to the rule: some microbes cannot be grown in the laboratory some diseases have more than one microbe involved |
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| 4 rules of Koch's postulate |
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| swallowing/coughing/sneezing mucous production that traps bacteria and the cilia move the mucous down the throat |
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| what are 2 mechanisms that help cleanse the upper respiratory tract? |
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| the common cold |
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| what is the most common infectious disease? |
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| exotoxin |
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| toxic proteins produced by some bacteria (mostly gram positive) and secreted or released after lysis. metabolic product of growing cell high toxicity but not fever producing can be destroyed more easily (unstable) |
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| endotoxin |
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| part of the outer portion of the cell wall (lipid A) of most gram negative bacteria, released on destruction of the cell. low toxicity and fever producing harder for the body to destroy |
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| Streptococcus pyogenes |
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| causes steptococcal pharyngitis (strep throat) gram positive coccus (chains); facultative anaerobe also infects other areas of the URT, skin, kidneys, etc. produces many exotoxins and enzymes the cause of 95% of bacterial sore throats it can spread initially, causing ear infections. If it becomes systemic it can cause scarlet fever (disorder of the heart valves) |
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| cytomegalovirus (CMV) infection |
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| causes pharyngitis largest human herpes virus (Herpesviridae) acquired from most bodily secretions and blood originally called salivary gland virus - transmitted by salivary glands persistent and latent infections; remains latent in neutrophils, t-cells, monocytes often asymptomatic but can spread to lymphoid tissue (agranulocytes in the spleen, lymph nodes), then salivary glands, kidneys, reproductive organs (shed) dangerous to babies (mental retardation, congenital abnormalities), immune impaired |
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| Epstein-Barr virus |
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| herpesvirdidae; transmitted in saliva replicates in B-cells virus is shed in saliva from infected salivary gland and oropharynx epithelial cells, spreads to B-cells in lymphoid tissue T-cells respond to infected B-cells, become hyperplastic (increase in number) infectious mononucleosis (fever, anorexia, lethargy, splenic rupture) |
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| paramyxoviridae |
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| causes parotisis: mumps typically airborne or salivary secretion transmission; lytic infection life long resistance to reinfection |
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| Pseudomonas aeruginosa may also be caused by: staphylococcus aureus or candida albicans; found as normal flora of the skin |
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| causes otitis externa: swimmer's ear gram negative bacillus aerobic it produces an exotoxin and an endotoxin |
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| Streptococcus pneumoniae; gram positive diplococcus, falcultative anaerobe Haemophilus influenzae; gram negative bacillus, facultative anaerobe RSV (respiratory syncytial virus) Streptococcus pyogenes |
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| 4 of the possible causes of otitis media or sinusitis |
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| Haemophilus influenzae |
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| causes epiglottitis typically small children called the most threatening disease of the URT |
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| Streptococcus pyogenes or Streptococcus pneumoniae |
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| causes laryngitis/tracheitis pain during inhalation/exhalation, hoarseness |
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| Respiratory Syncytial Virus |
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| is a paramyxovirus (like mumps) it is the most common cause of bronchiolitis and pneumonia in children under 2 it inflames bronchioles and restricts air to alveoli is an enveloped virus that possesses a fusion protein in its envelope. This confers the ability of the virus to fuse with the host cell membrane and thus allow entry of the infectious genomic material into the cell cytoplasm. During replication of the virus, expression of the fusion protein at the cell membrane can result in the fusion of neighboring cells, and the formation of multinucleated cells or syncytia. |
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| bronchitis |
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| example etiological agents: rhinoviruses, coronaviruses (like common colds), influenza virus. Also caused by allergies and smoking. Cough due to: irritation of bronchi, excess mucous, cilia impaired. Plugging of small airways. Effects the heart b/c there is decreased O2 supply. |
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| pneumonia |
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| acute inflammation of the lung. air spaces become filled with inflammatory exudate. most common cause of infection-related death in the US and Europe Adults: bacterial causes more common than viral (ex. streptococcus pneumoniae) Children: mainly viral (RSV) pathogens reach alveoli by inhalation of aerosolized materials or by aspiration of normal flora of the URT |
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| Pleurisy (pleuritis) |
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| inflammation of the pleural membranes can occur as a result of pneumonia or tuberculosis usually caused by a viral pathogen very painful; sharp, stabbing pain accompanies each inspiration |
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| influenza viral infection influenza A - epidemics, pandemics with animal reservoirs influenza B - epidemics, no animal hosts influenza C - mild |
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| an orthomyxovirus can cause endemic (very localized), epidemic (wider population), and pandemic (worldwide) fever, myalgia, headache, pharyngitis [image] H spikes allow viral recognition to host and attachment N spikes help virus exit the infected host cell viral strains based on H and N antigens |
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| Bordetella pertussis |
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| causes whooping cough (pertussis) gram negative coccobacillus aerobic attaches to and multiply in ciliated tracheal cells but don't invade deeper many toxins: tracheal cytoxin damages ciliated cells, pertussis toxin causes systemic symptoms, endotoxin cold symptoms, gasping for air (whoop); secondary complications can be CNS, anorexia, secondary pneumonia major cause of death world wide |
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| Mycobacterium tuberculosis |
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| causes tuberculosis gram positive bacillus aerobic ***waxy outer coat***, grows slowly and in clumps acquire by inhalation; if infective dose low, can fight via activated macrophages. If not: 1) Bacteria are ingested by alveolar macrophages and walled off in alveoli (tubercle) 2) lesion becomes calcified 3) if defenses fail, tubercle breaks down and bacilli are released into respiratory, lymphatic and cardiovascular systems TB patients respond with cell mediated immunity rather than humoral. this is the basis of the tuberculin skin test. |
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| only need a small amount to become infected people can live with it unknowingly for years and spread it during this time waxy outer coat makes it difficult for the macrophages to destroy waxy outer coat also makes it possible for it to live outside of a human host |
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| Why is Mycobacterium tuberculosis so successful? |
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| fungal aspergillus |
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| many species, spores inhaled regularly; most harmless Aspergillus fumigatus can cause allergic bronchopulmonary aspergillosis or aspergillomas - fungal balls of entangled hyphae |
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| Histoplasma capsulatum |
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| found in feces of starling, pigeons, chickens, bats. (soil with high nitrogen content) is dimorphic - yeast like in tissue growth, filamentous in soil resembles TB - lesions in lungs but spread via blood and lymphatics usually asymptomatic but 0.1% can be severe found in states along Mississippi and Ohio borders |
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| dysentery |
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| a disease characterized by frequent, watery stools containing blood and mucus |
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| enterocolitis |
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| inflammation of the epithelial lining of the SI or LI |
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| gastroeneritis |
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| inflammation of the epithelial lining of the stomach and intestines |
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| When you ingest a toxin in large enough amounts that they cause damage ingestion of pre-formed toxins |
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| What does the word intoxication mean? |
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| [image] |
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| defense mechanisms of the GIT |
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| Escherichia coli |
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| bacterial cause of diarrhea gram negative bacillus facultative anaerobe, motile normal gut inhabitant endotoxins (all strains); enterotoxins associated with diarrhea 5 groups associated with gastroenteritis |
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| Enteropathogenic E. coli |
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| type of E. coli that reduces the surface area of the SI by destroying microvilli interferes with SI absorption resulting in diarrhea non invasive does not produce toxins |
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| enterotoxigenic E. coli |
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| type of E. coli that secretes toxins when in the GI tract the toxins can increase GI motility b/c the intestines want to get rid of the toxin. the immune system secretes prostaglandins, cytokines to increase contractions in response non-invasive |
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| enteroaggregative E. coli |
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| type of E. coli that causes a decrease in surface area in the SI the body responds to the bacteria by producing a lot of mucous and traps the bacteria in an aggregate, eventually the mucous will break down the microvilli non invasive |
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| enterohemorrhagic E coli |
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| type of E. coli that causes hemorrhage secretes an extremely potent toxin (similar to the shiga toxin), breaks down LI lining as few as 100 bacteria can cause disease invasive |
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| enteroinvasive E. coli |
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| type of E. coli that invades the epithelial cells of the LI via endocytosis, toxins then enter the cell lives in the endocytotic vesicle, replicates, and can become systemic if it passes through the basement membrane invasive |
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| Campylobacter jejuni |
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| bacterial cause of diarrhea gram negative bacillus microaerophilic flagellar motility contaminated food and milk animal reservoirs (sheep, cow, chicken, cats, dogs, birds) bloody stools due to damage of the mucosal surface of the jejunum most common cause of bacterial gasteroenteritis in the US |
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| Salmonella spp. many species and serotypes but S. enterica is important in human infection |
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| bacterial cause of diarrhea gram negative bacillus facultative anaerobe most common cause of food born diarrhea in most developed countries humans acquire from poultry, meat, eggs, milk usually an acute infection and self-limiting except in the young and old invade epithelial cells of the ileocecal region and migrate to the lamina propria |
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| Vibrio cholera |
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| bacterial cause of diarrhea gram negative bacillus facultative anaerobe single flagellum virulence factors such as an enterotoxin strictly a human pathogen causing cholera colonization in the SI, enterotoxins cause rice water stools |
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| Shigella spp. |
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| bacterial cause of diarrhea 4 species cause bacillary dysentery (shigellosis) gram negative bacillus facultative anaerobe, non motile invades ileum, colon epithelial cells; rarely invades bloodstream exotoxin (Shiga toxin - very lethal, similar to enterohemorrhagic E. coli) usually transmitted via poor sanitation, overcrowding |
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| viruses |
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| Over 3 million infants die of gastroenteritis each year, and ( ) are the most common cause. |
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| Rotavirus |
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| causes viral diarrhea attach to the intestinal epithelium, damage transport mechanisms in the intestines most cases of viral gastroenteritis are diarrhea mechanism: [image] attach to epithelium and invade apical regions of the villi, don't go into the crypts. The tip of the villus will be destroyed, but the crypt cells will continue replicating so normal epithelium will be restored in 1 week. |
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| Staphylococcus aureus |
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| causes food poisoning caused by toxins from bacteria in food gram positive coccus facultative anaerobe enterotoxins act as superantigens binding to MHC causing T-cell stimulation heating can kill bacteria, toxins survive |
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| Clostridium botulinum |
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| causes food poisoning gram positive bacillus anaerobe common pathogen in birds, mammals; soil is normal habitat exotoxin (Botulinum toxin) produced in the gut after bacterium are ingested or from improperly canned or reheated food, absorbed from the gut into the blood site of action of the toxin are the nerve synapses |
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| Helicobacter pylori |
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| causes gastric ulcers gram negative microaerophilic bacterium involved in the majority of gastric and duodenal ulcers adhesins, urease, cytotoxins disrupt stomach and SI mucosa |
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| Salmonella typhi |
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| causes typhoid fever gram negative bacillus facultative anaerobe pathogen not found in animals, only spread by human fecal/oral route pathogens multiply in phagocytic cells, spread to the liver, spleen, and lyse, becoming blood borne frequent cause of death in parts of the world with poor sanitation much more serious than salmonellosis can become chronic carriers |
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| Hepatitis A |
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| single stranded RNA, can be grown in cell culture picornaviridae hepatovirus spread by fecally contaminated food, water, hands, or by anal intercourse multiplies in the intestinal epithelium, spreads to the liver, kidneys, spleen usually no lasting or permanent liver damage |
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| Entamoeba histolytica |
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| protozoan infection causes amoebic dysentery or amoebiasis: mild to severe diarrhea with blood, mucus, puss in stool food or water contaminated with cysts; stomach acid doesn't effect cysts worldwide but common in tropical countries Cycle starts in the encysted form that is excreted in the feces and if ingested will travel to the SI. Break out of the cyst and turn into the mature vegetative form. Remains in the intestines, can travel in the mature form in the circulation and infect the brain. |
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| Giardia lambilia |
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| protozoan infection causes giardiarsis mild to severe diarrhea with cyst and trophozoite form adhere to the microvilli of the SI most commonly diagnosed intestinal parasite in the US |
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| Ascaris lumbricoides |
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| helminth (nematode) infection causes ascariasis; roundworm infection spread via a fecal/oral route adult worms migrate usually not severe symptoms but can cause duct blockage [image] stages of life cycle: 1) in the SI, reproducing adults, potentially producing fertilized eggs 2) fertilized eggs excreted in the feces 3) fertilized egg is in the infective stage, turns into larva form still in the egg 4) ingestion of egg 5) larvae hatches/growth in the intestines 6) migrates to lungs via the circulatory system 7) coughed up from the lungs and swallowed and the life cycle repeats |
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| Necator americanus |
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| helminth infection causes hookworm disease once common in the SE US hookworm attaches to intestinal wall, feeding on blood, tissue (not food); may cause anemia [image] 1) eggs are excreted 2) larva hatch in nature (different than Ascaris lumbricoides) 3) larvae grow 4) bore into feet 5) enters circulation, goes to lungs, swallowed, attach to the SI (all in the larvae form then mature into adults in the SI) |
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| Enterobius vermicularis |
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| helminth infection causes pinworm disease migrates out of the anus to lay eggs; if ingested, larvae hatch in the SI best detected with a Graham sticky tape method most common helminth in the US |
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| Taenia spp. |
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| helminth (cestode) infection tapeworm 3 stages: 1) adult worm in intestines of humans, eggs excreted in feces 2) eggs ingested by grazers and hatch into larvae 3) humans eat undercooked meat, larvae develop into adults that attach to walls of SI |
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| Aspergillus flavus |
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| fungal infection of the GI tract: aflatoxin poisoning a common mold produces a mycotoxin, aflatoxin many foods, particularly peanuts and corn may contribute to liver CA and cirrhosis most potent natural carcinogen known |
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| tuberculosis aspergillosis histoplasmosis cystic fibrosis |
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| chronic lower respiratory tract infections |
