BIOM 250 Week 9
BIOM 250 Week 9 BIOM 250
Popular in Micro Hlth Sci: Infect Disease
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This 8 page Class Notes was uploaded by Davis Notetaker on Friday April 1, 2016. The Class Notes belongs to BIOM 250 at Montana State University taught by Kari Cargill in Winter 2016. Since its upload, it has received 16 views. For similar materials see Micro Hlth Sci: Infect Disease in Biology at Montana State University.
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Date Created: 04/01/16
Mon 3/28 Announcements: Fri 4/01 No Class, Watch NARRATED LECTURE on D2L: Microbial Control Part 1 EC opportunity: +10 pts, Case Study EC due Wed 4/20 Viruses Viruses & Teratogenesis TORCH series ● Screening test during pregnancy (if a problem is suspected) ● Txoplasma,ther transplacental infections(chicken pox, syphubella , R virusCMV, V ● Detects antibodies to teratogens ● TORCH may also be used on newborns showing birth defects Provirus ● Viral DNA inserts into host cell DNA, then replicates along with host cell DNA Ex: HIV ● Fun fact:Some human DNA portions, historically called “junk DNA” due to unknown purpose, are actually pieces of ancient viral DNA Viruses & Cancer ● ~10% cancers are virally induced ● Oncogenic virus has extremely high correlation to cancer ○ Causes uncontrolled cell growth (tumor) ● Ex: human papilloma viruses (HPV) > cervical cancer Hepatitis B virus (HBV) > liver cancer Genital HPV ~30 types are primarily genital (~100 total) 7580% sexually active people become exposed Most asymptomatic Ex: Condyloma genital warts ● Have the most overt signs ● Don’t cause cancer ● Treated with physical methods of removal ● Most clear over time without treatment 1%of HPV types become malignant 13 types cause 99% of cervical cancers Also can cause penile and anal cancers Recent: link to oral/throat cancers and HPV infections HPV Vaccine ● 3 doses ● Recommended for females & males age 926 (most likely age group to develop serious problems) ● Ex: Gardasil vaccine for ○ HPV types 16 & 18 (behind 70% of cervical cancers) ○ 6&11 (cause 90% warts) ● 30% of cervical cancers and 10% of genital warts not covered by vaccination Prevention techniques still include safe sex practices, pap tests Prions Infectious proteins ● Historically thought to be very small viruses, but no genetic material has been detected ● Not fully understood yet ● “Misfolded” protein that causes healthy host proteins to fold into prion form Neurological diseases: transmissible spongiform encephalopathies (TSE) ● Microscopic holes in the brain, caused by misfolded brain proteins, are characteristic of prion infections Mode of transmission to humans: ● Rare genetic disorder OR ● Ingested prion (infected meat, animal to animal uncertain) Symptoms ● Wasting (emaciation), loss of coordination, psychiatric effects, dementia, Death (invariably fatal after symptoms begin) ● Seen in a variety of animals Ex: ● First seen animal prion infection: scrapie in sheep ● Also, “mad cow’ in cattle Technical name is BSE bovine spongiform encephalopathy ● Chronic wasting disease (CWD) in deer/elk In humans ● CreutzfeldtJakob disease (CJD) genetic ● Variant CJD (vCJD) not genetic ○ Increase of cases seen in Great Britain ○ Eventually connected breakout to consumption of beef infected with “mad cow disease” ● First human form known: kuru “Laughter disease” Came from ritualistic cannibalism General ● Practices such as including dead animals in livestock feed lead to outbreaks ● Prion proteins are very hard to destroy, can’t be killed by thoroughly cooking meat ● No treatment exists for the infection Wed 3/30 HostMicrobe Relationships Terminology Contamination means that microbes are present. Can refer to: inanimate objects, skin, etc. Infection multiplication of m/o’s in or on the body (overgrowth) Disease an infection that disrupts the normal body functions Ex: Needle becomes contaminated with HIV, new user becomes infected with contaminant, infection leads to the disease Normal flora m/o’s that live in/on the human body, but don’t cause disease In fact, these are generally beneficial via microbial antagonism Microbial antagonism outcompete potential pathogens Pathogen causes disease Opportunist normal flora that cause illness in a vulnerable host (e.g. immunocompromised, presence of cut/lesion, etc) Opportunistic Disease: UTI disease/infection Urinary Tract Infections (UTI) etiologic agent Escherichia coli 80% of cases (caused by: name, type of m/o, other characteristics) reservoir (where it is harbored Natural human flora naturally) mode of transmission to Fecaloral route (contaminated food, water) humans (& susceptible people) pathogenesis (progression of Urine in bladder is normally sterile disease within body, virulence Urethritis infections of urethra factors) Cystitis bladder infection Pyelonephritis kidney infection (known by many other names) symptoms pain/burning when urinating More frequent urination Kidney pain (you might feel this in your back or abdomen)\ treatment/prevention/control Diagnosis: Urine culture Preliminary microscopic examination to identify the # and type of m/o Culture & identify m/o Antibiotic susceptibility testing to determine which antibiotic is most effective (exdisk diffusion tes) Treatment antibiotics Disk diffusion test petri dish with urine sample is sprinkled with evenly distributed antibiotics (different types). Lab clinicians can then visually determine which type is most effective and inhibiting the microbial growth Bacterial Virulence Factors These are defensive and offensive advantages pathogens might have Attachment Via pili or capsule Invasiveness Enzymes that break down tissue Ex: hyaluronidase digests hyaluronic acid (which holds tissues together) Tissue damage Enzymes that damage cells Examples: ● coagulase clots blood, then microbe can potentially “wall itself off” with clots ● Streptokinase dissolves blood clots, which counteracts an immune response to block off microbes with blood clots ● Leukocidins destroy WBC’s ● Hemolysins lyse RBC’s, hypothesized that this enables microbes to extract iron from blood Hemolysins are one way to study/identify m/o’s, in conjunction with usinlood Agar: ● Growth on Blood Agar (BA): agar plate to which blood is added (blood is usually harvested from sheep) ● Used to identify types of hemolysin and differentiate species ex: streptococci Blood Agar characterization (reactions in blood agar): ● Alphahemolysis (α) Partial lysis can see a greenish zone ● Betahemolysis (β) Complete lysis can see a clear zone where RBC’s have been destroyed Gammahemolysis (γ) No lysis can see no zone disease/infection “Strep Throat” streptococcal pharyngitis etiologic agent Streptococcal pyogenes (caused by: name, type of m/o, other characteristics) reservoir where it is harbored humans naturally) mode of transmission to Rheumatic fever: humans (& susceptible Fever,rash, arthritis people) pathogenesis (progression of Complications (occur w/o treatment) disease within body, virulence ~3% of cases progress to rheumatic fever factors) Autoimmune reaction Can lead to damage to heart valve Prophylactic antibiotics administered before dental work for susceptible people with heart valve damage symptoms Very sore throat, especially swallowing fever treatment/prevention/control Diagnosis Traditionally: throat swab plated on BA Incubated overnight, then see betahomolysis Rapid test: throat swab detects strep antigens (molecules) + Indicates strep Indicates there should be a follow up with BA, to test for a false negative Treatment: antibiotics (mostly penicillins) Fri 4/01 Video lecture on D2L Microbial Control Sterilization and Disinfection Sterilization destruction oal microbes (e.g., endospores, but not prions (must be incinerated)) Disinfection treatment of inanimate items, usually destroys vegetative cells (not endospores) Antiseptic treatment for external,living tissue Antibiotic kills bacteria, used internally and topically Sanitization lowers microbial presence to safe public health levels Physical Methods The following physical methods can be used to effectively control m/o growth: ● Heat (e.g. dry heat, boiling, autoclaving) ● Filtration (very fine filters) ● Cold (slow down growth but not necessarily destroy m/o’s) ● Desiccation (drying) ● Radiation Note: Autoclaving, filtration, and gamma ray radiation may achieve sterility Chemical Methods The following list describes the m/o’s resistance to chemicals, with the most resistant at the top and least resistant at the bottom: 1. Prions 2. Bacterial endospores 3. Cysts of protozoa 4. Gramnegative bacteria 5. Fungi, including most fungal spore forms 6. Naked viruses (have no envelope) 7. Grampositive bacteria 8. Viruses with lipid envelopes Know the top 3 & bottom 3 for exam Antimicrobial Therapy (Medication) Chemotherapeutic Agents Antibiotic chemical produced by m/o’s that inhibits other m/o’s (naturally occurring chemical that is harvested and used for medication) Synthetic drugs chemical compounds produced in a lab A good antibiotic is selectively toxic it harm’s m/o infection without causing too much harm to the host Antibiotics have varying spectrums of efficacy: ● Broad spectrum antibiotics that are effective against a wide range of bacteria, but may also be detrimental to host’s friendly bacteria ● Narrow spectrum antibiotics only effective against specific bacteria Mode of Action Mode of action the different mechanisms with which chemicals kill/inhibit m/o’s ● Damage to cell wall/inhibition of cell wall synthesis ● Disruption of cell membrane function ● Inhibit protein synthesis ● Inhibition of nucleic acid synthesis i.e. impede m/o ability to produce genetic material ● Act as an antimetabolite e.g. molecular mimicry, where antibiotic mimics a substance essential for m/o process but does not provide the same functionality Drug Resistance Methods that microbes have to counter drug medications: ● Destruction of the drug, after it has breached the cell wall ● Adaptation of cell wall so drug is no longer able to penetrate ● Mechanisms that eject the infiltrated drug ● Adapt the component being targeted by the drug How m/o’s develop drug resistance ● Mutation ● Acquire new gene from an R plasmid of another bacterium Antibiotic Misuse Multipledrug resistant (MDR) bacteria numbers are increasing, in part due to antibiotic misuse: ● Used to treat viral infection ● Use without prescription ● Use without completing use outlined in prescription ● Use of someone else’s leftover meds ● Overuse, in livestock feedlots ○ Can lead to runoff (gets into water) ○ EU has banned this manner of usage Superinfection resulting from antibiotic overuse, this kind of infection occurs when antibiotics destroy normal flora, enabling pathogens to flourish
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