超级细菌和它的全耐药（英文）anew superbacteria immune to most antibiotics found

A NEW SUPERBACTERIA, IMMUNE TO MOST ANTIBIOTICS, FOUND SPREADING FAST What is an antibiotic? /antimicrobial.html Natural antibacterial substances produced by microorganisms Semi-synthetic derivatives of natural antibiotics What are some sources of natural antibiotics? Molds e.g., penicillin G from Penicillium notatum Bacteria e.g. tetracycline from Streptomyces species Some examples of semi-synthetic antibiotics Penicillin “family” - methicillin, ampicillin, oxycillin Doxycycline is a semi-synthetic tetracycline What are some typical “targets” of some common antibiotics? Cell walls peptidoglycans - penicillin Ribosomes - tetracycline DNA replication enzymes (e.g., DNA gyrase) ciprofloxacin (“cipro”) What is DNA gyrase? Unwinds dsDNA to allow access to single-stranded template for DNA replication How do bacteria resist antibiotics? Cell wall and antibiotics Cell wall is an important antibiotic target Todors Online Textbook of Bacteriology: Antimicrobial Agents in the Treatment of Infectious Disease (page 3) /antimicrobial_3.html (scroll down to “Cell wall synthesis inhibitors”) Structure and Function Cell Wall Todors Online Textbook of Bacteriology: Structure and Function of Bacterial cells (page 5 only) Http://structure_5.html peptidoglycan - imparts some rigidity Sugar backbone - NAG “entero”) Fecal material deposited in soils Lets look at the actual “facts” Detection of Enterobacteriaceae Isolates Carrying Metallo-Beta-Lactamase - United States, 2010 What are “Enterobacteriaceae”? Escherichia coli Klebsiella pneumoniae Enterobacter cloacae Some characteristics and pathologies of the following two bacteria were written on the board in class on Wednesday, Sept 15 Klebsiella pneumoniae Enterobacter cloacae Lets look at the actual “facts” Detection of Enterobacteriaceae Isolates Carrying Metallo-Beta-Lactamase - United States, 2010 What are “Enterobacteriaceae”? Escherichia coli Klebsiella pneumoniae Enterobacter cloacae “NDM-1 gene (New Delhi metallo-beta-lactamase) Confers resistance to all beta-lactam agents except aztreonam (a monobactam antimicrobial) Unfortunately “all three isolates were also aztreonam-resistant, presumably by a different mechanism“ Carbapenem another beta-lactam antibiotic that is highly resistant to beta-lactamase “Carbapenems are one of the antibiotics of last resort for many bacterial infections” Carbapenemase enzyme generated by the NDM-1 gene that cleaves Carbapenem Spread of antibiotic resistance Plasmid :82/hurlbert/micro101/pages/Chap9.html#Plasmids Usually double-stranded, continuous DNA Size: 1000 25,000 base pairs 0-100s/cell Can be replicated without cell replication Properties associated with plasmids Antibiotic resistance Exotoxins Plasmid transfer (conjugation) Chromosomal transfer (high frequency recombination) Transferring plasmids using conjugation Need to use a plasmid that has special characteristics Often called an “F” plasmid Tra region genes that initiates conjugation (“transfer” of a plasmid) oriT origin of transfer Conjugation the closest bacteria come to having “sex” :82/hurlbert/micro101/pages/Chap9.html#Conjugation Donor cell is designated F+ (has an F plasmid) Recipient cell is initially designated F- (no plasmid) Tra gene - initiates conjugation Enables extension of a pilus (pili is plural) Nicking of one of the two DNA strands at oriT One DNA strand moves through pilus into F- Single-strand plasmid DNA serves as template in donor and recipient F- is now F+ “spread” of antibiotic resistance is very often via conjugation Animation /search?q=bacterial+conjugation&tbo=p&tbs=vid%3A1&source=vgc&hl=en&aq=f Clicker questions at the start of class 30 seconds to answer each question 1. Which one of the following is not a characteristic of members of the bacterial family, Enterobacteriaceae? 2. Which one of the following plasmids would not be capable of carrying out conjugation? Which one of the following is NOT a characteristic of members of the bacterial family, Enterobacteriaceae? A. that are facultative anaerobic (i.e., can function in the presence or absence of oxygen) B. they contain endospores (thus they are very difficult to eradicate from a contaminated water supply) C. the are “bacillus” in shape D. they would stain red after the gram stain Which one of the following plasmids would not be capable of carrying out conjugation? A. an E. coli pBR322 plasmid B. an F+ plasmid C. a plasmid that had a tra nucleotide sequence and an origin of transfer (oriT) nucleotide sequence D. NONE of the above plasmids would be capable of carrying out conjugation Lab Results & Scoring ALL aseptic transfers and ALL streak plates have now been scored. Scores for Tues & Wed sections have been entered into MyCourses. Scores for Thurs AM & Thurs PM sections will be entered in MyCourses later this morning. If you did NOT get full credit for your streak plate, you will have an opportunity to repeat the technique in a later lab to earn the full credit. All five media/four bacteria plates appear to be ready to view. Remember to put your plates into the walk-in cold room (details on page taped to 37oC incubator) after you have finished recording all of the pertinent observations. BONUS Clicker question Almost all antibiotic genotypes reside in bacterial plasmids. However, a very limited number of genotypes are actually within the chromosome. Which one of the following is an example of a chromosomal antibiotic genotype? A. ampicillin B. aztreonam C. tetracycline D. doxycycline High frequency recombination (Hfr) Transfer of a part of the chromosome during conjugation Plasmid needs to have insertion sequences (IS) Plasmid is called an “episome” plasmid (able to carry out Hfr) Will insert itself into bacterial chromosome using insertion sequences Conjugation initiated at oriT of plasmid “attached” strand of chromosomal DNA also moves across pilus Homologous recombination in recipient cell (usually) takes place “new” strand of DNA replaces “homologous” strand in recipient /sites/0072556781/student_view0/chapter13/animation_quiz_4.html How is antibiotic resistance monitored (epidemiology)? Emergence of a new antibiotic resistance mechanism in India, Pakistan, and the UK: a molecular, biological, and epidemiological study World Health Organization US Centers for Disease Control and Prevention (CDC) / National Center for Infectious Diseases (NCID) /orgs/hr2611.htm Summary of Notifiable Diseases /ncphi/disss/nndss/annsum/ Nationally Notifiable Infectious Diseases United States 2010 /ncphi/disss/nndss/phs/infdis2010.htm Morbidity and Mortality Weekly Report (MMWR) not your casual reading /mmwr/ Why is E. coli O157:H7 so especially dangerous? Escherichia coli O157:H7 enterohemorrhagic Very wide range of exotoxins (including enterotoxins) and endotoxins One very potent toxin causes internal hemorrhaging (especially kidneys) Damage can be significant and life-threatening Source is almost always animal feces (normal flora of livestock animals) beef - contaminated with fecal material during processing solid cuts - sufficient surface temperatures produced during “grilling“, etc. ground beef (“hamburger“) E. coli throughout entire beef patty - internal temperature must be high enough to kill E. coli and destroy exotoxins (approximates pasteurization temperature) What is pasteurization? Bacteria have temperature growth ranges Pathogens are in the blue range Pasteurization temperature is held at approximately 71-72oC for 15-20 seconds Kills ALL living pathogens (will not destroy all microorganisms or endospores) Why is E. coli O157:H7 so especially dangerous? Escherichia coli O157:H7 enterohemorrhagic Very wide range of exotoxins (including enterotoxins) and endotoxins One very potent toxin causes internal hemorrhaging (especially kidneys) Damage can be significant and life-threatening Source is almost always animal feces (normal flora of livestock animals) beef - contaminated with fecal material during processing solid cuts - sufficient surface temperatures produced during “grilling“, etc. ground beef (“hamburger“) E. coli throughout entire beef patty - internal temperature must be high enough to kill E. coli and destroy exotoxins (approximates pasteurization temperature) manure used as fertilizer (is this an example of “organic“ farming?) soil “contaminates“ food products many are consumed raw (lettuce, uncooked spinach, sprouts) Is washing with water good enough? apples that fall from trees (contaminated with soils) apple cider - to pasteurize or not pasteurize? E. coli 0157:H7 also found in Drinking Water /drink/contaminants/basicinformation/ecoli.cfm Most often “run-off” water from manure-fertilized fields and very dense poultry operations Accidental contamination of treated water supplies Floods that damage/contaminate water treatment facilities Floods threaten Nashvilles water supply Breaks in water lines that bring potable water to consumers Boil-water order issued for nearly 2 million in Mass. Cholera Another very dangerous and often deadly waterborne pathogen Cholera now threatens Pakistan in wake of flooding Ban visits Pakistan amid cholera concerns Cholera World Health Organization factsheet What is Cholera? Infection of the intestinal tract by Vibrio cholerae TWO Clicker questions at the start of class 1. High frequency recombination (Hfr) is best described by which one of the following? 2. Pasteurization of liquid food products is designed to do which one of the following? High frequency recombination (Hfr) is best described by which one of the following? A. conjugation using a pBR322 plasmid B. a form of conjugation using an F+ plasmid that has at least one insertion sequence (IS) C. the process in which most antibiotic resistance is naturally transferred from one bacterium to another, e.g., antibiotic resistance to ampicillin and tetracycline is most commonly transferred by Hfr D. a genetic process that is inhibited by carbapenamase Pasteurization of liquid food products is designed to do which one of the following? A. eliminate all enterohemorrhagic E. coli from apple cider and other fruit beverages B. destroy all endospores, including those of Bacillus anthracis and all species of the genus, Clostridium C. kill all pathogens in the food product that is being pasteurized D. kill all microorganisms in the food product that is being pasteurized Exam #1 information Monday (Sept 21) starts at 8 AM and ends at 8:51 AM Exam will cover all class discussions from the start of the quarter to the end of this coming Fridays class discussion 25 multiple choice questions worth 2 points each Most questions will have one answer Some questions may ask for more than one correct answer to be selected (partial credit is considered for these questions) You may use one standard size piece of paper with anything written, printed, copied on both sides during the exam You may not use any type of electrical device (including computers) during the exam More details will be sent by email (using MyCourses) as the exam is being written Cholera Another very dangerous and often deadly waterborne pathogen Cholera now threatens Pakistan in wake of flooding Ban visits Pakistan amid cholera concerns Cholera World Health Organization factsheet What is Cholera? Infection of the intestinal tract by Vibrio cholerae Vibrio cholerae /cholera.html Gram-negative “comma” shaped (considered rod-shaped with a slightly bent shape) polar flagellum allows bacterium to move through mucus that is covering intestinal epithelial cell layer can then actually attach directly to that layer of cells a necessary step in initiating pathology Pathology is caused by a Vibrio cholerae enterotoxin Exotoxins that affect the intestinal tract Bacterium adheres to endothelial cells (via fimbriae) Secretes A-B enterotoxin Two distinct functional parts B attaches to membrane GM1 ganglioside A enters - dramatically increases cAMP production High concentration of ions pumped into in lumen Water flows out of tissues in attempt to create equilibrium solute concentration Quantity of water loss from body can be huge Results of enterotoxin action Profuse diarrhea and vomiting Extreme (and very rapid) dehydration Loss of important electrolytes from the blood electrolytes move from the blood to “replace” ions pumped from endothlelial cells Death can occur is as few as 1-2 days if no treatment is provided How prevalent in Cholera? Cholera has always been endemic Endemic Cases of the disease and deaths occur on a “regular” basis Has existed on the Indian subcontinent for centuries 3-5 million new cases of cholera each year 100,000-200,000 deaths each year Cholera now threatens Pakistan in wake of flooding Cholera may now be an epidemic in Pakistan Very rapid increase in number of cases well above the “usual” endemic number Usually restricted to a geographic area/region (e.g., Pakistan in this case) Why? Carriers About 75% of people infected with V. cholerae do not develop any symptoms the bacteria are present in their feces for 714 days after infection are shed back into the environment (water), potentially infecting other people BONUS Clicker Survey any answer will receive full credit All incoming RIT students should be required to be tested for HIV infection before they are allowed to start classes. Each student tested will be informed of his or her HIV status (i.e., infected or not infected) A. Yes B. No New York State law requires the reporting of the name of any HIV-positive person to the state Department of Health, regardless of whether or not that person gave permission for his or her name to be reported. BONUS Clicker Survey any answer will receive full credit All incoming RIT students should be required to be tested for HIV infection before they are allowed to start classes. Each student tested will be informed of his or her HIV status (i.e, infected or not infected). A. Yes B. No Cholera now threatens Pakistan in wake of flooding Cholera may now be an epidemic in Pakistan Very rapid increase in number of cases well above the “usual” endemic number Usually restricted to a geographic area/region (e.g., Pakistan in this case) Why? Carriers About 75% of people infected with V. cholerae do not develop any symptoms the bacteria are present in their feces for 714 days after infection are shed back into the environment (water), potentially infecting other people Lack of sanitation or lack of proper treatment of fecal-contaminated water supply Floods completely disrupt any water purification and sanitation systems Disruption by war generate huge numbers of refugees in very congested areas Virtually no clean water available Drinking water is often also used as place to defecate Pandemic Cholera Large increase in number of cases not limited geographically Sometimes over the entire planet Global spread of cholera during the a pandemic, 1961-1971 Treatment of cholera Oral rehydration therapy immediate replacement of the fluid and salts lost through diarrhea prepackaged mixture of sugar and salts, mixed with water and drunk in large amounts 80-90% of diarrhea patients can be treated by oral rehydration alone patients who become severely dehydrated must be given intravenous fluids Antibiotics http:/sprojects.mmi.mcgill.ca/tropmed/disease/chol/treatment.htm#Trim Adults doxycycline (semi-synthetic tetracycline) Children Trimethoprim & Sulfamethoxazole (in combination) inhibit successive steps in the folate synthesis pathway Pregnant women Furazolidone cross links bacterial DNA No longer used in the US FDA considers it to be a mutagen/carcinogen Prevention of Cholera Vaccines Generate a protective response in vaccinated person before encountering the actual pathogen Types of cholera vaccines whole killed V. cholerae bacterial cells recombinant toxin “B“ (binding) unit called a toxoid safe version of toxin used for vaccination TWO Clicker questions at the start of class 1. “Carriers” are a rather troublesome problem in public health, as this makes the monitoring and subsequent control of the spread of an infectious disease very difficult. Which one of the following would be the best description of carriers as this term applies to infectious diseases? 2. The antibiotic, doxycycline (a semi-synthetic tetracycline), is often used to treat severe cases of skin acne. This same antibiotic is quite effective in treating adults who are showing the early symptoms of which one of the following diseases that is caused by an enteric pathogen? Tuesday Lab Section put your three “environmental” TSA plates into the box on the front table before you leave the classroom. Make sure your name is somewhere on the plates (or tape) and the three plates are taped together (there is labeling tape available on the table). These plates will be incubated both at 37oC and room To, then returned to you in lab next week. Wait for at least 48 hours (i.e., at least until tomorrow) before viewing normal flora plates to give the skin flora time to grow enough. You can even wait until Monday without affecting your ability to observe and describe selected colonies. Keep normal flora plates in cold room after viewing them. They will be scored and used in lab next week. “Carriers” are a rather troublesome problem in public health, as this makes the monitoring and subsequent control of the spread of