1、Wednesday & Thursday Lab Sections results (combined 47 students),ALL but four repeated gram stains were done successfully. Scores for Lab 1 have been updated.ALL but one aseptic transfers (broths and slants) were done successfully (2 points).XX/47 streak plates were successful (3 points). X had one
2、of the two colonies separated (2 points) can repeat in an upcoming lab; X had no colonies separated (1 point) can repeat in an upcoming lab.Agar plate cultures with “unique” characteristics - Be sure to record these unique characteristics in your lab notebook (will be scored in lab next week 2 point
3、s possible).Selective & differential media - Blood agar, EMB, MacConkey, Mannitol Salt not done this week (media not available). Will be done in next weeks (Week 3) lab (plenty of time to add this in next week). So be sure to bring your Week 2 lab procedure with you.,A NEW SUPERBACTERIA, IMMUNE TO M
4、OST ANTIBIOTICS, FOUND SPREADING FAST,What is an antibiotic? http:/ 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 St
5、reptomyces speciesSome examples of semi-synthetic antibiotics Penicillin “family” - methicillin, ampicillin, oxycillin Doxycycline is a semi-synthetic tetracycline,TWO Clicker question will be asked at the start of class 30 seconds to answer each question,1. Bacteria have many characteristics that c
6、ontribute to the ability to initiate or cause infectious diseases. For example, certain bacteria have cell components that enable those cells to attach to human body cells, which can be a necessary pre-requisite to an eventual pathology. Which ONE LETTER gives examples of TWO bacterial cell componen
7、ts that can be involved in attachment to human cells? (Select ONE letter as your answer)2. Autoclaving and its consumer equivalent, pressure cooking, are methods designed to destroy which one of the following components of bacterial cells? Hint: these components are most often found in members of th
8、e two genera, Clostridium and Bacillus.HANDOUT of modified ppt slide at ends of each classroom bench,Bacteria have many characteristics that contribute to the ability to initiate or cause infectious diseases. For example, certain bacteria have cell components that enable those cells to attach to hum
9、an body cells, which can be a necessary pre-requisite to an eventual pathology. Which ONE LETTER gives examples of TWO bacterial cell components that can be involved in attachment to human cells? (Select ONE letter as your answer),A. capsule and Lac permeaseB. capsule and fimbriaC. peptidoglycan and
10、 periplasmic spaceD. capsule and nutrient-binding casette,Autoclaving and its consumer equivalent, pressure cooking, are methods designed to destroy which one of the following components of bacterial cells? Hint: these components are most often found in members of the two genera, Clostridium and Bac
11、illus.,A. Endotoxins (lipid portions of bacterial LPS)B. capsules (either carbohydrate or protein)C. endosporesD. MRSA,Start of September 16 Discussion,A NEW SUPERBACTERIA, IMMUNE TO MOST ANTIBIOTICS, FOUND SPREADING FAST,What is an antibiotic? http:/ antibacterial substances produced by microorgani
12、sms 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 speciesSome examples of semi-synthetic antibiotics Penicillin “family” - methicillin, ampicillin, oxycill
13、in 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-s
14、tranded template for DNA replication DNA gyrase is not found in humans (analog is DNA helicase in humans)How do bacteria resist antibiotics?,Bonus Clicker question “have I seen this one before?” Penicillin, methicillin, and vancomycin are antibiotics all of which interfere with or destroy bacterial
15、peptidoglycans. Therefore the “target” of these antibiotics is which one of the following structures of bacterial cells?,A. lipopolysaccharides (LPS)B. cell wallC. cell membraneD. teichoic acids,Cell wall and antibiotics,Cell wall is an important antibiotic target Todors Online Textbook of Bacteriol
16、ogy: Antimicrobial Agents in the Treatment of Infectious Disease (page 3) http:/ (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:/ - imparts some rigidity Sugar bac
17、kbone - NAG & NAMA (Human lysozyme cleaves (1,4) bond) Amino acid cross links adds rigidity Peptidoglycan layer thickness,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)
18、 http:/ (scroll down to “Cell wall synthesis inhibitors”)Penicillin (produced by Penicillium notatum fungus) Penicillin binds to transpeptidases - cannot function Prevents cross-linking of peptide chains between adjacent sugar backbones Cell wall synthesis does not occur Replicating bacterial cells
19、cannot survive Bacterial cell wall components are NOT found anywhere in humans Penicillin will not harm humans (except for allergic reactions),Penicillin resistance,Todors Online Textbook of Bacteriology: Bacterial Resistance to Antibiotics (page 3) http:/ structure beta-lactam ring Beta-lactamase p
20、roduced by bacteria disrupts beta-lactam ring Penicillin is rendered inactive (can not bind to transpeptidases) Cell wall synthesis is normal (bacterium is resisting the antibiotics affect),Methicillin - responding to penicillin resistance,Methicillin (“semi-synthetic” penicillin) Methicillin also i
21、nterferes with transpeptidases Penicillin “family” all have same beta-lactam ring Differ in the side chain N-acyl group Methicillin and most other semi-synthetic penicillins are resistant to beta-lactamase Bacteria cannot inactive methicillin using beta-lactamase,Methicillin resistance,Some bacteria
22、 can alter their transpeptidases Still function to cross-link peptidoglycan sugar backbones Not affected by any of the penicillins Methicillin-resistant Staphylococcus aureus (MRSA),Vancomycin responding to methicillin resistance,Vancomycin is not a member of the penicillin family Thus not affected
23、in any way by beta-lactamase Does not act by interfering with transpeptidases So not affected by any change in transpeptidases Acts by binding to D-alanines at ends of peptides Prevents cross-linking Effective against gram-positive, but not gram-negative bacteria Outer membrane of gram-negative bact
24、eria prevents “penetration” of vancomycin into the cell wall area,Vancomycin resistance,Bacteria substitute another amino acid for D-alanine (e.g., D-serine) Vancomycin cannot bind to that other amino acid Does not interfere with cross-linking,D-Ser,D-Ser,Many more antibiotics exist to treat bacteri
25、a that have developed resistance to the “common” antibiotics http:/ (Scroll down to “Classes of Antibiotics and their Properties“)Resistance continues to develop against a growing list of these available antibioticsNew antibiotics continue to be developedBacteria continue to develop additional resis
26、tance“The race is on” Bacteria vs. the antibiotics,TWO Clicker questions at the start of class,1. Each antibiotic has a rather specific “target” that will be adversely affected by the antibiotic. For example, ciprofloxacin (“cipro”) has which one of the following components of a bacterial cell as it
27、s target?2. The probable basis for bacterial resistance to methicillin (a member of the beta-lactam penicillin “family) is which one of the following?Exam 1 next Monday (September 26) 25 multiple choice questions worth 2 points each = 50 points total Will cover only material discussed in class Info
28、about exam will be distributed (using MyCourses email addresses) as the exam is written,Each antibiotic has a rather specific “target” that will be adversely affected by the antibiotic. For example, ciprofloxacin (“cipro”) has which one of the following components of a bacterial cell as its target?,
29、A. transpeptidase that cross links NAG and NAMA peptidoglycan sugar polymersB. the 30S subunit of bacterial ribosomesC. DNA gyrase, an enzyme that “uncoils” the bacterial chromosomeD. the lipopolysaccharide (LPS) portion of a gram-negative outer membrane that has the properties of an endotoxin,The p
30、robable basis for bacterial resistance to methicillin (a member of the beta-lactam penicillin “family) is which one of the following?,A. beta-lactamase cleavage of the beta-lactam ring of methicillinB. alteration of the transpeptidase that is involved in forming the -1,4 glycosidic bonds between adj
31、acent NAG and NAMA sugars in the backbones of peptidoglycanC. use of a binding casette protein in the periplasmic space to “tie up” methicillin, rendering it inactiveD. alteration of the transpeptidase that is involved in forming the peptide cross-links between the sugar backbones of peptidoglycan,E
32、xam 1 next Monday (September 26) 25 multiple choice questions worth 2 points each = 50 points total Will cover only material discussed in class Info about exam will be distributed (using MyCourses email addresses) as the exam is written,Start of September 19 Discussion,“Superbacteria”,A NEW SUPERBAC
33、TERIA, IMMUNE TO MOST ANTIBIOTICS, FOUND SPREADING FAST Appear to be resistant to “every antibiotic known to man” (quote from the news media) probably a little media “hype” MRSA Methicillin-resistant Staphylococcus aureus “Flesh-eating bacteria” highly virulent form of Streptococcus pyogenesThe “Sup
34、erbacteria” in the article is more likely resistant to all of the “common” antibiotics (penicillin family)Antibiotics that affect bacterial cell walls are still the first choice No cell walls in human cells Relatively inexpensive (compared to antibiotics with other “targets”),Lets look at the actual
35、 “facts”,Detection of Enterobacteriaceae Isolates Carrying Metallo-Beta-Lactamase - United States, 2010What are “Enterobacteriaceae”? Groupings of bacteria now based on 16sRNA DNA nucleotide sequences,Taxonomy using DNA sequence that encodes for 16sRNA,Bacterial Ribosomes,Lets look at the actual “fa
36、cts”,Detection of Enterobacteriaceae Isolates Carrying Metallo-Beta-Lactamase - United States, 2010What are “Enterobacteriaceae”? Groupings of bacteria now based on 16sRNA DNA nucleotide sequences Family Enterobacteriaceae Gram-negative rods Facultative anaerobic (what does that mean?) Aerobic requi
37、res oxygen to metabolize Anaerobic can NOT survive in the presence of oxygen Facultative anaerobic can metabolize in presence and absence of oxygen At least 31 genera and 100 species Source is primarily the intestine (“enteric”; “entero”) Fecal material deposited in soils,Some important examples of
38、“Enterobacteriaceae”,Escherichia coli O157:H7 Escherichia honors Theodore Escherich coli refers to bacteriums usual habitat (colon) O157:H7 is a “strain” that considers biochemistry of cell components O-specific polysaccharide (the O157 designation)E. coli O157:H7 is a very dangerous human pathogen
39、Lipid A portion of LPS can act as an endotoxin Many other pathogen “virulence” factors,Some important examples of “Enterobacteriaceae,Klebsiella pneumoniae Has a very prominent capsule Very distinctive appearance when grown on lab agar plates shiny, “mucous-like” texture Can cause Urinary tract infe
40、ctions (UTI) Pneumonia Infections of the blood circulation (bacteremia),Some important examples of “Enterobacteriaceae,Enterobacter cloacae Can cause: Urinary tract infections Endocarditis (infection of the heart endocardium) Pneumonia Skin damage Soft tissue damage Eye damage,Lets look at the actua
41、l “facts”,Detection of Enterobacteriaceae Isolates Carrying Metallo-Beta-Lactamase - United States, 2010What are “Enterobacteriaceae”? Escherichia coli Klebsiella pneumoniae Enterobacter cloacae“NDM-1 gene (New Delhi metallo-beta-lactamase) Confers resistance to all beta-lactam agents except aztreon
42、am (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 infection
43、s”Carbapenemase enzyme generated by the NDM-1 gene that cleaves Carbapenem,Other examples of serious pathogens that are rapidly becoming antibiotic resistant (written on the board); with comments mentioned in class,Staphylococcus aureus (e.g., methicillin-resistant MRSA)Enterococcus faecalis (e.g.,
44、vancomycin-resistant; VRE)Streptococcus pyogenes (causes strep throat, among many other diseases)Serratia marcescens (red color when cultured at room temperature)Pseudomonas aeruginosa (green-brown, fruity/rubbery smell when cultured on stan)dard lab media,Spread of antibiotic resistance,Plasmid htt
45、p:/www.slic2.wsu.edu: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) Chromosom
46、al transfer (high frequency recombination),TWO Clicker questions at the start of class,1. Which one of the following is NOT a characteristic of members of the bacterial family, Enterobacteriaceae?2. Which one of the following microorganisms is a member of the family, Enterobacteriaceae, has a very p
47、rominent capsule, displays rather shiny, “mucous”-like colonies on standard lab agar medium, and has begun to phenotypically express the NDM-1 gene which confers resistance to the antibiotic, carbapenem?Tuesday Lab section turn in your 3 “environmental” plates in the box on the front table if you di
48、d not turn them in yesterday in lab. Nada please add your 3rd plate to the 2 you already submitted (are on the front table outside of the box) ALL streak plates repeated yesterday are successful! Scores will be update in MyCourses later today.,Which one of the following is NOT a characteristic of me
49、mbers 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 shapeD. they would stain red after the gram stain,
