MDL 237

1. MDL 237 Clinical Bacteriology Spring 06� Rhoads

3. Bacteria vs the other guys Kingdom Prokaryotae (Monera) Prokaryotes: cyanobacteria (blue-green algae) archae bacteria � here is our focus Note: facts in the next 2 slides are sometimes used to state differences in prokaryotes (vs eukaryotes) and other times to distinguish bacteria from everybody else. The latter is not really proper, but since we are only interested in bacteria we will do this.

4. Bacteria vs the other guys no �life cycle�: �vegetative� cells endospores (maybe) Clostridium, etc. small: 0.1 � 10uM range, but�. binary fission: simple = rapid exponential growth harder to stop / kill? bacteriastatic vs bacteriacidal simple intracellular organization: no organelles proximity of mRNA to ribosomes more is better? simple = harder to stop / kill? disadvantages? organization of DNA: DSCCC haploid chromosome plus plasmids VS multiple linear diploid chromosomeS cont�.

5. Bacteria vs the other guys envelope: cell wall composed of peptidoglycan exceptions: Mycoplasma,Mycobacterium,etc. membrane(s): cytoplasmic and maybe another �Gram� stain: Gram (+) vs Gram (-) other differences: nucleic acid homology ribosome size / structure huge metabolic diversity!!! others that I cant think of at the moment or is not worth discussing

6. Distinguishing bacteria: anatomy / morphology Morphology is very important in classification, characterization & identification of bacteria: 1. colony morphology 2. cellular moropholgy 3. Gram stain � not really morphology, but it is a 1st step 1. Colony morphology: what is a colony? how do you go about seeing a colony? what is growth �media�? what are the types? what are the basic differences in colony appearance? can colonial morphology differ based upon the medium, culture conditions, age, other? cont�.

8. No, you don�t need to know this for me

9. Distinguishing bacteria: anatomy / morphology 2. Cellular morphology: a) size: Chlamydia (0.3uM) vs Bacillus (5uM) b) shape: rod: varies a lot! see 2 slides ? other: spirochetes type of rod? see 1 slide cocci: round round is round, but�. see 1 slide c) arrangement: chains see cocci slide clusters other

14. Arrangement - rods

15. Distinguishing bacteria: anatomy / morphology 3. Gram stain: based on thickness of peptidoglycan cell wall Gram (+): thick = retains CV during decolorization Gram (-): thin = loses CV during decolorization Gram variable: Mycobacterium Mycoplasma Other ways to determine? presence or absence of lipopolysaccharide, etc.

16. Distinguishing bacteria: anatomy / morphology Differential stains: Gram stain Acid fast stain: Mycobacterium Nocardia other Motility: presence or absence of flagella motility soft agar deep

17. Distinguishing bacteria: anatomy / morphology Presence of absence of a capsule Presence or absence of endospores

18. Distinguishing bacteria: physiology Metabolism: aerobic respiration fermentation: presence or absence of oxygen = aerotollerant OR only under anaerobic conditions anaerobic respiration � using something other than oxygen as a terminal electron acceptor photosynthesis (but we are not concerned about that) Tests: O/F glucose, oxygen requirements, other

19. Distinguishing bacteria: physiology Oxygen requirements: overlaps with metabolism obligately aerobic: Pseudomonas must have O2 so� microaerophile: Campylobacter loves a little oxygen facultative (anaerobe): Staphylococcus, all enterics lots aerotollerant anaerobe: Streptococcus vs anaerobes? obligately anaerobic: Clostridium, Bacteroides, Fusobacterium, etc. More than 1 reason why anaerobic Degree of sensitivity varies: Clostridium not strict vs� Culture requirements: gas pak, other

20. Distinguishing bacteria: physiology Differential carbohydrate catabolism: ability to utilize glucose: Phenol red broth MR/VP O/F glucose ability to utilize lactose: MacConkeys EMB ability to utilize citrate: Simmon�s citrate ability to utilize mannitol: Mannitol salt agar etcetera, etcetera, etcetera�. Tests based upon pH changes with pH indicators in most cases.

21. Distinguishing bacteria: physiology 1. Selective media: growth or no growth 2. Differential media: appearance differs

22. Distinguishing bacteria: physiology Antimicrobial susceptibility testing: Kirby Bauer MRSA MIC

23. Distinguishing bacteria: physiology NUMEROUS other tests of many types! Please don�t do something crazy like learning this list! cytochrome C oxidase test catalase test nitrate reduction test sulfate reduction test amino acid decarboxylation test phenylalanine deamination test tryptophan hydrolysis test (indole) starch hydrolysis test (amylase) egg yolk lecithinase hydrolysis test (lipase) gelatin hydrolysis test (protease) and on and on it goes��.

24. About bacteria Relationships with host (�definitive�) mutualistic commensal parasitic = pathogens �Parasitology�? Pathogen VS �opportunistic� pathogen VS non-pathogen So, is an �infection� a bad thing? Some are, but most are not! Are the pathogens even helping you most of the time? Where are they on planet Earth? EVERYWHERE! What do they do? LOTS! Is Bacteriology synonymous with Medical Bacteriology? NO!

25. Bacterial virulence & pathogenicity Pathogen: disease causing microorganism Pathogenicity: ability to cause disease Virulence: 1. severity: �of condition, �of damage 2. infectivity: effectiveness of initiating infection

26. Bacterial virulence & pathogenicity Invasion: how do they get in how do they pass barriers, defenses Survival: evading defenses nutrition Pathology: physical / mechanical? Not likely vs fungi intracellular disrupt cellular homeostasis Rickettsia Chlamydia Mycobacterium others toxins page 29 next slide ?

27. Bacterial toxins a) exotoxins: Gram (+) & Gram (-) extracellular products disseminate ? systemic mechanism & severity varies: S. aureus enterotoxin vs C. diptheriae, C. tetani, C.botulinum good news: most are proteins so they�. are heat labile can be destroyed by proteases b) endotoxin: Gram (-) only they are all the same outer membrane component � NOT a product only disseminates as cell fragments lipopolysaccharide (LPS) pyrogen - hypothalamus