Midterm Flashcards
1
Q
What is Antibiotic Resistance?
A
- Occurs when bacteria, viruses, fungi and parasites no longer respond to antimicrobial medicines
- antimicrobial medicines become ineffective & infections become difficult or impossible to treat
2
Q
Biological Resistance Vs. Clinical Resistance
A
- Biological - refers to changes that result in reduced susceptibility of an organism to a particular antimicrobial agent
- Clinical - when this susceptibility is lost to an extent that the drug is no longer effective for clinical use
3
Q
What is Environmentally mediate Antimicrobial resistance?
A
- Resistance directly resulting from physical or chemical characteristics of the envmt that either directly altered the antimicrobial agent or alter the microorganism’s normal physiologic response to the drug
4
Q
Microorganism-mediated Antimicrobial Resistance
A
- Microorganism-mediated antimicrobial resistance refers to antimicrobial resistance that results from genetically encoded traits of the microorganism
5
Q
Intrinsic Resistance
A
- Naturally resistant to a certain antibiotic or family of antibiotics, w/out the need for mutation or gain or further genes
- Ex. Aerobic bacteria are NOT able to anaerobically reduce metronidazole to its active form
6
Q
Acquired Resistance
A
- Bacteria can acquire resistance through a new genetic mutation or by getting DNA from a resistant bacteria
- Resistance genes are often on plasmids or transposons (mobile genetic elements) that can be transferred horizontally b/w bacteria
7
Q
Steps in Transduction by a Bacteriophage
A
- Phage infects donor cell
- Phage DNA & proteins are made, bacterial chromosome is broken into pieces
- Pieces of bacterial DNA are packaged into phage capsid, when cell lyses it releases the phage carrying bacterial DNA
- A phage carrying bacteria DNA can infect a new host recipient cell
- Recombination can occur producing a recipient cell that has a genotype different from both the original recipient and host cells
8
Q
What are the 4 Mechanisms of Drug Resistance
A
- Modifications or destruction of the antimicrobial molecule
- Preventing the antibiotic from reaching its target
- Changes and/or bypass of target sites
- Resistance due to global cell adaptive processes
9
Q
Modifications of the Antimicrobial molecules
Mechanisms of Drug Resistance
A
- Chemical conjugation of Abx - Acetylation, Phosphorylation, Adenylation
- Destruction/deactivation of Abx - B-lactamases
10
Q
Preventing the Abx from reaching its target
Mechanisms of Drug Resistance
A
- Decreased permeability - decreasing amount of drug in bacteria can prevent cell death (changes in porins)
- Efflux pumps
11
Q
Changes in Target Site
Mechanisms of Drug Resistance
A
- Target Protection - Tet(M) dislodges tetracycline bound to ribosome
- Modification of Target - mutations of target site, enzymatic alteration of target, complete replacement or bypass of target site
12
Q
Changes in Global Cell Adaptive Processes
Mechanisms of Drug Resistance
A
- gene clusters that can work together to make Abx less effective
13
Q
Resistance to B-lactams Mechanism
A
- Enzymatic destruction of Abx
- Decreased uptake to B-lactams
- Altered target
14
Q
Resistance to Glycoproteins Mechanism
A
- Acquired high level resistance to vancomycin has been commonly encountered among enterococci
- The main resistance mechanism: change to target site, production of altered cell wall precursors that do not bind vancomycin w/ sufficient avidity to allow inhibition of peptidoglycan
15
Q
Resistance to Aminoglycosides Mechanisms
A
- Enzymatic modification - modifying enzymes causes affinity for binding ribosomal subunit to diminsh so protein synthesis can continue
- Altered target - changes in ribosomal binding site, aminoglycoside can’t bind
- Decreased uptake pathways - changes in # or characteristics of outer membrane porins
16
Q
Why is Abx Resistance on the Rise?
A
- Using Abx for common cold & other viral infections
- Using Abx in animal feed
- Using someone else’s leftover prescription
17
Q
What is Binary Fission?
A
- cell division in Prokaryotes
- similar to mitosis
- DNA replicates -> cell wall & PM constrict -> cell wall forms completely separating 2 DNA copies -> cells separate
18
Q
Gram +ve vs. Gram -ve cell components
A
- gram +ve - cell wall, plasma membrane
- gram -ve - cell wall, plasma membrane, outer membrane, periplasm
19
Q
Composition of Cell wall in gram +ve
A
- MANY peptidoglycan layers
- lipoteichoic & teichoic acid (surface Ags) - usually what our body targets in response
20
Q
Composition of Cell wall in gram -ve
A
- FEW layers of peptidoglycan
- Outer membrane - consists of lipopolysaccharide (LPS) & porins
- LPS has Lipid A attached to polysaccharide
21
Q
What has better Antibiotic Resistance Gram +ve or Gram -ve? why?
A
- Gram -ve
- outer membrane has porins, only small hydrophilic molecules can pass
- Large Abx molecules penetrate outer membrane SLOWLY
22
Q
Functions of the Cell wall
A
- protection against osmotic damage
- cell division (target this, can’t reproduce)
- responsible for shape
- target sites for Abx, lysozymes & bacteriophages
23
Q
What are Mycoplasma?
A
- naturally occurring bacteria which lack cell wall (ex. Mycoplasma pneumoniae)
24
Q
Gram +ve Gram Stain Colour
A
purple
25
Gram -ve Gram Stain Colour
pink
26
Gram Stain Steps
1. crystal violet - stains gram +ve purple (more peptidoglycan)
2. Iodine - fixes crystal violet
3. Alcohol - wash away excess
4. Safranin - stains gram -ve pink (less peptidoglycan)
27
What is the plasma membrane?
* thin, semipermeable layer of proteins & phospholipids
28
Plasma Membrane functions
* Permeability & transport
* Biosynthetic fns
* Electron transport chain & oxidative phosphorylation
* Chemotactic systems
29
Areas of Cytoplasm
* Amorphous matrix - ribosomes, nutrient granules & plasmids
* Nucleoid region of DNA
30
Bacteria create energy using extracellular electron transfer in what "organelle"?
* plasma membrane
31
What are the specialized features for adherence in Bacteria?
* Capsule/slime layer
* Flagella
* Fimbriae/Pili
32
What is the Glycocalyx?
* capsule or slime layer
* functions: adherence of bacteria to humans, enhances bacterial virulence, biofilm formation
33
What is Flagella?
* filamentous appendages of protein (flagellin) that protrudes through cell wall
* locomotion
34
What are Pili & Fimbriae?
* thin short filamentous appendages (mainly in gram -ve)
* composed of Pilin
* fimbriae - adherence, biofilm formation
* pili - motility, sex pili, adherence
35
What are Endospores?
* highly resistant dormant stage of bacteria formed in unfavourable envmt conditions (ex. starvation & desiccation)
36
Steps in Sporulation
1. sporm septum forms - isolates new DNA
2. PM surrounds DNA, cytoplasm & PM
3. formation of forespore
4. peptidoglycan layer forms b/w memebranes
5. spore coat forms
6. endospore released - has 2 layers PM, peptidoglycan layer, spore coat
37
What is Germination? Steps?
* endospore transformation to vegetative cell under suitable envmt conditions
1. activation
2. initiation
3. outgrowth
38
Autotrophs
* bacteria that can synthesice their essential metabolites (from CO2 & nitrogen)
39
Heterotrophs
* bacteria that CAN'T synthesize their own metabolites
* require preformed compounds for growth
40
Obligate aerobe
* undergo aerobic respiration
* oxygen is required
41
Obligate anaerobe
* can't use oxygen in respiration & whose growth is inhibited by oxygen
* oxygen is toxic
42
Facultative anaerobe
* able to live aerobically or anaerobically
* oxygen increases growth
43
Aerotolerant aerobes
* do NOT use aerobic metabolism but have some enzymes that detoxify oxygen's poisonous form
* only anaerobic growth, no effect of oxygen
44
Microaerophiles
* aerobes that require O2 levels from 2-10% & have limited ability to detoxify H2O2
* onyl aerobic growth
45
Mesophiles
* 10-50 degrees
* humans
* causative agents of disease will be mesophiles
46
Psychroptrophs & Psychrophiles
* Psychrotrophs - cold envmt 0-30
* Psychrophiles - cold envmt -10 - -15
47
Thermophiles & Hyperthermophiles
* Thermophiles - higher temp 40-70
* Hyperthermophiles - high temp 65-110
48
Neutrophiles
* bacteria that grow best in narrow range of pH 6-8
49
Acidophiles
* Bacteria that grow best pH <4
50
Alkaliphiles
* Bacteria that grow best pH>11.5
51
Generation time
* time required for a bacterial cell to divide
* 1-3 hours for most bacteria
52
Steps in Bacterial Growth Curve
1. Lag phase - growth doesn't begin immediately
2. Log phase - cells divide at exponential rate, more susceptible to antimicrobial drugs
3. Stationary phase - nutrient depletion or toxic product cause growth to slow, # new cells = # dying cells
4. Death Phase - marked decline at exponential rate
53
What is a Pathogen?
* a microorganism capable of causing disease
54
What are Opportunistic pathogens
* rarely cause disease in immunocompetent pts but can cause **serious infection in immunocompromised pts**
55
Virulence
* quantitative ability of an agent to cause disease
* severity or harmfulness of disease
* involves adherence, invasion & toxigenicity
56
Pathogenecity
* potential or ability to cause disease
57
Determinants of Bacterial Pathogenesis
1. Transmission
2. Adherence - capsule/slime layer, adherence proteins, lipoteichoic acid, fimbriae
3. Invasion & intracellular survival - hyaluronidasem coagulase, hemolysis, leukocidins, IgA1 protease
4. Toxins - Exotoxins & Endotoxins
5. Intracellular pathogenicity
58
Exotoxin
* produced inside gram +ve bacteria
* released during log phase
59
Endotoxin
* component of LPS in gram -ve bacteria
* released when bacteria dies & cell lyses
60
What are Biofilms?
* cell communities encased in slime
* primary component is **Extracellular Polymeric Substance (EPS) matrix**
* communication w/in them
61
Steps in Biofilm formation
1. Adhesion of planktonic cells
2. Formation of Monolayer & EPS
3. Microcolony formation (multi-layered)
4. Mature Biofilm w/ mushroom shape
5. Detachment & planktonic growth
62
Variables Affecting Attachment of Biofilm
* Substratum - texture, hydrophobicity, Conditioning film
* Media/fluid - flow velocity, pH, temp, cations, antimicrobial agents
* Cells - adherence proteins, fimbriae, capsule
63
Quorum sensing
* Bacteria in biofilm communicate via Quorum Sensing
* dependent on chemical signalling moleules **autoinducers (AI)**
* Inhibit their own expression when AI extracellular [ ] > AI intracellular [ ]
64
Benefits of Biofilms
* bacteria share nutrients & DNA
* sheltered from harmful factors - antimicrobials
* allow for mutual benefit - different colonies at different nutrient & O2 levels
65
Prevention of Biofilms
* Prevent adhesion - coating substratum
* Destruction of EPS matrix - mechanical, laser, enzyme approaches, heat, Ab approaches
* Specific targeting of Persister cells
66
Direct Specimens
* Collected from normally sterile body fluids (ex. Cerebrospinal fluid, blood)
* Positive findings are diagnostic & negative findings can exclude infection at the suspected site
67
Indirect Specimens
* Specimens of inflammatory exudates (ex. expectorated sputum) that have passed through sites known to be colonized w/ normal flora
* Some assessment of contamination w/ normal flor is necessary before interpreting results
68
Normal Flora Specimens
* Primary site of infection is an area known to be colonized w/ many organisms (ex. pharynx, large intestine)
* Exams are selectively made for organisms know to cause infeciton that are NOT normally found at infected site
69
Direct ELISA
* Have Ab that is specitic to the Ag
* Detection molecule bound to primary antibody
70
Indirest ELISA
* Primary Ab binds Ag
* Add secondary Ab that is bound by detection molecule
* Secondary Ab binds primary Ab
71
Sandwich ELISA
* Detects Ab at different site
* Capture Ab binds Ag, then Ab w/ detection molecule binds at diff site
* Useful is we want to look at 2 very similar bacteria that have same Ab on surfec, but we only want to detect 1
72
Latex Agglutination Test
* Looks for specific Ag in your sample
* Each well contains and Ab against the Ag conjugated to latex
* Add the sample to wells
* Positive test - forms clumps, means Ag is present
73
What is ELISA?
* Enzyme Linked Immunosorbent Assay
73
Polymerase Chain Reaction (PCR)
* Looking for specific DNA (instead of proteins or Ags)
* detection of DNA particles that contain a specific sequence
* start w/ primers specific to DNA sequence, dNTPs & polymerase
* many cycles -> 2^n copies
74
What are Bacterial Cultures
* most sensitive & specific means of diagnosis & is thus the method most commonly used
* bacteria grown in a variety of artifical media
75
What is a Colony-forming unit (CFU)
* unit which estimates the # of microbial cells
76
Defined Media
* chemical
* synthetic media
* all chemical components & their exact [ ] are known
* **no yeast, animal or plant tissue used - NOT from a biological source**
77
Complex Media
* **media derived from yeast, animal or plant products**
* unknown [ ]s
* blood is often added to provide additional growth factors
* ex. nutrient broth, trypticase soy agar & MacConkey agar
78
Selective Media
* select growth for a particular microorganism
* common selective markers include Abx such as ampicillin (selecting for Abx resistant strains)
79
Differential Media
* Either the presence of visible changes in medium or differences in appearances of colonies help differentiate various kinds of bacteria growing on the medium
* Takes advantage that diff bacteria utilize ingredients in different ways
80
Blood Agar
* Differential media
* Differentiate bacteria based on hemolytic properties
* B-hemolysis - completely digests RBCs, clearing zones
* A-hemolysis - partially lyses RBCs, reduces Hgb, greenish/brown zone
* G-hemolysis - do NOT digest RBCs, agar unchanged
81
MacConkey Agar
* Selective & differential media
* Selective - isolate gram -ve bacteria
* Differential - differentiation based on ability to ferment lactose, turns red when ferments lactose
82
Anaerobic Media
* stab culture
* anaerobic chamber - sodium bicarbonate & sodium borohydrate
83
Selective Toxicity
* drug is harmful to pathogen but not to the host
* relative - [ ] tolerated by host damages the infecting microogranism
* could target receptors not found in host, target biochemical pathways not essential for host
84
Broad Spectrum Antimicrobials
* works on wide range of bacteria & pathogens
* more likely to disrupt micrbiota or have off target effects
85
Narrow Spectrum Antimicrobials
* increased selection, reduce non-selective toxicity
* more info about bacteria is required
86
Antibiotics can inhibit the synthesis or disruption of...
* cell wall
* protein
* nucleic acid
* cell membrane
* metabolites
87
Inhibitors of Cell Wall Synthesis
| Abx mechanism
* B-lactams - Penicillins & Cephalosporins
* Others - Vancomycin
88
Inhibitors of Protein Synthesis
| Abx mechanism
* Anti-50S (ex. Chloramphenicol) - inhibit peptide chain elongation during protein synthesis
* Anti-30S (ex. Aminoglycosides, tetracycline) - interfere directly & cause misreading of mRNA
89
Inhibitors of Nucleic Acid Synthesis
| Abx mechanism
* DNA (ex. Quinolines & Fluoroquinolines) - inhibit DNA gyrase & topoisomerases, prevent unfolding of DNA
* RNA (ex. Rifampin) - interferes w/ bacterial dependent RNA polymerase
90
Disruptors of Cell membrane
| Abx mechanism
* Polymyxin B - binds to plasma membrane, increases its permeability & disrupts it's structure
91
Antimetabolite Antibiotics
| Abx mechanism
* Inhibitors of folic acid synthesis - ex. Sulfonamides & trimethoprim
* Inhibitors of mycolic acid synthesis - ex. Isoniazid
92
Bacteriocidal
* kills bacteria
* can be bacteriostatic at low [ ]
93
Bacteriostatic
* stops bacterial growth
* if removed can continue to grow
94
MIC
* Minimum Inhibitory Concentration
* lowest antimicrobial [ ] to inhibit visible growth of an organism
95
MBC
* Minimum Bactericidal Concentration (MBC)
* lowest antimicrobial [ ] reqiured to kill a particular bacterium
96
Standardized components of antimicrobial susceptibility testing
* Time
* [ ] of antimicrobial
* Total volume – 2 mL for microdilution, 100uL for microdilution
* Initial inoculum concentration
97
Broth Dilution Testing
* Series of doubling dilutions
* Lowest [ ] of Abx that inhibits the in vitro growth of the bacteria is recorded as the MIC
* Characterized - Susceptible, Intermediate, Resistant
98
Advantages & Disadvantages of Broth Dilution Testing
Advantages:
* Quantitative method (MIC)
* Straightforward & simple (easy reproducibility)
* Opportunity for automation (esp w/ micro dilutions)
* Flexible
Disadvantages:
* Time consuming & tedious (making sure they’re standardized)
* Media usage
* Possibility of error
99
Agar Dilution Testing
* Serial dilutions of Abx are added to melted solid media, which are then poured & left to cool & solidify
* each plate containing a diff [ ] of Abx
* fixed # of organisms inoculated on surface
100
Advantages & Disadvantages of Agar Dilution Testing
Advantages:
* More gradual changes
Disadvantages:
* Labor intensive
* Expensive
* Space inefficient
101
Disc Diffusion Method (Steps)
1. Make bacterial lawn
o Dip swab in broth, remove excess liquid
o Swab entire agar surface – 3 directions & around rim
o No bare spots or burhs strokes on agar
2. Dispense the Abx disks
3. Press GENTLY w/ forceps for disks to adhere, alcohol flame forceps to sterilize
4. Label plates on the edges
5. Invert plates & incubate
102
Advantages & Disadvantages of Disc Diffusion Method
Advantages:
* Simplicity
* Flexible
* Reduced labour
* Easily interpretable
* Inexpensive
* Consistent
Disadvantages:
* Diameter instead of [ ] need interpretation
* Qualitative
* Purchased discs means limited Abx
103
Epsilometer Test (E-test)
* MIC determined from point where zone of inhibition intersects w/ numerical scale
* egg shaped growth pattern
104
Advantages & Disadvantages of Epsilometer Test
Advantages:
* More consistent & accurate
* Relatively easy
* Well controlled Abx concentrations
Disadvantages:
* Higher costs
* Limited # of Abx
105
Advantages & Disadvantages of Automated Antimicrobial Susceptibility Testing
Advantages:
* Less tedious
* More reproducible
* Fast (3 hours)
* Automated data output
Disadvantages:
* Limited types of antimicrobials
* Limited ability to detect some forms of antimicrobial resistance (B-lactamases in gram -ve bacteria)
* Expensive
106
When Zone of inhibition decreases, MIC ___
increases
107
Susceptible Category
* IDEAL
* antimicrobial agent is appropriate choice
* bacterial resistance if absent or clinically insignificant
108
Intermediate Category
* some response rates
* buffer between resistant and susceptible categories
109
Resistant Category
* no clinical efficacy
* not a good choice of Abx for bacteria
110
Antimicrobial battery/panel
* The antimicrobial agents that are chose for testing against a particular bacterial isolate
111
Antibiogram
* visual representation how susceptible or NOT susceptible particular bacteria are to Abx
112
All Abx orders must have 3 pieces of info:
* When to take them
* How much to take (right dose)
* How many days you should take them
113
Gram Positive Bacteria
* cocci - staphalococcus, streptococcus, enterococcus
* bacilli non-spore - corynebacterium, listeria, lactobacilli
* bacilli spore - bacillus, clostridium
114
Catalase Test
* does organism breakdown hydrogen peroxide -> H20 + O2
* bubbles when H2O2 is added to culture
115
Coagulase Test
* if staphylocoagulase enzyme is present the plasma will clot
* differentiates **staphylococcus aureus** from other gram-positive
116
oxidase test
* does organism produce cytochrome c oxidase
* test if organism can change colourless redox reagent, changes colour when oxidized
117
Staphylococcus spp
* purple circular formed in clumps
* catalase positive
* facultative anaerobes
* not spore forming
118
Staphylococcus aureus
* gram +ve
* **most virulent species**
* catalase +ve
* coagulase +ve
* B-hemolysis
* VF: structures/enzymes that enable it to evade phagocytosis, production of enzymes, production of toxins
* Normal: nares, nasopharynx, perineal region, skin
* Disease: variety depending on site of infection
119
How does S. aureus evade phagocytosis
* neutrophil extravasion & chemotaxis - Staph superantigen-like proteins, inhibit host receptors
* inhibition of complement & phagocytosis - secrete inhibitory factors
* enzymes that prevent neutrophil killing - inhibit granule formation, antioxidants inactivating active oxygen species
* production of pore forming toxins to kill phagocytes
* coagulase
120
S. aureus Enzymes
* coagulase
* hyaluronidase or spreading factor
* staphylokinase - fibrinolysis (escapes blood clots)
* B-lastamase - resistance to B-lactam Abx
121
S.aureus Toxins
* hemolysins
* exfoliative toxins - dissolve mucopolysaccharide matrix of epidermis
* toxic shock syndrome toxin (TSST-1)
* enterotoxins - food poisoning, carb & protein foods
122
Examples of S.aureus Infections
* Food poisoning
* Toxic Shock syndrome
* Soft Tissue infections
* Impetigo
* Scalded skin syndrome (Ritter's disease)
* Endocarditis (infection of endocardium)
* Osteomyelisitis (infection of bone)
123
Staphylococcus epidermidis
* gram +ve
* catalase +ve
* coagulase -ve
* G-hemolysis
* VF: exopolysaccharide slime, exotoxins
* Normal: skin & mucosa
* Disease: oppurtunistic (immunocompromised)
124
Staphylococcus saprophyticus
* gram +ve
* catalase +ve
* coagulase -ve
* G-hemolysis
* Normal: skin & genitourinary tract & mucosa membranes
* Disease: UTIs
125
Streptococcus spp
* gram +ve cocci in pairs or chains
* catalase -ve
* coagulase -ve
* Facultative anaerobes
126
Streptococcus pyogenes
* Group A Streptococcus (GAS)
* Gram +ve
* catalase -ve
* coagulase -ve
* B - hemolysis
* VF: streptokinase (fibrinolysin - bacteria escapes clots), hemolysins, hyaluronidase (spreading factor)
* Normal: not normal flora
* Disease: several
127
Examples of S. pyogenes Infections
* Acute pharyngitis (strep sore throat)
* Impetigo
* Cellulitis - red swelling on skin & body
* Necrotizing fascitis
* Bacteremia
* Post-streptococcal diseases
128
Streptococcus agalactiae
* Group B streptococci
* Gram +ve
* catalase -ve
* coagulase -ve
* B-hemolysis
* VF: capsule
* Normal: vaginal flora & GI tract
* Diseases: most seen in neonates, postpartum infections, bacteremia, pneumonia, endocarditis
129
Enterococci
* previously group D streptococci
* **evade anti-microbials (intrinsically resistant)**
* Typically G-hemolysis
* VF: adhesions, cytolysins
* Normal: GI tract & female genitourinary
* Disease: Nosocomial infections (UTI & intra-abdominal infections)
130
Streptococcus pneumoniae
* lancet-shaped diplococci
* Gram +ve
* catalase -ve
* coagulase -ve
* A-hemolysis
* VF: polysachharide capsule, IgA protease, pneumolysin (suppression of oxidative burst in phagocytes)
* Normal: upper respiratory tract
* Disease: bacteremia, meningitis, bacterial pneumonia, acute otitis media in children
131
Viridans Streptococci
* Gram +ve
* catalase -ve
* coagulase -ve
* facultative anaerobes
* A or G - hemolysis
* VF: production of extracellular complex polysaccharides
* Normal: oral cavity, GI tract, female genital tract
* Disease: oppurtunistic pathogens of low virulence, may cause bacteremia & endocarditis
132
Listeria monocytogenes
* short motile rod or coccobacilli
* Gram +ve
* catalase + ve
* coagulase -ve
* Facultative anaerobes
* B-hemolysis
* VF: ActA, hemolysin, phospholipases
* Normal: soil, water, decaying vegetation & animals
* Disease: wide spectrum of diseases in animals & humans (ex. meningitis, Listeriosis), very importatn in food borne pathogens
133
Corynebacterium spp
* clubbed or irregularly shaped
* Gram +ve
* catalase +ve
* coagulase -ve
* Facultative anaerobes (oxidase -ve)
* G-hemolysis
* VF: Diphtheria toxin
* Normal: mucous membranes, resp tract, urinary tract & conjunctiva
* Disease: C.diphtheria pathogenic species (sore throat, fever, blockage of airways) -> Diptheria vaccine
134
Lactobacillus spp
* Bacillus
* Gram +ve
* catalase -ve
* coagulase -ve
* Facultative anaerobes
* G-hemolysis
* Normal: vagina
* Disease: infections rare
135
Bacillus spp
* large Gram +ve rods in chians
* catalase +ve
* coagulase -ve
* obligate aerobes or facultative anaerobes
* spore-forming +ve
136
Bacillus anthracis
* Gram +ve
* catalase +ve
* coagulase -ve
* obligate anaerobe
* G-hemolysis
* spore-forming +ve
* VF: capsule, Anthrax toxin (cell binding protective Ag, Edema factor, Lethal factor)
* Normal: primarily disease of herbivores
* Disease: contact w/ infected animals, can be cutaneous, gastrointestinal or pulmonary OR bioterrorism
137
Bacillus cereus
* motile
* Gram +ve
* catalase +ve
* coagulase -ve
* B-hemolysis
* spore-forming +ve
* VF: enterotoxins, pyogenic toxin
* Normal: disease of herbivores
* Disease: oppurtunistic pathogen (food poisoning)
138
Clostridium spp
* large anaerobic gram +ve bacilli
* motile
* catalase -ve
* coagulase -ve
* anaerobes (mostly obligate some aerotolerant)
* B-hemolysis
* Spore-forming +ve
* VF: decompose proteins or form toxins or do both)
* Normal: soil or intestinal tract
* NOTE: C. botulinum, C.difficilem C.perfringens, C.tetani
139
Gram Negative Bacteria
* Escherichia coli
* Shigelle spp
* Salmonella spp
* Acinetobacter spp
* Pseudomonas aerginosa
* Haeomphilus influenzae
* Haemophilus ducreyi
* Neisseria gonorrhoeae
* Neisseria meningitidis
* Moraxella catarrhalis
140
Enterobacteriaceae family
* enteric gram -ve rods, enteric bacteria or coliforms
* many genera (Escherichia, Shigella, Salmonella, Enterobacter, Klebsiella, Serratia, Proteus)
* complex antigenic structure and produce a variety of toxinz & other virulence factors
* facultative anaerobes (most oxidase -ve)
* grow well on MacConkey agar (lactose & non-lactose fermenting)
* ferment glucose (rather than oxidize)
* generally do NOT have capsules
141
Escherichia coli
* gram -ve
* catalase -ve
* facultative anaerobes (oxidase -ve)
* hemolysis strain dependent
* MacConkey growth
* +ve lactose ferment
* VF: endotoxin, pili
* Normal: GI, female genital tract
* Disease: UTI, bacteremia, neonatal meningitis, GI infections
142
Shigella spp
* gram -ve
* catalase -ve
* facultative anaerobes (oxidase -ve)
* G-hemolysis
* MacConkey growth
* -ve lactose
* VF: adhesion, invasion factors, intracellular spread, shigella toxins
* Normal: only in humans in infections
* Disease: dysentery (diarrhea)
143
Salmonella spp
* gram -ve
* catalase -ve
* facultative anaerobes (oxidase -ve)
* G-hemolysis
* MacConkey growth
* -ve lactose
* VF: factors tha tpormote adherence & allow survival in pahgocytes, facilitate dissemination to other tissues
* Normal: intracellular pathogens
* Disease: gastroenteritis, enteri fever, bacteremia
144
Acinetobacter spp
* gram -ve
* catalase +ve
* facultative aerobes (oxidase -ve)
* B-hemolysis
* MacConkey growth
* -ve lactose
* Normal: soil & water, hospital envmt
* Disease: nosocomial infections, rarely UTI/bacteremia/endocarditis
145
Pseudomonads family
* distributed in soil & water
* motile, non-spore forming, aerobic rods, some produce pigments
* psuedomonas aeruginosa rarely present in normal intestinal florw & on skin
146
Pseudomonas aeruginosa
* gram -ve
* catalase +ve
* obligate aerobes (oxidase +ve)
* typically B-hemolysis
* MacConkey growth
* -ve lactose
* VF: pili, exotoxin A, endotoxins, intrinsic resistance to antimicrobials. alginate, pyocyanin
* Normal: soil, water, skin flora
* Disease: oppurtunistic in immunocompromised
147
Haemophilus spp
* small, non motile pleomorphic rods
* coccobacilli or short rods
* require enriched media, containing blood
* catalase +ve
* facultative anaerobe (oxidase +ve)
* no growth on blood agar, satelittle phenomenon around S.aureus
* Normal: upper respiratory tract (except ducreyi)
148
Haemophilus influenzae
* gram -ve
* 2 types: typeable, H.influenzae type b (Hib)
* Hib vaccine not effective against non-typeable
* MacConkey -ve
* catalase +ve
* facultative anaerobe (oxidase +ve)
* VF: cacpsule, antiphagocytic pili
* Disease: meningitis, otitis media, pneumonia, bacteremia
149
Haemophilia ducreyi
* gram -ve
* MacConkey -ve
* catalase +ve
* facultative anaerobes (oxidase +ve)
* VF: pili, capsular factors, toxins
* Normal: GI, female genital tract
* Disease: chancroid (STI)
150
Legionella pneumophila
* gram -ve rods, motile
* need media supplemented w/ iron & L-cysteine
* MacConkey -ve
* catalase +ve
* obligate aerobes (oxidase +ve)
* VF: genes for type II secretion systems
* Normal: intracellular parasites, lakes/streams/rivers, air-cons
* Disease: Legionnaires disease, Pontiac fever
151
Neisseria spp
* non-motile gram -ve diplococci
* kidney bean shaped
* MacConkey -ve
* catalase +ve
* obligate aerobes (oxidase +ve)
* VF: pili, capsule, lipoligosaccharide (endotoxin)
* Normal: human resp tract
* Disease: species specific
152
Neisseria gonorrhoeae
* gram -ve
* MacConkey -ve
* catalase +ve
* obligate aerobes (oxidase +ve)
* VF: pili, capsule, lipoligosaccharide (endotoxin)
* Normal: mucous membranes of genitalia, eyes, rectum & throat
* Disease: STI (gonorrhea), gonococcemia, pharyngitis, conjunctivitis
153
Neisseria meningitidis
* gram -ve
* MacConkey -ve
* catalase +ve
* obligate aerobes (oxidase +ve)
* VF: IgA
* Normal: oropharyngeal & nasopharyngeal mucous membranes, can carry w/out sx
* Disease: meningitis, bacteremia
154
Moraxella catarrhalis
* gram -ve diplococci
* MacConkey -ve
* catalase +ve
* obligate aerobes (oxidase +ve)
* G-hemolysis
* Normal: upper resp tract & female genital tract
* Disease: resp tract infections & otitis media, sinusitis & pneumonia
