Microbiology: Bacteria Flashcards
1
Q
Peptidoglycan
A
Gives rigid support, protects against osmotic pressure
- Sugar backbone with peptide side changes crosslinked with transpeptidase
2
Q
Cell wall/ cell membrane
A
Major surface antigen
- Peptidoglycan for support
- Lipoteichoic acid induces TNF and IL-1
3
Q
Outer membrane
(gram negative)
A
Site of endotoxin
- Lipopolysaccharide (LPS)
- major surface antigen
- Lipid A induces TNF and IL1
- O polysaccharide is the antigen
4
Q
Plasma membrane
A
Site of oxidative and transport enzymes
- Phospholipid bilayer
5
Q
Ribosome
A
- Protein synthesis
- 50s and 30s
6
Q
Periplasm
A
Space between the cytoplasmic membrane and outer membrane in gram negative bacteria
- Contains many hydrolytic enzymes
- B-lactamase
7
Q
Capsule
A
Protects against phagocytes
- Polysaccharide ( except in B. anthracis, which contains D-glutamate)
8
Q
Pilus/ Fimbria
A
mediate adherence of bacteria to cell surface
- Sex pilus: attachment between 2 bacteria during conjugation
- Glycoprotein
9
Q
Flagellum
A
Motility
- made of protein
10
Q
Spore
A
Resistant to dehydration, heat and chemicals
- keratin-like coat, dipicolinic acid,
- peptidoglycan
11
Q
Plasmid
A
Contains a variety of genes for antibiotic resistance, enzymes and toxins
- Made of DNA
12
Q
Glycocalyx
A
Mediate adherance to surfaces
- made of polysaccharides
13
Q
Cell wall of Gram negative
A
- Cytoplasmic membrane
- Periplasm*
- Peptidoglycan
- Outer membrane (endotoxin, LPS) *
- Capsule
- Flagellum/ pillus
14
Q
Cell wall of gram positive
A
- Cytoplasmic membrane
- cell wall with peptidoglycan
- capsule
- Lipoteichoic acid (G+ only)
- pillus/ flagellum
15
Q
Bacterial Morphology:
Coccus
A
Gram (+)
- Staphylococcus
- Streptococcus
Gram (-)
- Neisseria
16
Q
Bacterial Morphology:
Bacillus
A
Gram (+)
- Clostridium
- cornyebacterium
- bacillus
- listeria
- mycobacterium
Gram (-)
- E. Coli, Shigella, Salmonella, Klebsiella, Proteus, Enterobacter, Serratia, vibrio, campylobacter, helicobacter, pseudomonas, bacteroides
- Haemophlius, legionella, bordetella
- Grancisella, Brucella, Bartonella
17
Q
Bacterial Morphology:
Branching Filamentous
A
G (+)
- Actinomyes
- Norcadia
18
Q
Bacterial Morphology:
Pleomorphic
A
G (-)
- Rickettsiae
- Chlamydiae
19
Q
Bacterial Morphology:
Spiral
A
G (-)
- Borrelia
- Leptospira
- Treponema
20
Q
Bacterial Morphology:
No cell wall
A
Mycoplasma
- does not gram stain
21
Q
Mycoplasma cell membrane
A
Contains sterols and have no cell wall
22
Q
Mycobacteria Cell wall
A
Contain mycolic acid
High lipid content
23
Q
Bugs that do not gram stain well
A
- Treponema: too thin to be visualized
- Mycobacteria: high lipid content in cell wall (acid fast)
- Mycoplasma: no cell wall
- Legionella pneumophilia: primarily intracellular
- Rickettsia: intracellular parasite
- Chlamydia: intracellular parasite
24
Q
Giemsa Stain
A
- Chlamydia
- Borrelia
- Rickettsiae
- Trypanosomes
- Plasmodium
25
PAS (periodic acid-schiff)
* Stains glycogen
* Whipple disease (tropheryma whipplei)
26
Ziehl-Neelsen (carbol fuscin)
Acid fast organisms
* Norcadia
* mycobacterium
27
India Ink
Cryptococcus neoformans
* Mucicarmine can also be used to stain polysaccharide capsule red
28
Silver Stain
* Fungi ( pneumocystis)
* Legionella
* H. pylori
29
Special Cultures:
N. Influenzae
Chocolate agar with factor V and X ( NAD+ and Hematin)
30
Special Cultures:
N. gonorrhoea
N. Meningitidis
* Thayer-Martin (VPN) media
* Vancomycin ( inhibits G+)
* Polymyxin (inhibits G-, except Neisseria)
* Nystatin (inhibits fungi)
31
Special Cultures:
B. pertussis
Bordet-Gengou (Potato) agar
[Bordet for Bordetella]
32
Special Cultures:
C diptheriae
Tellurite agar
Loffler medium
33
Special Cultures:
M. tuberculosis
Lowenstein-jensen agar
34
Special Cultures:
M. pneumoniae
Eaton agar
requires cholesterol
35
Special Cultures:
Lactose fermenting enterics
Pink colonies on MacConkey agar ( fermentation makes acid that turns colonies pink)
36
Special Cultures:
E. coli
Eosin-methylene blue (EMB)
colonies with metallic green sheen
37
Special Cultures:
Legionella
Charcoal yeast extract agar buffered with cysteine and iron
38
Special Cultures:
Fungi
Sabourad agar
39
Obligate Aerobes
use an oxygen dependent system to generate ATP
* Norcadia
* Pseudomonas **_aer_**uginosa
* MycoBacterium TB
P. aeruginosa
* burn wounds, complication of diabetes, nosocomial pneumonia, pneumo in CF
TB
* Reactivation of TB has predilection for apices of lung (highest O2)
40
Obligate anaerobes
Lack catalase or superoxide dismutase making them susceptible to oxidative damage
* foul-smelling
* difficult to culture
* producegas in tissue (CO2 and H2)
* aminoglycosides are inffective
Examples:
* Clostridium
* Bacteroides
* Actinomyces
41
Intracellular bugs
Rickettsia, Chlamydia
* cant make own ATP
42
Facultative Intracellular
* Salmonella
* Neisseria
* Brucella
* Mycobacterium
* Listeria
* Franciscella
* Legionella
* Yersina pestis
43
Encapsulated bugs
* Streptococcus pneumoniae
* Haemophilus Influenzae type B
* Neisseria meningitidis
* E. Coli
* salmonella
* Klebsiella pneumoniae
* Group B Strep
Opsonized and cleared by the spleen
* asplenic--\> increased risl for infections
* give S. pneumoniae, H. influenzae, N. meningitidis vaccines
44
Catalase positive
Catalase degrades H2O2 before it can be converted to microbicidal products by Myeloperoxidase
* NADPH oxidase deficiency= chronic granulomatous disease have recurrent infections with catalase + organisms
organisms
* Pseudomonas
* Listeria
* Aspergillus
* Candida
* E. Coli
* S. aureus
* Serratia
45
Encapsulated Bacteria vaccines
* Some vaccines containing polysaccharide capsule antigens are conjugated to a carrier protein
* enhances immunogenicity by increasing T cell activation and class switching
* Pneumococcal vaccine (PV- prevnar)
* Pneumococcal polysaccharide vaccine with no conjugated protein (PPSV= pneumovax)
* HiB: conjugate vaccine
* Meningococcal vaccine (conjugate)
46
Urease positive bugs
* Cryptococcus
* H. pylori
* Proteus
* Ureaplasma
* Norcadia
* Klebsiella
* S. epidermidis
* S. Saphrophyticus
47
Pigment producing bacteria
* Actinomyces isrealii: yellow sulfur granules
* S. aureus: yellow pigment
* Pseudomonas aeruginosa: blue-green pigment
* Serratia marcescens: red pigment
48
Virulence Factor:
Protein A
Binds Fc region of IgG
* Prevents opsonization and phagocytosis
* Expressed by S. aureus
49
Virulence Factor:
IgA protease
Enzyme that cleaves IgA to colonize respiratory mucosa
* S. peneumoniae
* H. influenzae type B
* Neisseria
50
Virulence Factor:
M protein
Helps prevent phagocytosis
* Expressed by group A strep
51
Exotoxins
* Secreted from cell
* polypeptide
* genes are located on plasmid or bacteriophage
* High toxicity
* Induces high titer antibodies
* Toxoids are used as vaccines
* Destroyed at 60\* (except staphylococcoal toxin)
* Disease: tetanus, botulism, diptheria
52
Endotoxins
* Source: outer membrane of most gram negative bacteria
* Lipopolysaccharide
* Genes are on bacterial chromosome
* Low in toxicity
* Fever, shock, hypotension, DIC
* Induces TNF, IL1, IL6
* Poorly antigenic
* no toxoids-\> no vaccine
* Stable at 100\* for 1 hour
* Disease: Meningococcemia, sepsis by gram (-) rods
53
Bacteria with Exotoxins:
Inhibit protein synthesis
* C. diptheriae
* Diptheria toxin: inactivates EF-2
* pharyngtitis
* P. aeruginosa
* Exotoxin A: inactivates EF-2
* causes host cell death
* Shigella
* Shiga toxin: inactivates 60S
* GI mucosal damage--\> dysentary, HUS
* EHEC (0157:H7)
* Shiga like toxin: inactivates 60S
* enhances cytokine release causing HUS
54
Bacteria with Exotoxins:
Increase fluid secretions
* ETEC
* Heat labile toxin: overactivates adenylate cyclase--\> inc. cAMP --\> Cl- secretion to cause watery diarrhea
* Heat Stable toxin: overactivates guanylate cycle--\> inc. cGMP--\> decrease reabsorption of NaCl and water in gut
* B. antracis
* Edema factor: mimics adenylate cyclase enzyme to increase cAMP
* edematous borders of black eschar in cutaneous anthrax
* Vibrio Cholerae
* Cholera toxin: overactivates adenlate cyclase (inc. cAMP) by permanantly activating Gs to increase Cl- secretion in gut
* Rice water diarrhea
55
Bacteria with Exotoxins:
Inhibit phagocytic ability
Bordetella pertussus
* Pertussis toxin
* overactivates adenylate cyclase (cAMP) by disabiling Gi
* impairs phagocytosis
* Whooping cough
* child coughs on expiration and whoops on inspiration
* 100 day cough in adults
56
Bacteria with Exotoxins:
Inhibit release of neurotransmitter
* Clostridium tetani
* Tetanospasmin: protease that cleaves SNARE proteins required for neurotransmitter release
* Spasticity, lock jaw
* toxin prevents release of inhibitory (GABA and glycine) nt from Renshaw cells in spinal cord
* Clostridium botulinum
* Botulinum toxin: protease that cleaves SNARE
* flaccid paralysis, floppy baby
* toxin prevents stimulatory (ACh) signals at NMJ
57
Bacteria with Exotoxins:
Lyse cell membranes
* Clostridium pefringens
* Alpha toxins: phospholipase that degrades tissue and cell membranes
* Myonecrosis (gas gangrene)
* Hemolysis (double zone on blood agar)
* Streptococcus Pyogenes
* Streptolysin O: Protein that degrades cell membrane
* Lyses RBCs contributes to beta hemolysisi
* Host antibodies against toxin (ASO) used to diagnose rheumatic fever
58
Bacteria with Exotoxins:
Superantigens causing shock
* Staphylococcus aureus
* Toxic Shock syndrome Toxin: Bring MCH II and TCR in proximity outside of antigen binding to cause overwhelming release of INF-y and IL2
* Toxic shock syndrome: fever, rash, shock
* other toxins: Scalded skin syndrome (exfoliative toxins), Enterotoxin (food poisoning)
* Streptococcus Pyogenes
* Exotoxin A: causes overwhelming relase of INF-y and IL2 leading to shock
* Toxic shock syndrome: fever, rash, shock
59
Endotoxin Manifestations
LPS found in outer membrane of gram (-) bacteria
* Activates macrophages
* IL-1: fever
* TNF: fever & hypotension
* NO: hypotension
* Activates complement
* C3a: hypotension, edema
* C5a: Neutrophil and chemotaxis
* Activates tissue factor
* Coagulation cascade--\> DIC
60
Transformation
Ability to take up naked DNA from environment
* S. pneumoniae
* H. influenzae type B
* Neisseria
61
Conjugation
F+ x F-
* F+ plasmid contains genes required for sex pillus and conjugation
* Plasmid (dsDNA) is replicated and transferred through pilus from F+ cell
* no transfer of chromosomal genes
62
Hfr x F-
F+ plasmid can become incorporated into bacterial chromosomeal DNA ( high frequency recombination)
* Replication of recombinant DAN may include some flanking chromosomal DNA
* transfer of plasmid and chromosomal genes
63
Transposition
Segment of DNA ( transposons) that can jump from one location to another
* Can transfer genes from plasmid to chromosome and vice versa
* When excision occurs, may include some flanking chromosomal DNA which can be incorporated into plasmid and trasferred to another bacterim (antibiotic resistance genes)
64
Transuduction- generalized
Packaging event
* lytic phage infects bacterium
* leads to cleavage of bacterial DNA
* parts of bacterial chromosomeal DNA may become packaged into viral capside
* phage infects another bacterium transferring genes
65
Tranduction- specialized
Excision event
* Lysogeic phage infects bacterium
* viral DNA incorporated into bacterial chromosome
* when phage DNA is excised, flanking bacterial genes may be excised with it
* DNA is packaged into phage capsid and vira phage can infect another bacterium
* Bacterial toxins that are encoded in a lysogenic phage
* ShigA- like toxin
* Botulinum toxin
* Cholera toxin
* Diptheria toxin
* Erythrogenic toxins of S. pyogenes
66
Lactose Fermenting Enteric bacteria
Grow pink colonies on **MacConkey** agar
* **C**itrobacter
* **K**lebsiella
* **E**. coli
* **E**nterobacter
* **S**erratia (weak)
*
67
68
Argyll Robertson pupil
* constricts with accommodation but is not reactive to light
* associated with tertiary syphilis
69
VDRL false positives
* VDRL detects nonspecific antibody that reacts with beef cardiolipin
* test for syphilis
* sensitive but not specific
* many false positives
* Viruses (mono, hepatitis)
* Drugs
* Rheumatic fever
* Lupus and leprosy
70
Jarisch-Herxheimer reaction
Flu-like syndrome after antibiotics are started due to killed bacteria releasing pyrogen
