Bacteriology Exam Flashcards

Terms Definitions
 
 
 
 
 
Endotoxins
 
 
 
 
 
LPS
gull-wing shape
Campylobacter
rickettsia
gram -ve
bullous impetigo
S. aureus
no cell wall
mycoplasma
 
 
 
 
 
Common Staphylococcus strains outside of SIG
 
 
 
 
 
 
Staphylococcus aureus
Staphylococcus hyicus
>40 spp of coagulase - Staphylococcus
 
 
 
 
 
Actinomyces hordeovulnaris
 
 
 
 
Cutaneous pyogranulomas, pyothorax, osteomyelitis often associated with tissue migrating foxtail awns
small, extrachromosomal, self-replicating, mostly circular strands of DNA
plasmids
Actinomyces
gram-positive aerobic bacilli; non-acid fast; very slow-developing chronic infections in humans; low virulence; small colonies produce sulfa granules; can only infect when normal barriers have already been broken down
cause of tuberculosis
Mycobacterium tuberculosis
Vincent's Angina
-ulcerating, necrotizing gingivitis-caused by fusobacterium nucleatum-known as TRENCH MOUTH
 
 
 
 
 
Spp of non-spore-forming obligate anaerobes
 
 
 
Fusobacterium spp
Bacteroides spp
Porphyromonas spp
Prevotella spp
 
 
 
 
 
Coagulase-negative Staphylococcus
 
 
Aka Staphylococcus epidermidis
Can only differentiate via genomic studies
Infections associated with medical devices
Common cause of subclinical bovine mastitis
trepanoma
gram -ve spirochetes
Self-replicating gene unit
replicon
infections acquired during hospitalization
nosocomial
Clostridium perfringens
anaerobic spore-forming, gram-positive rod; most common clinical isolate of Clostridium; causes wound infections, skin infections, food poisoning, soft tissue infection; characterized by large amounts of N and H gas; subset that causes food poisoning acts by an enterotoxin that acts like the superantigen of staph
saddle nose; hutchinson's teeth
congenital syphilis
grows on "chocolate" agar
Neisseria gonorrhea
 
 
 
 
 
Staphylococcus pseudintermedius
 
 
 

MOST common pyogenic agent of dogs: pyoderma, infections of respiratory tract, bones, joints, wounds, etc...
Dacryocystitis
streptococcus pneumoniae most commonly involved and stephylococciInfection in lacrimal apparatus
Examples of exotoxins:
neurotoxins, cytotoxin, enterotoxin
associates with TLR4 conferring responsiveness to LPS
MD-2
leading cause of typical pneumoniae
Streptococcus pneumoniae
leading cause of otitis media
Streptococcus pneumoniae
Rx of Tb
isoniazide; rifampin; streptomycin; perazanomide
gastoenteritis (esp. in pregnant women)
Listeria monocytogenes
sepsis
a systemic overreaction to microbial invasion
What are mesosomes?
o Invagination of plasma membraneo Division/secretion
 
 
 
 
 
Clostridium piliform
 
aka Bacillus piliformis, Tyzzer's bacillus
Tyzzer's dz: acute fatal infection causing focal necrotic hepatitis, enteritis and colitis
Lab mice, foals and other animals
Reservoire is probably infestine of rodents
 
 
 
 
 
Clostridium difficile
 
Enterocolitis and diarrhea in horses, pigs, and dogs
Fibrin and plasma leakage --> hemorrhage too
Important nosocomial problem, some strains with increased virulence
Difficult to isolate, not all strains are toxigenic - test for toxins

No vaccine
Spores hard to rid of --> nosocomial problems
Diagnosis
provide info for selection of appropriate therapeutic proceduresId of pathogenSeek a common source to prevent widespread transmission
Mutation
substitution of one nucleotide for anotherdeletion of one or more nucleotidesinsertion of additional nucleotidesframeshift- sequence is shifted
Epidemiology
study of the determinants, occurrence, distribution, and control of health and disease in a defined population. Goal is to define the parameters of a disease including risk factors to est effective control and prevention
Sign:
an objective indication of some medical fact or characteristic that may be detected by a physician during a physical examination of a patient.
What type of antibiotics is pseudomonas typically resistant to?
Many
pandemic
occurring over a large geographical area
pattern recognition protein of the innate immune system
CD14
globulin proteins produced by the animal in response to bacterial or viral antigens which will react specifically with these antigens
antibody
Rx of otitis externa
topicals (neomycin, polymixin); corticosteroids
pneumonia of milder infection, only one lobe involved, gradual onset, dry cough, fever, headache
atypical pneumonia
chancroid; dwarf lesions; school of fish
Hemophilus ducreyi
fomite
inanimate object on which bacteria can survive
genus Rickettsiales
infect endothelial cells; rash, edema, vasculitis, headache, fever; usually transmitted by blood-sucking arthropods
toxins A (enterotoxin) and B (cytotoxin)
Clostridium difficile
What are biomarkers?
help differentiate between infectious and non-infectious causes of SIRS:o C reactive protein (released in response to infection)o Procalcitonin (only released in pts with systemic infections)
Escherichia coli (Lambs)
EPEC: nonspecific enteritis, no enterotoxinETEC: systemic colibacillosis, general or localized
 
 
 
 
 
Periodontal dz

Periodontal dz begins as reversible gingivitis
normal flora in mouth interact with nutrients
form plaque which mineralize to form calculus on teeth

Calculus blocks oxygen diffusion (Porphyromonas spp proliferate in biofilms and produce toxins destructive to the tissue)
Inflammatory rxn releases enzymes in subgingival space and periodontal pockets

non-reversible destruction of periodontal lig, bone loss, eventually leading to tooth loss
Pili
Similar to fimbriae - required for mating.
Rifamycins
bind to DNA dependent RNA polymerase and prevents RNA synthesis. Used for mycobacterium tuberculosis and aerobic gram pos cocci.
neisseria gonorrhoeae contd
humans only reservoirprim reservoir- asymp men and women who are chronic carriersgonococcal conj- sex trans ocular dis. opthalmia neonatorum- infant eye contamin thru birth canallatex agg or ELISA using pus sample.speciemens cultured on thayer martin at inc CO2 concengram stain reveal PMNsTreat: systemic. Resis common. ceftriaxone and erythromycin or doxycycline
Collagenase
a spreading factor that breaks down connective tissue of muscle
mechanical vector?
transport the infectious agent w.o. being infected
What are endotoxins?
LPS in gram - bacteria
What occurs during breakdown of proteins that is commonly associated w/ anaerobic bacterial infxn?
Foul odors
toxemia due to presence of bacterial lipopolysaccharide in blood stream
endotoxemia
enzymes that produce complementary copies of nucleic acid segments
Polymerases (DNA, RNA)
stools devoid of blood, pus, or mucous
non-inflammatory diarrhea
causative agents of acute bronchitis
Mycoplasma pneumoniae, Chlamydia pneumoniae; Streptococcus pneumoniae
streptokinase and staphylokinase
enzymes produced by their respective organism to move through or dissolve host-derived fibrin barriers
identifying features of Shigella
inflammatory diarrhea; gram negative rods; lactose negative; hydrogen sulfide negative; non-motile
What are the Non-Enteric Gram (-) Rods?
1. Pseudonomas2.Burkholderia3.Legionella
What is Septic Shock?
bacteria in bloodstream (cultures positive)
What are spores?
usually produced in response to nutrient deficiencies; very resistant to environmental changes
ABC Transporter - Uptake
Solute binding protein binds substrate, attaches to transporter and releases substrate, which is moved across membrane with ATP hydrolysis.
Toxins: Exotoxins: A-B exotoxins
More localized than endotoxinA-B exotoxins- two domains. B subunit- binding specificity to host cell. A subunit-determines mechanism of action.Ex) Neurotoxins- act on nervous sys. prevent the release of inhib NT so muscle keeps contracting (tetanus, botulinum) Cytotoxins- inhib protein syn.(diptheria)Enterotoxins- affect intestinal tract. Cause diarrhea and vomiting. (cholera and E coli) membrane active exotoxins- directly damages host cell membrane causing leakage or lysis. Ex) Leukocidins- des
How can a communicable disease transmit to others?
directly or indirectly
Quorum Sensing of Biofilms
cell-to-cell communication via signal molecules. Population density determines the expression of specific genes.
morbidity rate
num of person afflicted w/ infectious disease
Peptidoglycan
linear polymers of NAG and NAM linked with beta-1,4 bond
Examples of virulence strains that produce toxins coded for by bacteriophage genes from transduction
Corynebacterium diphtheriae, Clostridium spp, Streptococcus pyogenes
used to describe cells of all higher organisms
eucaryotic
Domain that is prokaryotic in cell structure
Domain bacteria
toxic invasive factors of Pseudomonas aeruginosa
adhesins; endotoxins; motility- especially in burns and wounds; exotoxin A- protein-synthesis blocker; exoenzyme S; elastase- degrades elastin layer in blood vessels, particularly useful in lung tissue; pyocyanin- blue pigment and toxic factor, disrupts ciliary action in respiratory tissue; aliginate- found in capsule, used as adhesin for binding to lung epithelium, forms biofilm; enterotoxin- occasional diarrhea; antibiotic resistance
What is a capsule?
- Not all microorganisms have them, but many medically important ones do (in order to survive bloodstream)- Hydrophilic gel-like substance - Usually made of polysacharrides- Completely surrounds the cell- Impedes phagocytosis, penetration of toxins (including antibiotics)- Picture fresh tomato seeds- Loose Slime is the same material may amorphously surround the cell
 
 
 
 
 
Staphylococcus
Gram positive cocci that tend to be in clusters
Commensals of upper respiratory tract and skin of all endotherms
Unlike strep, prolonged survival in inanimate environ.
Spread of strains b/w diff animal species very limited
Pyogenic, associated with abscess formation and suppuration
Invasive enzymes: hyaluronidase, protease, lipase, fibrinolytic enzymes
Capsules and Protein A = antiphagocytic (fxns as Fc receptor)
Exotoxins (leukotoxins and cytolysins = alpha toxin, which is a pore forming hemolysin) can cause cell death and release of inflammatory mediators
Superantigens cause massive T cell stimulation
antimicrobial susceptibility testing
take microorg from specimen and asses its response to antimicrobial agents

Dont always equate with patient response to therapy 

MIC- min inhib concen. highest dilution of an antimicrobial agent that is able to inhibit growth of a test org
Bacterial Endotoxins
LPS in gram - bacteria; Active portion is lipid A
mortality rate:
the total number of deaths in a population due to a certain disease
What are types of fluorescent antibody and immunofluorescence testing?
1. direct
2. indirect
How are biofilms assembled?
- Planktonic bacteria explore env.
- decision to settle causes upregulation of genes involved in matrix prod
- control is quorum sensing
What are human infxns involving biofilms?
native valve endocarditis
central venous catheter
urinary catheter
intrauterine devices
contact lenses
do not have a cell wall, but have specific requirement for sterols
Mycoplasma
6 types of enteric E. coli
1. ETEC (enterotoxigenic)- watery diarrhea, both LT (heat labile) and ST (heat stable) toxins; 2. EPEC (enteropathogenic); 3. EIEC (enteroinvasive)- inflammatory diarrhea; 4. EAEC (enteroaggressive); 5. EHEC (enterohemorrhagic)- can't ferment sorbitol, Shiga toxin which blocks translation of ribosomes leading to cell death as well as hemorrhagic colitis
severe phase of Leptospirosis leads to
extreme jaundice and conjunctivitis, kidney and liver dysfunction
H influenzae pathogenicity hails from what three factors?
1. Polysaccaride capsule: inhibits phagocytosis2. IgA protease: Increased colonization3. Endotoxin: triggers macros
What are the predisposing factors of S. aureus?
- WBC chemotaxis defecto Trisomy 21o Diabeticso Rheumatoid arthritis- Antibody opsonization defecto Complement deficiency- Intracellular killing defecto Following phagocytosis, the inability to mount the oxidative burst of H2O2 to kill bacteriao Lukemia, granulomatous diseases- Severe skin traumao Recent burns, incisionso Foreign bodies – IV lines, sutures, caths, prosthetic devices- Prior infectionso Reduced granulocytes - Chronic underlying diseaseo Malignancy, alcoholism- Recent administration of antibiotics
What are the comman manifestations of enterococcus and non-GAS strep?
- Primarily Nosocomialo UTI, soft tissue, intra abdominal, endocarditis, bacteremia
Normal flora of skin
varies depending on enviro. in axilla, perineum, toe webs, hand, face, trunk, upper arms and legs. Predominant types- coagulase negative staphylococcus, propionibacterium(zits), staphylococcus aureus
Pathogens that infect during pregnancy
TORCH (toxoplasmosis, other such as hepatitis, rubella, cytomegalovirus, and herpes simplex virus) are the common infections of fetus and neonate
What are the 5 approaches to taxonomy?
1. phenotypic characteristics
2. serologic reactivity
3. bacteriophage typing
4. antibiotic sensitivity
5. genetic classification
Describe micro-broth dilution
- agent suspended in medium to given concentration and added in 2-fold dilution to microtiter plate w/ broth medium and agar w/ innocu.
- MIC determined as concentration visibily inhibiting growth
What are the 3 classifications of bacteria based on temperature adaptations?
1. psychrophile
2. mesophile
3. thermophile
What are nonliving reservoirs?
human hosts in reg. contact w/ environmental sources (soil, water)
7 upper respiratory infections
1. otitis externa; 2. otitis media; 3. sinusitis; 4. epiglottitis; 5. pharyngitis; 6. diptheria; 7. pertussis
2 types of virulence factors
1.endotoxins- part of gram - cell wall, outer membrane containing LPS; high levels lead to gram - sepsis; low levels produce immunostimulation and alarm reactions2.exotoxins- secreted from pathogen for a purpose; generally, secreted only nutritional or environmental needs are sufficient (i.e. Corynebacterium diptheriae produces diptheria toxin to kill cells for their iron)
What are the S. epidermidis pathogenic factors?
1. PS/A – capsular lysaccharide/adhesin 2.PIA – polysaccaride intracellular adhesions 3.Fibrinogen Binding Protein 4.Fatty acid modifying enzyme 5.Lipase6. Ab Resistance – MRSE, VRSEProduces almost nothing for toxins
What are the general characteristics of Gram - Rods?
- Soil, animals, human flora; free-living and endogenous- Very diverse- Being gram negative, they can cause sepsis when they gain access to blood- Can set up metastatic sites of infection- 1-2micrometers in length, usually motor (shigella, chicken salmonella), usually polar or peritrichisly (covered in flagella) motile- All ferment glucose (not all lactose)- Non-spore forming- Oxidase negative, most reduce nitrate- Tons of UTIs and diarrheaso UTIs – opportunistic pathogens, usually from colono Diarrheas – cytotoxic and invasive, causing inflammatory response, or cause watery diarrhea
How do you ID Salmonella?
Gram (-) rods- Lactose (-)- Usually motile, produce Hydrogen Sulfide
bacterial growth
inc in cell numbers as a result of an inc in all cell structures.
How do infectious agents enter the skin?
Nicks, abrasions, punctures. Intact skin is very tough allowing few microbes to penetrate.
What do biochemical tests include?
biochemical tests - inc. patterns of substrate utilization, metabolic product formation, sugar fermentation and unique chemical constituents
What is quorum sensing w/ biofilms?
cell-cell comm, via signal genes

ex. pathogenicity islands, plasmid transfer and 2ndary metabolisms, inc. glycocalyx prod
Advantages of biofilm for bacteria?
- Structure acts as anchor
- traps nutrients
- helps protect from biocides, antibiotics and antibiodies
PCR technique in which the RNA or DNA sequence is simultaneously amplified and quantified
Real time PCR
inhibition of the phagosome-lysosome function
a form of bacterial subversion of the cell-mediated response in which microbe inhibits fusion via mycolic acid (i.e. Mycobacterium tuberculosis)
What are the general charcteristics of Shingella?
*Like Salmonella, do not produce Lactose- All non-motile, all non-H2S producersHumans are primary reservoirUsually fecal-oral route via water suppliesTransmission: Flies, Food, Feces, Fomites
How are pathogens transmitted thru non-living reservoirs?
human hosts in regular contact with environmental sources such as soil and water
What are the 3 names for bacterial surface coating?
1. glycocalyx
2. capsule
3. K antigen
depression of normal white cell function
a form of bacterial subversion of the cell-mediated response inwhich toxins cause an increase in intracellular cAMP, which shuts off the normal functioning of the cell
What is Fatty acid modifying enzyme ?
inactivates FAs produced by host cells to inactivate bacteria – allows for long-term colonization of epithelial cells
what should one assume about all patient specimens?
they could all be harboring infectious agents
What are the 3 steps for bacteria to become established?
1. portal of entry (exogenous/endogenous)
2. attaching to host
3. Surviving host defenses (escaping phagocytosis)
Types of appendages used for attachment
LPS; M protein used by group A strep; pili; fimbriae; flagella; E. coli utilize pili, R pilus for attachment to viruses, I pilus used for general attachment, F pilus used for DNA transfer, P pilus used for attachment to renal epithelial cells
What are the two ways that antimicrobials can affect nucleic acid synthesis?
1. ribosome function - bind and stop translation
2. DNA and RNA function - bind irreversibly to DNA preventing transcription and translation (mutagenic agents)
1. What is the avg. generation time under optimal conditions?
2. What is the shortest time of generation?
3. ex of bacterial generation w/ times
1. 30 - 60 mins
2. 10 - 12 mins
3. Mycobacterium leprae - time of 10-13 days; Salmonella enteriditis - time of 20-30 mins
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