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PA Microbiology 1

Bacterial morphology, growth genetics, human flora, pathogenesis, antibiotics

QuestionAnswer
What are the 3 types of phenotypic classification? 1. Biotyping 2. Serotyping 3. Susceptibility
Biotyping does identifies WHAT by WHAT METHOD? Biotyping identifies SPECIFIC BACTERIA by identifying BIOCHEMICAL MARKERS
What is the special feature and identification method of Serotyping? Special Feature: Rapid identification Identification Method: Detects unique surface antigens
What technique/test is used to determine bacterial susceptibility? Kirby Bauer Test
What is the basis of the Kirby Bauer Test? diameter/ measure zone of inhibition
What is an antibiogram? A report of antibiotic susceptibilities of various bacteria
Which bacterial classification method is the most precise? Genotyping
What laboratory technique is utilized in genotyping? How does it work? PCR- amplifies genes/DNA for sequencing and matching to a specific bacterium
What are the 6 classes of bacterial shapes? 1. Coccus 2. Bacillus 3. Coccobacillus 4. Vibrio 5. Spirillum 6. Spirochete
What is the definition of a coccus-shaped bacteria? Round/Sphere
What is the definition of a bacillus-shaped bacteria? Rod
What is the definition of a coccobacillus-shaped bacteria? Short rod
What is the definition of a vibrio-shaped bacteria? Curved rod
What is the definition of a spirillum-shaped bacteria? Rigid, spiral-shaped rod
What is the definition of a spirochete-shaped bacteria? Flexible, thin, spiral-shaped rod
What is the difference between Spirillum and Spirochete shapes? Spirillum is a RIGID, spiral-shaped rod. Spirochete is a FLEXIBLE, THIN, spiral-shaped rod
Different bacterial structural arrangements are typically associated with what shape? Coccus
What are the 4 different morphological arrangements of bacteria? 1. Diplo 2. Strepto 3. Staphylo 4. Tetrad
What is the definition of a bacteria with a diplo arrangement? Pair (2)
What is the definition of a bacteria with a Strepto arrangement? Chain
What is the definition of a bacteria with a Staphylo arrangement? Grape-like cluster
What is the definition of a bacteria with a Tetrad arrangement? pack of 4 cells
What is a major difference between human cell membranes and most bacterial cell membranes? Lack of sterols/cholesterol in bacterial cell membranes
Which bacteria contain sterols/cholesterol in their cel membranes and are therefore similar to human cell membranes? Mycoplasma and Ureaplasma = Respiratory and Urogenital infections
What are the 6 functions of bacterial cell membranes? 1. Regulate transport 2. Synthesize cell wall components 3. Attachment site for chromosomes during cell division 4. Secrete proteins 5. Site of Cellular Respiration and ATP production 6. Anchors flagella
What is the main structural component of bacterial cell walls? Peptidoglycan
What is the structural components of Peptidoglycan backbone? Repeating NAG and NAM disaccharides
What is the linking of the disaccharides in the peptidoglycan backbone called? Transglycosylation
What is the cross-linking of the peptides in the peptidoglycan backbone called? Transpeptidation
Why is the cell wall an antimicrobial target? It is not present in humans... aka it is unique to bacteria
What is the primary stain in a gram stain? Crystal Violet (Purple/blue in color)
What is the Counterstain in a gram stain? Safranin (Pink/Red in color)
What color does a G+ bacteria stain, and what is the reason for this? Blue/Purple... thick peptidoglycan layer of cell wall retains the Crytal Violet stain
What color does a G- bacteria stain, and what is the reason for this? Pink/Red...thin peptidoglycan layer of cell wall does not retain Crystal Violet stain, but retains Safranin stain
The G- cell envelope contains which structures not found in G+ cell envelopes? Periplasmic space, and outer membrane
What notable structure is found in the outer membrane of G- cells? LPS... aka endotoxin
Name the 3 parts that make up the LPS/Endotoxin structure? 1. Lipid A 2. Core Polysaccharide 3. O Antigen
What role does Lipid A play in the function of LPS endotoxin? Lipid A is the virulence factor... elicits a toxic response from the immune system= it is the endotoxin
What is the function of the core polysaccharide in the LPS/Endotoxin of G- bacteria? Links Lipid A to the O Antigen
What is the function of the O Antigen, a component of the LPS/Endotoxin of G- bacteria? It is composed of carbohydrates; it's structure is species and strain specific, which makes it useful in identifying bacterial strains (Serotyping)
What causes the onset of Systemic Inflammatory Response Syndrome (SIRS)? Release of cytokines due to the release of LPS/Endotoxin
What are the 4 clinical manifestations of Systemic Inflammatory Response Syndrome (SIRS)? 2 or more of: 1. Temperature >38*C or <36*C 2. Tachycardia >100 bpm 3. Tachypnea >20 breaths/min 4. Leukocytosis >12,000/mm^3 or Leukopenia <4,000/mm^3
Why is it important not to kill G- bacteria too quickly? Cell lysis causes release of Lipid A/Endotoxin. Lots of Lipid A may induce SIRS, which can lead to Septic Shock or Multiple Organ Dysfunction Syndroms (MODS)
What is the location and function of porins in G- cell envelopes? Porins are 3-part proteins found in the OUTER MEMBRANE that control diffusion of small metabolites (sugars, amino acids, ions)
What Cell Envelope component(s) is/are unique to G+ bacteria? Teichoic/Lipoteichoic acids in the peptidoglycan/Cell Wall
What is the function/purpose of teichoic acid in the G+ cell wall? Allows bacteria to adhere/attach to other cells
What is the function/purpose of lipoteichoic acid in the G+ cell wall? They are anchored to the cell membrane
What action of G+ bacteria causes a release of inflammatory cytokines in humans? Shedding of the cell wall containing teichoic/lipoteichoic acids = virulence factors
Which antibiotics target the bacterial cell wall to inhibit peptidoglycan synthesis/transpeptidation? Beta lactams (Penicillin, cephalosporins) and Vancomycin
What is the target of antibiotics such as Beta lactams (Penicillin and cephalosporins) and Vancomycin? Peptidoglycan synthesis/transpeptidation
What are 4 antibiotics/classes of antibiotics that target the cell wall? 1. Beta lactams (Penicillin, cephalosporins) 2. Vancomycin 3. Bacitracin 4. Cycloserine
What effect does a lysozyme have on bacteria? Lysozymes are lytic enzymes that degrade the glycan backbone/peptidoglycan of bacterial cell wall
Lysozymes function under which class of immune system: Innate or Adaptive? Innate
Where are lysozomes found in humans? Tears, saliva, mucus, WBC lysosomes
What Cell Envelope structural feature is unique to Acid-Fast bacteria? Mycolic Acid layer (outermost layer)
What is the purpose/function of the mycolic acid layer in Acid-Fast bacteria? Mycolic Acid creates a waxy coat, enabling the bacterial cell to resist desiccation, some antibiotics, and phagocytosis
What is the Ziehl-Neelsen or Kinyoun Stain used to identify? Acid-Fast Bacteria
What color do Acid-Fast bacteria stain in Ziehl-Neelsen or Kinyoun Stains? Red... retains primary stain of Carbol fuchsin
What color do non-acid fast bacteria stain in Ziehl-Neelsen or Kinyoun Stains? Blue...cell retains methylene blue counterstain
Where is the glycocalyx of bacteria located? Outside the cell wall
In which bacterial classifications is the glycocalyx found? G+ and G-
What important structure does the Glycocalyx contain? K antigen (*serotyping) *E. coli K12
What are 4 important functions of the glycocalyx? 1. Protect against desiccation 2. Acts as a barrier to toxic hydrophobic molecules (antibiotics) 3. Inhibits phagocytosis 4. Promotes adherence to other cells (bacterial/host, etc.)
What bacterial structural component is responsible for biofilm formation? Glycocalyx- Slime layer
What are the 2 forms of glycocalyx? 1. Slime layer 2. Capsule
What are the differentiating characteristics between the slime later glycocalyx and capsule glycocalyx? Slime layers are loose, non-uniform, and diffuse **Partake in biofilm formation Capsules are rigid, uniform, and closely surround cell
What are the 3 common locations of biofilm formation? 1. Catheters 2. Teeth 3. Mucous membranes of GI Tract
What is the Quellung test used for? To identify a capsule glycocalyx
?Which 4 bacteria are known to have a capsule glycocalyx? 1. Streptococcus 2. Haemophilus 3. Klebsiella 4. Neisseria
What is the source of the H antigen? Flagella. Used in serotyping
What are the 2 different arrangements of flagella? 1. Polar 2. Peritrichous
What is the meaning of peritrichous? Flagella is positioned laterally/over entire cell surface
What is the function of fimbria(e)? To adhere to other bacteria/host cells
What is the arrangement of fimbriae on a bacterial cell? Peritrichous
What is the function of a Pilus (pili)? Attach and bring other bacterial cells close for DNA transfer
What 3 types of Pili are there? 1. Sex pilus 2. F pilus 3. Conjugation pilus
What is the unique ribosomal structure of bacteria? 70S ribosomes *30S and 50S subunits (odd digits)
What is the ribosomal structure of eukaryotes? 80S ribosomes *40S and 60S subunits (even digits)
Which 2 antibiotics classes target the 70S ribosomes of bacteria? 1. Aminoglycosides (streptomycin) 2. Macrolides (erythromycin)
What is a unique feature of bacterial nuclear/DNA-containing region? There is no nuclear membrane
What 2 benefits does lack of a nuclear membrane offer bacteria? 1. Faster protein synthesis (Transcription and translation are coupled) 2. Coupled T&T plus polysomes allow quick enzyme/structural protein responses to changing environments
What are the benefits to bacteria of producing endospores? They are in a dormant, protective stage that is resistant to harsh environments (heat, disinfectants, acids, etc.)
?What are 3 G+ bacterial genera that produce endospores? Bacillus (G-?) and Clostridium
What are the 4 phases of bacterial growth? 1. Lag phase = metabolically active but not dividing 2. Log/Exponential phase = Rapid division at a constant rate 3. Stationary phase = rate of cells dividing equals rate of cells dying 4. Decline/Death phase = Cells die at a log rate
What is a clinical application of acute bacterial infections? They have a short doubling time... they require only short-term treatment
What is a clinical application of chronic bacterial infections? They have a long doubling time... they require long-term treatment
What are the 3 classes of bacteria whose growth is affected by pH? 1. Acidophiles: pH <5.4 2. Neutralophiles: pH b/w 5.4-8.5* 3. Alkaliphiles: pH >8.5
What pH class is the greatest threat to humans? Neutralophiles
What are the 3 classes of bacteria whose growth is affected by temperature? 1. Psychrophiles: 15-20*C 2. Mesophiles: 25-40*C 3. Thermophiles: 50-60*C
What temperature class of bacteria is the greatest threat to humans? Mesophiles
What is the definition of obligate? obligated/requires; Physically and biochemically limited to one specific habitat
What is the definition of facultative? able to adapt to specific environmental conditions and can survive under a range of conditions; physically and biochemically able to adapt to more than onehabitat
Bacteria are divided into which 5 groups according to their oxygen requirements? 1. Obligate Aerobes 2. Obligate Anaerobes 3. Facultative Anaerobes 4. Microaerophiles 5. Aerotolerant Anaerobes
What is the oxygen requirement of obligate aerobes? MUST have O2 present. *Mycobacterium tuberculosis
What is the oxygen requirement of obligate anaerobes? O2 must NOT be present. *Clostridium botulinum
What is the oxygen requirement of facultative anaerobes? They can grow with or without O2. They prefer O2 = aerobic metabolism, but can use fermentation without O2. *E. coli
What are the 2 products of bacterial fermentation? 1. Lactic Acid 2. H2 gas
What product of bacterial fermentation is responsible for dental caries? Lactic Acid
What product of bacterial fermentation is responsible for gangrene? H2 gas
Lactic acid production from bacterial fermentation can cause what health problem in humans? Dental caries
H2 gas production from bacterial fermentation can cause what health problem in humans? Gangrene
What is the oxygen requirement of microaerophiles? Require small amounts of O2 *Treponema pallidum
What is the oxygen requirement of aerotolerant anaerobes? Survive in the presence of O2 but do not utilize O2 *Lactobacillus acidophilus
What is the importance of Superoxidase dismutase (SOD)in certain bacteria? It converts superoxide O2 to H2O2 = antioxidant = neutralizes O2 radicals
What is the importance of Peroxidase or Catalase in certain bacteria? They decompose H2O2
What enzymes do obligate anaerobes lack that make their exposure to oxygen lethal? Superoxidase dismutase (SOD), Catalase, and Peroxidase
What environment are halophiles adapted to survive in? High salt. *Vibrio cholerae *S. aureus
What is the difference between Fastidious and Nonfastidious nutritional requirements in bacteria? Nonfastidious bacteria can grow in standard lab media Fastidious bacteria require specific nutrients for survival
Clostridium- growth requirements C. botulinum = obligate anaerobe
Bacillus
E. coli- gram class, defining structural features, growth requirements G-, Have H and O antigens (=flagella and LPS/Endotoxin/identifiable by serotyping), facultative anaerobe
S. aureus- gram class, growth requirements G+, Facultative Halophile, Coagulase +
S. pyogenes- infection, defining structural feature Cause acute infection = short treatment, streptococcus have capsule glycocalyx, Beta hemolysis
Antibiotic resistance is transferrable between bacteria via what structure? Plasmid
What are the 3 processes bacteria use for genetic exchange? 1. Transformation 2. Conjugation 3. Transduction
What does the process of transformation entail? Naked DNA released from a lysed cell is uptaken by a COMPETENT bacteria.
What does the process of conjugation entail? Sex pilus brings two bacterial cells into contact, where DNA is exchanged b/w cells *plasmids or chromosome segments
What are the 3 ratings used to describe effects of acquiring new genes in bacteria? 1. Positive = gene is beneficial 2. Negative = inserted gene causes inactivation 3. Null = no change in gene
What does the process of transduction entail? Injection of DNA into a bacterium by a bacteriophage/virus
What are the 2 types of transduction? 1. Generalized 2. Specialized
What is the process of Generalized Transduction? A virulent phage (intent to kill) infects a bacterial cell, replicates, &bacterial DNA (fragments) is packaged into a newly-formed viral capsid rather than viral DNA=defective phage. The lytic cycle is induced from start & utilized to release new phages.
What is the process of Specialized Transduction? A temperate phage (stays dormant in cell until lytic cycle induced) infects a host bacterial cell, inserts viral DNA into chromosome = prophage. When lytic cycle is induced, bacterial DNA near viral DNA is packaged into a capsid.
What are the 4 parameters that regulate the type of bacteria in a flora population? 1. Physiology 2. Age 3. Geographic habitat/location 4. Diet
What are 4 benefits provided by normal bacterial flora? 1. Induce cross-reacting antibodies to stimulate an immune response in pathogenic bacteria 2. Produce K and B vitamins 3. Compete with pathogens for nutrients 4. Produce substances that inhibit/kill pathogens
Describe the concept of tissue tropism. The physiological/environmental factors specific to certain tissues/areas of the body select for/against specific flora/bacteria
What are two factors that facilitate the concept of tissue tropism? 1. Growth factors availability varies depending on habitat/tissue type 2. Receptor sites for microbe attachment vary depending on habitat/tissue type
What 2 conditions may cause normal flora to cause disease? 1. Displacement Ex:Endocarditis when oral bacteria enter bloodstream, or UTI when intestinal bacteria enter urinary tract 2. Prolonged antibiotic use causing species overgrowth. Ex: C. albicans = yeast; C. difficile
What is the function of coagulase? Converts fibrinogen to fibrin. Forms clots that prevents WBC access/phagocytosis
What genus is the coagulase test used to differentiate? Staph
Which species tests positive for coagulase? Staph aureus
What is the function of hemolysin? Lyses RBC membranes. *Hemolysis test uses blood agar
What genus is the hemolysis test used to differentiate? Streptococci
Complete/Beta hemolysis is produced by what bacteria, and what results are seen? Strep pyogenes, and Strep agalactiae produce a white colony with a clear halo.
Partial/Alpha hemolysis is produced by what bacteria, and what results are seen? Strep mutans produce a gray/green colony with a partial halo.
What 2 structures in the skin are responsible for inhibiting most bacterial and fungi growth? Sebaceous glands = fatty acids, Sweat glands = salt
What are 3 bacterial genus/species that are resident flora of dry skin, and what is their gram-type? Gram Positive 1. Staph epidermidis 2. Proprionibacterium acne 3. Corynebacterium spp.
What are the oxygen requirements, coagulase activity, and salt tolerance of the dry skin resident Staphylococcus epidermidis? Gram positive Facultative anaerobe Coagulase negative Halophile
A Mannitol salt agar turns from red to yellow with the growth of a bacteria. What might the identity of the bacteria be? Staphylococcus epidermidis... Staph.
In addition to Staph epidermidis, Propionibacterium acnes, and Diphtheroids found as resident flora on dry skin, what 2 other bacteria reside on moist skin, and what is their gram type? Gram negative 1. E. coli 2. Acinetobacter sp.
What transient skin resident is commonly found in the nose? Staph aureus
What transient skin resident is commonly found around the perineum and thighs of diabetics, and is also associated with gas gangrene? Clostridium perfringens
What is the predominant resident 2 bacteria found in the mouth, and what is their gram type? Gram positive 1. Viridans Streptococci 2. Strep mutans
What bacterial species is responsible for formation of dental plaque and caries? Strep mutans
What 5 bacteria are commonly found in the eye/conjunctiva, and what are their gram types? Gram Positive: 1. Staph epidermidis 2. Staph aureus *rare 3. Streptococcus pneumoniae Gram Negative: 4. Neisseria spp. 5. Moraxella catarrhalis
What 2 types of bacteria are comon in the naso- and oropharynx of the upper respiratory tract, and what is their gram type? Gram positive 1. viridans streptococci 2. Strep. pneomoniae
What 6 G- bacteria are common in the upper respiratory tract, and what are their shapes? Diplococci 1. Moraxella catarrhalis 2. Neisseria meningitidis Bacilli 3. E. coli 4. Klebsiella sp. 5. Proteus sp. Pleomorph 6. Maemophilus influenzae
Which structures in the body should be relatively sterile when healthy? Sinuses, lower respiratory tract, synovial fluid, bladder urine, spinal fluid, bone, muscle, blood, connective tissue, kidneys, bladder
What two components of the GI tract help to control bacterial populations? Acidic pH, and bile
What are the two bacterial species common in the stomach, and what are their gram types? Gram positive 1. Lactobacillus sp. Gram negative 2. Helicobacter pylori
What 2 bacterial species are common in the duodenum and jejunum and what is their gram type? Gram Positive 1. Lactobacillus sp. 2. Enterococcus faecalis
What 2 bacterial species are common in the colon, and what are their gram types? ANAEROBES Gram positive: 1. Bifidobacterium sp. **breast fed infants Gram negative: 2. Bacteroides sp. **Meat-lovers
What is the predominant microbe in the vagina during child-bearing years, and what is its gram type? Gram Positive: Lactobacillus acidophilus
What vaginal-residing microbe can cause neonatal meningitis and should be screened for in pregnant women? Gram Positive Streptococcus agalactiae
What are the 4 points of Koch's Postulates? 1. Same bug found in diseased-of-interest ppl, but not in healthy ppl 2. Bug isolated and grown in culture 3. Isolated bug must cause original disease when inoculated in healthy person 4. Bug re-isolated from new victim
What are 2 potential problems with Koch's Postulates? 1. Not all microorganisms grow well in labs/mediums 2. The disease may be a result of bacterial co-infection
What is the difference between opportunistic and virulent pathogens? Opportunistic pathogens can be a part of normal flora, & do not produce disease in their normal habitat. Also if the patient's defenses are down: trauma, defective immune system, preexisting condition. Virulent pathogens are always associated with diseas
Name 6 examples of opportunistic pathogens and their gram type. 1. Staph aureus (G+) 2. E. Coli (G-) 3. Candida albicans (acid fast) 4. Clostridium difficile (G+) 5. Pseudomonas aeruginosa (G-) *burn victims/cystic fibrotic lungs 6. Nocardia asteroides (G+) *lungs in immuno-compromised ppl
Name 2 examples of virulent bacteria and their gram type. 1. Mycobacterium tuberculosis (acid fast) 2. Neisseria gonorrheae (G-)
What are 4 mechanisms by which bacteria cause disease? 1.Metabolic by-products destroy tissues 2. Invasins damage local tissues/cells to help pathogen grow/spread 3. Adhesins allow bacteria to attach to host cell/tissue receptors 4. Toxins
Streptococcus mutans uses which pathogenic mechanism to cause dental caries? Production of lactic acid as a metabolic byproduct
What are the 4 types of invasins used by pathogens to help their spread/growth? 1. Hyaluronidase destroys hyaluronic acid in connective tissue *flesh-eating 2. Collagenase breaks down collagen in muscles 3. Neuraminidase degrades neuraminic acid within cells 4. Streptokinase/Staphylokinase break down blood clots- fibrinolysins
What are the 3 targets for adhesins of pathogens to bind? 1. Glycoproteins/carbohydrates *biofilms 2. Fimbriae/pili 3. Afimbrial adhesins/proteins on cell envelope
What are the 3 types of toxins utilized by pathogenic bacteria? 1. Exotoxins are secreted into ECF and bind host cell receptors 2. Enterotoxins bind host cell receptors and are commonly associated with GI symptoms 3.Superantigens activate T cells in antigen absence and cause massive cytokine release
What are the 2 important components of exotoxins and their functions? 1. B subunit binds toxin to the host cell 2. A subunit attacks cell
Name 2 diseases caused by toxins. 1. Tetanus 2. Botulism
What is a toxoid? A denatured toxin that provokes an immune response; used in vaccines
What is a functional exotoxin? An active toxin that elicits an immune response and is deadly at very low concentrations
How does a membrane-active exotoxin function, and what are 3 examples? They attack the cell membrane of host cells. Ex: 1. Proteases 2. Lipases 3. Hemplysins *targets RBCs and phagocytes. *Strep pyogenes
What is an example of a condition caused by a superantigen? Toxic Shock Syndrome- Staph aureus
What is an example of an endotoxin? LPS in (G-)... Lipid A is the toxic component
Name 2 methods by which bacteria evade an immune response. 1. Encapsulation with poorly antigenic polysaccharide, deters phagocytosis 2. Intracellular growth to escape detection
What are the 5 stages of disease? 1. Incubation 2. Prodromal 3. Acute 4. Decline 5. Covalescent
Describe the signs and symptoms, immune system activity, pathogen, and whether the stage is contagious in the Incubation stage. Signs and Symptoms: None Immune Response: Not Activation Pathogen: dose must be infectious Contagious: No
Describe the signs and symptoms, immune system activity, pathogen, and whether the stage is contagious in the Prodromal stage. Signs and Symptoms: Early s&s begin, non-specific Immune Response: Innate immune system activated Pathogen: Numbers increased since incubation Contagious: yes
Describe the signs and symptoms, immune system activity, pathogen, and whether the stage is contagious in the Acute stage. Signs and Symptoms: Characteristic of disease Immune System: Acquired immune system is now activated, either pathogen or immune system is winning Pathogen: Stationary numbers +/- Contagious: Yes
Describe the signs and symptoms, immune system activity, pathogen, and whether the stage is contagious in the Decline stage. Signs and Symptoms: Dwindling Immune System: Reduced activity, antibodies have been formed Pathogen: cleared from host Contagious: only if host becomes a carrier
Describe the signs and symptoms, immune system activity, pathogen, and whether the stage is contagious in the Convalescent stage. Signs and Symptoms: None Immune System: Not active toward pathogen Pathogen: Cleared from host Contagious: No... no pathogen present
What is the difference between bactericidal and bacteriostatic antibiotics? Bactericidal antibiotics kill the target organisms. Bacteriostatic antibiotics inhibit growth of target organisms.
In what patient population should bacteriostatic drugs not be used? Immunocompromised
What is one major difference between eukaryotes and prokarytoes that allow for selective toxicity? Ribosomes : 70S in prokaryotes, 80S in eukaryotes
What structure is very similar between eukaryotes (humans/fungi) that make selective toxicity difficult? Cholesterol in human cell membranes, and ergosterol in fungal cell membranes have very similar structures.
What are 7 important properties in an effective antibiotic? 1. Soluble in bodily fluids 2. Selective toxicity 3. Toxicity not easily altered 4. Nonallergenic 5. Stable, degraded/excreted slowly 6. Resistance not easily acquired 7. Reasonable cost
What are the 5 classes of antibiotics, separated according to their target? 1. Cell wall synthesis inhibitors 2. Disrupt cell membrane function 3. Inhibit protein synthesis 4. Inhibit nucleic acid synthesis 5. Acts as an antimetabolite
What is the mechanism of action of cell wall inhibitors (antibiotics)? They interfere with peptidoglycan synthesis *G+ and G-. *Bactericidal
Which antibiotics function as cell wall inhibitors? Beta lactams Vancomycin Cycloserine Bacitracin
What compound is responsible for beta lactam resistance? Beta lactamase
What are 3 penicillin analogs given in combination to increase sprectrum activity? 1. Clavulanic acid (given with amoxicillin or ticarcillin) 2. Sulbactam (given with ampicillin) 3. Tazobactam (Piperacillin)
What is the relationship between gram activity and cephalosporin generation? Higher generations (1 to 4) have increasingly greater G- activity
Which Cephalosporin generations are able to cross the BBB? 4th and some 3rd = meningitis
Which cephalosporin generations have an increased resistance to beta lactamase? 3rd and 4th
What antibiotic functions by disrupting the cell membrane? Polymyxins
What is the mechanism of action of cell membrane disrupters/polymyxins? Act as a cationic detergent and disrupts lipid bilayers
Why are cell membrane disrupters/ polymyxins only used on localized, external infections? They are toxic to the host... not specific to bacteria
Which two classes of antibiotics target the 30S ribosome to inhibit protein synthesis? 1. Aminoglycosides 2. Tetracyclines
Are aminoclycosides bacteriostatic or bactericidal? Bactericidal
Are tetracyclines bacteriostatic or bactericidal? Bacteriostatic
What is a major contraindication of tetracycline? Children/Pregnant women... they chelate Ca = inhibit bone growth
What two classes of antibiotics target the 50S ribosome to inhibit protein synthesis? 1. Chloramphenicol *causes aplastic anemia 2. Macrolides (Erythromycin, Clarithromycin, Azithromycin)
What two classes of antibiotics functions by inhibiting nucleic acid synthesis? 1. Rifamycins (Rifampin) 2. Fluoroquinolones
What is the specific target of Rifampin? Inhibits transcription via inhibiting DNA-dependent RNA polymerase
What is the specific target of Fluoroquinolones? Inhibit DNA gyrase
What two classes of antibiotics function by inhibiting folic acid synthesis that is necessary for nucleic acids (aka antimetabolites)? 1. Sulfonamides 2. Trimethoprim
What is the reasoning behind Sulfonamide's mechanism of action as an antimetabolite? It is an analog of PABA, needed for folic acid synthesis
Are sulfonamides bacteriostatic or bactericidal? Bacteriostatic
What is the reasoning behind trimethoprim's mechanism of action as an antimetabolite? It is an analog of dihydrofolic acid, needed for folic acid synthesis
What are 2 genetic-based reasons for development of antibiotic resistance? 1. Random mutations in DNA allow resistance development = Chromosomal resistance 2. Acquisition of chromosomal/extrachromosomal DNA by transferring plasmids/genes (R factors)
What is the reference designated for plasmids carrying antibiotic resistance genes? R Factor
What are 4 specific mechanisms of antibiotic resistance used by bacteria? 1. Bacteria alter the drug targets (Ribosomes, etc.) = drug can't bind 2. Bacteria alter their membrane permeability or transport drug out of cell 3. Bacteria synthesize enzymes that inactivate antibiotic 4. Bacteria alter their metabolic pathway
What are 3 examples of antibiotics that are ineffective due to bacterial alteration of the drug target? 1. Erythromycin 2. Rifamycin 3. Streptomycin
What are 2 examples of antibiotics that are ineffective due to bacterial alteration of membrane permeability or increased drug transport? 1. Erythromycin 2. Tetracycline
What are 2 examples of bacterial structures utilized in the Membrane Permeability Alteration/Drug Transport mechanisms of antibiotic resistance? 1. Biofilm 2. Efflux pumps
What are 4 examples of antibiotics that are ineffective due to bacterial synthesis of enzymes to inactivate the antibiotic? 1. Beta lactams (by beta lactamases) 2. Chloramphenicol 3. Aminoglycosides 4. Tetracycline
What are 2 examples of antibiotics that are ineffective due to bacterial alteration of metabolic pathways? 1. Sulfonamides 2. Trimethoprim
What 3 bacterial species are resistant to all known antibiotics? 1. Enterococcus faecalis 2. Mycobacterium tuberculosis 3. Pseudomonas aeruginosa
What 5 secondary factors are contributing to the development of antibiotic resistance? 1. Antibiotic use in animals 2. Social factors (poverty, drug overuse, globalization = travel/trade) 3. Inappropriate antibiotic use by pt. 4. Disrupt normal flora 5. Lack of hygiene (hand washing, etc.)
What are the 2 fundamental characteristics of viruses? 1. They are Obligate Intracellular Parasites 2. They are small
What is the difference between lytic viruses and non-lytic viruses? Lytic viruses aim to replicate rapidly at the expense of the host cell while non-lytic viruses remain dormant in the host cell (= prophage), causing no harm to the host until environmental conditions induce lytic stage.
What are the 3 main types of infections? 1. Latent 2. Chronic 3. Transforming
Describe the process of a latent viral infection. Times of acute virus production, mixed with an almost total absence of viral particles.
What is an example of a virus that exhibits latent infection? Herpes Simplex Virus
Describe the process of a chronic viral infection. Non-lytic virus production; high number of viral particles is continually present
What is an example of a virus that exhibits chronic infection? Hepatitis B
Describe the process of a transforming viral infection. Host cells are transformed to suit the needs of virus. "Immortalized".
What is an example of a virus that exhibits a transforming infection? Human Papilloma Virus
What are 8 common symptoms associated with gastroenteritis? Nausea, WATERY diarrhea, vomiting, cramps, malaise, anorexia, myalgia, and headache
What is the main feature of gastroenteritis? Acute, watery diarrhea
What are 6 high-risk populations for gastroenteritis? Hospital wards, daycare centers, nursing homes, immunosuppressed individuals, travelers, military
What are the 2 diagnostic tests for gastroenteritis pathogens? Enzyme immunoassay to detect antigens. *Rotavirus Latex agglutination screen
What is the treatment for gastroenteritis? Replenish water, electrolytes, and sugar.
What is the source/epidemiology of Noroviruses? Raw shellfish, fecally contaminated food = outbreaks
What is a preventative method used against Rotaviruses? Vaccine- Rotateq, Rotarix
Is there a vaccine against Noroviruses? No
What 2 viruses are a common cause of endemic severe diarrhea in infants? Rotavirus, Adenovirus
What is interesting about the timing of Rotavirus outbreaks? Pattern is predictable; outbreaks are common in winter
What formerly used Rotavirus vaccine was withdrawn from the US due to increased risk of intestinal intussusception? Rotashield
What is the length of symptoms seen with Rotavirus infection? 5-7 days
What is the length of symptoms seen with Adenovirus? 5-12 days
What are a few potentially distinguishing features between Rotavirus and Adenovirus? Adenovirus has no obvious seasonality, has an extended symptomatic phase, and is detectable by immunoassay.
What diarrhea/vomit-causing virus group is commonly associated with older children and adults? Caliciviruses/Noroviruses
What is the innoculation method of Noroviruses? Associated with food/shellfish
What is the length and severity of symptoms seen with Norovirus? Mild, self-limited, 24-48 hours
How is Norovirus spread during outbreaks? Person-to-person
What is the main feature/sign of cholera infection? Acute, massive, watery diarrhea. "Rice water" stools
"Rice water" stools is a description of diarrhea commonly associated with what bacterial infection? Vibrio cholerae
What are the most worrisome side effects associated with cholera infection? Rapidly deplete fluids and electrolytes Hypovolemic shock/metabolic acidosis/death
Watery diarrhea, muscle cramps, poor skin turgor, wrinkly skin on fingers, sunken eyes, missing pulse in extremities are all symptoms commonly associated with what pathogen? Vibrio cholerae
What is the gram type, shape, oxygen requirements, and mechanism of travel of Vibrio cholerae? G-, bent rod shape, non-spore forming, facultative anaerobe, motile via polar flagellum
Which Cholerae serogroup (O antigen) is the cause of classic epidemic cholera? O-1
What is a newer Cholerae serogroup (O-antigen) that can cause cholera even after O-1 exposure? O-139
What is the treatment for cholera? Replace fluids and electrolytes
What is the common method for spreading cholera infection? Contaminated drinking water and food
What is the primary mechanism for cholera prevention? Sewage control
What Vibrio species is a common cause of seasonal, food-borne illness in Japan? Vibrio parahaemolyticus
What Vibrio species is commonly associated with oysters (via ingestion or wound contact) Vibrio vulnificus
An alcoholic (patient debilitation) presents with bullous skin lesions, shock, and history of oyster consumption suspect of what causative organism? Vibrio vulnificus sepsis
Describe the disease process of Enterotoxigenic E. Coli. (ETEC) Adhere to mucosa of small intestine and release toxin (O antigen/LPS) = induce diarrhea
Traveler's diarrhea is commonly associated with what organism? Enterotoxigenic E. Coli (ETEC) T is for Travel
Which E. coli organism is associated with bloody diarrhea? Enterohemorrhagic E. coli (EHEC)
Hemolytic Uremic Syndrome is a potentially fatal result of infection by what organism? Enterohemorrhagic E. coli (EHEC)
Which EHEC serotype cannot ferment sorbitol, and hence grows as while colonies on MacConkey's agar? O157:H7
What is the key virulence factor (toxin) of EHEC? Shiga-like toxin
What infectious organism is associated with beef and raw milk? EHEC O157:H7
What newly recognized strain of Enteroaggregative E. coli expresses Shiga toxin and is associated with alfalfa sprouts? O104:H4
What is the gram type, shape, motility allowance, oxygen requirements, and growth temperature of Campylobacter jejuni? G-, curved rod, motile, microaerophile, 42*C
A patient presents with a prodrome of fever, headache, malaise, and myalgia 12 hours before diarrhea ad RLQ abdominal pain. What is the suspected pathogen? Campylobacter jejuni
What is the common reservoir of Campylobacter jejuni? Intentinal tract of birds/poultry
What pathogen is known for transmission via undercooked chicken/poultry? Campylobacter jejuni
Guillain-Barre is a complication commonly due to what pathogen? Campylobacter jejuni
What is the treatment for Campylobacter jejuni infection? None- it is self limiting
Chronic gastritis and peptic ulceration are consequences of infection by what organism? Helicobacter pylori
What is the gram type, shape, and motility allowance of H. pylori? G-, curved rod, highly motile
What organism stains well with Giemsa? H. pylori
What human structure is the target of H. pylori Epithelial cells
Cramps, halitosis, nausea, and vomiting are signs/symptoms of what infectious organism? H. pylori
What is the virulence factor of H. pylori? Urease
What are 3 diagnostic tests for H. pylori? 1. Biopsy sample 2. Culture 3. CLO test to detect urease activity
What treatment is offered to treat H. pylori? Tetracycline/antibiotics plus bismuth-containing drugs (Pepto-Bismol)
What are 3 preventative methods of GI infection? 1. Control fecal excretion 2. Proper food handling/washing 3. Educate travelers on boiling/peeling/cooking water/food.
Initial symptoms of fever cramps, vomiting, and water diarrhea, followed by progression to dysentery: blood/mucous in stools, fever, and cramps is indicative of what pathogen? Shigella
What is the gram type, oxygen requirements, motility of Shigella? G-, facultative anaerobe, non-motile
What biotype result distinguishes Shigella from other E. coli? Shigella is non-lactose fermenting
Bloody stool should cause suspect of which 2 organisms? 1. EHEC 2. Shigella
What is the most effective treatment for Shigella? Fluid replacement
What are 2 potential complications of Shigella? 1. Reiter's syndrome 2. Hemolytic Uremic Syndrome (HUS)
Which two species of E. coli should antibiotics be contraindicated in, and why? O157:H7 and Shigella. Both produce Shiga toxin, which is potentially deadly and may cause dysentery
Which two Shigella species are most common in the U.S.? S. flexneri and S. sonnei
Describe the severity among Shigella serotypes A-D. Group A (S. dysenteriae) is the most sever, group D (S. sonnei) is the least severe
What is the gram type, oxygen requirements, and motility in Salmonella? G-, facultative anaerobe, motile
What diagnostic methods are used to identify Salmonella? Presence of fecal leukocytes under microscope Culture feces/blood/water/food DOES NOT FERMENT LACTOSE
Which two bacterial species are known not to ferment lactose? Shigella and Salmonella
What is the treatment for Salmonella infection? Supportive- fluid and electrolyte maintenance
What are the primary reservoirs of Salmonella? Animals: Eggs, beef, cattle, pigs/pork, dogs, cats, pet reptiles
What is a major difference between Salmonella and Shigella (Hint: dose) Salmonella is a high dose microbe
What is an explanation for increasing Salmonella infection? Animal handling: feeding slaughterhouse remains to chickens... infection spreads to eggs. Must change this process/consumer preferences
What is the causative organism of Pseudomembranous colitis? Clostridium difficile
What is a reason for increasing cases of C. difficile infection? Antibiotic use
What is the gram type, shape, oxygen requirements of C. difficile? G+, rod-shaped, anaerobic **Forms spores
What are the diagnostic techniques used for Pseudomembranous colitis by C. difficile? EIA and latex agglutination to detect toxin in feces Gram stain of stool Culture
What is the treatment for pseudomembranous colitis by C. difficile? Fluid and electrolyte replacement, stop original antibiotic and start new one
What are preventative methods for C. difficile? Wash hands, keep bathrooms clean, quickly identify and treat pts.
What is the gram type, motility, and dose and oxygen requirements of Clostridium perfringens? G+, non-motile, high dose organism, aerotolerant anaerobe, ***Forms spores
What is the suspected causative organism that causes moderate-severe diarrhea with complete recovery in one day - FAST course of disease? Clostridium perfringens
What is the method of transmission of C. perfringens, and why is it so worrisome? Contaminated meat and poultry; Cooking meat does not destroy spores
What is the treatment for C. perfringens? Supportive
What is the gram type, shape, oxygen requirements, motility, and spore status of Bacillus cereus? G+, rod-shaped, aerobic, motile, **FORMS spores
What are the two possible clinical manifestations associated with B. cereus? 1. Emetic form: preformed toxin causes upper GI symptoms: cramping, vomiting, diarrhea 2. Diarrheal form: vegetative cells ingested, will produce toxin: ab. pain, profuse watery diarrhea
What source is a common finding of B. cereus spores? Rice. Also grains and vegetables
What is the treatment for B. cereus infection? Relieve symptoms
What is a preventative method for B. cereus transmission? Refrigerate grains quickly after cooking
What organism causes disease by consumption of heat stable, preformed toxins in food? Staphylococcus
What is the suspected causative organism in a person with nausea, vomiting, diarrhea, cramps, and acute salivation 1-6 hours after eating? Staphylococcus
What is the virulence factor of Staph? Enterotixin A... water soluble, heat stable
A person who ate custard-filled baked goods, canned goods, processed meats, or potato salad is at risk for infection by what organism? Staphylococcus
What is the treatment for GI infection of Staph? Symptomatic- Fast course of disease
What are the three bacterial species that cause foodborne disease via toxin production? Staphylococcus, B. cereus, C. perfringens = ANTIBIOTICS NOT USEFUL
Created by: mccullough87