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165 Cards in this Set

  • Front
  • Back
What is sterilization
process that eliminates all viable microorganisms, including viruses
What is disinfection
physical or chemical process used to destroy vegetative pathogens but NOT endospores
What is the difference between disinfectant and antiseptic
Disinfectant is on inanimate objects and antiseptic is on antimate
prevents growth of bacteria
destroys bacteria
What are the modes of action for sterilization and disinfection?
denature proteins, dessication, alkylation, oxidation, solubilization and disruption of nucleic acids
What factors affect microbial control/death?
nature of the micoorganism and the number at the start and the concentration of the antimicrobial agent
What is a safe initial concentration to give and how often does it need to be re-administered
how quickly is it excreted from the body?
half life
Is it absorbed into all tissues?
What are the modes of action for antimicrobials?
inhibition of cell wall synthesis, disruption of plasma membrane, inhibition of protein synthesis and nucleic acids, anti-metabolites
Methods of antibiotic resistance used by bacteria
target tissue alteration through mutations, active efflux of the drug, inactivation or degradation of the agent, decreased uptake or production of decoy molecules
Where are most resistant genes encoded?
on plasmids or transposons so they can jump around and into the pathogen
Selective Toxicity
ability to kill pathogen instead of or before killing the host
Broad spectrum of activity vs. narrow spectrum
ability to kill many different types of microbes vs. only killing a few types
Minimum Inhibitory Concentration
lowest concentration of a drug that prevents growth
Therapeutic Index
ratio of drugs toxic does to its minimum therapeutic dose; is organism resistant or sensitive to drug
Antibiotic Synergism
A+B= increased killing
Antibiotic Antagonism
C+D= D is less effective when C is added
Each drug alone has an effect and two added together have the same effect as each one alone
What is the function of Beta-Lactams and what class is it in; Penicillins and Cephalosporins
bind to and block action of PBPs; inhibitor of cell wall synthesis
Glycopeptides; Vancomycin
bind to and block tetrapeptide linkage; inhibitor of cell wall synthesis
interferes with recylcing of transport molecules; also interefers with cytoplasmic membrane integrity; inhibitor of cell wall synthesis
blocks synthesis of mycolic acid; acid fast cell walls
blocks synthesis of arabinogalactan; acid fast
Cell wall inhibitors must
bind/associate bacteria, penetrate through the outer membrane and periplasmic space in gram-, interact with PBPs, activate/upregulate an autolysin that degrades the cell wall murein
How does the bacteria provide resistance to cell wall synthesis inhibitors
production of enzymes that break down the drug- beta lactamases; alteration of the target
Aminoglycosides; streptomycin and kanamycin
intereferes with binding of f-met tRNA; bactericidal and inhibitor of protein synthesis
inhibits tRNA entry into acceptor sites; bacteriastatic and inhibitor of protein synthesis
Macrolides; Erthyromycin and Azithromycin
blocks translocation; inhibitor of protein synthesis
bidn to 50s subunit to block assembly of ribosome; inhibitor of protein synthesis
Protein synthesis inhibitors must:
penetrate teh outer membranes of gram-, associate and be transported via an active transport system in the cell membrane, bind to ribosomal subunits or translation factors and block function
How does bacteria provide resistance to protein synthesis inhibitors?
mutation of the ribosomal binding site, enzymatic modification of the antibiotic, decreased uptake, active efflux, production of proteins that act as a decoy and protect the 30s ribosome
Quinolones; Ciprofloxacin
inhibits DNA gyrase in gram+ and topoisomerase IV in gram-; bacteriacidal and inhibitor of nucleic acid synthesis
Rifampin and rifamycin
inhibits DNA dependent RNA polymerases
Binds DNA; effective against anaerobic organisms and parasites; inhibitor of nucleic acid synthesis
For Nucleic Acid Synthesis inhibitors to be effective:
penetrate the outer membrane of gram-, associate and be transported into cell membrane and bind to nucleic acid or the enzymes or transcription factors and block their function
How does bacteria provide resistance to nucleic acid synthesis inhibitors
changes in DNA gyrase subunit structure to lower affinity of the drug and changes in the cell wall permeability leading to decreased uptake
compete with PABA as a substrate for folic acid synthesis; anti-metabolite
inhibits dihydrofolate reductase; anti-metabolite
How is resistance to anti-metabolites generated?
permeability barriers, alteration in target enzyme, exogenous source of folic acid and intrinsic resistance in organisms which use exogenous thymidine
inserts increasing cell permeability; inhibitors of cytoplasmic membrane function
inserts to trigger rapid depolarization; inhibitor of cytoplasmic membrane function
How is resistance to Cytoplasmic membrane function inhibitors produced in bacteria?
mutation of the binding site, enzymatic modification, decreased transport
Why are there less antiviral agents?
selective toxicity is mandatory, advanced before detected and rapid mutation
What are some targets for antivirals?
attachment/pentration, uncoating, nucleic acid synthesis, protein synthesis, assembly and release
What are the mechanisms for resistance to antivirals?
mutation of the binding site, enzymatic modification, decreased uptake
Where is ergosterol found?
cell membrane in fungi
inserts in fungal membrane next to ergosterol and causes pore formation; antifungal
target cytochrome P450; antifungal
inhibits synthesis of glucan components; antifungal
Base analogs
ingibit RNA function and/or DNA synthesis; antifungal
What are the mechanisms for resistance to antifungals?
decreased permeability, active efflux and decreased production of the target enzyme
What is an example of an antiviral agent that targets attachment?
Antiviral agent that targets uncoating?
Amantadine and Rimantatine
Antiviral agent that targets base analogs?
Antiviral that targets nucleotide biosythesis?
Antiviral that targets DNA polymerase?
Acycloivr and Ganciclovir
Antiviral that targets reverse transcriptase?
Antiviral that attacks protein synthesis?
Antiviral that attacks assembly?
Antiviral that attacks release by inhibiting neuraminidase or hemagglutinin
What are some limitations to antiparsitic drugs?
low selective toxicity, cuticles limit effectiveness, complex life cycles
What are the targets for antiparasitic drugs?
folic acid biosynthesis, DNA replication, protein synthesis inhibition, interference with neuromediators and interaction with transport
What is Chloroquine?
animoquinoline analog that interferes with DNA replication
What is Pentamidine?
prevents synthesis by binding to DNA
What is an example of a nitroimidazole?
metronidazole that inhibits synthesis of DNA
What is an example of a drug that inhibits folic acid biosynthesis?
What is an antiparasitic drug that inhibits protein syntheis?
What is an example of a antiparasitic drug that is involved in transport disruption?
Benzimidazole; Mebendazole: inhibit glucose transport fumurate reductase, disrupts microtubules
What is an example of a Tetrahydropyrimidine?
pyrantel pamoate; blocks neuromuscular action
Example of Piperazines
Piperazine; GABA antagonists
Example of Avermectins?
Ivermectin; block neuromuscular action
Example of Pyrazinoisoquinoline?
Praziquantel; calcium agonist; tegumental disruption
What are the methods of resistance to antiparasitic agents?
efflux mechanisms, mutations in targets, alternative pathways and life cycle alteration
How does the mucociliary lining in the nasal cavity provide a defense mechanism?
hair filters large particles and mucus collects those particles not filtered by hair
What are lymphoid organs in the upper respiratory tract in the back of the throat?
adenoids and tonsils
How does the ciliary elevator work?
it is a layer of mucus and ciliated cells covering the lower portion of the lower respiratory tract; pathogens trapped in the mucus layer are driven upwards by cilia
What are some evasive techniques by the pathogens in the respiratory tract?
must avoid being caught in the mucus layer and if in the lower tract must avoid phagocytosis
Why is the respiratory tract a common site for infection?
exposed to many potential pathogens via smoke, soot and dust
What are some mechanisms used by pathogens to initiate disease in the respiratory tract?
adherence factors, extracellular toxins, intracelluar growth in host tissue and evasion of host defense mechanisms
What causes the majority of respiratory infections?
What is significant about bacterial infections?
more severe but treatable
Examples of pathogens causing pharyngitis?
adenovirus, HSV, coxsackieviruses, EBV, strep pyogenes, corynebacterium diphtheriae, neisseria gonorrheae
examples of pathogens that cause the common cold
rhinoviruses, coronaviruses, adenoviruses, myxoviruses, echoviruses, coxsackie viruses, mycoplasma pneumoniae, chlamydophila pneumoniae
pathogens that cause sinusitis?
strep pneumoniae, haemophilus influenzae, moraxella catarrhalis
pathogens causing otitis media?
strep pneumoniae, haemophilus inifluenzae, moraxella catarrhalis, respiratory syncytial virus, rhinovirus
pathogen causing epiglottitis
haemophilus influenzae
pathogen causing diphtheria
corynebacterium diphtheriae
pathogen causing whooping cough
bordetella pertussis
pathogens causing croup
parainfluenza viruses and respiratory syncytial virus
What bacteria are part of the normal oral, nose and throat flora?
streptococci, staphylococci, lactobacilli, bacteroides, corynebacteria, actinomyces, mycoplasmas, fungi, yeast, viruses
Signs and symptoms of pharyngitis
sore throat, pain when swallowing, fever, enlarged lymph nodes in neck, runny nose and postnasal drip, headache
what is the most common bacterial throat infection?
group A beta-hemolytic streptococcus (pyogenes)
What are some complications of strep throat?
scarlet fever and bactermia and streptococcal toxic shock syndrome
What does the sequelae in pharyngitis cause?
rheumatic fever and glomerulnephritis
What are some pathogenesis of strep pyogenes?
otitis media, sinusitis, tonsilitis, pharyngitis, adenitis, pneumonia
Charaterisitics of streptococcus pyogenes
gram + cocci, facultative anaerobe, extracellular, upper respiratory tract
What are some virulence factors of streptococcus pyogenes?
M protein and lipoteichoic acid, Group A, capsule, enzyme, pyrogenic exotoxins
How is the capsule a virulence factor in strep pyogenes?
hyaluronic acid capsule inhibits phagocytosis
What are the S/S for GABHS pharyngitis?
fever, tonsillar exudate, NO cough, tender anterior cervical lymphadenopathy
What causes scarlet fever?
it is a lysogenized streptococcal pharyngitis caused by pyrogenic exotoxin
When does scarlet fever occur?
1-2 days after onset of pharyngitis from strep pyogenes
What are some S/S of scarlet fever?
erythematous rash on upper chest that blanches with pressure, sandpaper feel to rash, white and red "strawberry tongue", high fever, nausea and vomiting
What are pastias lines?
rash in the folds of skin seen in patients with scarlet fever
What is Jones Criteria diagnostic for?
rheumatic fever
What are the major diagnostic criteria for rheumatic fever?
carditis, polyarthritis, chorea, erythema marginatum, subcutaneous nodules
What are the minor diagnostic criteria for rheumatic fever?
fever, arthralgia, previous rheumatic fever, prolonged PR interval, acute phase reactions
How does glomerulonephritis occur?
acute inflammation of the renal glomeruli due to immune complex formation on the basement membrane
What are some S/S with glomerulonephritis?
edema, hypertension, hematuria, proteinuria
How is microscopy used to detect glomerulonephritis?
presence of leukocytes with streptococci necessary
How is antigen detected for S. pyogenes?
enzyme immunoassay or latex agglutination
What is the characteristic for the Ag detection test for S. pyogenes?
high specificity and low sensititivy
How is the Ag test confirmed for S. pyogenes?
culture, beta-hemolysis, catalase negative, bacitracin sensitive, PYR test positive
When is a throat culture recommended for S. pyogenes?
confiramatory test when - rapid antigen test; not recommmended as primary test b/c it takes 24 hrs. to grow
On what patients does a rapid antigen test need to be done?
2 or more S/S of GABHS present but only treat if + test result
What is the treatment for those afflected with GABHS?
penicillin G, erythromycin or oral cephalosporin
What does early treatment of S. pyogenes prevent in those with pharyngitits?
rheumatic fever but not glomerulonephritis
S/S for sinusitis
thick colored post nasal drainage, congested nasal passage, headache, fever, facial pain, cough, loss of taste and smell, halitosis, ear stuffiness
When is it most common to get sinusitis or otitis media?
following an upper respiratory viral infection
What causes most acute otitis media?
S. pneumoniae
S/S for otitis media?
fever, irritability, otalgia, anorexia, vomiting, bulging tympanic membrane and middle ear effusion
Most common bacterial infection in children
otitis media
H. influenzae
gram negative bacilli, facultative anaerobe
What does H. influenzae require for growth?
hemin (X factor)
NAD+ (V factor)
chocolate agar
What is a nontypeable strain of H. influenzae?
has no capsule
What type of H. influenzae is more virulent?
type B (Hib)
Virulence factors of H. influenzae
PRP capsule, IgA protease, pili
What is the primary cause of meningitis in children?
Hib if not vaccinated
What are some diseases that H. influenzae may cause?
otitis media
What does H. influenzae produce making them antibiotic resistant?
When is epiglottitis at it's peak?
children 2-4 and adults 20-40 yrs.
What is the most common cause of epiglottitis?
S/S epiglottitis
sore throat, fever, drooling, dysphagia, muffled voice and respiratory distress
Lab diagnosis of H. influenzae
microscopy, culture with chocolate agar or rapid PRP capsular antigen for Hib only
Tx for epiglottitis
amoxicilliin/clavulanic acid (augmentin) or trimethoprim-sulfamethoxazole
characterisitics of moraxella catarrhalis
gram - cocci, obligate parasite of the mucous membrane, normal pharyngeal flora, oxidase positive, DNase
What is the treatment for M. catarrhalis?
Augmentin because it contains beta-lactamase so it is penicillin resistant
What does M. catarrhalis cause?
otitis media and sinusitis
characterisistics of corynebacterium diphtheriae
gram + coryneform (irregular or clubbed shaped), aerobic
Virluence factor of C. diphtheriae
AB exotoxin
What does the AB toxin in C. diphtheriae do?
inhibits protein synthesis by inactivating EF-2, a transcription factor in ADP ribosylation
Where is the C. diphtheriae toxin encoded?
on the phage
What regulates the C. diphtheriae toxin?
chromosomal diphtheria toxin repressor protein (DTxR)
What does DTxR respond to?
low levels of tissue iron activate the toxin and high levels of iron repress the toxin
What is the mechanism for the diphtheria toxin?
1. toxin bound by B subunit
2. endocytosed
3. enzymatic cleavage of protein by furin into A and B
4. A translocated to cytoplasm so that enzymatic activity is at the cytoplasm
What is characteristic of diphtheria?
pseudomembrane which is exudate filled with PMNs, necrotic epithelial cells, erythrocytes and bacteria in a fibrin mesh
What is the biggest complication of diphtheria?
breathing obstruction
What is a classic sign of diphtheria?
"bull neck" edema from cheek to clavicle
Would you use microscopy to determine diphtheria?
no because too many FP and FN
What culture does C. diphtheriae grow on?
potassium tellurite which inhibits growth of most normal flora
What is the preventative method against C. diphtheriae?
DPT vaccine series followed by boosters
How is toxin testing done?
Elek test
What is the mechanism of an Elek test?
where there is toxin a precipitate band will form in an oblique direction
characterisitics of bordetella pertussis
gram - coccobacillus, aerosol trasmission
Virulence factors for B. pertussis
filamentous hemagglutinin, pertactin, pertussis toxin
What type of toxin is pertussis?
AB exotoxin
What is the A subunit of pertussis?
ADP ribosyl transferase
What is the mechanism for pertussis toxin?
A subunit transfers ADP ribosyl moiety of NAD to Gi, Gi is then inactivated and cannot function to inhibit adenylate cyclase so cAMP levels rise
What is the important clincal sign of B. pertussis?
whooping cough
What are the 3 stages of whooping cough?
1. catarrhal (1-2 weeks) resembles common cold, contagious
2. paroxysmal (2-4 weeks) persistent cough lasting for weeks
3. convalescent
What is the agar for B. pertussis?
CCBA- charcoal-cephalexin blood agar
What is the serology for pertussis?
antiserum agglutination where titers form against the toxin and hemagglution
What is important to remember when doing a serology test for pertussis?
need to use both acute and convalescent serum to test Ab level difference
What is the preventative treatment for pertussis?
DaPT vaccine, where a is acellular mean it has a varitey of virulence factors and is just as effective with less side effects