infectious disease Flashcards
fungi characteristics
eukaryotic
have cell walls with thick carbohydrates
multiple growth forms
types of fungal infections
mycoses
superficial mycoses
subcutaneous
systemic
protozoa
eukaryotic parasite
single cell organism
example of protozoa
malaria
trypanosomiasis
helminth
eukaryotic parasite
parasitic worm
examples of helminths
tape worms
schistosomiasis
bacteria
prokaryotic
large group of unicellular microorganisms
have cell walls
lack organelles and an organized nucleus
prions
protein particle
causes protein misfolding disease
contains no nucleic acid
highly resistant to inactivation
routes of transmission
direct contact exchange of fluid contamination airborne vector
portals of entry
mucosal membranes
skin
parenteral route
common types of vaccines
inactivated pathogen
live attenuated
subunit purified antigen
toxoid
host factors that influence course of infection
nonspecific immune response immune status genetics age nutritional status hormones personal habits fever microbiome
Plasmid
Circular DNA
Extra.
Codes for certain characteristics such as antibiotic resistance
What does the cell wall determine
Cell shape
Gram stain characteristics
Gram positive bacteria characteristic
Thick peptidoglycan with lots of sugar layers.
Can retain stain
Gram negative bacteria characteristic
Thin peptidoglycan layer with second membrane layer on top.
Have 2 membranes and peptidoglycan layer
Gram stain steps
Fixation Crystal violet Iodine Decolorization Counterstain saffanin.
Bacterial replication
DNA origin replicates DNA replication continues bidirectionally DNA starts next round Septum forms Division in 2 cells
Antibiotics
Cell wall synthesis
B lactam penicillin Cephalosporins Carbapenems Monobactams Glycopeptides
Antibiotics
Folate synthesis
Sulfonamides
Trimethoprim
Antibiotics
Protein synthesis
50S
Macrolide
Oxazolidinone
Chloramphenicol
Antibiotics
Protein synthesis
30S
Aminoglycosides
Tetracycline
Antibiotics
RNA polymerase
Rifamycin
Antibiotics
Cell membrane disrupters
Polymixins
Antibiotics
Nucleic acid synthesis
DNA gyrase
Quinolone
No selective growth media
Blood agar
Chocolate agar
Selective growth media
Addition of reagents
Macconkey
Growth media differential agar
Different growth or fermentation patterns
Molecular identification
Nucleic acid amplification
Ag detection
MS
Virulence factors directly involved in pathogenesis
Secreted toxins and enzymes
Capsule
Cell surface structures
Virulence factors indirectly involved in pathogenesis
Siderophores
Secretion machinery
Catalase
Regulatory factors
Catalase test
Differentiates gram positive strep and staph
Catalase breaks down H peroxide into O2.
Lab tests if gram positive infection
CBC Electrolytes Blood cultures Procalcitonin EKG if endocarditis is suspected Jt aspiration if septic jt suspected
Gram positive infection
Physical
Bulbous impetigo Draining sinus tracts Erythema Fever Murmur if endocarditis Petechiae if tss Superficial abscess Warmth
Catalase test steps
Slide
Drop of hydrogen peroxide
Bubble = positive
Positive catalase test
Staph
Bubbles
Negative catalase test
No bubble
Strep
Coagulate test positive
Staphylococcus aureus
Clotted
Coagulase test negative
Plasma liquidy
S epidermidis or
S saprophyticus
Coagulase test
Used to differentiate between S. Aureus and other Staph species.
Staph aureus
Superficial lesions
Toxinoses - food poisonings, scalded skin syn, tss
Systemic and life threatening cond- endocarditis, osteomyelitis, predominant, brain abcesses, meningitis, and bacteremia
Virulence factors of S. Aureus
Adherence factors
Expo rote is
Antibiotic susceptibility tests
Broth dilution
Antimicrobial gradient
Disc diffusion
Broth dilution
Concentration of antibiotics has minimal inhibitory effect
Problem> labor intensive
Antimicrobial gradient
Agar plate
Strips of abx with dilution going down
Disc diffusion
Agar plate disc
Different abx with known concentration.
Abx diffuse out of disc> clearing
Mechanisms of abx resistance
Permeability changes in cell wall restrict abx access
Active efflux of abx
Degradation of abx
Acquisition of alternative metabolic pathway
Modification of abx target
Overproduction of target enzyme
Acquisition of abx genes
Chromosomal mutations
Transformation
Transfer/acquisition of new genetic material
Conjugation
Conjugation
Through pilus.
Bacterial “sex”
Transformation
Nucleoid/ plasmid from dead cell just hangs out. New cell picks it up
Transduction
Use a virus/ phage.
Abx Moa
Inhibition of protein synthase
Inhibition of DNA and RNA synthesis
Interfere with cell wall
Inhibit energy metabolism (folate synthesis)
Abx cell wall synthesis
Beta lactams
Penicillin
Cephalosporin
Carbapenem
Monobactam
Abx cell wall synthesis
Vancomycin
Bacitracin
Abx cell membrane
Polymixins
Abx nucleic acid syn
folate synthesis
Sulfonamide
Trimethoprim
Abx nucleic acid syn
DNA gyrase
Quinolone
Abx nucleic acid syn
Rna polymerase
Rifampin
Abx protein synthesis
50 s subunit
Macrolides Clindamycin Linezoid Chloramphenicol Streptogramin
Abx protein synthesis
30 s subunit
Tetracycline
Aminoglycosides
S aureus abx resistance
Phage transduction (phage type 80/81)
Conjugation plasmids
Transformation
SCCmec (methicillin resistance)
SCCmec type ii
Methicillin resistance
Hospital acquired
SCCmec type iv
Methicillin resistance
Gen pop
Life cycle of biofilm
Single floating bacti land on surface
Bacti cells aggregate and attach
Growth and division of bacti for biofilm formation
Mature biofilm disperses to release free floating bacti for further colonization
Cycle repeats.
Biofilms
Aggregates of bacti
Extremes resistance to abx
Resistant to phagocytosis
Gene regulation
Streptococcus species classifications
Colony morphology
Hemolysis
Biochemical rxns
Serologic specificity
Beta hemolytic
Complete lysis - clear
Alpha hemolytic
Incomplete lysis.
Green brown
Gamma hemolytic
None
Streptococcus species
Streptococcus Pygenes group a
Pharyngitis, scarlet fever, impetigo, cellulitis
Invasive infections - necrotizing fasciitis
Immune mediated sequelae - acute rheumatic fever
Tend to form chains/ clump together
Streptococcus pneumonia’s
Pneumonia, meningitis
Tend to couple. Diploid cocci
Beta hemolytic
Susceptible to p disc- optochin
Strep agalactiae
Neonates - meningitis, neonate sepsis
Adults - vaginitis, puerperal fever
Viridans strep
Endocarditis
In mouth > teeth
Enterococcus
Uti
Biliary tract infection
Spore forms of gram positive bacilli
Clostridium
Bacillus (anthracis and cereus)
Spore formation
Environmental resistant microorganism.
Good conditions: germinate
Bad conditions: inactive
Anaerobes
Fastidious organisms
Difficult to grow
Requires proper collection and culture
Diagnosis requires clinical suspicion
