Introduction to Infectious Disease Flashcards
Host flora
Occupy space and compete for nutrients
Stimulate cross-protective antibodies
Suppress growth of potentially pathogenic bacteria and fungi
Can normal flora become pathogenic
Yes
Colonization vs Infection
Colonization- organism present
Infection- organism present, organ damage, and inflammation.
Autoimmune disease- organ damage and inflammation
Monitoring Parameters
Fever- >37 C (98.6 F) in adults Erythema- redness of the skin Purulence- discharge of pus Swelling Leukocytosis- elevated WBC
WBC- Leukocytes
1% of blood volume
Carry out immune system functions and recognize self from non-self.
Average life span 13-20 days
Differential WBCs
Neutrophils- 50-70% Lymphocytes 25-35% Monocytes- 2-6% Eosinophils- 0-6% BBasophils- 0-3%
Granlocytes
Neutrophils, eosinophils, and basophils
Neutrophils mechanism
Prevent microorganism invasion, kill invading organisms
Attracted to site of infection by chemotactic factors. Then Phagocytize the microorganisms. Release toxic substances from granules within cell into vacuole containing organism.
Neutrophils
Contain multi-lobed nuclie (segs)
Production stimulated by interleukins and other colony stimulating factors (CSF)
Increased bands in circulation causing left shift
Segs
Term used to describe a mature working neutrophil, if found then you know they are actively trying to prevent infection
Bands
Immature neutrophil, increased means that more immature cells are being pushed out of the marrow (eukemia)
Absolute Neutrophil Count (ANC)
The lower the value the higher the risk of infection
WBC # x (%segs+%bands)
Neutropenia
Not enough neutrophils Mild= ANC 1000-1500/mm3 Moderate= ANC 500-1000mm3 Severe= ANC <500mm3 This gives an idea of how a pt can handle an infection process on their own.
Lymphocytes
Effector cells of immune system, recognize invaders, tag them for removal and kill them.
Make antibodies- Tcells 80% and B cells 20%
WBC-Monocytes
Serve to replenish tissue with macrophages prior to and during immune response
WBC- Eosinophils
Responsible for immuner processes against helminths and parasites (also involved in allergic rxn)
WBC- Basophils
Mediate inflammatory response
Gram stain- Gram (+) Cocci
chains- streptococcus pyrogens, viridans streptococcus
Pairs- streptococcus pneumoniae and enterococcus spp.
Clusters- coagulase-positive staphylococcus (S. aureus) Coagulase -negative Staphylococcus (S. epidermis)
Gram stain- Gram (+) Bacilli
Listeria and lactobacillus
Gram stain- Gram (-) Cocci
Neisseria menigitidis and Neisseria gonorrhoeae
Gram stain- Gram (-) Bacilli
Escherichia Coli Klebsiella Spp Enterobacter spp Proteus spp serratia marcescens Pseudomonas spp
Gram stain- Gram (-) Coccobaccili
Haemophilus influenzae
Cell wall- Gram Positive
Rigid, thick
Made up of mostly peptidoglycan (50-60%)
A series of cross-linking (transpeptidases) help to create the building blocks of the cell wall
Cell wall- Gram Negative
Cell wall thin layer-one or two glycan chains
Cell wall protected by lipoprotein outerlayer- which functions as a penetration barrier.
Lipopolysaccharide (LPS)
Matrix protein (porin)- important for regulating the influx of molecules
Phospholipids
Cell walls- Walls of mycobacteria (Acid fast bacteria)
Contains peptidoglycan w/ polysaccharide and glycolipids
Associated with staining characteristics
Cell Walls- Cytoplasmic membrane
Osmotic barrier
Energy production (electron transport-energy grandient- ATPases)
Biosynthesis transport (nutrient uptake, enzyme secretion)
Protein and lipid- lacks sterols
Antimicrobial Susceptibility- MIC
Minimun inhibitory concentration (MIC) lowest concentration of antibiotic that inhibits visible growth of bacteria. Want to shoot for 2-4x above this in treatment.
Antimicrobial Susceptibility- Breakpoints
Susceptible- isolates may be appropriately treated with the recommended doses
Intermediate- isolates may be appropriately treated in body sites where the drug is physiologically concentrated or when a high dosage of a drug can be used
Resistant- isolates are not inhibited by the achievable concentrations of a normal dose
Gram Positive cocci (Aerobic)- Staphylococcus
Staphylococcus aureus (Coag+)- MSSA, hospital or community acquired MRSA. Staphylococcus epidemidis(Coag -) Staphylococcus saprophyticus (Coag -)
Gram Positive cocci (Aerobic)- Enterococcus
Enterococcus Faecalis
Enterococcus faecium
Enterococcus durans
Gram Positive cocci (Aerobic)- B hemolytic
Streptococcus pyogenes (Grp A) Streptococcus agalactiae (Group B) Streptococcus bovis (nonenterococci, grp D)
Gram Positive cocci (Aerobic)- Viridans streptococci- alpha hemolytic
Streptococcus sanguis
Streptococcus salivarius
Streptococcus mitis
Streptococcus mutans
Gram Positive cocci (Aerobic)- Streptococcus pneumoniae
Pneumococcus
Staphylococci- colinzation
Skin and nose
Staphylococci- Infections caused
Cellulitis, wounds, trauma Bacteremia/endocarditis Pneumonia Osteomyelitis UTI
Staphylococci- post surgery
Major players in post surgical infections.
Adhere to foreign material and catheters
Staphylococcal Resistance
Penicillin resistant- beta-lactamase production
Methicillin resistant- MecA gene codes for Novel PBP2a (50% S. aureus and 70% CoNS are resistant)
Methicilin-suspectible isolates are also susceptible to cephalosporins and carbapenems.
Streptococcus- Colinzation
Skin- grou A- S. pyogenes
Mouth- viridans streptococcus, anaerobes (e.g. peptostreptococcuss)
Nasopharynx- group A S. pyogenes
Lower GI- group D- S. bovis, viridans streptococcus and anaerobes
Female Genital tract- Group B- Agalactiae
Streptococcus- infections caused- cellulitis
Group A- S. pyogenes may result in Nec fascitis
Streptococcus- infections caused- Dental carries
Viridans Streptococcus
Streptococcus- infections caused- pharyngitis (Strep throat)
Group A- S. Pyogenes
Streptococcus- infections caused- bacteremia/endocarditis
Viridans Streptococcus
Streptococcus- infections caused- neonatal meningitis
Group B- S. Agalactiae
Streptococcus treatement
Penicillin
More resistance seen with alpha-hemolytic strep, specifically S. Mitis
Pneumococci
Alpha hemolytic
Pneumococci- colonization
Oropharynx and nasopharynx
Pneumococci- infections caused
Otitis media, sinusitis, bronchitis, Pneumoni (CAP Community required pneumonia), and meningitis
Pneumococci- Asplenia
Without the spleen patients are at risk for fulminant sepsis syndrome.
Lack filtration mechanism of spleen macrophages
Cannot clear encapsulated organisms- S. pneumoniae, H. influenzae, and N. menigitidis
Pneumococci- treatment
Penicillin resistant strains due to PBP alterations
3rd generation cephalosporins (ceftriaxone)
May de-escalate with cultures and sensitivities
Enterococci- colonization
Gastrointestinal tract and female genital tract
Resistance is the best defence
Enterococci- infection
Opportunistic
UTI
Bacteremia/Endocarditis
Intra-abdominal infections
Gram Negative (aerobic)
Rods- Enterobacter spp, escherichia coli, klebsiella pneumoniae, proteus vulgaris, proteus mirabilis, serratia marcenena, pseudonomas aeruginosa, cocc/coccobaccilli
Enterobacteraciae
GI tract colonization
Exposure comes from soil, water, vegetation
LPS cell wall component and endotoxin.
Enterobacteraciae- infections
UTI Intra-abdominal infections Bacteremia Nosocomial pneumonia Diabetic foot infections
Enterobacteraciae- resistance
Prevalent
More common in hospital-acquired infections
Tx guided by in vitro susceptibility
Pseudomonas aeruginosa
Not considered normal flora (sold, water, vegetation)
Can colonize upper respiratory tract of immunocompromised patients- cystic fibrosis, COPD
Opportunistic- immunocompromised pt, broad spectrum ABX, ventilation equiptment
Pseudomonas- infections
Nosocomial infections Hospital acquired pneumonia (HAP) Febrile neutropenia Skin and soft tissue infections (burns, trauma, post-surgical) UTI
SPACE Organisms- double covering
Double covering- Tx w/ 2 ABX Serratia Psuedomonas Acinetobacter Citrobacter Enterobacter More adverse effects, no more resistance
Gram (-) Cocci/Coccobacilli- Haemophilus Influenzae
Encapsulated- more virulent, not regular colonizer, causes meningitis
No capsule- Colonizes upper respiratory tract, causes otitis media, sinusitis, CAP
Gram (-) Cocci/Coccobacilli- Neisseria Menigitidis
Humans only nature host
Colonizes oro/nasopharynx
Encapsulated
Causes meningitis and less commonly pneumonia
Polysaccharide capsule (PS)
Eludes immune system
Requires speen for elimination
PS capsule is target for vaccines- Hib vaccine and meningococcal vaccine
Anaerobes- above diaphragm
Petpstreptococcus spp (gram + cocci) Actinomyces spp (gram + rod) Fusobacterium (gram - rod)
Anaerobes- below diaphragm
Bacteroides fragilis (gram - rod) Lactobacillus (gram + rod) Clostridium spp (gram + rod)
Gram negative isolates
Usually penicillinase prodcuers
Anaerobes- colinization
Upper and lower Gi and vagnial colonizers.
Anaerobes- infection
Intra-abdominal infection, aspiration pneumonia, endometritis, PID, diabetic lower extremity infections, dental carries, head and neck.
Atypicals
Not normal colonizers
Not able to gram stain
Mutiply intracellularly
Result in CAP
Atypicals- organisms
Mycoplasma pneumonia
Legionella pneumophilia
Chlamydophila pneumoniae
Atypicals
Even Some Super Killers Have Pretty Nice Capsules Escherichia Coli Streptococcus Pneumoniae Salmonella Klebsiella pneumoniae Haemophilus influenzae Pseudomonas geruginosa Neisseria meningitidis Cryptococcuss neofromans (yeast)
9 classes of bacterial pathogens- Streptococci
Group A strep, viridans strep
9 classes of bacterial pathogens- Streptococcus pneumoniae
Streptococcuss pneumoniae
9 classes of bacterial pathogens- Enterococcuss
usually faecalis
9 classes of bacterial pathogens- Staphylococci
S. aureus, coagulase-negative
9 classes of bacterial pathogens- atypical bacteria
Mycoplasma, chlamydia, legionella
9 classes of bacterial pathogens- Haemophilus influenzae
haemophilus influenzae
9 classes of bacterial pathogens- Gram negative rods
E. coli, Klebsiella, Proteus, ect
9 classes of bacterial pathogens- Pseudomonas aeruginosa
Psuedomonas aeruginosa
9 classes of bacterial pathogens- Anaerobes
Bacteriodes, clostridia, pervotella
Nine Important “Classes” of Bacterial Pathogens
Streptococci Streptococcus Pneumoniae Enterococcus Staphylococci Atypical bacteria Haemophilus Influenzae Gram negative rods Peudomonas Aeruginosa Anaerobes
