Keywords: 15-29 Flashcards
15 Pneumonia
Infection of lower airways/alveoli
Visible as “infiltrate” or “consolidation” of lung on CXR
16 Common Foodborne Pathogens:
Bacterial intoxications (3)
Bacteria producing enterotoxins in vivo (4)
Bacteria that invade the intestinal epithelium (5)
Viruses (2)
Parasites (1)
Heat stable enterotoxin, 1-6 hour incubation, vomitting
- Staph aureus
- Bacillus cereus (emetic form)
Heat labile neurotoxin, 12-72 hour incubation, paralysis
- Clostridium botulinum
Heat labile enterotoxin, 12 hour incubation, diarrhea & cramps
- Clostridium perfringens (common)
- B. cereus
- EHEC
- ETEC
Invasion & inflammation, fever
- Nontyphoid Salmonella (common)
- Shigella spp.
- Campylobacter jejuni (common)
- Yersinia enterocolittica
- Listeria monocytogenes
Hepatitis A
Noroviruses (common)
Tricheinella spp.
16 Common Waterborne Pathogens:
Bacteria (2)
Parasites (3)
Viruses (4)
- Vibrio cholerae
- Other gram-negatives, e.g., E. coli, Shigella
- Giardia spp.
- Entamoeba histolytica
- Cryptosporidium spp.
- Hepatitis A virus
- Noroviruses
- Rotavirus
- Enterovirus
18 Category A Agents (6)
Bacillus anthracis (anthrax)
Francisella tularensis (tularemia)
Yersinia pestis (plague)
Variola major (smallpox)
Arenaviruses and filoviruses (Viral hemorrhagic fevers)
Clostridium botulinum toxin (botulism)
18 Variola vs. Varicella
Smallpox
• Rash most dense on face and extremities (centrifugal)
• Lesions appear over 1-2 days and evolve at the same rate
• Rash occurs on palms
• Doesn’t itch
Chicken Pox
• Greater concentration of lesions on the trunk (centripetal)
• Lesions appear in crops, different stages of maturation in adjacent areas
• Rarely seen on palms or soles
• Pruritic (itchy)
18 Botulism:
Biological Characteristics
Toxin Characteristics
Clinical Features
Treatment
Contagious?
BC
- Clostridium botulinum
- Gram+ spore-forming anaerobic bacillus
TC
- Exotoxin prevetns release of ACh (neurotoxin)
CF
- Bilateral symmetric descending acute paralysis
- Cranial nerve dysfunction without sensory symptoms
- No fever, tachycardia, or mental status changes
T
- Supportive care
- Heptavalent anti-toxin
C
- No
21 FUOs: bone marrow cultures vs. blood cultures
Bone marrow cultures are probably not justified for routine initial evaluation of FUO because the yield is low and it is more invasive than blood culture with no clear superiority
22 Generalizations of respiratory infections:
Upper respiratory infections (above the larynx)
- Viral vs. bacterial
- Pathology
- Spread
Lower respiratory tract infections
- Viral vs. bacterial
- Pathology
- Spread
Common themes
- Common vs. rare
- Viral vs. bacterial
- 6 most common pathogens
- Inhalation vs. aspiration
- Pathology
- Viral > bacterial
- Endogenous flora taking advantage
- Local spread
- Viral ~ bacterial
- Aspiration
- Systemic spread (bacteremia)
- Common
- Viral > bacterial
- adenovirus, influenza, parainfluenza, rhinovirus, human
metapneumovirus, and coronavirus - Aspiration
- Upper airway colonization –> aspiration with poor defenses or damage –> lower respiratory tract disease (pneumonia)
22 Adenovirus:
Key Features
Biologic Characteristics (3)
Reservoir (1)
Transmission (4)
Clinical Disease (3)
Virulence Factors (3)
Pathogenesis (2)
Diagnosis (4)
Treatment (2)
Prevention (2)
KF
- Epidemic pneumonia + probable viral source
BC
- Non-enveloped dsDNA virus
- Serotypes determined by antibody to fiber protein
- Fiber gives tissue specificity which gives specific diseases
R
- Humans are only reservoir
T
- Respiratory secretions/droplets
- Most URI, can aspirate to LRT
- GI secretions/stool
- Waterborne source
CD
- Endemic or epidemic
- Serotypes associated w/ disease
- Infects throughotu the year
VF
- Early genes hijack normal growth resources for viral replication
- Immune evasion by blocking cell signaling (E3)
- Cell destruction (cytopathic effect) releases new virions
P
- Virus binds local epithelial / lymphoid cells & enters
- Subsequent lytic infection leads to viremia & dissemination to other sites
D
- Culture (shell vial)
- Serum antibodies
- Antigen detection
- PCR (most important)
T
- Supportive care
- Cidofovir in select patients
P
- Limit contacts
- Vaccine
22 Haemophilus influenzae:
Key Features
Biologic Characteristics (5)
Reservoir (1)
Transmission (2)
Clinical Disease in Children (4)
Clinical Disease in Adults (4)
Virulence Factors (5)
Pathogenesis (2)
Diagnosis (4)
Treatment (2)
Prevention (1)
Lack of immunization + toddlers
BC
- Pasteurelleaceae family
- Small, gram-negative coccobacilli
- Fastidious (hematin & NAD)
- Encapsulated or nonencapsulated strains
- Grows well on chocolate agar (lysed RBCs) but not blood agar (intact RBCs)
R
- Humans are only reservoir
T
- Respiratory droplets
- Protective antibodies (from vaccine or exposure)
CD: Children
- Otitis media/sinusitis (nontypeable): antibiotic resistance
- Epiglottitis (type b): emergency
- Pneumonia (type b)
- Meningitis/bacteremia (type b): hearing loss
CD: Adults
- Only nontypeable strains
- Otitis media & sinusitis
- Meningitis rare
- LRT: nontypeable, in pts w/ COPD
VF
- Capsules: for immune evasion
- Hib: most important capsular strain
- Endotoxin (LOS): adhesin & inflammation
- IgA protease
- Obtain iron & heme from transferrin
P
- Involves transmission, immunity, virulence factors, & environment
- Most important: capsule association w/ Hib
D
- Gram stain
- Culture (chocolate agar)
- Latex particle agglutination
- Serotyping
T
- Cephalosporins & amoxicillin/clavulanate
- Carriers: rifampin
P
- Hilleman’s vaccine: PS conjugated to protein vaccine (PRP-OMP)
22 Mycoplasma pneumoniae:
Key Features
Biologic Characteristics (4)
Reservoir (1)
Transmission (2)
Clinical Disease (2)
Virulence Factors (4)
Pathogenesis (2)
Diagnosis (4)
Treatment (3)
Prevention (2)
Persistent cough + erythema multiforme + anemia
BC
- Prokaryote w/o cell wall
- Cell membrane w/ sterols
- Small size & genome
- Slow & difficult to grow
R
- Humans are only reservoir
T
- Respiratory droplets
- Colonizes respiratory epithelium, doesn’t enter alveoli
CD
- URT & LRT
- Rare to be invasive
VF
- Adhesins: attachment
- CARDS toxin: epithelial damage, chronic asthma
- Peroxides: damages epithelium
- Inflammatory response to cell membrane proteins
P
- Manifestations caused by autoantibodies:
- erythema multiforme
- hemolytic anemia
- thrombotic thrombocytopenic pupura
D
- Clinical symptoms
- Serology
- Cold agglutinins
- Culture (not useful)
- PCR (most important)
T
- No cell wall, so no beta-lactams
- Targets ribosome: tetracyclines & macrolides
- Targets DNA: FQs
P
- Droplet precautions
- Azithromycin (macrolides) for prophylaxis
23 Bloodborne Infections:
Mechanisms of Transmission (6)
Risks (7)
Prevention (4)
- Vertical: mother to infant
- Horizontal: contact
- Sexual: microabrasions
- Percutaneous: sharing needles
- Iatrogenic/Nosocomial: medical procedure (doctor/hospital), HBV
- Transfusion: RBC
- IV drug use
- Blood transfusion
- Hemodialysis
- Exposure to blood products
- Tattooing/Piercing
- Sexual exposure
- Birth to infected mothers
- Screen/test blood products
- Pre-screen blood donors (IV drug use, recent travel)
- Blood & body fluid precautions
- Hepatitis B vaccination
23 Transplantation-Associated Infections:
Risks (4)
Prevention (3)
R
- Iatrogenic immunosuppressive medications (caused by physicians)
- Nosocomial infections (hospital acquired)
- Reactivation of latent infections or recurrence of chronic infections
- Donor-organ associated transmission (ex. CMV)
P
- Screening of donor organs
- Prophylactic antiviral & antibiotic therapy
- Vaccination
24 Pathogen Colonization:
Involves… (2)
Qualify as…
Gives the pathogen… (2)
How pathogen overcomes normal flroa occupying sites for adherence
How pathogen overcomes host defenses & normal flora
- Adherence: pathogen sticks to target tissues using adhesins
- Multiplication: pathogen multiplies in target tissues
Virulence factors
- Sustained presence in the host
- Access to nutrients &/or host factors
Produces novel adhesins that allow them to adhere to unoccupied mucosal sites
Colonization after normal flora numbers are reduced by antibiotics
24 Adherence:
Specific interactions mediated by… (2)
Nonspecific interactions mediated by…
Adhesins
- Pili (fimbriae): long appendages on surface that facilitate long-range bacteria:host interactions
- Nonfimbrial adhesins: closely associated w/ surface, facilitate short-range bacteria:host interactions
Bacterial surface charges (hydrophobicity)
