Keywords: 15-29 Flashcards Preview

Micro Remediation > Keywords: 15-29 > Flashcards

Flashcards in Keywords: 15-29 Deck (21):
1

15 Pneumonia

Infection of lower airways/alveoli

Visible as "infiltrate" or "consolidation" of lung on CXR

2

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.

3

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

4

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)

5

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)

6

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

7

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

8

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)

9

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

10

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)

11

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

12

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

13

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

14

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

15

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)

16

24 Differentiating Enterobacteriaceae:

(1) Glucose Utilization
(2) Lactose Utilization
(3) H2S
(4) Motility

Escherichia

Salmonella

Shigella

Escherichia
(1) Glucose +
(2) Lactose +
(3) H2S -
(4) Motile

Salmonella
(1) Glucose +
(2) Lactose -
(3) H2S +
(4) Motile

Shigella
(1) Glucose +
(2) Lactose -
(3) H2S -
(4) Non-Motile

17

24 Major Enterobacteriaceae pathogens for "healthy" people (4)

Escherichia coli: diarrhea, dysentery, urinary tract infections (UTIs)

Shigella spp.: dysentery

Salmonella spp.: diarrhea, enteric fever (typhoid fever)

Yersinia spp.: plague, diarrhea, lymphadenitis

18

24 Major opportunistic members of the Enterobacteriaceae (6)

E. coli: UTIs, neonatal/childhood meningitis

Proteus spp.: UTIs

Klebsiella spp.: UTIs, bacteremias/septicemias, and pneumonias

Enterobacter spp.: UTIs and septicemias

Serratia spp.: UTIs, bacteremias/septicemias, and pneumonias

Citrobacter spp.: UTIs and septicemia

19

27 Examples of Molecular Mimicry

Neisseria meningitidis

Streptococcus pyogenes

Staphylococcus aureus

Streptococcus pyogenes

Campylobacter jejuni

Disguise: Serotype B capsule similar to human neuronal sialic acid

Disguise: hyaluronic acid capsule similar to human ground substance
Disguise: M protein binds Factor H, a complement cascade component

Disguise: Protein A binds immunoglobulin via Fc portion, coating membrane without causing phagocytosis

Autoantigen: M protein induction of autoantibodies which react with cardiac tissue

Autoantigen: Ganglioside sugars mimic neuronal tissue and are associated with Guillain-Barre syndrome

20

28 Organisms w/ surface structures w/ an antiphagocytic function:

Pili

M protein

Outer membrane

Capsules

Neisseria gonorrheae

Streptococcus pyogenes

Salmonella typhi (O antigen blocks complement)

Streptococcus pneumoniae

21

28 Why M protein is important for Group A Streptococcus pathogenesis (4)

Antigenic variability

Adherence (by binding LTA)

Prevents phagocytosis by...
- Molecular mimicry
- Binding factor H to prevent complement

Immunopathologic antibody response that cross-reacts w/ cardiac muscle