Micro: Intro & Bacteria & others Flashcards
(74 cards)
1
Q
Staphylococcus?
ex?
what is coagulase-negative staph?
A
gram+ve cocci aerobe clusters -normal flora: ex: -Staphylococcus aureus = MRSA
Coagulase-negative: have proteins that coagulate in plasma = form fibrin clot around bacteria to hide
-S. epidermidis, S.lugdunensis (bacteremia, endocarditis), S.saprophyticus (UTI)
2
Q
Streptococcus?
ex?
alpha vs beta hemolytic?
A
gram+ve cocci aerobe chains -normal flora: ex: Beta-hemolytic: hemolysis through culture -S. pyogenes (Group A streptococci) -S. agalactiae (Group B strepto)
Alpha-hemolytic: cells look green
-S. pneumoniae: **gram+ve DIPLOCCI!
3
Q
Enterococcus?
causes»
A
gram+ve, cocci, aerobe, chains -normal flora: ex: -E faecium, E. faecalis -VRE
-GI tract, GU tract normal flora
-contact transmission
-virulence: adhesin, hemolysin
» UTI, abdo
4
Q
Corynebacterium?
A
gram+ve baccilli aerobe (look like zigzag Vs) -normal flora: ex: C. jeikeium, C. urealyticum, C. diphtheriae causes: UTI
5
Q
Bacillus?
A
gram+ve baccilli aerobe -forms spores -normal flora: skin ex: B. anthracis
6
Q
Ecoli
A
gram-ve, baccilli, aerobe
-normal flora: GI
-contact
virulence: fimbriae, hemolysin, flagella, cytoxin, enterotoxin
» UTI, hospital-ac pneumonia, abdo, gastroenteritis
7
Q
Haemophilus?
A
gram-ve
coccobacilli
aerobe
-normal flora: oropharynx
H.influenzae
-contact, droplet
virulence: capsule IgA protease
»pneumonia, sinusitis, otitis media, meningitis
8
Q
Neisseria?
A
gram-ve diplococci aerobe -normal flora: ex: N. meningitidis, N. gonorrhea
9
Q
Clostridium?
A
gram+ve baccilli ANerobe -soil, hospital, GI tract -contact -virulence: spores, exotoxins ex: Cdiff, C. tetani, C.botulinum, C.perfringens
> > tetanus, botulism, gas gangrene, diarrhea
10
Q
Bacteroides?
A
gram-ve baccilli ANerobe -normal flora: GI virulence: lipase, protease, capsule >>intraabdo abscesses, bacteremia
11
Q
Gram Staining procedure?
A
- get sample
- assess adequacy (too much squamous epithelial cells = reject), identify any non-bacteria present
- smear (from specimen or from grown culture), fix smear
1. Crystal violet - stains purple
2. Idodine - set stain
3. Wash with alcohol, water - thick stays purple; thin washs off
4. Safranin - dye pink. thick stays purple, thin pink.
see under microscope:
purple = gram +ve (thick peptigoglycan wall)
pink = gram -ve (thin wall)
12
Q
Why does gram staining work?
A
- peptidoglycan layer: thick crosslinkage resistat alcohol decolourization
- magnesium ribonucleate in gram +ve wall: affinity for crystal violet-iodine
- cell wall permeability: gram +ve less lipid = less effect of decolourizer
13
Q
Yeast?
ex?
A
-fungi
-single eukaryotic, ovoid/spherical
-rigid cell wall
-budding
fuzzy, hyphae
ex: Candida
14
Q
Chlamydia trachomatis?
A
atypical bacteria: inracellular
- GU tract
- contact
virulence: intracellular
> > UTI, pelvic inflammatory disease
15
Q
Staphylococcus aureus? morph: resevoir: transmission: virulence factors: causes>
A
-gram+ cocci, aerobe, clusters Resevoir: skin, nares transmission: contact, fomites virulence factors: -adhesin - stick -Protein A - disable Ab -capsule - prevent phago -leukocidin -hemolysin - break down RBC, WBC -catalase - break down phago -DNAase -exotoxins > Toxic Shock Syndrome, Exfoliatin, Enterotoxin
causes> lots
- skin infections > abscess
- bacteremia
- endocarditis
- pneumonia
- food poisoning
- toxic shock
16
Q
What is Protein A?
M protein
A
A; binds Ab to prevent action
M: prevents phagocytosis
-virulence factor for bacteria
17
Q
Virulence Factors are based on 2 things?
A
- invasion
- host damage
18
Q
Staphylococcus epidermidis?
A
- gram+ cocci, aerobe, clusters
- skin
- contact
virulence: adhesins, capsule, biolfilm - less virulent than S.aureus
19
Q
What is group A strep?
A
-Streptococcus pyogenes
-gram+, cocci, chains, aerobe
-in skin, pharynx
-contact, droplet
virulence factors = adhesins, M protein, capsule, hemolysins, enzymes
-SPExotoxin = superantigen
causes>
- pharyngitis
- impetigo - skin-skin lesion
- necrotizing fasciitis
- bacteremia
- toxic shock
- septic arthitis, rheumatic fever, glomerulopnerphritis)
20
Q
Streptococcus pneumoniae?
A
-gram+, DIPLOCOCCI, aerobe
-normal flora: oropharynx
-droplet, contact
-virulence: capsule, autolysin, pneumolysin, protein A
» pneumonia, sinusitis, otitis media, meningitis, bacteremia
21
Q
What are enteric pathogens?
A
GI: gram-ve bacilli
ex: ecoli, salmonella, shigella, campylobacter
virulence: enterotoxin, cytotoxin
> > gastroenteritis: diarrhea, hemolytic uremic syndrome, bacteremia
22
Q
Neisseria meningiditis?
A
- gram-ve DIPLOCCI, aerobe
- oropharynx
- contact, droplet
- virulence: capsule, IgA protease, endotoxin
> > meningitis, meningococcemia
23
Q
Neisseria gonorrhoeae
A
- gram-ve DIPLOCCI, aerobe
- GU tract
- contact
- virulence: pili, antigenic variation, IgA protease
> > UTI, pelvic inflammatory disease, gonoccocemia
24
Q
What are atypical bacteria?
ex?
A
- intracellular (chlamydia)
- lack rigid cell wall (mycoplasma)
- acid fast bacilli (mycobacterium)
- partial acid fast (nocardia)
- spirochetes (treponema pallidum)
25
```
Strict Aerobes
Facultatie anaerobes
microaerophilic
aerotolerant
strict anaerobes
```
- need O2 else dies
- can do both but prefers O2
- depends on O2 but die if too high
- use anerobic fermentation but can survive in O2
- dies in O2
26
Types of virulence factors: invasion (5)
- portal of entry: skin, tracts, transplantattion/transfusion
- surface colonization: adhesins, use host receptors
- surviving host defences: Protein A, viral latency, Ab proteases, changing surface antigens, immunosuppression by depleting T cells or messing it up via superantigen, biolfim, intracellular passage, capsules, exotoxins that kill immune cells, adhesins
- portal of exit: skin, tracts, transplantattion/transfusion
- transmission
27
Routes of transmission? (5)
| ex:
- contact: direct (mucosa, skin); indirect (hands, fomites), faecal-oral
ex: HIV, herpes, cdiff
- droplet: large (>=5microm) propelled 2m through air, land on nasal/oral mucosa
ex: influenza, resp, neisseria meningtidis
- airborne: small droplets or skin squams (<5microm) - remain suspended
ex: TB, measles, varicella zoster
- vector borne: carried by insects, ticks, mosqu
ex: west nile, malaria
- common vehicle: single contaminated item, food
28
Types of virulence factors: host damage (4)
- damage due to host response (inflammation, loss of func, septic shock)
- toxins: endo vs exo
- apoptosis: triggers (HIV, herpes) or block (HPV)
- mechanical : ex - helminths obstruction
29
Endotoxins vs exotoxins?
| ex?
endo: LPS on cell wall is toxic
exo: bacteria treat to help spread or lyse host cells: block protein synthesis, affect cell func, block nerve fnc
-ex:
Tetanus toxin: CNS GABA> stiffness
Botulism: PNS Ach> paralysis, floppy
30
Normal flora:
| skin, oropharynx, colon, GU?
- skin: staphylococcus, corynebaceterium, bacillus
- oropharynx: streptocci, neisseria, harmophilus, candida
- colon: enterococcus, ecoli, bacteriodes, clostridium, candida
- GU: streptococci, candida
31
Benefits vs harm of normal flora
Benefits:
- helps train immune system
- infection prevention
- nutrition
- digestion
Harms:
- opportunistic infections
- contaminations
32
Define virulence factors? pathogenicity?
vf = traits that make organism pathogenic
| p=ability to cause disease
33
Define resevoir. ex?
- living/nonliving thing on which organism lives
| ex: human, animal, soil, objects
34
Define incubation period?
-time of entry > first sign/symptoms
35
Define period of communicability?
-time agent able to be transmitted
36
What are control measures?
- to reduce transmission
| - public health, hospital infection control
37
What are public health control measures? (6)
- vaccination
- post-exposure prophalyxis
- reporting systems to surveillance
- contact tracing
- quarantine
- outbreak investigation
38
What are infecton control measures? (6)
- surveillance
- routine practice: washing, ppe, sharps, housekeeping
- additional precautions: contact, droplets, airborne
- decolonization: drugs
- post-exposure prophalyxis: drugs, vaccines
- outbreak investigation
39
(7) steps of outbreak investigation?
1. confirm outbreak
2. define cases
3. epicurve, line listing
4. assemble team
5. control measures
6. evaluate
7. decide when its over
40
Approach to CXR?
-name
-L/R markers
-assess of rotation: clavicle ant; spinous = post
-penetration: should see verterbral body of spine
-degree of inspiration: count ribs - 6th ant; 10th post
if expiration: bigger heart, bigger mediastinum, less ribs
41
What is spine sign?
silhoutte sign?
bronchograms?
- normally: post lung gets darker lower down
- abnormal: loss of borders bt structures b/c density contrast loss
- abnormal: see broncho. usually airways same as lung so don't see. suspect consolidation
42
Chest Xray - what's white and black?
```
higher density = white
bone
soft tissue/water
blood
air=black
```
43
airspace disease (Consolidation) vs instititial disease (edema)
c: white lungs, see airways, loss of borders
institial: see thick white borders
44
Atypical signs:
cavitations
miliary
ex:
cavitations: black holes with air in lung
ex: pneumonia, TB, fungal
miliary: dissemination > white tiny dots everywhere
ex: TB, fungal
45
Signs of edema on CXR?
- instititial disease
- cardiomegaly
- see extra lines: kerly B, thicker fissures, thickened bronchioles (cuffing), "butterfly" (borders are spared)
46
pathogenesis of pneumonia (3 mech)
1. Aspiration - normal flora down resp, inhalation from vomiting, those on ventilation
2. Inhalation- inhale aerosols with streptrococci pneum
3. Hematogenous-
47
community vs hosp acquired pneumonia organisms
```
CAP:
S. pneumoniae
H.influenzae
viruses
*children: more viruses
```
HAP:
gram-ve bacilli: Ecoli, klebsiella, p.aeruginosa, S.aureus
48
What is pneumonia?
- infectio of lungs > proliferation of organism in alveoli > inflammation.
- lower resp tract
49
Symptoms of Pneumonia: typical vs atypical?
- fever, chills, cough, sputum, pleuritic chest pain, dyspnea, tachy
- consolidation on CXR
atypical: dry cough, maybe fever, CXR may not show
50
Complications of pneumonia
- lung abscess
- empyema - pus in pleural space
- PEffusion
- bacteremia
- metastatic infection
51
Work up of pneumonia:
```
hx
pe
CXR
arterial blood gas
CBC
blood culture
sputum gram stain and culture
```
-sometimes: urine antigen for Legionella, serology, pleural fluid culture, sputum for acid fast bacilli (TB)
52
Tx for pneumonia
- Supportive: oxygentation, hydration
- antimicrobial drugs
prevention: flu vaccine, pneumococcal vaccine
53
```
Describe common cold
cause:
symptoms:
dx
tx
```
- viruses: rhinoviruses, coronaviruses, parainfluenza viruses, adenoviruses...
- URI: mild resp infection: sore throat, malaise, fever, muscle aches maybe, nasal congestion, rhinorrhea, cough
- peak 3-4 days; lasts up to 10
tx: nasal decongestants
**No antibiotics, no antivirals, antihistamines vit C questionable
54
```
Describe ACUTE SINUSITIS (rhinosinusitis)
cause:
symptoms:
dx
tx
```
-usually viral
-bacteria: Strep pneumoniea, H.influenzae, S. aureus
-URI + longer 7 days or worsen after 5 days
-bloody nasal discharge, sinus pain, tenderness, toothache, fever, cough
>>osteitis, meningitis, brain abscess, venous infection
-last less than 4 wks
-dx: Xray/CT to see inflammation
tx: nothing or antibiotic if bacterial and worsening; inhale steam, irrigation of nasal
55
PHARYNGITIS - common causes
- usually viral - EBV (mono)
- bacteria: Group A strepto, chlamydia, mycoplasma pneumoniae
- candida : oral thrush
56
Pharyngitis - Streptococcal
-sore throat, fever, abdo, nausea, vomiting, tonsils, lymphnodes, erythema in oral
-self limiting: 3-4days
-antibiotic if risk for rheumatic fever, peritonsillar abscess, worse complications
Dx: throat swab, culture, rapid antigen detection tests
Tx: Penicillin V, amoxicillin
if allergic: Macrolide
if allergic: Clindamycin
57
Pharyngitis - EBV
-Mono
-in teens
-sore throat, fever, lymphnodes
-MonoSpot Test: positive for IgM; CBC
>>can cause neuro issue, spleen rupture, obstruct airway
-Tx: prednisone
58
What are symptoms of laryngotracheitis?
CROUP:
-horse voice, barking cough, inspriatory stridor, possible resp distress
causes: parainfluenza virus, influenza A/B, adenovirus
*agitated children
Tx: IV fluids, oxygen, dexamethasone, epinephrine
-no antibiotics
59
What are symptoms for epiglottitis? causes?
- symptoms: fever, sorethroat, stridor, chills, cyanosis, drooling, breathing diff, swallowing diff, hoarseness
- Chest Xray - see inflammed epiglottis = thumb sign
- Tx: support airway, antibiotics
60
What is acute bronchitis?
-cough, with/wihtout phlegm, up to 3 weeks
-usually viruses: influenza A, B, parainflu, resp syncytial virus, corona, rhino
-bacteria: mycoplasma, chlamydia pneumoniae, pertussis
dx: CXR
-rule out asthma, COPD
tx: salbutamol puffer
no antibiotics
61
What is influenza?
- influenza A & B
- symptoms: fever, myalgia, headache, rhinitis, malaise, cough, sore throat
dx: antigen testing
tx: supportive care; antivirals: AMANTIDINE, ASELTAMIVIR
62
normal body temp?
Febrile neutropenia?
Fever of unknown origin?
- 37.8-37.9degrees C ; abnormal >=38
- FN: >=38.3 or greater than 38 for >=1hr.
- FUO >=38.3 over 3 weeks; no causes found after initial, standard investigations - pt otherwise well.
63
Pathophysiology of fever?
-microbe products > activate leukocytes > IL1, TNF, IFN, IL6 > increase PGE2 > increase hypothalamic set point range
-HYPOTHALAMUS RESETS set point at higher T- thinks we're cold so need heat
-low > heat: shivering, decrease cutaneous blood flow
=CHILLS, FEVER
-common pathway in inflammation
(-high > cooling: increase blood flow, sweating, decrease blood flow)
64
Ddx of fever
```
Infectious
Noninfectious (autoimmunity; increased IL1)
Malignancy
Vascular - thrombosis, dvt
endo/metabolic (ex: thyroid)
drugs (malignant hyperthermia)
```
65
Meds for fever. How do antipyretics work?
*TREAT UNDERLYING CAUSE! not just treat fever alone.
-antipyretics > block COX > decrease PGE2 > block the reset on hypothalamus > block fever changes
ex:
ASA
Acetaminophen -prefered
NSAIDS
-corticosteroids has effects on fever but a lot others too - avoid!
66
adv and disadv of fever?
adv: survival to kill microbes?
disadv: symptoms - chills, sweats, tachy, tachypnea, delirium, myalgia
kids: FEBRILE SEIZURES (T>=39)
67
When is elevated T NOT fever?
| tx?
EMERGENCIES!
* Hyperthermia - setpoint unchanged, T goes up because body can't lose heat
- tx: cooling, specific therapy. NOT antpyretics.
ex: heat stroke, malignant hyperthermia, neuroleptic malignant syndrome
- Hyperpyrexia (T>41)
ex: CNS hemorrhage
- tx: cooling and antipyretics
68
What are common causes of FUO
- changes with time - before infection > malignancy>inflammatory.
- now don't know since we are pretty good at diagnosing the others.
- hx, pe
- usually outcome ok
69
SIRS?
def
causes
systemic inflammatory response syndrome
Need at least 2:
-T>38 or 90
-RR>20 or PaCOs 1200 or <4000 or immature bands
*Causes: INFECTION!
-pancreatitis, burns, trauma, ischemia, hemorrhagic shock
70
Sepsis
=SIRS due to INFECTION
71
Severe Sepsis
-sepsis with organ dysfnc, hypotension, hypoperfusion
| >ICU
72
Septic Shock
-severe sepsis with hypotension that DOESN"T respond to fluid resuscitation and requires pressors
73
Pathogenesis of sepsis?
-host response to infection becomes self-perp, unregulated, adn systemic!
normal inflammation >cytokines > vascular perm, blood flow, cell activation
-too much inflammation > pro-inflamm cells and components spread to non-infected tissues > hypotension, ARDS, thrombosis, hypoxia of tissue, immunosuppression
74
Management of sepsis?
1. treat underlying cause EARLY!
- broad-spectrum antibiotics > narrow spectrum once organism detected
- SOURCE CONTROL: remove lines, brain abscesses, remove blockages, repair ruptured that is causing infection source
2. Goal-directed therapy: Ensure perfusion; resusciate; IV fluids
3. Adjunctive therapy:
- Corticosteroids if septic shock persists even after using IV fluids and vasopressins
- treat to get normal glucose
- enteral nutrition within ~48hrs
