Micro: Intro & Bacteria & others Flashcards
Staphylococcus?
ex?
what is coagulase-negative staph?
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)
Streptococcus?
ex?
alpha vs beta hemolytic?
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!
Enterococcus?
causes»
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
Corynebacterium?
gram+ve baccilli aerobe (look like zigzag Vs) -normal flora: ex: C. jeikeium, C. urealyticum, C. diphtheriae causes: UTI
Bacillus?
gram+ve baccilli aerobe -forms spores -normal flora: skin ex: B. anthracis
Ecoli
gram-ve, baccilli, aerobe
-normal flora: GI
-contact
virulence: fimbriae, hemolysin, flagella, cytoxin, enterotoxin
» UTI, hospital-ac pneumonia, abdo, gastroenteritis
Haemophilus?
gram-ve
coccobacilli
aerobe
-normal flora: oropharynx
H.influenzae
-contact, droplet
virulence: capsule IgA protease
»pneumonia, sinusitis, otitis media, meningitis
Neisseria?
gram-ve diplococci aerobe -normal flora: ex: N. meningitidis, N. gonorrhea
Clostridium?
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
Bacteroides?
gram-ve baccilli ANerobe -normal flora: GI virulence: lipase, protease, capsule >>intraabdo abscesses, bacteremia
Gram Staining procedure?
- 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)
Why does gram staining work?
- 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
Yeast?
ex?
-fungi
-single eukaryotic, ovoid/spherical
-rigid cell wall
-budding
fuzzy, hyphae
ex: Candida
Chlamydia trachomatis?
atypical bacteria: inracellular
- GU tract
- contact
virulence: intracellular
> > UTI, pelvic inflammatory disease
Staphylococcus aureus? morph: resevoir: transmission: virulence factors: causes>
-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
What is Protein A?
M protein
A; binds Ab to prevent action
M: prevents phagocytosis
-virulence factor for bacteria
Virulence Factors are based on 2 things?
- invasion
- host damage
Staphylococcus epidermidis?
- gram+ cocci, aerobe, clusters
- skin
- contact
virulence: adhesins, capsule, biolfilm - less virulent than S.aureus
What is group A strep?
-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)
Streptococcus pneumoniae?
-gram+, DIPLOCOCCI, aerobe
-normal flora: oropharynx
-droplet, contact
-virulence: capsule, autolysin, pneumolysin, protein A
» pneumonia, sinusitis, otitis media, meningitis, bacteremia
What are enteric pathogens?
GI: gram-ve bacilli
ex: ecoli, salmonella, shigella, campylobacter
virulence: enterotoxin, cytotoxin
> > gastroenteritis: diarrhea, hemolytic uremic syndrome, bacteremia
Neisseria meningiditis?
- gram-ve DIPLOCCI, aerobe
- oropharynx
- contact, droplet
- virulence: capsule, IgA protease, endotoxin
> > meningitis, meningococcemia
Neisseria gonorrhoeae
- gram-ve DIPLOCCI, aerobe
- GU tract
- contact
- virulence: pili, antigenic variation, IgA protease
> > UTI, pelvic inflammatory disease, gonoccocemia
What are atypical bacteria?
ex?
- intracellular (chlamydia)
- lack rigid cell wall (mycoplasma)
- acid fast bacilli (mycobacterium)
- partial acid fast (nocardia)
- spirochetes (treponema pallidum)
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
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
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
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
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
Normal flora:
skin, oropharynx, colon, GU?
- skin: staphylococcus, corynebaceterium, bacillus
- oropharynx: streptocci, neisseria, harmophilus, candida
- colon: enterococcus, ecoli, bacteriodes, clostridium, candida
- GU: streptococci, candida
Benefits vs harm of normal flora
Benefits:
- helps train immune system
- infection prevention
- nutrition
- digestion
Harms:
- opportunistic infections
- contaminations
Define virulence factors? pathogenicity?
vf = traits that make organism pathogenic
p=ability to cause disease
Define resevoir. ex?
- living/nonliving thing on which organism lives
ex: human, animal, soil, objects
Define incubation period?
-time of entry > first sign/symptoms
Define period of communicability?
-time agent able to be transmitted
What are control measures?
- to reduce transmission
- public health, hospital infection control
What are public health control measures? (6)
- vaccination
- post-exposure prophalyxis
- reporting systems to surveillance
- contact tracing
- quarantine
- outbreak investigation
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
(7) steps of outbreak investigation?
- confirm outbreak
- define cases
- epicurve, line listing
- assemble team
- control measures
- evaluate
- decide when its over
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
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
Chest Xray - what’s white and black?
higher density = white bone soft tissue/water blood air=black
airspace disease (Consolidation) vs instititial disease (edema)
c: white lungs, see airways, loss of borders
institial: see thick white borders
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
Signs of edema on CXR?
- instititial disease
- cardiomegaly
- see extra lines: kerly B, thicker fissures, thickened bronchioles (cuffing), “butterfly” (borders are spared)
pathogenesis of pneumonia (3 mech)
- Aspiration - normal flora down resp, inhalation from vomiting, those on ventilation
- Inhalation- inhale aerosols with streptrococci pneum
- Hematogenous-
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
What is pneumonia?
- infectio of lungs > proliferation of organism in alveoli > inflammation.
- lower resp tract
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
Complications of pneumonia
- lung abscess
- empyema - pus in pleural space
- PEffusion
- bacteremia
- metastatic infection
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)
Tx for pneumonia
- Supportive: oxygentation, hydration
- antimicrobial drugs
prevention: flu vaccine, pneumococcal vaccine
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
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
PHARYNGITIS - common causes
- usually viral - EBV (mono)
- bacteria: Group A strepto, chlamydia, mycoplasma pneumoniae
- candida : oral thrush
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
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
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
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
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
What is influenza?
- influenza A & B
- symptoms: fever, myalgia, headache, rhinitis, malaise, cough, sore throat
dx: antigen testing
tx: supportive care; antivirals: AMANTIDINE, ASELTAMIVIR
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.
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)
Ddx of fever
Infectious Noninfectious (autoimmunity; increased IL1) Malignancy Vascular - thrombosis, dvt endo/metabolic (ex: thyroid) drugs (malignant hyperthermia)
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!
adv and disadv of fever?
adv: survival to kill microbes?
disadv: symptoms - chills, sweats, tachy, tachypnea, delirium, myalgia
kids: FEBRILE SEIZURES (T>=39)
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
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
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
Sepsis
=SIRS due to INFECTION
Severe Sepsis
-sepsis with organ dysfnc, hypotension, hypoperfusion
>ICU
Septic Shock
-severe sepsis with hypotension that DOESN”T respond to fluid resuscitation and requires pressors
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
Management of sepsis?
- 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 - Goal-directed therapy: Ensure perfusion; resusciate; IV fluids
- Adjunctive therapy:
- Corticosteroids if septic shock persists even after using IV fluids and vasopressins
- treat to get normal glucose
- enteral nutrition within ~48hrs
