Week 12 - Microbiology I Flashcards
Candidiasis
Gastroenteritis
Skin and Soft Tissue Infections
from superficial to deep
- Impetigo
- Erysipelas
- Furuncle
- Cellulitis
- necrotizing fasciitis
- pyomyositis
Skin and Soft Tissue Infection: Impetigo
presentation, etiology, treatment
Presentation
- Discrete purulent vesicular papular infection
Etiology
- S. pyogenes
- S. aureus
- peak children age 2-5
Treatment
- mupirocin ointment tid x7 days
- cephelexin, clindamycin, or amoxicillin x 7days
Skin and Soft Tissue Infection: Cellulitis
presentation, etiology, treatment
Presentation
- diffuse, spreading skin inflammation due to infection involving deeper dermis and subcutaneous fat
- occurs in any location but most common in lower extremities
Etiology
- S. pyogenes
- S. aureus
- enters through breaches in the skin ( tinea pedis, stasis dermatitis, wound)
Treatment
- elevate, treat underlying condition (route of entry)
- typically oral meds - cephalexin, clindamycin
- severely ill, cant tolerate oral - vancomycin, cefezolin, cloxacillin, clindamycin
- duration - 7 to 10 days
Recurrent?
each attack causes lymphatic inflammation and possible permanent damage
Tuberculosis
what, risk factors, etiology, pathogenesis, diagnosis/manage, prevention
A disease that primarily affects the Lungs but can also affect other systems like the brain, kidney, spine
Risk Factors -
- HIV
- chronic Kidney disease needing dialysis
- transplantation related immunosupression
- undernourished or underweight
- diabetes
- smoking
- TNF-alpha inhibitor
- Poverty, low SES
- in Canada -> indigenous communities, those in prisons
- immigrants from endemic regions
Etiology
- mycobacterium tuberculosis complex
- nocardia spp
Pathogenesis
- transmission through aerosolization of infectious particles through coughing
- TB aerosolized –> inhaled into alveoli of new host –> macrophages take up TB, T cell accumulation and macrophage recruitment –> 5% reactivation, 95% no disease –> Laten TB Infection –> granuloma formation in lung
Diagnosis
- could be diagnosed 1) active TB disease or 2) Latent TB infection (LTBI)
- active TB –> ongoing active disease making the person sick, possibly infectious, requires treatment and public health reporting –>
a) CXR
b) sputum for direct acid-fast smeer
c) mycobacterial culture and drug susceptibility testing (DST)
d) Nucleic acid amplication tests
- LTBI –> not sick, at risk of reactivation in the future –> diagnose with TB skin test and the Interferon-gamma release assay
- chest infiltrate along with signs and symptoms
- sputum for gram stain and Culture and Sensitivity (C&S)
- 2 blood culture sets
Management:
standard
- initial phase (first 2 months)
- INH (isoniazid), RMP (rifampin) , PZA (pyrazinamide), EMB (ethambutol) ( daily ( or 5days/week)
- continuation phase
- INH, RMP for 4 months daily (or 3 time/week)
Elderly or at risk for hepatotoxicity is the same except no PZA
Prevention
- airborne precautions - N95 mask
- Ventilation
- Negative Pressure
- HEPA filter
- Short wave ultraviolet germicidal irradiation
Sepsis and Septic Shock
Pneumonia
what, risk factors, etiology, pathogenesis, diagnosis/manage, prevention
Infection of the lung parenchyma
Risk Factors -
- age 65+
- smoking
- alcohol abuse
- asthma
- immuno suppression
- seasonal (flu season)
Etiology
CAP
- streptoccocus pneumoniae
- haemophilus influenzae
atypical
- legionella pneumophila
- chlamydophila pneumoniae
HAP
- more likely gram negatives like Enterobacteriaceae, Pseudomonas
- S. aureus
Pathogenesis
- microaspiration, normally oropharyngeal flora –> alveolar macrophage phagocytose them –> organism evades and multiplies –>immune response in alveolar sac = no air exchange in alveolar sacs
Diagnosis
- history and physical, CXray
- chest infiltrate along with signs and symptoms
- sputum for gram stain and Culture and Sensitivity (C&S)
- 2 blood culture sets
Management
- CRB-65 assessment : Treatment at home -> hospital treatment -> urgent hopsital admission
Prevention
- smoking cessation
- vaccination
- reduce alcohol
General Classification of Microorganisms
- Bacteria
- Viruses
- Fungi
- Parasites
Classification of Bacteria
- gram staining (- or +)
- microscopic morphology
- aerobic or anerobic
Gram Staining
Gram positive - thick peptidoglycan
gram negative - thin peptidoglycan
- apply a primary stain (crystal violet)
- add a mordant to set the stain (iodine)
- quick rinse with alcohol to decolorize, rinse with water
a. gram positive - purple
b. gram negative - clear - counterstain with safranin. drain rinse and blot
a. gram + cocci = purple
b. gram - rods = red(pink)
Common Modes of Transmission
- Contact (direct, indirect, fecal-oral)
- Droplet
- Airborne
- Vector Borne
Public Health Measures
- Vaccination
- Post-Exposure Prophylaxis (PEP/PrEP)
- Mandatory reportable disease
- Contact tracing
- Quarantine
- Outbreak Investigation
Streptococcus pyogenes
Neisseria gonorrhoeae
