Infections - Skin, Ocular, Respiratory, Sterile Body Sites Flashcards
Normal flora of skin
- Diphtheroids
- S. epidermidis
- Other coag neg staph
- Propionibacterium (Cutibacterium) acnes
Folliculitis
Minor hair follicle infection
Papules or pustules pierced by a hair with redness
Furuncle (boil)
Abscess that started off as a red nodule with a hair follicle
Painful, full of pus
Carbuncle
Furuncle that spreads into deep dermis and subcutaneous tissue
Usually have multiple sites
Drain to skin surface (sinuses)
Macule
Flat, discoloration of skin
Dermatophytes, T. pallidum, Enteroviruses
Papule
Elevated, solid lesion (<5 mm diameter)
HPV, pox virus, scabies, S. aureus, P. aeruginosa
Nodule
Raised, solid lesion (>5 mm diameter)
Corynebacterium diphtheriae, Sporothrix schenckii (Rose Gardener’s Disease), fungi, Mycobacterium marinum (fish), Nocardia sp.
Rose Gardener’s Disease
Sporothrix schenckii
Pustule
Raised, pus filled lesion with leukocytes and fluid
Candida sp., dermatophytes, HSV, N. gonorrhoeae, S. aureus, GAS, varicella-zoster virus
Vesicle
Raised, fluid filled (blister-like) lesions (<5 mm diameter)
Varicella-zoster virus
Bulla
Raised, fluid filled lesions (>5 mm diameter)
Clostridium (gas gangrene), HSV, G(-) rods, S. aureus, vibrios
Scales
Dry, horny, platelike lesions
Dermatophytes
Ulcer
Lesion with loss of epidermis and dermis
B. anthracis, bowel flora, Haemophilus ducreyi, T. pallidum
ErySIPELAS
Painful, red, swollen lesions
Fever
Regional lymphadenopathy
GAS, Group B, C, G strep sometimes
Cellulitis
Infection spreading to deep layers of the dermis
GAS, S. aureus
Impetigo
Erythematous lesions
GAS (nonbullous)
S. aureus (bullous)
Dermatophytosis
Fungal infection
Ringworm
EryTHRASMA
Chronic infection of keratinized layer of epidermis
Corynebacterium minutissimum
ErySIPELOID
Purplish lesion with irregular, raised border
Erysipelothrix rhusiopathiae
Necrotizing fasciitis caused by
GAS
S. aureus
Bacterial synergistic gangrene caused by
Microaerophilic strep
S. aureus
Myositis
Inflammation of muscle
S. aureus - hematogenous spread (gets into blood)
Most common postoperative infection agent
S. aureus
Animal bite agents
Pasteurella
Fusobacterium
Burn agents & why are burns bad?
S. aureus
P. aeruginosa
Enterococci
Enterobacter
E. coli
Skin is unable to protect
Diabetes patients
Foot infection
Agents: S. aureus, GAS, Enteric/E. coli, anaerobes
Collection for:
- Erysipelas & cellulitis
- Vesicles
- Bullous lesions
- Wound infections
- Erysipelas & cellulitis - clinical observation mainly but can culture swab of lesions
- Vesicles - swab and culture
- Bullous lesions - blood culture
- Wound infections - anaerobic conditions
Normal eye flora
S. epi
S. aureus
Lactobacillus
Propionibacterium (Cutibacterium) acnes
H. influenzae
Blepharitis
Inflammation of eyelids/glands near eyelids
- Stye/cyst
- Bacteria: S. aureus
- Parasite: Phthirus pubis (louse on eyelashes)
- Viruses: HSV
Conjunctivitis
Inflammation of conjunctiva
- Pink eye
- Allergies/infection
- S. pneumo, S. pyogenes (GAS), S. aureus, Haemophilus, Chlamydia trachomatis, N. gonorrhoeae, Moraxella sp
- Viruses: Adenoviruses, HSV, VZV
Keratitis
Inflammation of cornea (can cause ulcers and lead to blindness)
- Reduced vision, sudden pain, sensitivity to light, excessive tearing/discharge
- Non-infectious: from contact lenses
- Infectious: from bacteria, viruses, fungi, parasites
- Bacteria: S. aureus, S. pneumo, P. aeruginosa (cause green in eye), Moraxella, Bacillus
- Viruses: Adenoviruses, HSV, VZV
Chorioretinitis & uveitis
Inflammation of retina and choroid/uvea
- Blurred vision, pink eye, light sensitivity, continuous tearing
- Candida, Toxoplasma, Toxocara (roundworm), M. tuberculosis, T. pallidum, B. burgdoriferi
- Viruses: Cytomegalovirus (CMV), HSV
Endophthalmitis
Infection of aqueous or vitreous humor (liquid in the eye)
- usually after surgery or trauma, can lead to blindness
- Bacterial or fungal
Lacrimal infections and canaliculitis
Inflammation of lacrimal canals
- Actinomyces, Propionibacterium
Dacryocystitis
Inflammation of lacrimal sac (near tear duct)
- S. pneumo, S. aureus, S. pyogenes, H. influenzae
- Fungi: Candida albicans, Aspergillus sp
DacryoADENITIS
Inflammation of lacrimal gland (outer eyelid, near brow)
- Viruses (most common): mumps, EBV, VZV
- Bacteria: S. pneumo, S. aureus, S. pyogenes, T. pallidum, C. trachomatis
Tzanck smear
HSV
- multinucleated epithelial cells
For eye gram stain
Normal ear flora
Normal flora of external ear canal is sparse
Pneumococci
Propionibacterium (Cutibacterium) acnes
S. aureus
Enterobacteriaceae
P. aeruginosa
Candida sp
Otitis Externa
Acute:
S. aureus
S. pyogenes
P. aeruginosa
Other G(-) rods
Chronic:
P. aeruginosa
Anaerobes
Otitis media
Middle ear infection
Mastoiditis - infection of bone
- Acute: S. pneumo, H. influenzae, Moraxella catarrhalis, S. pyogenes, influenza virus
- Chronic: anaerobes
Laryngitis
Inflammation of larynx (vocal cords)
- Symptoms: hoarseness/weak/loss of voice, tickling sensation, rawness
- Cause: overuse or irritation (yelling, smoking, viral or bacterial infection)
- Treatment: supportive care (biopsy in chronic case)
Epiglottis
Above vocal cords
Cause swelling/blockage of trachea —> can be life threatening
- Symptoms: fever, severe sore throat, difficulty swallowing and breathing
- H. influenzae, pneumococcus, Group A, B, C strep
- Culture is not recommended
Parotitis
Inflammation of salivary glands under cheeks
- Symptoms: swelling of tissues, dry mouth, strange taste, mouth or facial pain, fever, chills
- Sjogren’s syndrome (autoimmune)
- Bacteria: S. aureus, strep, Haemophilus
- Viruses: Mumps, parainfluenza, influenza, CMV, EBV, HIV
Rhinitis (common cold)
Viral infection of URT
- Symptoms: sore throat, cough, watery eyes, sneezing, congestion, low grade fever, mild fatigue
- Associated with rhinovirus
- Higher risk in preschool children
- No treatment necessary unless fever, etc.
Pharyngitis - Tonsillitis
Infection of pharynx —> sore throat
- Symptoms: tonsil abscesses, upper airway obstruction, can become systemic (rheumatic fever, acute glomerulonephritis)
- Can be caused by viruses in colder months
- Bacteria: S. pyogenes (primary), Group C and G strep, Arcanobacterium haemolyticum (in adolescents)
Diphtheriae
- Symptoms: febrile/fever, sore throat, malaise
- Pseudomembranous membrane - main sign of diphtheria, exudate or gray-white membrane forms on tonsils
- Corynebacterium diphtheriae
- Throat swab. SBA, CTBA, TIN, Loeffler slant, Elek test. Incubate 35°C in O2 or 5-10% CO2 for 48 hrs
Whooping cough
- Bordetella pertussis
- Symptoms: dry cough, fever, runny nose, paroxysmal (violent) cough
- Nasopharyngeal swab (incubate directly at patient’s bedside), culture must contain charcoal because fastidious. Incubate 35°C O2
Vincent’s angina
- Fusobacterium
- Trench mouth: acute necrotizing ulcerative gingivitis
Sinusitis
Acute: postnasal discharge, pressure over sinus area. H. influenzae, S. pneumo, S. pyogenes, Moraxella cat
Chronic: inadequate drainage, impaired mucociliary clearance, mucosal damage
Stomatitis
Inflammation of oral cavity mucous membranes
Canker sores (non contagious) and cold sores (HSV)
Thrush
White patches on exudate on cheek, mucosa, tongue, or oropharynx
Candida sp.
Periodontal infections
Root canal and orofacial odontogenic: anaerobes, streptococci
Perimandibular space: staph, Eikenella corrodens
Neck Infections
Caused by oral flora - anaerobes, Viridans strep
How to collect for URT infections
Calcium alginate swab is best for cultures
- Do not use cotton swabs for Neisseria or Bordetella
- Dacron or rayon are best for PCR
- Keep swabs moist for 4 hours, except GAS can stay dry
Throat swabs (URT)
GAS
Corynebacterium diphtheriae
Mycoplasma
Chlamydia
Candida
Nasopharyngeal swabs (URT)
Bordetella, Neisseria
Bronchitis (LRT)
Inflammation of tracheobronchial tree
Bronchiolitis (LRT)
Inflammation of smaller diameter bronchiolar surfaces (causes obstruction from swelling)
Pleural Infection (LRT)
Organisms infect lungs and go into pleural spaces (covering of lungs)
Empyema - pus in body cavity
Pleurisy - inflammation of pleura
Typical/acute pnuemonia & community-acquired pneumonia in adults
S. pneumoniae
Think “S” for senior
Atypical pneumonia & community-acquired pneumonia in young adults (under 30 yo)
Mycoplasma pneumoniae
Think “M” as in me
Community acquired pneumonia in children under 5
Viruses: RSV, parainfluenza, influenza
Bacteria: S. aureus, S. pneumoniae, M. pneumoniae, C. pneumoniae, H. influenzae
Hospital-Acquired Pneumonia
Increased risk in intubated patients
P. aeruginosa, Enterobacter, Klebsiella, S. aureus (MRSA emerging), Acinetobacter, S. pneumo, anaerobes, Legionella, H. influenzae
Most likely cause of chronic LRT infections
M. tuberculosis
Patients with AIDS have a high risk for
Pneumocystis jirovecii
Specimen collection of LRT
Bronchial brush
Other invasive techniques
What defines a good gram stain for LRT?
<25 WBC
Little or no squamous cells
Transudate vs Exudate Pleural Fluid Effusion
Transudate - without inflammation, fluid leaks out from tissue. High fluidity, low protein/solid material content
Exudate - with inflammation, fluid escapes from blood vessels and goes to tissues. High protein/cellular debris due to inflammation. Everything is increased in Exudate, may clot
Pleural Fluid
Lines thoracic cavity, lubricates the pleura
Peritoneal Fluid
Lines abdomen
Ascites
Accumulation of fluid in peritoneal cavity
Peritonitis
Inflammation of peritoneal membrane
Primary: Infection spread from blood and lymph nodes
Secondary: trauma, surgery, perforated organ, obstruction
Peritoneal Dialysis Fluid
During end stage of renal disease
Fluid injected into peritoneal cavity to allow salt and water exchange and remove waste products (that is typically done by the kidneys)
Pericardial Fluid
Around the heart, typically caused by viruses
Myocarditis
Inflammation of heart muscle
- Coxsackie virus, Echovirus, Adenovirus
Joint (Synovial) Fluid
Arthritis - inflammation of joint space
Hematogenous spread, infection from bone, injection/insertion of material (like hip replacement)
Septic arthritis caused by
S. aureus (most common)
N. gonorrhoeae (young adults)
H. influenzae (young children)
Strep
anaerobic bacteria (Bacteroides)
Osteomyelitis
Infection of bone
Children: affects long bones (legs and arms)
Adults: spine
Result of hematogenous spread, invasion of bone, trauma/surgery, poor circulation (diabetes)
Collection of Solid Tissue
Sterile container, mince specimen
Meninges layers
Dura mater (outer)
Arachnoid
Pia mater (inner)
Meninges is the inner CNS covering
CNS consists of
Brain and spinal cord
What are the two coverings of CNS?
Meninges (inner)
Bone (outer)
Cerebrospinal fluid
Surrounds brain and spinal cord (CNS)
In subarachnoid space
Cushions brain from injury, removes waste, carries metabolites
Meningitis
Infection of subarachnoid space (between brain and skull)
2 categories: Purulent (many PMNs) vs Aseptic (viral, many lymphocytes)
S. pneumoniae, N. meningitidis, H. influenzae, Listeria monocytogenes, E. coli, GBS
Most common bacterial meningitis in adults
S. pneumoniae
Why can neonates get Acute Meningitis?
- Immature immune system
- Increased blood-brain barrier permeability
- Bacteria in vaginal tract
Most common pathogens: GBS, E. coli, Listeria monocytogenes
Encephalitis and Meningoencephalitis
Encephalitis - inflammation of brain parenchyma, accompanied with Meningoencephalitis
Viral (Enteroviruses, mumps, HSV, arboviruses)
Glucose and cell count will be ___ in Acute Bacterial Meningitis
Glucose reduced
Cell count increased (lymphocytes increased)
How can you tell if there is a contaminant vs pathogen in a blood culture?
Contaminant: multiple organisms, clinical presentation not consistent with sepsis, organisms from primary site are not the same as organisms in blood culture.
- Bacillus, Corynebacterium, Propionibacterium acnes, coagulase negative Staph grow
Pathogen: same organisms grown in repeated cultures, suspected pathogens grow, certain organisms like GAS grow, commensal flora is isolated from patients with suspected bacteremia
