Microbiology, Dr. Lampe Scribe fools: Eric C. and Joe R.
Monday, October 2, 10am
Clinical Spectrum of Staph and Strep Infections
I. Staphylococcal Infections
a. Staphylococcal aureus- gram positive coccus, resistant to penicillin because of β lactamase activity
Is part of normal skin flora and when there is a break in the skin, it can invade causing disease
i. Skin Syndromes
1. Impetigo
a. infection of the skin caused by either Staph or Strep
b. causes crust, boli
c. can’t distinguish by observation if caused by Staph or Strep
2. Bullous impetigo
a. Patient presents with red, large vesicles, blister (bullous)
b. Due to S. aureus producing exfoliation toxin that makes the skin peel
3. SSSS (Staphylococcal Scalded Skin Syndrome)
a. Is from systemic absorption of the toxin that causes the symptoms
b. Body has a Staph infection and that toxin affects the whole body’s skin
c. The skin presents being bright red erythema and tender (looks like a sunburn)
d. Touch of the skin hurts, will have spontaneous peeling (superficial peeling- intraepidermal) like a snake skin
4. Staphylococcal scarletina
a. Presented with fever, bright erythematous rash (looks like sunburn) but no peeling
b. 99% of the time from Group A β hemolytic Strep
c. the erythrogenic toxin of S. aureus has much similarity to TSST (Toxic Shock Staphylococcal Toxin) that causes toxic shock syndrome
ii. Respiratory Syndromes
1. S. aureus does not cause Tonsillopharyngitis (Bold is Key!!!!!!!)
2. Pneumonia/Empyema
a. Pus forming abscess in the pneumothorax- Empyema
i. Can be caused by S. aureus or Group A Strep
ii. Shows purulent fluid (cloudy on X-ray) with a bunch of white cells
b. 90% of Pneumonia have associated Empyema
3. Parotitis
a. inflammation of parotid gland
b. if have MMR, unlike to get parotitis from the mumps virus
c. can get it from other viruses
d. Unilateral parotitis is red and swollen which include Staph as a cause of infection
4. Bacterial tracheitis
a. inflammation of the trachea
b. child gets fever and then stridor (bad wheezes in inspiration), similar to croup
c. etiology include S. aureus
5. adenitis
a. inflammation of a gland
b. inflammation of glands in the neck called cervical adenitis (caused by Staph and Strep)
c. can happen from secondary infection from chicken pox
iii. Bone and Joint syndromes
1. Osteomyelitis
a. Leading cause is S. aureus
b. Most primary is blood-borne (85% of children is primary)
i. When child falls down and breaks in the skin and become bacteremic and it lodges in the bone
ii. Most common bone affected is the femur because it gets most of the blood
c. Secondary osteomyelitis is from direct inoculation (ex. car wrecks and where you break a bone)
2. Septic arthritis
a. Leading cause is S. aureus
b. Can affect many joints of the body
iv. Bacteremia
a. Major cause of morbidity and mortality is from secondary infection from chicken pox
v. Toxic Shock Syndrome
vi. Cardiovascular syndromes
a. Endocarditis
i. Children with congenital heart disease if they have abnormal valves, pressure, damaging their endothelium in their heart, they are susceptible to get a bacterial infection of the heart
ii. Bacteria is always floating around and if it lodges in one of these susceptible areas, endocarditis can occur
iii. Other causes are from rheumatic heart disease (rarely)
iv. Etiology from Staph and Strep (from green α-hemolytic Strep because that is what is in your mouth, can become bacteremic, and can lodge in the damaging areas of the heart- one of the leading causes of endocarditis)
v. Treatment with myriad of antibiotics (covering Staph and Strep)
b. Pericarditis
i. Patient presents breathing fast, tachycardia
ii. Enlarged heart with pericardial sac filled with purulent fluid
iii. Etiologies are Staph and Strep
vii. Staphylococcus epidermis- not pathogenic in normal hosts (coagulase negative Staph)
a. Most likely infection of the CNS shunt is S. epidermis because on the skin of immunocompromised host
b. Can be a contaminant because it is on everybody’s skin
II. Streptococcal Infections
a. Streptococcal infection
i. Skin Syndromes
1. Erysipelas
a. Skin infection from Strep (Group A β hemolytic)
b. Presents very tender, red, well-defined border
2. Scarlatina
a. β hemolytic Strep Group A in a clinical presentation causes it 99% of time
b. can occur 3 times (because 3 types of toxin, A, B, C)
c. Group A Strep making erythrogenic toxin
3. BDD (blistering distal dactylitis)
a. Caused by Group A β hemolytic Strep
b. Can get through thumb sucking of a child causing blisters in the thumb
ii. Respiratory Syndromes
1. Tonsillopharyngitis
a. The leading cause of Tonsillopharyngitis is Group A β hemolytic Strep
b. There is only 2 non-pus forming or non-supporative that come from Group A tonsillopharyngitis (are Rheumatic fever “heart” and Acute Glomerulonephritis “kidney”)
c. Usually pus forming (exudate) with tender anterior cervical nodes during winter time, school-age children, without a running nose
2. Peritonsillar abscess
a. Mass on the anterior tonsillar pillar (on the soft palate)
b. Person has a voice that sounds like they are having problems, they’ll have trismus (persistent contraction of the masseter muscles, where you can’t open your mouth well)
c. Can be polymicrobial (Strep and Staph along with other anaerobes)
3. Mastoiditis
a. Mastoid air cells that connect to middle ear cavity
b. Ear cavity can get infected with Strep
4. TURF (Typical Upper Respiratory Flora)
a. Generally group A is not normal flora, expect to see Staph as normal flora
iii. Soft tissue syndromes
1. vaginitis
a. children, strep in throat ends up on hands and can travel everywhere
2. perianal cellulites
a. children, strep in throat ends up on hands and can travel everywhere
iv. Lancefield Group B neonatal sepsis
1. leading cause of neonatal sepsis which is S. agalactiae (group B β hemolytic Strep)
2. passed to little babies when they go through the birth canal because mothers carry it in their vaginal flora or rectal flora (20-30% of women carry it)
3. if a mother is Group B strep positive at the time of delivery, mother is given antibiotics before labor which reduces Group B strep in children
v. Leading cause of joint infections in little babies is S. aureus (the same as osteomyelitis and septic arthritis)
1. what happens is that when the baby comes through the birth canal, they experience some trauma and then that bacteria lodges in some of the joint areas
2. humerus is the favorite place to lodge instead of femur in babies because of the trauma associated with delivery (babies head and shoulders come out first)
vi. Streptococcal Toxic shock like syndrome
1. usually from secondary chicken pox infections
2. fever in the late phase of chicken pox, that’s from secondary bacterial infection (Staph or Strep)
3. leading cause of secondary infection is β hemolytic Group A Strep or Staph