In Da Club (Diphtheria)
What are the 1st line antibiotics for diphtheria? (bonus points for administration route & length of Tx)
erythromycin PO for 14 days
penicillin G IM until pt can tolerate oral, then penicillin V PO for 14 days
A 21-year-old male is transferred from a community hospital for suspected necrotizing fasciitis. He was seen today at their ED. Two days ago, he suffered an accidental traumatic injury and abrasion of the left knee. Today he complains of extreme thigh pain, weakness of the leg, and a rash on the thigh. CT scan there shows marked inflammatory stranding and low attenuation with suspicion of necrosis in the rectus femoris. Intravenous clindamycin and piperacillin/tazobactam were started and the patient transported. On arrival he is febrile at 40°C (104°F), blood pressure 90/60, heart rate 120, respirations 24, satting 98% on room air. He is in significant distress. There is crepitus in the thigh. He is bolused with fluids and taken to the OR for debridement. Blood cultures from this admission are negative, though blood cultures from the initial presentation match cultures of the debrided infected tissue. They reveal bacitracin-sensitive, catalase-negative, Gram-positive cocci that are β-hemolytic.
Based on the information, what is the most likely organism?
Streptococcus pyogenes
How many craniovertebral joints are there & what are they?
bonus points if you can describe the motion at each
1 atlanto-occipital joint (nod yes)
2 lateral atlanto-axial joints (gliding)
1 median atlanto-axial joint (pivot)
What direction should you pull the auricle when visualizing the tympanic membrane? (bonus points if you can compare/constrast what TM looks like in otitis media vs normal)
superiolaterally
normal: translucent with cone of light & malleus
otitis media: erythema, cloudy TM, no cone of light visible
Describe the spleen & its immune function.
splenic a. brings APCs in; splenic v. brings APCs out.
white pulp = immune function (cortex is lined with B cells & paracortex lined with T cells is right behind it — deepest spot/medulla there are capillaries where APCs gain access to these centers)
red pulp = hematologic function (large spaces between capillaries so RBCs, WBCs, platelets get through capillaries - if its too big to get through fenestrated capillaries, it gets killed (most pathogens are smaller than APCs & can fit through))
List as many characteristics of Corynebacterium diphtheriae as you can remember. (bonus points if you can list more than 5)
gram-positive bacilli ("club-shaped")
non-motile
catalase positive
acid-fast negative
non-encapsulated
aerobic (facultative anaerobe)
grows best on blood or serum-containing agar
A total of 18 people attending a retirement party became ill, all within 3–4 hours of food being served. A combined nausea and vomiting was predominant, but over half also had diarrhea. No one appeared febrile. After 24 hours, the syndrome remitted spontaneously. Investigation of the food led to the discovery of Staph. aureus contamination of the ham. It was discovered that the preparer of the food had cooked the ham at home, transported it to her workplace, sliced it while it was hot, then refrigerated the ham covered with foil. The ham was served the next day without being reheated.
Given the clinical syndrome, what is the most likely pathogenic mechanism?
enterotoxin A
Name what structures are derived from the 4th pharyngeal arch.
BV: right subclavian a., aortic arch
N: CN X (superior laryngeal n.)
M: cricothyroid m.
skeletal: epiglottic & thyroid cartilages
What 3 supplements can be taken daily to help prevent infection?
vitamin C
vitamin D
zinc
Describe the process of T cell maturation in the thymus.
bonus points if you correlate to histology
T cells undergo positive selection (survive if they bind MHC molecules presenting foreign antigens) in the cortex & negative selection in the medulla (survive if they do not bind self-antigens)
Explain the pathogenesis of Corynebacterium diphtheriae infection. (Be specific)
1. C. diphtheriae enters nose & mouth via respiratory droplets or enters breaks in skin via contact with fomites or wounds.
2. adheres to cells in nose, throat, tonsils, or larynx (if inhaled) via pili or fimbriae
3. secretes diphtheria toxin (DT)
4. DT binds to heparin-binding epidermal growth factor (HB-EGF) receptor, which is present on heart & nerve cells
5. DT-receptor complex is taken up via endocytosis
6. proteases & acidic environment of vesicle changes the shape of DT
7. A subunit of DT is released into cytoplasm & ADP-ribosylates elongation factor-2 (EF-2), terminating host cell protein synthesis & killing the cell
A 76-year-old woman is in the intensive care unit being treated for E. coli pyelonephritis and bacteremia. It is day seven of piperacillin/tazobactam: the blood cultures have cleared, but she has not improved. Her lactic acid remains elevated and her blood pressure low despite infusion with vasopressors—norepinephrine and vasopressin. Both her urine cultures and blood cultures grew E. coli. She is sedated, paralyzed, and on ventilator support. Her prognosis is grim.
What is most likely responsible for her current condition?
lipopolysaccharide
(specifically lipid A)
What type of gland is the ceruminous gland? (bonus points if you can explain what this word means)
apocrine
cell secretes cytoplasm & proteins alongside secretory material; compared to holocrine (cell lysis ---> contents released into ECM as the secretion) & merocrine (cell secretes secretory material & none of the cellular material is released)
Name the somatic dysfunction of a person whose SC joint doesn't move when they horizontally flex their shoulder. (bonus points if you can describe the appropriate treatment)
horizontal flexion = protraction should pull the SC joint posterior; if it doesn't then the SC joint is anterior/horizontally extended
Tx: push SC joint posterior while you move pt ipsilateral arm medially (see photo)
What vaccines should a 9-year-old have (if on vaccine schedule as indicated by CDC)?
birth: HepB, RSV
1-2 mo: DTaP (diphtheria, tetanus, pertussis), Hib (H. influenzae), IPV (polio), PCV (pneumococcal), Rotavirus
7 mo: start getting annual flu
1 yr: chickenpox, HepA, MMR (measles, mumps, rubella)
An 8-year-old male is brought to the emergency department for evaluation of a sore throat and fever. The family recently immigrated to the United States from Ecuador and have yet to establish primary care with a pediatrician. The child's medical history is unremarkable. The mother denies any sick contacts. Physical examination reveals pharyngeal erythema and edema with gray exudate. Bilateral, tender cervical lymphadenopathy is present. A throat culture is performed and grows non-spore-forming, gram-positive rods. What is the most appropriate next step?
administration of a preformed antibody that binds to a bacterial toxin (antitoxin)
A 5-year-old male is brought to a local urgent care by his father for an odd noise the child is making. They are migrant workers and have immigrated from Mexico. The family has received no vaccinations. The patient presents with a series of coughing fits, interrupted by loud whoops of inhalation. He had two weeks of rhinorrhea, malaise, fever, and anorexia. The fever and malaise have disappeared but now he has the coughing fits. Sometimes he coughs so hard for so long that he vomits. PCR is positive for pertussis toxin.
On what agar will the diagnosis be confirmed?
Bordet-Gengou agar
A 32-year-old man presents with a 1-week history of hearing loss in his right ear. He denies a history of audiological problems, otalgia, otorrhea, or a recent upper respiratory infection. He reports frequent use of earbuds to listen to music. On physical examination, the pinnae appear normal bilaterally. The left ear canal has a significant amount of cerumen, but the tympanic membrane is visible and appears normal. The right ear canal is completely occluded by cerumen, and the tympanic membrane cannot be visualized. What are the expected findings of Weber and Rinne tuning fork tests?
Weber lateralizes to right: Rinne negative
What are the steps of ENT lymphatic drainage (in order)? (bonus points if a team member demonstrates on a peer)
1. facilitated segments - paraspinal inhibition (ST) T1-T4
2. thoracic inlet release (MFR)
3. suboccipital release (ST)
4. hyoid/anterior cervical arches release (ST)
5. cervical chain drainage
6. submandibular drainage (MFR)
7. Galbreath technique/mandible drainage (ST)
8. auricular drainage (ST)
9. frontonasal distraction
10. trigeminal nerve stimulation
11. facial effleurage
Name 3 inflammatory mediators, their source, & function.
- histamine (from mast cells, basophils, platelets): vasodilation, vascular permeability, endothelial activation
- prostaglandins (from mast cells, leukocytes): vasodilation, pain, fever
- leukotrienes (from mast cells, leukocytes): vascular permeability, chemotaxis, leukocyte adhesion & activation
- cytokines (TNF-alpha, IL-1, IL-6; from macrophages, endothelial cells, mast cells): local- expression of adhesion molecules, systemic- fever, vascular permeability
- chemokines (from leukocytes, activated macrophages): chemotaxis, leukocyte activation
- complement (plasma): chemotaxis, kills organisms
A 35-year-old male presents to the clinic with the complaints of sore throat and trouble swallowing. The patient is an Iranian immigrant who states that his throat discomfort has been getting worse over the past 4 days. The patient says he has not been eating because of the pain. Physical examination reveals mild fever and a dark gray coating in the back of the mouth. Palpation of the neck reveals enlarged cervical lymph nodes and signs of edema. The organism causing this disease has what mechanism of action?
blocks protein synthesis (EF-2)
C. diphtheriae releases A subunit of diphtheria toxin into host cell, which ADP-ribosylates EF-2, resulting in cell death.
A 16-year-old male is brought to the emergency department by his father due to difficulty breathing. The patient also has a sore throat but tested negative on a rapid streptococcal antigen test at an urgent care center last week. The patient reports mild weight loss due to early satiety and has frequently fallen asleep in class over the past month. He denies nausea, vomiting, chills, dysuria, or myalgias. He has never been sexually active. His past medical history is significant for attention-deficit/hyperactivity disorder and oppositional defiant disorder. His medications include methylphenidate and a daily multivitamin. Vital signs include a temperature of 37.0°C (98.6°F), blood pressure of 110/85 mmHg, heart rate of 130 beats/min, and respiratory rate of 28 breaths/min. The patient is in obvious respiratory distress. Cardiopulmonary auscultation is remarkable for tachypnea and mild tachycardia. There is dullness to percussion and tenderness in the left upper quadrant. Significant bilateral cervical lymphadenopathy is noted. What is most likely responsible for this patient's presentation?
Epstein-Barr virus
Draw every triangle in the cervical region & list the contents of each.
Submental triangle: submental LN, small vv.
Submandibular triangle: submandibular gland & LN, facial a. & branches, facial v., marginal mandibular n. (VII), myelohyoid n. (V3), hypoglossal n.
Carotid triangle: common carotid a., internal carotid a., internal jugular v., vagus n. (CN X), carotid sinus & body, ansa cervicalis, hypoglossal n.
Muscular triangle: sternohyoid m., superior belly of omohyoid m., sternothyroid m., thyrohyoid m., thyroid gland, parathyroid gland, larynx, trachea, esophagus
Occipital triangle: spinal accessory n. (CN XI), cutaneous & muscular branches of cervical plexus, uppermost part of brachial plexus, transverse cervical a. & v., supraclavicular n.
Supraclavicular triangle: 3rd part of subclavian a., subclavian v., supraclavicular a. & nerves., trunks of brachial plexus
Describe the mechanism of echinacea.
activates innate immune cells (macrophages & NK cells), increasing their ability to engulf pathogens (phagocytosis)
active compounds stimulate cytokine production (IL-2, IL-8) & modulate inflammatory responses by inhibiting pro-inflammatory cytokines (TNF-alpha)
boosts T-cell function
offers antiviral/antibacterial effects, via multiple pathways to strengthen resistance to infections
A 50-year-old man presents for a follow-up visit. A history of present illness reveals that he underwent a screening colonoscopy that demonstrated a polyp with malignant transformation. His medical history includes inflammatory bowel disease. The histology report identified a population of small, round, darkly-staining cells without apparent cytoplasm directly killing the tumor. In what compartment or compartments do these cells bind to the major histocompatibility complex (MHC)?
thymus
describing CD8+ cytotoxic T cells