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Take Home Points – Infectious Disease

Tetanus

Pathophysiology

- Clostridium tetani – anaerobic G+ rod, produces two exotoxins that invades the nervous system and prevents release of inhibitory neurotransmitters, causing sympathetic overactivity

- From contaminated wounds, puncture wounds, lacerations, abrasions, IVDU

Symptoms

- Acute onset of hypertonia and/or painful muscular contractions, usually muscles of the jaw (lockjaw) and neck, without other apparent medical causes

- Muscle spasms– trismus, sardonic smile, dysphagia, arm flexion, clenched fists, extension of the lower extremities

- Autonomic changes – (2nd week) tachycardia, labile hypertension, profuse sweating, hyperpyrexia, urinary excretion

- Complications – rhabdomyolysis and long-bone fractures from violent muscle contractions, laryngospasms/respiratory muscle contraction leading to respiratory compromise, prolonged hospitalization leading to PE/aspiration pna/sepsis

- Diagnosis is clinical

Treatment

- Mechanical ventilation, sedation, neuromuscular blockade (succinylcholine, vecuronium)

- Tetanus Ig 3000-6000 units IM (some portion around wound site); place opposite side of Toxoid; reduces mortality; administer before wound debridement

- Tetanus Toxoid 0.5mL IM at presentation, 6 weeks and 6 mos after presentation

- Would debridement

- Metronidazole 500mg IV q6h – limited value but traditionally given (do NOT give Penicillin)

- Muscle relaxation – versed

- Autonomic dysfunction – Magnesium, Labetalol, Morphine, or Clonidine

Vaccination Post Exposure

- Give Tetanus IG 250U - unknown or 10 years since last dose)

Rabies

Pathophysiology and Exposure Risk

- Rabies virus replicates in mammalian CNS, transmitted by direct contact (often saliva) causing encephalitis

- Factors that determine risk of transmission – number of bites, depth, location, type (scratch vs. bite)

Prophylaxis

- Pre-exposure prophylaxis available and recommended for persons with activities at high risk of rabies exposure

- Dogs/Cats/Ferrets – should not begin vaccination unless animal develops clinical rabies if animal can be observed

- Skunks/Raccoons/Foxes/Bats – consider immediate immunization

- Squirrels/Hamsters/Guinea Pigs/Chipmunks/Mice/Rabbits – never need post exposure prophylaxis

- General wound care including soap+water, irrigation of wound with diluted povidine-iodine

- Regimen = HRIG 20 IU/kg ideal wt + 4 doses of rabies vaccine over 14 days (28 if immunocompromised) – Days 0, 3, 7 14

- If previously vaccinated, only need vaccine day 0, 3

- Side effects – local effects (erythema, swelling), HA, n/v, abd pain, muscle aches, dizziness, serum sickness-like reaction

- Special Populations: pregnancy safe; children same dose for vaccine (Ig is wt based); assess travelers upon return to US

Clinical Rabies

- Incubation: 20-90 days (reports of 4 days, 6 years)

- Prodrome: 2-10d (of symptoms onset) malaise, HA, F, n/v

- Acute Neuro: 2-7d anxiety, agitat’n, depress’n, hypervent’n, hydrophobia, aerophobia, pharyng spasm, confusion, delirium

- Coma: 0-14d hypotension, hypoventilation, apnea, pituitary dysfunction, cardiac arrhythmia, pneumothorax, cardiac arrest

Diagnosis and Treatment

- Consider in unexplained, acute, rapidly progressive encephalitis, especially with autonomic instability, dysphagia, hydrophobia, aerophobia, paresis, paresthesia

- Antigen and Antibody testing from serum, CSF, saliva, other tissue but only once symptoms are evident

- Steroids are contraindicated (shortens incubation period)

- No specific therapies have demonstrated to have proven benefit, previously 100% mortality; a new experimental treatment called the Milwaukee Protocol with chemically induced coma has shown 5 survivors out of 36

Occupational Exposure

Portals for Exposure

- Percutaneous, mucous membrane, respiratory, dermal

Hep B/Hep C/HIV Potential Exposure

- Wound care (irrigate, wash)

- Obtain relevant history: circumstances, source, vaccination of exposed

- Labs from exposed, source (using consent when required)

- Determine need for Hep B PEP, HIV PEP

( Hep B: Give HBIG if exposed is unvaccinated/nonimmune or known nonresponder and source patient is HBsAg+;

----Give HB Series if exposed is unvacc/nonimmune or known nonresponder and source is HBsAg+ or -;

( HIV: Start PEP as soon as possible (within 24-36hrs) if source is HIV Ab+ or suspected (discontinue later if negative)

----3+ Antiretrovirals for at least 4 weeks; hotline available (1-888-448-7737) for uncommon cases

- Counsel risk/benefits, side effects; arrange f/u within 72 hours with employee health

Other Common Exposures

- TB: airborne precautions; vaccine outside US popular; prophylactic post exposure available but little research to support

- Measles: airborne, part of primary immunizations, vaccine may prevent disease if unimmunized and given within 72hrs

- Mumps: droplets, part of primary series, vaccine unlikely to prevent disease if unimmunized

- Rubella: droplet and contact, part of primary series, vaccine unlikely to prevent disease if unimmunized

- Varicella: airborne and contact, vaccine may prevent, IG may prevent/modify disease if within 4 days for unimmunized, work leave of absence from days 10-21 post exposure

- Influenza: droplet, vaccine will not prevent postexposure but may protect in future cases; consider oseltamivir or zanamivir for chemoprophylaxis in higher risk employees with significant exposure

- Meningococcus: droplet, post exposure for mouth-to-mouth/intubated/suctioning without mask (Rifampin, Rocephin, Cipro)

- Scabies, Lice: contact precautions, no postexposure recommended

Infection Control and Standard Precautions

- Hand washing, PPE, decontamination, environmental engineering, waste disposal

- Airborne Precautions = Measles, Varicella, TB

- Droplet Precautions = Hib, Neisseria, Serious Bacterial Respiratory, Diphtheria, Mycoplasma, Pertussis, Pneumonic Plague, Strep Pharyngitis/PNA/Scarlet Fever, Serious Viral, Adenovirus, Influenza, Mumps, Parvovirus, Rubella

- Contact Precautions = Multi-drug resistant infections, C. diff, Ecoli 0157:H7, Shigella, Hep A, Rotavirus, RSV, Parainfluenza, Enteroviral, Infectious Skin (Diphtheria, HSV, Impetigo, major abscesses/cellulitis/decubiti), Lice, Scabies, Zoster, Viral Hemorrhagic Conjunctivitis, Viral Hemorrhagic Infections (Ebola, Lassa, Marburg, Crimean-Congo)

Sepsis Review (Not Meant to be Comprehensive Lecture)

Intro:

Sepsis is an exaggerated/dysregulated inflammatory response to a local infection which carries a high degree of mortality

Definitions:

• SIRS - 2 or more signs of inflammatory response

1. Temp >38C, 90 (or >2 SD above normal for age)

3. RR >20 (PaCO2 12 or < 4; Bands >10

• Sepsis - SIRS + suspected source of infection; some estimates have mortality ~30%

• Severe Sepsis - ?no longer a category?; evidence of end organ dysfunction secondary to tissue hypoperfusion (some say lactate >2); some estimates have mortality ~50%

• Septic Shock – cardiovascular failure as evidenced by persistent elevated serum lactate (some say lactate >4), persistent hypotension, or need for vasopressors despite adequate fluid resuscitation; some estimates have mortality ~80%

• qSOFA – screening tool attempting to identify patient at higher risk death/mortality; components = AMS, RR>22, systolic 65 if adequate fluid resuscitation & persistent hypotension, early if suspect overload

Pearls:

- Consider septic shock in all undifferentiated shock/hypotensive patients

- US can be useful – determining IVC, septic cardiomyopathy, other causes of shock (cardiac tamponade, ptx)

- Steroids for persistent hypotension? Consider but mixed data

- Consider switching to LR when crystalloids are needed in large volumes to avoid hyperchloremic metabolic acidosis

- Abx ideally within 1 hour of recognition of sepsis/severe sepsis

- Most consider norepinephrine as the ideal first-line vasopressor for septic shock

- Abx empirically after every cardiac arrest? Some emerging research may suggest improved outcomes

Rereferences:

Tintinalli 8e: Chapters 151, 156, and 157, 162

Centers for Disease Control and Prevention ()

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