Infectious Disease


Botulism

Rapid Review

  • Background
    • Botulism is a neuro-paralytic disease caused by the ingestion, injection, or inhalation of a pre-formed toxin produced by Clostridium botulinum
    • The toxin can be found in incorrectly canned/preserved foods and honey
  • Signs/Symptoms
    • Facial paralysis, descending weakness, respiratory arrest
  • Diagnosis
    • Clinical diagnosis based on history and physical exam
    • Confirmation of diagnosis requires identification of toxin in serum, stool, vomit, or food sources (may take 1-6 days)
  • Treatment
    • Early ventilatory management and wound debridement
    • Heptavalent antitoxin
  • Disposition
    • Admission is required for most patients. ICU required if any respiratory involvement.

Pearls

  • Early administration of antitoxin (ex. H-Bat) is vital. Although it will not reverse paralysis, it will halt it’s progression. Do not give HBAT for infants < 1 year of age.
  • Wound botulism will require thorough wound debridement and parenteral antibiotics (ex. metronidazole or penicillin)

Deep Dive

Video Credit: USMLE Pass


Chlamydia

Rapid Review

  • Background
    • Chlamydia is the most common sexually transmitted infection in the US caused by the baceteria Chlamydia trachomatis. It is a leading cause of infertility.
    • Can affect the cervix, urethra, salpinges, uterus, and epididymis.
  • Signs/Symptoms
    • Dysuria, mucopurulent urethral discharge, +/- fever
    • Over 50% of infected individuals are asymptomatic
  • Diagnosis
    • NAAT (urine or vaginal swab)
  • Treatment
    • Ceftriaxone IM + Azithromycin PO
    • Provide prescription for expedited partner treatment
  • Disposition
    • Discharge is appropriate for most patients. Follow up with PCP encouraged for to ensure adequate treatment of infection and for additional STI testing as needed.

Pearls

  • Infection can present in other areas as well, such as the rectum or the pharynx. Obtain samples from those areas if they are symptomatic in those regions.
  • Have a low threshold for testing for chlamydia/gonorrhea in young women, as they are very often asymptomatic. 
Video Credit: USMLE Pass


COVID-19

Rapid Review

  • Background
    • Acute respiratory illness caused by the novel SARS-CoV-2 virus
    • Often causes pulmonary, cardiac, and neurological complications
  • Signs/Symptoms
    • Range from mild cold-like symptoms to respiratory failure
    • Most common symptoms include fever, dry cough, fatigue, and SOB. 
    • Associated with cardiac complications and thromboembolic phenomenon. 
  • Diagnosis
    • Viral testing (Rapid antigen and/or RT-PCR testing)
  • Treatment
    • Pulmonary support (O2, NIPPV, Intubation)
    • Consider Dexamethasone and Remdesivir for moderate-severe infections
  • Disposition
    • Most patients can be discharged if healthy, vaccinated, and hemodynamically stable
    • Admission is necessary for patients with tachypnea, hypoxia, or with significant comorbidities.

Pearls

  • Paxlovid (nirmatrelvir/ritonavir) is an oral antiviral drug that can be used for mild/moderate COVID-19 infections. However, it cannot be used in patients with severe renal disease (GFR < 30) and it has several drug interactions.
  • The current dominant variant (Omicron) is more transmissible and resistant to vaccines/monoclonal therapy than it’s predecessor (Delta), but overall causes less hospitalization and severe disease.
Video Credit: Osmosis


Meningitis

Rapid Review

  • Background
    • Inflammation of the meninges and subarachnoid space. May be bacterial (most lethal), viral (most common), or in rare cases due to fungal or tuberculosis infection. 
    • Bacterial meningitis is most commonly caused by Streptococcus pneumoniae
  • Signs/Symptoms
    • Fever, headache, nuchal rigidity, photophobia
    • (+) Brudzinski sign, (+) Kernig Sign
  • Diagnosis
    • Lumbar puncture w/ CSF fluid analysis 
  • Treatment
    • Broad-spectrum antibiotics (ex. Ceftriaxone + Vancomycin) and corticosteroids (ex. Dexamethasone)
    • If viral, treat with Acyclovir
  • Disposition
    • Admission is required for any known/suspected bacterial infections. ICU is required for any toxic-appearing patients.
    • Discharge with close follow-up is appropriate if the infection is clearly viral and symptoms are controlled.

Pearls

  • When in doubt, just do the lumbar puncture! Failure to diagnose meningitis early can be life-threatening  and often results in medicolegal consequences for providers.
  • Although a head CT is often performed prior to lumbar puncture, this can cause a significant delay in diagnosis/treatment. Reserve early CT imaging for patients with AMS, neurological deficits, papilledema, or history of CNS disease.
Video Credit: Osmosis


Osteomyelitis

Rapid Review

  • Background
    • Infection of the bone with persistent inflammatory destruction. Most commonly caused by bacteria (Staph aureus, pasteurella multocida, pseudomonas aeruginosa), but can also be caused by fungi. 
  • Signs/Symptoms
    • Localized bony tenderness w/ warmth, swelling, erythema
    • May experience weight loss, fatigue, and fever.
  • Diagnosis
    • X-ray  (will show bony erosions, regional osteopenia, periosteal elevation)
    • Radiography may be normal the first 2-3 weeks of symptoms. CT/MRI will provide earlier detection.
  • Treatment
    • Empiric broad-spectrum antibiotics (ex. Vancomycin + Piperacillin/Tazobactam)
    • Obtain bone cultures prior to initiating antibiotics
  • Disposition
    • Admission is usually required. 
    • Some cases of chronic or subacute osteomyelitis can be managed outpatient if debridement not needed and home IV antibiotics can be arranged.

Pearls

  • The WBC count is often normal, especially in pediatric or subacute/chronic cases.
  • Osteomyelitis can be difficult to diagnose in pediatrics (they often present afebrile with no leukocytosis). However,the combination of ESR and CRP elevation has a 98% sensitivity for diagnosing osteomyelitis in the pediatric population.
Video Credit: Medmastery

Brandon Simpson, PA-C
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  • Blog - 25 Feb 2021