INFECTIOUS DISEASES Flashcards
What is the difference in location between congenital CMV and Toxoplasmosis CNS lesions?
CMV: periventricular calcifications
Toxoplasmosis: calcifications scattered throughout cortex
What are clinical features of congenital CMV infection?
Cataracts Purpuric rash ("blueberry muffin") Seizures from CMV CNS lesions Hepatosplenomegaly IUGR Microcephaly Prolonged neonatal jaundice
What cells are involved in humoral immunity? What cells are involved in cellular immunity?
Humoral: B-cell
Cellular: T-cell
Testing for HIV in child < 18 months?
Testing for HIV in child > 18 months?
Child < 18 months: cannot do HIV ELISA looking for antibodies against HIV since will still have maternal antibodies in system. Need to perform HIV DNA PCR which needs to be positive on two separate occasions
Child > 18 months: HIV ELISA (enzyme linked immunosorbent assay to look for HIV IgG: 99% specificity and sensitivity); if positive, confirm diagnosis with Western Blot (direct visualization of antibodies against the virus)
What is a soft tissue complication of varicella infection?
GAS invasive soft-tissue infection: necrotizing fasciitis, myositis, cellulitis, toxic shock syndrome
Treatment: Penicillin and clindamycin
What is the classical triad of Wiskott-Aldrich syndrome?
- Complications (2)
- mode of inheritance
Classic triad (in 1/3 of patients):
- Eczema
- Thrombocytopenia
- Immunodeficiency
Complications:
- Immunodeficiency:
- T and B cell function is reduced
- recurrent pneumonia/otitis media/sepsis/meningitis/sinusitis
- progressive
- can have hepatomegaly - Risk of malignancy (10-20%)
- leukemia/lymphoma
Mode of inheritance:
-X-linked
How do neonates with Wiskott-Aldrich usually first present?
Present at birth with thrombocytopenia features: bruising, petechiae, bloody diarrhea
Eczema by 1st month of life, recurrent infections by 3 months of life
In Wiskott-Aldrich, describe the levels of immunoglobulins seen.
IgA & IgE: elevated
IgM: reduced
IgG: normal, reduced or elevated
What investigations should be ordered for 1-3 mo febrile infants meeting clinical criteria for low risk SBI?
- CBC + diff
- Blood culture
- Bag for urine –> cath if positive
In febrile patients, when should a UA always be ordered? (5)
- All boys age < 6 months
- Uncircumcised males
- All females < 2 years old
- Prior diagnosis of UTI
- Known renal abnormality
What is the definition of a UTI?
- Urine with > 10 wbc/hpf
- Colony count of single organism > 50,000/ml
- **Remember that if child has been symptomatic < 48 hrs, may have absence in WBCs
- absence in WBCs in urine does not rule out UTI!
In children 3-36 months, what percentage of fevers are viral in origin?
> 95%
Clinical presentation of lyme disease (6)?
- Arthritis
- Erythema migrans: painless, annular, central clearing, minimum size 5 cm
- Aseptic meningitis
- Cranial nerve palsies
- Heart block
- Ocular involvement
What are the most common clinical presentations of urethritis (2)?
-What is the most common etiology of urethritis?
- Dysuria
- Penile discharge
Most common etiology: Chlamydia trachomatis (3x more common than Neisseria gonorrhoeae)
What is the best test for chlamydia and gonorrhea?
Urine PCR
What is the management of a patient diagnosed with urethritis?
- medical therapy
- advice to give patients (ie. how long to abstain from sex)
- Empiric treatment for chlamydia and gonorrhea
- Azithromycin 1 g PO x 1 for chlamydia
- Ceftriaxone 250 mg IM x 1 for gonorrhea - Instruct patients to abstain from sexual intercourse x 1 wk after single-dose therapy and until all partners are treated to prevent reinfection
- Test for other possible STIs (syphillis, HIV, hepatitis, etc.)
What is a possible GI side effect of ceftriaxone?
Increased gallbladder sludge and subsequent cholelithiasis
What is the pathophysiology of retropharyngeal cellulitis/abscess?
The retropharyngeal nodes that drain the mucosal surfaces of the upper airway and digestive tracts (between the pharynx and the cervical vertebrae, extending down into the mediastinum) become infected
- once infected, the nodes progress through 3 stages: cellulitis, phlegmon, abscess
- most patients have history of recent ear/throat/nose infection
What are the possible causes of retropharyngeal abscess?
- Localized infection of oropharynx extending to the retropharyngeal lymph nodes
- Penetrating trauma
- Vertebral osteomyelitis
- Dental infection
Retropharyngeal abscess are most common in what age group and why?
Most common in children < 5 years old
-after the age of 5, retropharyngeal nodes involute and thus infection is much less common in older children and adults
What are clinical manifestations of retropharyngeal abscess? (7)`
Think upper airway obstruction!
- Respiratory distress
- Stridor
- Drooling
- Fever
- Refusal to eat
- Obstructive sleep apnea
- Neck stiffness/torticollis
What is the differential diagnosis of retropharyngeal abscess? (5)
- Acute epiglottis
- Lymphoma
- Meningitis (if neck stiffness present)
- Foreign body aspiration
- Vertebral osteomyelitis
What is the underlying bacterial etiology of retropharyngeal abscess?
Polymicrobial! Most commonly:
- GAS
- Staph aureus
- Oral anaerobes
What is the treatment for retropharyngeal abscess?
- abx choice
- indications for surgical drainage (2)
Intravenous antibiotics until clinical improvement, then switch to PO abx (ideal duration of treatment unknown)
- 3rd generation cephalosporin + clindamycin
- studies have shown that > 50% of children can be successfully treated without surgical drainage
Indications for surgical drainage:
- Respiratory distress
- Failure to improve with IV abx