Infectious Diseases Flashcards
UTI rate in febrile uncircumcised boys?
UTI rate in uncircumcised febrile boys <3 mo was 20.7%
UTI rate in febrile circumcised boys < 3 months?
2.4% if circumcised
After what age is it unusual for boys to have their first UTI?
3 years
Most positive urine Cx in infants >2 mo with bronchiolitis are due to what?
Contamination or aSSx bacteruria
What methods can you collect a urine sample?
A midstream urine sample for urinalysis and culture in toilet-trained children
Otherwise catheter or by suprapubic aspirate, or clean catch
bagged urine sample may be used for urinalysis but should not be used for urine culture
negative bag culture rules out a UTI but a positive result is not useful
What on a urinalysis is highly sensitive for a UTI?
Urinalysis
o nitrite – measures conversion of dietary nitrate to nitrite by Gram-negative bacteria
- positive nitrite result means UTI is likely (very sensitive)
- BUT may be falsely positive in Gram positive organisms
What count of a leukocyte esterase is positive for a UTI on urinalysis?
leukocyte esterase is a measure of pyuria and may be falsely negative
- absence of pyuria does not exclude UTI
- 10 white blood cells per microliter is positive for UTI
What are the minimum colony counts for a positive UTI?
Minimum colony counts for UTI Dx:
o Clean catch (midstream) ≥ 105 CFU/ml or ≥ 108 CFU/L
o In and out catheter ≥ 5 x 104 CFU/ml or ≥ 5 x 107 CFU/L
o Suprapubic aspiration: any growth
What are the common organisms causing UTIs?
Common organisms: o Escherichia coli o Klebsiella pneumoniae o Enterobacter species o Citrobacter species o Serratia species o Staphylococcus saprophyticus (adolescent females only)
When do you need to order renal function in the setting of a UTI?
• Renal function only if it is a complicated UTI or aminoglycosides for > 48 hours
When do you order a blood culture in the setting of a UTI?
• Blood Cx is not needed unless hemodynamically unstable/sepsis, or Dx UTI unclear
How do you treat (duration and route) an uncomplicated UTI?
Management
o Antibiotic treatment for 7-10 days is recommended for febrile UTI
o PO when the child is not seriously ill and is likely to tolerate every dose
Caution if 2-3 months old as safety data for PO only (no IV) is lacking
Do you treat pyelonephritis with PO or IV antibiotics?
o No convincing evidence that IV abx are superior to PO for 10-14 d for pyelo
Management of cystitis?
Cystitis: UTI without fever is usually a lower tract infection (cystitis)
mainly in postpubertal girls and presents as dysuria and frequency
Rx 2-4 day course PO that covers E coli
What are the features of a complicated UTI?
Features concerning for complicated UTI – order RBUS to r/o obs or abscess and switch to IV
o Hemodynamically unstable
o elevated serum creatinine level at any time
o bladder or abdominal mass
o poor urine flow
o not improving clinically within 24 h
o fever is not trending downward within 48 h of starting appropriate antibiotics
When and why would you order a RBUS in the context of a UTI?
renal/bladder ultrasound (RBUS)
Children <2 yo after their first febrile UTI, within 2 weeks
Can detect hydronephrosis – usually occurs with high grade (IV or V) VUR
When and why would you order a VCUG in the setting of a UTI?
o radiographic (voiding cystourethrogram)
Not required for children with a first UTI unless the renal/bladder ultrasound shows vesicoureteral reflux, selected renal anomalies, or obstructive uropathy
VCUG is indicated for children <2 yo with a second well-documented UTI
Best test to dx VUR, assessing the degree of VUR , and anatomy of male urethra
Risks: expense, exposure to radiation, the risk of causing a UTI, discomfort
When do you order a DMSA scan?
o radioisotope (dimercaptosuccinic acid [DMSA]) techniques Indication: dx acute pyelonephritis or identify renal scars primarily useful when the diagnosis of acute UTI or of repeated UTIs is in doubt
What are some antibiotic options for UTIs?
• Antibiotic Options and Doses
o Ampicillin 200 mg/kg IV/day (divided every 6 h)
o Ceftriaxone 50–75 mg/kg IV/IM every 24 h
o Cefotaxime 150 mg/kg/day IV (divided every 6 h or 8 h)
o Gentamicin 5–7.5 mg/kg IV/IM once per day
o Tobramycin 5–7.5 mg/kg once per day
o Amoxil 50 mg/kg/day (divided in three doses)
o Amoxicillin/clavulanate (7:1 formulation) 40 mg/kg/day (divided in three doses)
o Co-trimoxazole 8 mg/kg/day of the trimethoprim component, divided in two doses (0.5 mL/kg/dose)
o Cefixime 8 mg/kg/day (given as a single dose)
o Cefprozil 30 mg/kg/day (divided in two doses)
o Cephalexin 50 mg/kg/day (divided in four doses)
o Ciprofloxacin* 30 mg/g/day (divided in two doses)
What is the incidence of UTI in children?
•UTIs are common in infants & young children: 8% of girls and 2% of boys by 7 yo
o with a recurrence rate of 10% to 30%
Who gets prophylactic antibiotics for UTIs?
Antibiotic prophylaxis is no longer routinely recommended after a UTI but may still be considered when a child has grade IV or V VUR, or a significant urological anomaly
o Abx no longer than 3-6 months, then reassess
What antibiotic is used for prophylaxis?
Trimethoprim/sulfamethoxazole or nitrofurantoin
o traditionally, ¼ to 1/3rd of the daily total treatment dose is given once per day
o no evidence for alternating abx choice monthly
Why are broad spectrum antibiotics not used for prophylaxis?
broader-spectrum agents for prophylaxis (cefixime or ciprofloxacin) often results in a UTI with an organism that is resistant to any remaining oral options for therapy
What is the life cycle of lice?
o Lice live 3-4 weeks if untreated, but the continue to reproduce/create turnover
o adult head lice can survive for only 1 to 2 days away from the human host
o eggs can survive away from the host for up to 3 days
How do you diagnose a lice infestation?
o misdiagnosis is common – need to see LIVE louse
o SSx itching, but some asymptomatic for weeks
How are lice transmitted?
• Transmission - direct head-to-head (hair-to-hair) contact
o Transmission w/ fomites is debated; pets are NOT a vector, carpet/pillow cases unlikely
How do you treat a lice infestations?
o topical insecticides
pyrethrins – apply to dry hair/scalp, rest 10 mins, wash out, repeat in 7-10 days
• may causing itching/burning to scalp, allergic reaction is rare
permethrin 1% - shampoo hair, apply cream, rest 10 mins, rinse, repeat in 7 d
• may causing itching/burning to scalp, no allergic reaction
Toxicity
• pyrethrins and permethrin have minimal percutaneous absorption and favourable safety profiles, but avoid sitting child in bath to rinse hair
• Topical steroid or antihistamine may help with side effects
• Lindane is not used because of the potential risks for neurotoxicity and bone marrow suppression following percutaneous absorption
Resistance is increasing
• If 2 permethrin doses 7 days apart do not eradicate live lice, consider resistance and use another medication class; note that the treatment can cause itching and is NOT a SSx of re-infestation (need live louse)
o Topical non-insecticidal
Isopropyl myristate + ST-cyclomethicone solution for ≥ 4 yo, treat once, then repeat in 1 week
Dimeticone solution for ≥ 2 yo, treat once, then repeat in 8-10 days
Benzyl alcohol lotion 5% for > 6 months, repeat in 9 days, expensive
o Other treatments
No evidence for septra
Ivermectin (special access) is potentially neurotoxic, do not use < 15 kg
Wet combing has little evidence as primary treatment
Thick creams/oils, tea tree oil do not have enough evidence of efficacy
When can kids return to school with lice?
o Excluding children with nits or live lice from school or child care has no rational medical basis and is not recommended (just avoid close head to head activities)
o Notify parents of children in the same classroom of head lice case, and review that it is not a sign of disease or poor hygiene
Environmental cleaning for children with lice?
• Environmental Decomtamination
o environmental cleaning is not warranted
o At most, washing items in close/prolonged contact with the head (hats, pillowcases, brushes) may be warranted
wash in hot water (≥66°C) and dry them in a hot dryer for 15 minutes
storing any item in a sealed plastic bag for 2 weeks will kill both live lice and nits
Acute Osteomyelitis occurs within what time frame?
o Acute osteomyelitis is < 2 weeks
How long before you can consider it a chronic osteomyelitis?
o Chronic osteomyelitis is > 1 month with avascular bone alone (sequestrum) or surrounded by new bone (involucrum) is present (Brodies’ abscess)
When to suspect osteomyelitis vs septic arthritis?
• Acute hematogenous osteomyelitis and septic arthritis are not uncommon infections in children and should be considered as part of the differential diagnosis of limb pain and pseudoparalysis
How do most bone infections occur?
o Most bone infections arise secondary to hematogenous seeding of bacteria into bone
What are the most common bugs in osteomyelitis and septic arthritis?
Most common pathogens are Staphylococcus aureus and Kingella kingae (resp bugs)
Others: Streptococcus pneumoniae and Streptococcus pyogenes
Sickle cell anemia are prone to Salmonella
How does Osteomyelitis and septic arthritis present?
Clinical Presentation
o PAIN can be the only symptom
o Often with pseudoparalysis or limping
o Fever may or may not be present
o Most common site is the metaphysis in long tubular bones: femur, tibia, or humerus
o Always consider osteomyelitis in S aureus bacteremia with no source
o SA alone: specific swelling of the joint, joint effusion, pain on movement of the joint
Most common sites for osteomyelitis infection?
o Most common site is the metaphysis in long tubular bones: femur, tibia, or humerus
How would transient synovitis of the hip present?
Transient synovitis of hip
Usual age is 4–10 years Hip pain and new limping, +/- fever \+/- weight-bear Hx URTI in the preceding 2 weeks Nontoxic appearance CRP is usually < 20 mg/L. Gradually improves over several days, may be hastened by NSAIDs.
How would fracture or trauma present?
Fracture or trauma (Toddler’s #)
Acute onset of pain while active or after a known trauma
Localized pain, hematoma, bruising, swelling, no fever
How would Lyme Arthritis present?
Hx Lyme area within past 12 month
Usually monoarthritis of knee (occasionally hip or other large joints) without constitutional SSx
Much less painful than SA, will weight bear.
Baker’s cyst may be present.
CRP is < 40 mg/L.
How would cellulitis present?
Rapid development of swelling, redness and pain over hours-day.
Erythema usually precedes the development of pain. Area of erythema, warmth, swelling, tenderness.
Usually more extensive (not focal).
Can have lymphangitis.
Often normal ROM.
How would CRMO present?
Chronic recurrent multifocal
osteomyelitis (CRMO) (first
presentation)
Insidious onset of bone pain. Often metaphysis and epiphysis, and unusual sites (clavicle, jaw, scapula). May have fever and malaise. Pain is often worse at night. Dx based on a relapsing course. CXR intense sclerosis with healing. \+/- tenderness, warmth, swelling \+/- fever, malaise, weight loss
May have palmoplantar pustulosis,
psoriasis or other dermatologic
conditions
How would a malignancy present (hematologic)
Constitutional SSx, arthralgia, limb or muscle pain.
Metaphyseal lucencies and periosteal reactions, as with AO.
No localized pain to palpation but may have joint swelling and evidence of mild synovitis.
How would a bone neoplasm present?
Bone neoplastic lesion (benign or
malignant, including histiocytosis)
Typically, gradual onset in the diaphysis or in flat bones.
Pain is often worse at night and
with refusal to weight-bear.
Pain
May have a palpable soft tissue or bony mass.
How would JIA present?
Typically gradual onset (weeks).
Oligoarthritic (< 4 joints) or poly.
More likely to be symmetric, often with extra-articular symptoms.
Often, symptoms are less severe compared with bacterial SA.
May have contracture if subacute.
May need synovial fluid analysis to exclude SA (if mono appearance).
Fewer white blood cells in joint fluid compared with SA.
How would SLE present?
Constitutional SSx (fever, wt loss, fatigue, anorexia, diffuse LAD).
Cutaneous symptoms (rash, ulcers) are also common.
Arthritis is usually milder than SA.
May have hematologic (anemia, leukopenia) and U/A abnormalities.
How would reactive arthritis present?
Oligoarthritis of larger joints, usually 2-3 weeks after a preceeding GI or GU infection.
May have ocular and urinary SSx.
Arthritis is more subacute and less severe compared with bacterial SA
How would post strep reactive arthritis present?
Acute onset of symmetrical or asymmetrical arthritis.
Usually polyarticular, nonmigratory and can be persistent or recurrent.
Usually 3–14 days after strep.
May have extra-articular manifestations (vasculitis, GN).
Acute rheumatic fever: joints are Tender/swollen with characteristic migratory feature and exquisite
response to NSAIDs or ASA.
How do you diagnose Osteomyelitis or septic arthritis?
o Blood Cx before abx and while febrile is important as AO and SA are hematogenous
Take larger volume to increase yield; repeat in 24-48 hrs if positive
o Pathological assessment of a bone specimen is the gold standard for the diagnosis of AO
o MRI with gadolinium enhancement – most sensitive and specific noninvasive test for AO
bone marrow edema can be seen
do not need MRI if clinical dx is supported by labs and response to treatment
o Xray – classic lytic lesions and localized periosteal lifting only seen 7-21 days after onset
Xrays may be normal in acute phase, but r/o other pathology (neoplasm, #)
o U/S – fluid in subperiosteal areas and soft tissues in OA, or fluid in the joint space in SA
o Bone scan – less specific than MRI, but may be useful if multifocal presentation
o CT – if MRI or bone scan are not available
o CRP – if normal in the first new days, unlikely to be SA or osteo (better sens than ESR)
o CBC – may have leukocytosis
o Diagnose SA with joint aspiration before abx! If not possible, consider U/S or MRI
o Blood, bone and joint fluid cultures commonly test negative
How do you manage osteomyelitis or septic arthritis?
o Children with septic arthritis should be evaluated promptly by ortho for aspiration and possible debridement of concomitant osteomyelitis
o Cefazolin 100-150 mg/kg/day divided q6-8 hours
Some widen coverage to include Hib with cefuroxime
Note that kingae is predictably resistant to clindamycin, vanco, and cloxacillin
o Step down to PO abx (cephalexin) when there is clinically improved and decreasing CRP
Cloxacillin can be used, but it has poor palatability
Use clinda, septra, or linezolid for MRSA
o Antibiotics for 3 to 4 weeks total – d/c when clinically well and CRP normalized
Follow up xray not needed unless near growth plate or not responding to Rx
What procedures require IE prophylaxis?
Prophylaxis for all dental procedures that involve the manipulation of gingival tissue, the periapical region of teeth, perforation of the oral mucosa, or incision or biopsy of the respiratory mucosa (biopsy, T+A)
o Not for routine orthodontic care or anesthetic injection in healthy tissue
o Not routine for GI or GU procedures; may add enterococci to pre-op abx coverage
What cardiac conditions is IE prophylaxis recommended for?
Prophylaxis is recommended for:
o Prosthetic cardiac valve or prosthetic material used for valve repair
o Previous IE
o Congenital heart disease
Unrepaired cyanotic CHD, including palliative shunts and conduits
Completely repaired defect with prosthetic material, in first 6 months post-op
Repaired CHD with residual defects at the site or adjacent to the site of a prosthetic patch or prosthetic device (which inhibit endothelialization)
o Cardiac transplant recipients who develop cardiac valvulopathy
o Rheumatic heart disease if prosthetic valves or prosthetic material used in valve repair
Which CHD is IE prophylaxis NOT recommended for?
• No prophylaxis for:
o ASD, VSD, PDA, MVP, pulmonic stenosis, calcified AS
o Previous Kawasaki disease
o Hypertrophic cardiomyopathy
o Previous coronary artery bypass graft surgery
o Cardiac pacemakers (intravascular and epicardial) and implanted defibrillators
o Bicuspid aortic valves
o Coarctation of the aorta
What do you give for endocarditis prophylaxis?
Prophylactic Principles
o Antibiotics given in a single dose before the procedure
If not given before, give within 2 hours post procedure
o PO: Amoxil 50 mg/kg is preferred
Second line: cephalexin or another first-generation cephalosporin, clindamycin, azithromycin, or clarithromycin
o IV: ampicillin, ceftriaxone, or cefazolin
Most common bugs causing meningitis in children > 1 month
• Most common in healthy children > 1 mo: S pneumoniae and N meningitidis
o but E coli and GBS should be considered up to 3 mo
Contraindications for LP?
Contraindications: coagulopathy, cutaneous lesions at site, signs of herniation (papilledema, focal neuro sign, dec LOC), or an unstable clinical status
Do CT or MRI to rule out herniation risk (CNS lesion)
o Do not delay antibiotics for LP or imaging, but do blood Cx first
Blood Cx volumes: 2 ml if > 4 kg, up to 20 ml if > 26 kg to improve yield
Complications of meningitis?
• Complications
o SIADH
o Raised ICP
Management of ?meningitis in >1 month
o Cephalosporin is first line (ceftriaxone or cefotaxime) due to PCN resistance
Ceftriaxone 100 mg/kg/day divided BID (max 4 g/day)
Cefotzxime 300 mg/kg/day divided QID
o Add vanco (60 mg/kg/day) for cephalosporin-resistant S pneumoniae, pending Cx result
o Add ampicillin (300 mg/kg/day) to cover Listeria if immunocompromised
o Switch to ampicillin or PenG if susceptible
o Neonates with GBS: add gentamicin x5-7 days until CSF sterility confirmed
o Meropenem if unable to use a 3rd gen cephalosporin
How long to you treat for meningitis?
o Duration depends on organisms: GBS 14-21 days Strep pneumo 10-14 days Hib 7-10 days Neisseria 5-7 days
Why do we give steroids for HiB meningitis?
Steroid Adjuvant Therapy for Hib meningitis
o There is a reduction in severe hearing loss if corticosteroids are given just before or within 2 h of antimicrobials
When do you have to repeat a CSF?
• Repeat CSF recommended by some if: GBS or gram negative pathogen
When do we do neuroimaging for meningitis?
• CNS imaging if CSF fails to clear, neuro SSx, or complications arise
What is neonatal ophthalmia?
• Neonatal ophthalmia is conjunctivitis occurring within the first 4 weeks of life
