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