Pediatric Examination and Board Review (212 page)

Chapter 15

NEPHROLOGY

CASE 121: A 4-DAY-OLD WITH FEEDING PROBLEMS

A 4-day-old boy has become anorexic and comes to your office for evaluation. Mom reports that he had begun to breast-feed avidly but seems much less interested in feeding today and last night. He was the product of a 38-week pregnancy. His mom is 24 years old and had prenatal care. By serology, she had no antibodies to rubella or human immunodeficiency virus (HIV). Routine nontreponemal serology for syphilis was negative. She lacked the hepatitis B surface antigen. The baby had an uneventful hospital course. The Apgar scores were 8 and 9 at 1 and 5 minutes. His birthweight was 3100 g. The physical examination reveals a generally healthy-looking male infant, with somewhat decreased spontaneous activity. His vital signs and physical examination are normal. You decide to perform some laboratory tests.

SELECT THE ONE BEST ANSWER

1.
Which of the following statements is correct regarding evaluation for sepsis in this patient?

(A) a blood culture is not indicated; the patient is afebrile and fever almost always accompanies bacteremia

(B) a urine culture need not be performed unless the patient is shown to be bacteremic

(C) a lumbar puncture (LP) need not be part of an initial sepsis evaluation because all patients with neonatal meningitis are bacteremic

(D) the incidence of neonatal urinary tract infection is roughly equal for males and females

(E) a blood leukocyte count has a strong negative predictive value for neonatal bacteremia

2.
Which statement is true regarding evaluation of the urine in a neonate?

(A) urine obtained in a sterile plastic bag can be sent for a clinically useful culture provided the genital area is carefully cleaned in advance

(B) a specimen should be obtained by bladder puncture or catheterization to minimize the likelihood of contamination

(C) having more than 10
⁵
bacteria per milliliter of urine in a “bagged” specimen is diagnostic of a urinary tract infection (UTI)

(D) A and C

(E) B and C

3.
Assume that the laboratory tests in the patient in the vignette allowed the diagnosis of a UTI. Which of the following statement(s) is/are correct?

(A) an ultrasound of the kidneys and a voiding cystourethrography (VCUG) should be performed on all patients with proven neonatal UTI

(B) patients with neonatal UTI should be treated with a 14-day course of an oral sulfonamide

(C) intravenous pyelography (IVP) should be performed at the time of diagnosis because Wilms’ tumor is a common concomitant to UTI

(D) an ultrasound of the kidneys will allow adequate assessment of a male child with a UTI (but not a female)

(E) B and C

4.
Which of the following is (are) true regarding uncomplicated cystitis in school-age children?

(A) fever is usually absent or low grade

(B) uncircumcised boys are at risk roughly equal to girls, although circumcised boys are at lower incidence compared with girls

(C) dysuria is often absent

(D) A and C

(E) A, B, and C

5.
Which of the following is true regarding asymptomatic bacteriuria in school-age children?

(A) occurs in about 13% of healthy girls

(B) is a known predictor of end-stage pyelonephritis in later life

(C) should be managed with oral antibiotics once identified

(D) is usually cleared spontaneously

(E) none of the above

6.
Which of the following is incorrect about pyuria?

(A) it is defined by more than 5 white blood cells per high power field on urinalysis

(B) it is a sensitive marker for UTI

(C) it is nonspecific and often absent in a UTI

(D) it often occurs in Kawasaki disease

(E) it often occurs during measles infection and after intense exercise

7.
The nitrite dipstick detection test is

(A) nonspecific when positive

(B) a sensitive test for UTI

(C) never positive when the cause of the UTI is a gram-positive bacterium

(D) A and C

(E) all of the above

8.
The leukocyte esterase (LE) dipstick detection test

(A) is nearly 99% sensitive in detection of UTI

(B) has relatively low specificity of about 75%

(C) is positive only when gram-negative bacteria are the etiologic agents

(D) is performed on the blood of patients with true pyelonephritis

(E) detects mercury when this metal is in high concentrations in the urine

9.
You diagnose an
Escherichia coli
UTI in a 6-yearold girl with dysuria and a low-grade temperature. You decide she is not clinically toxic, nor has high fever, so you will manage her as an outpatient on oral antimicrobial therapy. You tell the parents which of the following?

(A) this infection is contagious; other children living in the same house as the index patient are at risk for infection

(B) amoxicillin is appropriate initial therapy because nearly all
E coli
isolates are susceptible to it

(C) trimethoprim-sulfamethoxazole in a single dose will sterilize her urinary tract and thus is now usually used for initial therapy

(D) radiologic studies are an important part of the ongoing evaluation for UTI and should be scheduled

(E) C and D

10.
The mother of a 3-year-old patient with unilateral grade 3 vesicoureteral reflux demonstrated by VCUG comes to you for advice. You tell her that

(A) urgent referral to urology for ureteral reimplantation is warranted

(B) there is no convincing direct relationship between reflux and renal scarring

(C) most pediatricians advise prophylactic antimicrobials in this situation aimed at urinary antisepsis; amoxicillin is a good choice

(D) most children will grow out of this condition; reflux will usually cease within a few years

(E) B and D

11.
Which of the following is (are) known to increase the incidence of UTIs in childhood?

(A) constipation

(B) frequent baths

(C) public swimming pool exposure

(D) wiping after urination from back to front

(E) all of the above

12.
All of the following can cause cystitis except

(A) pinworms

(B) ibuprofen

(C) insertion of foreign bodies into the urethra

(D) cyclophosphamide therapy for cancer

(E) adenovirus

13.
Management of acute pyelonephritis

(A) usually includes a third-generation cephalosporin antimicrobial such as cefotaxime

(B) usually includes a first-generation cephalosporin antimicrobial such as cefazolin

(C) initial therapy should include ceftazidime because
Pseudomonas
spp. is a common etiology

(D) usually involves initial parenteral therapy

(E) A and D

14.
Which of the following is true regarding the interpretation of a urine culture performed on urine from a school-age child?

(A) The bladder is normally sterile. Any bacteria grown from a bladder puncture or uretheral catheterization is diagnostic of a UTI

(B) Recovery of several species from a clean catch urine is suggestive of a renal abscess

(C) Growth of more than 100,000 bacteria per milliliter of “clean-catch” urine is predictive of bacteria in the bladder

(D) A and C

(E) All of the above

15.
Which of the following are risk factors for UTI among adolescents?

(A) ingestion of chocolate

(B) infectious mononucleosis

(C) ingestion of bladder irritants like spicy foods

(D) use of a diaphragm with a spermicide

(E) all of the above

ANSWERS

1.
(D)
Neonates who are septic will most often be afebrile. A physician who waits for fever before initiating a septic workup and treatment has often waited too long. A urine culture (along with blood and cerebrospinal fluid [CSF] culture) should be part of the evaluation for sepsis in this age group. Meningitis can occur in the absence of bacteremia that may have been cleared by the host without therapy. Although girls of nearly every age group have UTIs at a higher frequency than boys, the singular exception is the neonate where the gender prevalence is roughly equal. The blood leukocyte count in a septic neonate may occasionally be abnormally high or low and may provide a clue as to the presence of a septic process. Most often, however, it is normal.

2.
(B)
Urine obtained in a sterile plastic bag is often contaminated with minute amounts of stool even after attempted cleaning. Because there are large amounts of bacteria in stool, it takes only minuscule contamination of the bagged specimen to yield a “positive” culture result. Any positive culture from this bag must be confirmed by obtaining a specimen of bladder urine before a diagnosis of UTI can be made. The best specimens are those obtained by bladder puncture or catheterization. Bladder urine should be sterile (see answer 14 for more details).

3.
(A)
The frequency of anatomic abnormalities of the urinary tract that may require urologic intervention or long-term antimicrobial prophylaxis is sufficiently high to warrant radiologic assessment after even the first well-documented UTI; in the neonatal period, a renal and bladder ultrasound (US) plus VCUG are obtained. Oral antimicrobial therapy in the neonatal period is generally avoided because of the few data available regarding absorption or outcomes. Sulfonamides may promote hyperbilirubinemia and are also to be avoided in this age group. The less invasive ultrasound has replaced IVP for evaluation of the upper urinary tract but offers no genderspecific advantage.